Yoga and other holistic practices improve blood sugar control in diabetics

Yoga and other holistic practices improve blood sugar control in diabetics

Only 51% of patients with type 2 diabetes succeed in properly controlling their blood sugar, i.e., reaching the therapeutic target of <7% glycated hemoglobin (HbA1c). The quantification of glycated hemoglobin is a reflection of long-term blood glucose (about 2–3 months), unlike fasting blood glucose, which is a snapshot of the glycemic state. Thus, the higher the blood sugar level over a prolonged period in an individual, the higher the proportion of glycated hemoglobin (containing a sugar) will be. The normal HbA1c value is between 3.5% and 6%.

Why do half of patients with type 2 diabetes fail to control their blood sugar, despite the wide variety of medications available to manage high blood sugar? Several factors contribute to this inadequate glycemic control, including polypharmacy (use of multiple drugs), socio-economic status, psychiatric disorders, and health disparities.

One way to improve blood sugar control by people with diabetes is through holistic activity (involving the body and the mind), such as yoga, qigong, guided imagery, mindfulness-based stress reduction (MBSR), and other forms of meditation. Researchers recently conducted a systematic review and meta-analysis of studies on the effect of holistic interventions on glycemic control in diabetics. The results of the meta-analysis, which included 28 intervention studies published between 1993 and 2022, indicate that, overall, holistic practices significantly lower the level of glycated hemoglobin or HbAc1 by 0.84%. Reductions in HbAc1 (and therefore better glycemic control) were observed for all types of intervention: MBSR: -0.48%; qigong: -0.66%; and yoga: -1.00%. The duration of yoga sessions did not have a significant effect on the HbAc1 level, but the frequency did: for each additional day with a yoga session, the HbAc1 level decreased by an average of 0.22%. Fasting blood glucose was also significantly improved following the holistic practices, with an average decrease of 22.81 mg/dL.

These reductions in glycated hemoglobin and fasting blood glucose levels are clinically significant, suggesting that mind-body practices may be effective complementary non-pharmacological interventions for people with diabetes.

Harmful health effects of exposure to “Forever Chemicals”

Harmful health effects of exposure to “Forever Chemicals”

OVERVIEW

  • Per- and polyfluoroalkyl substances (PFAS) are added to a variety of products (e.g., cosmetics, food packaging, non-adhesive cookware) to make them resistant to heat, water, oil and corrosion.
  • These “Forever Chemicals” are found in tap water, bottled water and in the blood of almost everyone in the West.
  • The presence of PFAS in the blood has been associated with higher risks of developing hypertension and type 2 diabetes in women.
  • PFAS are possibly associated with several health problems, including preeclampsia, impaired liver enzymes, increased blood lipids, decreased response to vaccines, and low birth weight.

Per- and polyfluoroalkyl substances (PFAS) are widely used in industrial and everyday consumer products, such as cosmetics, food packaging, non-adhesive cookware and floor coverings. PFAS contain extremely stable chemical bonds between fluorine and carbon atoms (F–C bonds), hence their pun-like nickname “Forever Chemicals” (see Figure 1). PFAS should not be confused with phthalates, another class of industrial products potentially harmful to health (see our article on the subject). It should be noted that another class of “Forever Chemicals” related to PFAS, hydrofluorocarbons or HFCs, are used to replace CFCs in refrigerants since they do not affect the ozone layer, but they are now being gradually withdrawn from the market since they are still greenhouse gases.

Figure 1. Structure of 3 per- and polyfluoroalkylated substances (PFAS) used in everyday consumer products.

PFAS are added to a host of products to make them resistant to heat, water, oil and corrosion. For example, the wrappers in which burgers, pizzas, salads, and other take-out food are wrapped contain PFAS, which helps prevent oil or dressing leaks. PFAS can migrate into food, especially when it contains a lot of fat and salts. In addition, the packaging is ultimately buried in landfills where there is the possibility of contaminating the soil and groundwater or, if they are incinerated, they can end up in the air. Consumer Reports tested more than 100 packaging products used in US restaurants and supermarkets and found PFAS in several products such as wrapping paper for french fries, hamburgers, disposable plates, and moulded fibre salad bowls. Further testing by Consumer Reports found that PFAS are present in tap water and bottled water in the United States. PFAS were detected in the blood of 98% of Americans tested.

During the first 60 years of PFAS production, many believed that the potential adverse effects only affected workers exposed to these products at an industrial level and not the general population. That was until in 1998 a farmer in Virginia in the United States started sounding the alarm about the effects of pollution produced by a DuPont factory on the health of his cows. Perfluorooctanoic acid (PFOA, also known as “C8”) may have affected approximately 70,000 people who got their water from the same contaminated source, according to the ensuing class action lawsuit in US courts. A committee set up to examine the dangerousness of PFOA subsequently established probable links between exposure to this product and several diseases, including thyroid disease, hypercholesterolemia, kidney and testicular cancer, pregnancy-induced hypertension, and ulcerative colitis.

Three PFAS (PFOS, PFOA and LC-PFCAs) are now banned in Canada because of the risk they pose to human health and the environment. It appears that the new PFAS that are being used today as replacements for the banned PFAS could also be harmful to human health and the environment. Therefore, the Government of Canada is considering regulating the use of all PFAS. PFAS are associated with several health problems, including preeclampsia, impaired liver enzymes, increased blood lipids, decreased response to vaccines, and low birth weight (see profile report of PFAS by the US Agency for Toxic Substances and Disease Registry).

Cosmetics
PFAS have been found in the ingredient list of several dozen cosmetic products sold in Europe and Asia, where they are added to make foundations, mascaras and liquid lipsticks more durable, waterproof and easier to spread. In a recent study, where more than 231 North American cosmetic products (including 21 from Canada) were analyzed, 52 products had a high fluorine content, indicating the presence of PFAS in high concentration. The presence of PFAS was confirmed in 29 products by mass spectrometry. Most of these cosmetic products, however, did not mention PFAS in the list of ingredients on the label. PFAS have been found particularly in products advertised as “long-lasting” or “wear-resistant”. Specifically, high levels of fluorine (from PFAS) were detected in 82% of water-resistant mascaras, 58% of other eye cosmetics (eye shadows and creams, eyeliner), 63% of foundations, and 62% of lipsticks. Among the 17 Canadian cosmetic products considered in the study, only one indicated the presence of PFAS in the list of ingredients.

Why are PFAS found in cosmetic products when they are not included in the list of ingredients? Some basic ingredients such as mica and talc can be treated with PFAS to improve their durability. Other ingredients such as acrylates, methicone, and other silicone polymers can be purchased in a form containing PFAS. It therefore seems that some cosmetic manufacturers use ingredients containing PFAS, yet don’t include them in the list of ingredients. It is best to avoid as much as possible using cosmetic products containing PFAS as they can be harmful to health and the probability of absorption through the skin is very high. The results of the study show that there are cosmetic products containing very little or no fluoride (and therefore PFAS), but they are difficult to identify since PFAS are not included in the ingredient lists of most cosmetic products. It is recommended to avoid using products advertised as “water-resistant”, “long-lasting” or “wear-resistant” which are likely to contain PFAS.

Hypertension
A prospective study found an unfavourable association between blood PFAS concentration and the risk of hypertension. The data comes from the Study of Women’s Health Across the Nation-Multi-Pollutant Study (SWAN-MPS) with 1058 middle-aged, normotensive women at baseline, who were followed from 1999 to 2017. During these years, 470 women became hypertensive (systolic pressure ≥140 mmHg or diastolic pressure ≥90 mmHg). Women who had the highest concentrations of PFOS, PFOA and EtFOSAA (a precursor to PFOS) in their blood had 42%, 47% and 42% higher risks, respectively, of developing hypertension compared to those who had the lowest concentrations of these PFAS. Women who had the highest concentrations of total PFAS had a 71% higher risk of developing hypertension. No significant association was observed for the following PFAS: perfluorononanoic acid (PFNA) and perfluorohexanesulfonic acid (PFHxS).

Type 2 diabetes
The same research group that conducted the study on the association between PFAS and the risk of hypertension also evaluated the association with the incidence of type 2 diabetes. The prospective study was conducted among 1237 women in the SWAN-MPS cohort who were 45-56 years old and nondiabetic at the start of the study (1999). During the study period (18 years), 102 women became diabetic. The latter had higher blood concentrations of PFAS than the non-diabetic women. Women who had high levels of PFAS in their blood were more likely to be black, to smoke or have smoked cigarettes, to be menopausal, or to have a higher body mass index (BMI). However, the data were adjusted to take into account several confounding factors, including race/ethnicity, place of residence, level of education, smoking, alcohol consumption, total energy intake, physical activity, menopause, and BMI.

Women who had the highest concentrations of n-PFOA, PFHxS, sm-PFOS and MeFOSAA in the blood had 67%, 58%, 36% and 85% higher risks, respectively, of developing type 2 diabetes compared to those with the lowest concentrations of these PFAS. Women who had the highest concentrations of four common PFAS (n-PFOA, PFNA, PFHxS and total PFOS) had a 64% higher risk of developing type 2 diabetes.

How to reduce exposure to PFAS?
PFAS have many important applications and eliminating them completely seems out of the question. The most problematic PFAS (PFOA, PFOS and LC-PFCAs) are no longer used in Canada. PFOA was used, among other things, for the manufacture of kitchen accessories with Teflon coating. The major problem with accessories containing Teflon is not that they release PFOA during use (very low level), but that their manufacture can release this “Forever Chemical” into the environment. Ceramic coatings and anodized aluminum are good alternatives. If the demand for kitchen accessories containing PFAS decreases, production will decrease and less of these substances will end up in the environment. Fast food wrapped in waterproof packaging or containers, cosmetics and body care products that contain PFAS should be avoided as much as possible, especially “water-resistant” or “wear-resistant” cosmetics. These are simple actions that can reduce exposure to these products that are potentially harmful to health.

The cardiovascular benefits of avocado

The cardiovascular benefits of avocado

OVERVIEW

  • Avocado is an exceptional source of monounsaturated fat, with content similar to that of olive oil.
  • These monounsaturated fats improve the lipid profile, in particular by raising HDL-cholesterol levels, a phenomenon associated with a reduced risk of cardiovascular disease.
  • A recent study confirms this cardioprotective potential of avocado, with a 20% reduction in the risk of coronary heart disease observed in regular consumers (2 or more servings per week).

There is currently a consensus in the scientific community on the importance of favouring dietary sources of unsaturated fats (especially monounsaturated and omega-3 polyunsaturated fats) to significantly reduce the risk of cardiovascular disease and premature mortality (see our article on this subject). With the exception of fatty fish rich in omega-3 (salmon, sardines, mackerel), plant-based foods are the main sources of these unsaturated fats, particularly oils (olive oil and those rich in omega-3 like canola oil), nuts, certain seeds (flax, chia, hemp) as well as fruits such as avocado. Regular consumption of these foods high in unsaturated fats has repeatedly been associated with a marked decrease in the risk of cardiovascular events, a cardioprotective effect that is particularly well documented for extra-virgin olive oil and nuts.

A unique nutritional profile
Although the impact of avocado consumption has been less studied than that of other plant sources of unsaturated fat, it has been suspected for several years that this fruit also exerts positive effects on cardiovascular health. On the one hand, avocado stands out from other fruits for its exceptionally high monounsaturated fat content, with a content (per serving) similar to that of olive oil (Table 1). On the other hand, a serving of avocado contains very high amounts of fibre (4 g), potassium (350 mg), folate (60 µg), and several other vitamins and minerals known to participate in the prevention of cardiovascular disease.

Table 1. Comparison of the lipid profile of avocado and olive oil. The data corresponds to the amount of fatty acids contained in half of a Haas avocado, the main variety consumed in the world, or olive oil (1 tablespoon or 15 mL). Taken from USDA. FoodData Central.

Fatty acidsAvocado (68 g)Olive oil (15 mL)
Total10 g12.7 g
Monounsaturated6.7 g9.4 g
Polyunsaturated1.2 g1.2 g
Saturated1.4 g2.1 g

This positive impact on the heart is also suggested by the results of intervention studies that examined the impact of avocado on certain markers of good cardiovascular health. For example, a meta-analysis of 7 studies (202 participants) indicates that the consumption of avocado is associated with an increase in HDL cholesterol and a decrease in the ratio of total cholesterol to HDL cholesterol, a parameter which is considered to be a good predictor of coronary heart disease mortality. A decrease in triglycerides, total cholesterol and LDL cholesterol levels associated with the consumption of avocado has also been reported, but is, however, not observed in all studies. Nevertheless, the increase in HDL cholesterol observed in all the studies is very encouraging and strongly suggests that avocado could contribute to the prevention of cardiovascular disease.

A cardioprotective fruit
This cardioprotective potential of avocado has just been confirmed by the results of a large-scale epidemiological studycarried out among people enrolled in two large cohorts headed by Harvard University, namely the Nurses’ Health Study (68,786 women) and the Health Professionals Follow-up Study (41,701 men). Over a period of 30 years, researchers periodically collected information on the dietary habits of participants in both studies and subsequently examined the association between avocado consumption and the risk of cardiovascular disease.

The results obtained are very interesting: compared to people who never or very rarely eat them, regular avocado consumers have a risk of coronary heart disease reduced by 16% (1 serving per week) and 21% (2 servings or more per week) (Figure 1).

Figure 1. Association between the frequency of avocado consumption and the risk of coronary heart disease. The quantities indicated refer to one serving of avocado, corresponding to approximately half of the fruit. Taken from Pacheco et al. (2022).

There are therefore only benefits to integrating avocado into our eating habits, especially if its monounsaturated fats replace other sources of fats that are less beneficial to health. According to the researchers’ calculations, replacing half a serving of foods rich in saturated fat (butter, cheese, deli meats) with an equivalent quantity of avocado would reduce the risk of cardiovascular disease by approximately 20%.

Avocados are increasingly popular, especially among young people, and are even predicted to become the 2nd most traded tropical fruit by 2030 globally, just behind bananas. In light of the positive effects of these fruits on cardiovascular health, we can only welcome this new trend.

Obviously, the high demand for avocado creates strong pressures on the fruit’s production systems, particularly in terms of deforestation for the establishment of new crops and increased demand for water. However, it is important to note that the water footprint (the amount of water required for production) of avocado is much lower than that of all animal products, especially beef (Table 2). In addition, as is the case for all plants, the carbon footprint of avocado is also much lower than that of animal products, the production of an avocado generating approximately 0.2 kg of CO2-eq compared to 4 kg for beef.

Table 2. Comparison of the water footprint of avocado and different foods of animal origin. Taken from UNESCO-IHE Institute for Water Education (2010) 

FoodWater footprint
(m3/ton)
Beef15,400
Lamb and sheep10,400
Porc6,000
Chicken4,300
Eggs3,300
Avocado1,981

Childhood obesity, a ticking time bomb for cardiometabolic diseases

Childhood obesity, a ticking time bomb for cardiometabolic diseases

OVERVIEW

  • Obesity rates among Canadian children and teens have more than tripled over the past 40 years.
  • Childhood obesity is associated with a marked increase in the risk of type 2 diabetes and cardiovascular disease in adulthood, which can significantly reduce healthy life expectancy.
  • Policies to improve the diet of young people are key to reversing this trend and preventing an epidemic ofcardiometabolic diseases affecting young adults in the coming years.

One of the most dramatic changes to have occurred in recent years is undoubtedly the marked increase in the number of overweight children. For example, obesity rates among Canadian children and adolescents have more than tripled over the past 40 years. Whereas in 1975, obesity was a fairly rare problem affecting less than 3% of children aged 5–19, the prevalence of obesity has made a gigantic leap since that time, affecting nearly 14% of boys and 10% of girls in 2016 (Figure 1). If data on overweight is added to these figures, then approximately 25% of young Canadians are overweight (a similar trend is observed in Quebec). This prevalence of obesity appears to have plateaued in recent years, but recent US surveys suggest that the COVID-19 pandemic may have caused an upsurge in the number of overweight young people, particularly among 5-11-year-olds.

Figure 1. Increase in the prevalence of obesity among Canadian children over the past 40 years. From NCD Risk Factor Collaboration (2017).

Measuring childhood obesity
Although not perfect, the most common measure used to determine the presence of overweight in young people under the age of 19 is the body mass index (BMI), calculated by dividing the weight by the square of height (kg/m²). However, the values obtained must be adjusted according to age and sex to take into account changes in body composition during growth, as shown in Figure 2.

Figure 2. WHO growth standards for boys aged 5–19 living in Canada. Data comes from WHO (2007).

Note that a wide range of BMI on either side of the median (50th percentile) is considered normal. Overweight children have a BMI higher than that of 85–95% of the population of the same age (85th-95th percentile), while the BMI of obese children is higher than that of 97% of the population of the same age (97th percentile and above). Using z-scores is another way to visualize childhood overweight and obesity. This measurement expresses the deviation of the BMI from the mean value, in standard deviation. For example, a z-score of 1 means that the BMI is one standard deviation above normal (corresponding to overweight), while z-scores of 2 and 3 indicate, respectively, the presence of obesity and severe obesity.

This marked increase in the proportion of overweight children, and particularly obese children, is a worrying trend that bodes very badly for the health of future generations of adults. On the one hand, it is well established that obesity during childhood (and especially during adolescence) represents a very high risk factor for obesity in adulthood, with more than 80% of obese adults who were already obese during their childhood. This obesity in adulthood is associated with an increased risk of a host of health problems, both from a cardiovascular point of view (hypertension, dyslipidemia, ischemic diseases) and the development of metabolic abnormalities (hyperglycemia, resistance to insulin, type 2 diabetes) and certain types of cancer. Obesity can also cause discrimination and social stigma and therefore have devastating consequences on the quality of life, both physically and mentally.

Another very damaging aspect of childhood obesity, which is rarely mentioned, is the dramatic acceleration of the development of all the diseases associated with overweight. In other words, obese children are not only at higher risk of suffering from the various pathologies caused by obesity in adulthood, but these diseases can also affect them at an early age, sometimes even before reaching adulthood, and thus considerably reduce their healthy life expectancy. These early impacts of childhood obesity on the development of diseases associated with overweight are well illustrated by the results of several recent studies on type 2 diabetes and cardiovascular disease.

Early diabetes
Traditionally, type 2 diabetes was an extremely rare disease among young people (it was even called “adult diabetes” at one time), but its incidence has increased dramatically with the rise in the proportion of obese young people. For example, recent US statistics show that the prevalence of type 2 diabetes in children aged 10–19 has increased from 0.34 per 1000 children in 2001 to 0.67 in 2017, an increase of almost 100% since the beginning of the millennium.

The main risk factors for early diabetes are obesity, especially severe obesity (BMI greater than 35) or when the excess fat is mainly located in the abdomen, a family history of the disease, and belonging to certain ethnic groups. However, obesity remains the main risk factor for type 2 diabetes: in obese children (4–10 years) and adolescents (11–18 years), glucose intolerance is frequently observed during induced hyperglycemia tests, a phenomenon caused by the early development of insulin resistance. A characteristic of type 2 diabetes in young people is its rapid development. Whereas in adults, the transition from a prediabetic state to clearly defined diabetes is generally a gradual process, occurring over a period of 5–10 years, this transition can occur very quickly in young people, in less than 2 years. This means that the disease is much more aggressive in young people than in older people and can cause the early onset of various complications, particularly at the cardiovascular level.

A recent study, published in the prestigious New England Journal of Medicine, clearly illustrates the dangers that arise from early-onset type 2 diabetes, appearing during childhood or adolescence. In this study, the researchers recruited extremely obese children (BMI ≥ 35) who had been diagnosed with type 2 diabetes in adolescence and subsequently examined for ten years the evolution of different risk factors and pathologies associated with this disease.

The results are very worrying, because the vast majority of patients in the study developed one or more complications during follow-up that significantly increased their risk of developing serious health problems (Figure 3). Of particular note is the high incidence of hypertension, dyslipidemia (LDL-cholesterol and triglyceride levels too high), and kidney (nephropathies) and nerve damage (neuropathies) in this population, which, it should be remembered, is only 26 years on average. Worse still, almost a third of these young adults had 2 or more complications, which obviously increases the risk of deterioration of their health even more. Moreover, it should be noted that 17 serious cardiovascular accidents (infarction, heart failure, stroke) occurred during the follow-up period, which is abnormally high given the young age of the patients and the relatively small number of people who participated in the study (500 patients).

Figure 3. Incidence of different complications associated with type 2 diabetes in adolescents. From TODAY Study Group (2021).

It should also be noted that these complications occurred despite the fact that the majority of these patients were treated with antidiabetic drugs such as metformin or insulin. This is consistent with several studies showing that type 2 diabetes is much harder to control in young people than in middle-aged people. The mechanisms responsible for this difference are still poorly understood, but it seems that the development of insulin resistance and the deterioration of the pancreatic cells that produce this hormone progress much faster in young people than in older people, which complicates blood sugar control and increases the risk of complications.

This difficulty in effectively treating early type 2 diabetes means that young diabetics are much more at risk of dying prematurely than non-diabetics (Figure 4). For example, young people who develop early diabetes, before the age of 30, have a mortality rate 3 times higher than the population of the same age who is not diabetic. This increase remains significant, although less pronounced, until about age 50, while cases of diabetes that appear at older ages (60 years and over) do not have a major impact on mortality compared to the general population. It should be noted that this increase in mortality affecting the youngest diabetics is particularly pronounced at a young age, around 40 years of age.

These results therefore show how early type 2 diabetes can lead to a rapid deterioration in health and take decades off life, including years that are often considered the most productive of life (forties and fifties). For all these reasons, type 2 diabetes must be considered one of the main collateral damages of childhood obesity.

Figure 4. Age-standardized mortality rates for diagnosis of type 2 diabetes. Standardized mortality rates represent the ratio of mortality observed in individuals with diabetes to anticipated mortality for each age group. From Al-Saeed et al. (2016).

Cardiovascular disease
In recent years, there has been an upsurge in the incidence of cardiovascular disease in young adults. This new trend is surprising given that mortality from cardiovascular diseases has been in constant decline for several years in the general population (thanks in particular to a reduction in the number of smokers and improved treatments), and one might have expected that young people would also benefit from these positive developments.

The data collected so far strongly suggests that the increase in the prevalence of obesity among young people contributes to this upsurge of premature cardiovascular diseases, before the age of 55. On the one hand, it has been shown that a genetic predisposition to develop overweight during childhood is associated with an increased risk of coronary heart disease (and type 2 diabetes) in adulthood. On the other hand, this increased risk has also been observed in long-term studies examining the association between the weight of individuals during childhood and the incidence of cardiovascular events once they have reached adulthood. For example, a large Danish study of over 275,000 school-aged children (7–13 years old) showed that each one-unit increase in BMI z-score at these ages (see legend to Figure 2 for the definition of the z-score) was associated with an increased risk of cardiovascular disease in adulthood, after 25 years (Figure 5).

This increased risk is directly proportional to the age at which children are overweight, i.e., the more a high BMI is present at older ages, the greater the risk of suffering a cardiovascular event later in adulthood. For example, an increase of 1 in the z -score of 13-year-old children is associated with twice as much of an increase in risk in adulthood as a similar increase in a 7-year-old child (Figure 5). Similar results are observed for girls, but the increased risk of cardiovascular disease is lower than for boys.


Figure 5. Relationship between body mass index in childhood and the risk of cardiovascular disease in adulthood. The values represent the risks associated with a 1-unit increase in BMI z-score at each age. From Baker et al. (2007).

Early atherosclerosis
Several studies suggest that the increased risk of cardiovascular disease in adulthood observed in overweight children is a consequence of the early development of several risk factors that accelerate the process of atherosclerosis. Autopsy studies of obese adolescents who died of non-cardiovascular causes (e.g., accidents) revealed that fibrous atherosclerotic plaques were already present in the aorta and coronary arteries, indicating an abnormally rapid progression of atherosclerosis.

As mentioned earlier, type 2 diabetes is certainly the worst risk factor that can generate this premature progression, because the vast majority of diabetic children and adolescents very quickly develop several abnormalities that considerably increase the risk of serious damage to blood vessels (Figure 3). But even without the presence of early diabetes, studies show that several risk factors for cardiovascular disease are already present in overweight children, such as hypertension, dyslipidemia, chronic inflammation, glucose intolerance or even vascular abnormalities (thickening of the internal wall of the carotid artery, for example). Exposure to these factors that begins in childhood therefore creates favourable conditions for the premature development of atherosclerosis, thereby increasing the risk of cardiovascular events in adulthood.

It should be noted, however, that the negative impact of childhood obesity on health in adulthood is not irreversible. Indeed, studies show that people who were overweight or obese during childhood, but who had a normal weight in adulthood, have a risk of cardiovascular disease similar to that of people who have been thin all their lives. However, obesity is extremely difficult to treat, both in childhood and in adulthood, and the best way to avoid prolonged chronic exposure to excess fat and damage to cardiovascular health (and health in general) which results from it is obviously to prevent the problem at the source by modifying lifestyle factors, which are closely associated with an increased risk of developing overweight, in particular the nature of the diet and physical activity (psychosocial stress may also play a role). Given the catastrophic effects of childhood obesity on health, cardiovascular health in particular, the potential for this early preventive approach (called “primordial prevention”) is immense and could help halt the current rise in diabetes and premature mortality affecting young adults.

Ideal cardiovascular health
A recent study shows how this primordial prevention approach can have an extraordinary impact on cardiovascular health. In this study, researchers determined the ideal cardiovascular health score, as defined by the American Heart Association (Table 1), of more than 3 million South Koreans with an average age of 20–39 years. Excess weight is a very important element of this score because of its influence on other risk factors also used in the score such as hypertension, fasting hyperglycemia and cholesterol.

Participants were followed for a period of approximately 16 years, and the incidence of premature cardiovascular disease (before age 55) was assessed using as the primary endpoint a combination of hospitalization for infarction, stroke, cardiac insufficiency, or sudden cardiac death.

Table 1. Parameters used to define the ideal cardiovascular health score. Since there is 1 point for each target reached, a score of 6 reflects optimal cardiovascular health. Adapted from Lloyd-Jones et al. (2010), excluding dietary factors that were not assessed in the Korean study.

As shown in Figure 6, cardiovascular health in early adulthood has a decisive influence on the risk of cardiovascular events that occur prematurely, before the age of 55. Compared to participants in very poor cardiovascular health at the start (score of 0), each additional target reached reduces the risk of cardiovascular events, with maximum protection of approximately 85% in people whose lifestyle allows achieving 5 or more ideal heart health targets (scores of 5 and 6). Similar results were obtained in the United States and show how early health, from childhood through young adulthood, plays a key role in preventing the development of cardiovascular disease during aging.

Figure 6. Influence of cardiovascular health in young adults on the risk of premature cardiovascular events. From Lee et al. (2021).

Yet our society remains strangely passive in the face of the rise in childhood obesity, as if the increase in body weight of children and adolescents has become the norm and that nothing can be done to reverse this trend. This lack of interest is really difficult to understand, because the current situation is a ticking time bomb that risks causing a tsunami of premature chronic diseases in the near future, affecting young adults. This is an extremely worrying scenario if we consider that our healthcare system, in addition to having to contend with diseases that affect an aging population (1 out of 4 Quebecers will be over 65 in 2030), will also have to deal with younger patients suffering from cardiometabolic diseases caused by overweight. Needless to say, this will be a significant burden on healthcare systems.

This situation is not inevitable, however, as governments have concrete legislative means that can be used to try to reverse this trend. Several policies aimed at improving diet quality to prevent disease can be quickly implemented:

  • Taxing sugary drinks. A simple and straightforward approach that has been adopted by several countries is to introduce a tax on industrial food products, especially soft drinks. The principle is the same as for all taxes affecting other products harmful to health such as alcohol and tobacco, i.e., an increase in prices is generally associated with a reduction in consumption. Studies that have examined the impact of this approach for soft drinks indicate that this is indeed the case, with reductions in consumption observed (among others) in Mexico, Berkeley (California) and Barbados. This approach therefore represents a promising tool, especially if the amounts collected are reinvested in order to improve the diet of the population (subsidies for the purchase of fruit and vegetables, for example).
  • Requiring clear nutrition labels on packaging. We can help consumers make informed choices by clearly indicating on the front of the product whether it is high in sugar, fat or salt, as is the case in Chile (see our article on this subject).
  • Eliminating the marketing of unhealthy foods for children. The example of Chile also shows that severe restrictions can be imposed on the marketing of junk food products by prohibiting the advertising of these products in programs or websites aimed at young people as well as by prohibiting their sale in schools. The United Kingdom plans to take such an approach very soon by eliminating all advertising online and on television of products high in sugar, salt and fat before 9 p.m., while Mexico has gone even further by banning all sales of junk food products to children.

There is no reason Canada should not adopt such approaches to protect the health of young people.

Cycling: A particularly beneficial exercise for the health of diabetics

Cycling: A particularly beneficial exercise for the health of diabetics

OVERVIEW

  • Exercise and physical activity bring many benefits for people with type 2 diabetes.
  • Among a large cohort of 110,944 people from 10 European countries, 7,459 people had type 2 diabetes, 37% of whom were cyclists.
  • After a 5-year follow-up, the researchers found that fewer premature deaths and deaths from cardiovascular disease occurred proportionately among cyclists than among non-cyclists.
  • Participants who started cycling after the start of the study also saw their risk of death significantly reduced, showing that it is never too late to get on that bike and reap the health benefits.

Diabetes increases the risk of developing cardiovascular disease and of dying prematurely from cardiovascular causes and from any cause. Regular physical activity and exercise reduce risk factors for cardiovascular disease in people with diabetes.

Benefits of aerobic exercise
In diabetics, aerobic training (brisk walking, running, cycling, etc.) increases insulin sensitivity, mitochondrial density (production of energy in cells), vascular reactivity, immune and pulmonary functions, and cardiac output. In addition, regular training lowers the level of glycated hemoglobin and triglycerides in the blood as well as blood pressure.

Benefits of resistance exercise
Diabetes is a risk factor for having poor muscle tone, and it can lead to a faster decline in muscle strength and function. A few mechanisms have been proposed to explain this phenomenon in diabetics, including: 1) endothelial dysfunction secondary to high blood glucose levels which cause vasoconstriction of the vessels that nourish muscles and 2) disruption of skeletal muscle energy metabolism through a dysfunction of the mitochondria (elements of the cell that produces its energy).

Benefits of resistance training (weightlifting, use of a resistance band, etc.) in the general population include improvements in muscle mass and strength, fitness, bone mineral density, insulin sensitivity, blood pressure, lipid profile, and cardiovascular health. For diabetics (type 2), resistance training improves blood sugar control, insulin resistance, blood pressure, muscle strength, lean body mass vs. fat mass.

Benefits of other types of exercise
People with diabetes are particularly affected by the loss of joint mobility, a condition caused in part by the build-up of end products of glycation that occurs during normal aging, but is accelerated by hyperglycemia. People with diabetes can therefore benefit from stretching exercises that allow them to increase the flexibility and mobility of their joints.

Cycling and mortality risk in diabetics
Is there one physical activity that is more beneficial than others to improve the health of people with diabetes and reduce the risk of premature death? A prospective study of 7,459 adults with diabetes, with an average age of 55.9 years, assessed whether there is an association between time spent cycling and cardiovascular mortality or from any cause. Participants, who had been diabetic for an average of 7.7 years at the start of the study, completed detailed questionnaires upon enrollment and 5 years later. Compared with participants who did not cycle at all (0 minutes/week), those who did had a lower risk of death from any cause, from 22% (1 to 59 min/week) to 32% (150 to 299 min/week). Reductions of the same order of magnitude (21 to 43%) were observed for cardiovascular mortality. These reductions in mortality risk were independent of other physical activities reported by participants and other confounding factors (level of education, smoking, adherence to the Mediterranean diet, total energy intake, occupational physical activity).

Another question the study researchers wanted to answer was whether stopping or starting to cycle during the 5-year follow-up had an effect on the risk of death of participants with diabetes. The results indicate that participants who cycled after the start of the study had a significantly lower risk of cardiovascular and all-cause mortality compared to non-cyclists. Participants who instead stopped cycling after starting the study had a similar risk of premature death to that of non-cyclists. It is therefore never too late to start cycling and reap significant health benefits, provided that this exercise is practised regularly, without interruption.

Other researchers found it surprising that the association between cycling and a reduction in the risk of mortality is independent of other physical activities. They point out that there is a relationship between the amount of physical activity and the reduction in mortality (4% reduction in risk per 15 minutes of additional physical activity per day) for healthy people and those with cardiovascular disease according to published data. They questioned whether a bias comparable to that of the “healthy worker effect” is not at issue here. This bias could be caused in this case by the fact that diabetics who cycle are healthier than those who do not, resulting in lower premature mortality. In their response to this criticism, the study authors say they agree that cyclists might be healthier than non-cyclists, but they say they did all they could to minimize this potential bias by adjusting the results to take into account risk factors for premature mortality, including diet, physical activity other than cycling, incidence of myocardial infarction and cancer, and excluding smokers, former smokers and individuals who play sports. The authors conclude that they are convinced that cycling can directly contribute to reducing premature mortality, but that in this type of study it is always possible that there are known or unknown confounding factors.

An earlier study had previously reported that cycling had advantages over other physical activities. This study was carried out about 20 years ago with 30,640 participants in the Copenhagen region of Denmark. In the 14.5 years of follow-up, people who cycled to work had a 40% lower risk of dying prematurely than non-cyclist participants, after accounting for possible confounding factors, including the amount of physical activity during leisure time.

Cycling requires being fit, having a good sense of balance, and having the financial means to buy a bicycle. In addition, cycling must be done in a safe environment, which is increasingly possible with the addition of cycle paths in recent years. In Quebec, cycling cannot be practised safely during the winter, namely for more than 4 months, but it is fortunately possible to ride a stationary bike at home or in training centres. In recent years, there has been real enthusiasm for cycling, including the electric bicycle, which allows older or less fit people to climb slopes without much effort. Let’s hope that this enthusiasm continues so that more people who are healthy or have a chronic illness can benefit from the health benefits of this extraordinary physical activity.

The benefits of extra virgin olive oil on cardiovascular health

The benefits of extra virgin olive oil on cardiovascular health

OVERVIEW

  • In addition to being an excellent source of monounsaturated fat, olive oil is the only vegetable oil that contains a significant amount of phenolic compounds with antioxidant and anti-inflammatory properties.
  • These molecules are found in much larger quantities in extra virgin quality oils compared to refined olive oils.
  • Several studies indicate that the presence of these phenolic compounds contributes to the many positive effects of extra virgin olive oil on cardiovascular health.

The traditional Mediterranean diet has several positive effects on cardiovascular health by improving the lipid profile (cholesterol, triglycerides) and by reducing chronic inflammation, blood pressure, blood sugar and the risk of diabetes. Several studies have clearly established that these effects result in a significant reduction in the risk of cardiovascular disease.

The Mediterranean diet is characterized by the abundant consumption of plant-based foods (fruits, vegetables, whole-grain cereals, legumes, nuts, herbs), a moderate intake of fermented dairy products (yogurt, cheese), fish, seafood and red wine as well as a low consumption of red meat and added sugars. It is therefore an exemplary diet, in which complex plant sugars are the main sources of carbohydrates and where the proteins come mainly from fish and legumes instead of red meat.

Another important feature of the Mediterranean diet is the daily use of large amounts (60–80 mL) of olive oil as the main source of fat for cooking. Several studies have reported that countries that are heavy consumers of olive oil have a much lower incidence of cardiovascular disease than those that consume mainly animal fats, suggesting a positive role of olive oil in this protective effect. Traditionally, these beneficial properties of olive oil have been attributed to its very high content (around 80%) of oleic acid, a monounsaturated fatty acid that contributes to its antioxidant properties. However, and unlike most vegetable oils, olive oil also contains a host of minor compounds (1–3% of the oil) that also play very important roles in its positive effects on cardiovascular health (see below). This is particularly the case for several phenolic compounds found exclusively in olive oil, including phenolic alcohols such as hydroxytyrosol and tyrosol and polyphenols of the secoiridoid family such as oleuropein, ligstroside, oleacein and oleocanthal (Figure 1).

 

Figure 1. Molecular structures of the main phenolic compounds of olive oil.


One fruit, several types of oils
Most vegetable oils come from seeds that have been extracted with an organic solvent (e.g. hexane) and subsequently heated to a high temperature to evaporate this solvent and remove impurities that give them an undesirable smell and flavour. These drastic procedures are not necessary for olive oil as the olives are simply pressed and the oil in the pulp is extracted by mechanical pressure, without using chemical processes or excessive heat.

Olive oils are classified according to the quality of the oil that is obtained by the pressing procedure (Figure 2). Good quality oils, i.e. those with low acidity (<2% free oleic acid) and that meet certain taste, bitterness and spiciness criteria are called “virgin” olive oils or, if their acidity is less than 0.8%, “extra virgin” olive oils. These oils contain the majority of the polyphenols in the starting olives and, after centrifugation and filtration, can be consumed as is.

On the other hand, some olive varieties give an inferior quality oil due to too high acidity (> 2%) and/or an unpleasant smell and taste that does not meet the established criteria. These oils, which are unfit for consumption, are called “lampantes” (a name which comes from their ancient use as fuel in oil lamps) and must be refined as is done for other vegetable oils, i.e. using different physicochemical procedures (neutralization with soda, high temperature bleaching and deodorization, hexane extraction, etc.). These steps remove the compounds responsible for the excess acidity and the unpleasant taste of the oil and produce a “neutral” olive oil that has lost its acidity and its flaws, but that is now devoid of the smell, flavour, colour and most of the phenolic components of the starting virgin olive oil. To stabilize these oils and improve their taste, a certain proportion (15–20%) of virgin olive oil is subsequently added and the final product, which is a mixture of refined olive oil and virgin olive oil, is what is sold in grocery stores as “pure olive oil” or simply “olive oil”.

In short, there are three main types of olive oil on the market: virgin olive oil (VOO), extra virgin olive oil (EVOO), and regular olive oil (OO).

Figure 2. The different types of olive oil. From Gorzynik-Debicka et al. (2018).

 

These manufacturing differences obviously have a huge impact on the amount of polyphenols present in virgin, extra virgin, and refined oils (Table 1). For OO-type olive oils (which contain refined oils), the polyphenols come exclusively from virgin olive oil that has been added to restore a minimum of taste and colour (from yellow to greenish) to the chemically treated oil. The amount of these polyphenols is therefore necessarily less than in VOO and EVOO and, as a general rule, does not exceed 25–30% of the content of these two oils. This difference is particularly striking for certain polyphenols of the secoiridoid family (oleuropein, oleocanthal, oleacein and ligstroside) whose concentrations are 3 to 6 times greater in EVOO than in OO (Table 1). It should be noted, however, that these values ​​can vary greatly depending on the origin and cultivar of the olives; for example, some extra virgin olive oils have been found to contain up to 10 times more hydroxytyrosol and tyrosol than regular olive oils. The same goes for other polyphenols like oleocanthal: an analysis of 175 distinct extra virgin olive oils from Greece and California revealed dramatic variations between the different oils, with concentrations of the molecule ranging from 0 to 355 mg/kg.

It should also be mentioned that even if the quantities of phenolic compounds in regular olive oil are lower than those found in virgin and extra virgin oils, they nevertheless largely exceed those present in other vegetable oils (sunflower, peanut, canola, soy), which contain very little or none at all.

FamilyMoleculesOO (mg/kg)VOO (mg/kg)EVOO (mg/kg)
Secoiridoidsoleocanthal38.95 ± 9.2971.47 ± 61.85142.77 ± 73.17
oleacein57.37 ± 27.0477.83 ± 256.09251.60 ± 263.24
oleuropein (aglycone)10.90 ± 0.0095.00 ± 116.0172.20 ± 64.00
ligstroside (aglycone)15.20 ± 0.0069.00 ± 69.0038.04 ± 17.23
Phenolic alcoholshydroxytyrosol6.77 ± 8.263.53 ± 10.197.72 ± 8.81
tyrosol4.11 ± 2.245.34 ± 6.9811.32 ± 8.53
Flavonoidsluteolin1.17 ± 0.721.29 ± 1.933.60 ± 2.32
apigenin0.30 ± 0.170.97 ± 0.7111.68 ± 12.78
Phenolic acidsp-coumaric -0.24 ± 0.810.92 ± 1.03
ferulic -0.19 ± 0.500.19 ± 0.19
cinnamic - -0.17 ± 0.14
caffeic -0.21 ± 0.630.19 ± 0.45
protocatechuic -1.47 ± 0.56 -
Table 1. Comparison of the content of phenolic compounds in olive oil (OO), virgin olive oil (VOO) and extra virgin olive oil (EVOO). Please note that the large standard deviations of the mean values reflect the huge variations in polyphenol content depending on the region, cultivar, degree of fruit ripeness, and olive oil manufacturing process. Adapted from Lopes de Souza et al. (2017).

 

Anti-inflammatory spiciness
The amounts of polyphenols contained in a bottle of olive oil are not indicated on its label, but it is possible to detect their presence simply by tasting the oil. The polyphenols in olive oil are indeed essential to the organoleptic sensations so characteristic of this oil, in particular the sensation of tickling or stinging in the throat caused by good quality extra virgin oils, what connoisseurs call “ardour”. Far from being a defect, this ardour is considered by experts as a sign of a superior quality oil and, in tasting competitions, the “spiciest” oils are often those that receive the highest honours.

It is interesting to note that it is by tasting different olive oils that a scientist succeeded, by coincidence, in identifying the molecule responsible for the sensation of spiciness caused by extra virgin olive oil (see box).

Plant ibuprofen

Chance often plays a role in scientific discoveries, and this is especially true when it comes to the discovery of the molecule responsible for the typical irritation caused by olive oil. On a trip to Sicily (Italy) to attend a conference on the organoleptic properties of different foods, Dr. Gary Beauchamp and his colleagues were invited by the organizers of the event to a meal where guests were encouraged to taste extra virgin olive oil from olive trees cultivated on their estate. Even though it was the first time he had tasted this type of olive oil, Dr. Beauchamp was immediately struck by the tingling sensation in his throat, which was similar in every way to that caused by ibuprofen, and that he had experienced multiple times as part of his work to replace acetaminophen (paracetamol) with ibuprofen in cough syrups. Suspecting that olive oil contained a similar anti-inflammatory drug, Dr. Beauchamp and his team subsequently managed to isolate the molecule responsible for this irritation, a polyphenol they called “oleocanthal”. They subsequently discovered that oleocanthal had, like ibuprofen, a powerful anti-inflammatory action and that regular consumption of extra virgin olive oil, rich in oleocanthal, provided an intake equivalent to about 10 mg of ibuprofen and therefore may contribute to the well-documented anti-inflammatory effects of the Mediterranean diet. 

But why is the stinging sensation of olive oil only felt in the throat? According to work carried out by the same group, this exclusive localization is due to a specific interaction of oleocanthal (and ibuprofen, for that matter) with a subtype of heat-sensitive receptor (TRPA1). Unlike other types of heat receptors, which are evenly distributed throughout the oral cavity (the TRPV1 receptor activated by the capsaicin of chili peppers, for example, and which causes the burning sensation of some particularly hot dishes), the TRPA1 receptor is located only in the pharynx and its activation by oleocanthal causes a nerve impulse signalling the presence of an irritant only in this region. In short, the more an olive oil stings in the back of the throat, the more oleocanthal it contains and the more anti-inflammatory properties it has. As a general rule, extra virgin olive oils contain more oleocanthal (and polyphenols in general) than virgin olive oils (see Table 1) and are therefore considered superior, both in terms of taste and their positive effects on health.

The superiority of extra virgin olive oil
Several studies have shown that the higher polyphenol content in extra virgin olive oil is correlated with a greater positive effect on several parameters of cardiovascular health than that observed for regular olive oil (see Table 2). For example, epidemiological studies carried out in Spain have reported a decrease of about 10–14% in the risk of cardiovascular disease among regular consumers of extra virgin olive oil, while regular consumption of olive oil had no significant effect. A role of phenolic compounds is also suggested by the EUROLIVE study where the effect of daily ingestion, over a period of 3 weeks, of 25 mL of olive oils containing small (2.7 mg/kg), medium (164 mg/kg), or high (366 mg/kg) amounts of polyphenols was compared. The results show that an increased intake of polyphenols is associated with an improvement in two important risk factors for cardiovascular disease: an increase in the concentration of HDL cholesterol and a decrease in oxidized LDL cholesterol levels. Collectively, the data gathered from the intervention studies indicate that the polyphenols found in extra virgin olive oil play an extremely important role in olive oil’s positive effects on cardiovascular health.

Measured parameterResultsSources
Incidence of cardiovascular disease10% reduction in risk for every 10 g/day of EVOO. No effect of regular OO.Guasch-Ferré et al. (2014)
14% reduction in risk for each 10 g/day of EVOO. No effect of regular OO.Buckland et al. (2012)
Lipid profileLinear increase in HDL cholesterol as a function of the amount of polyphenols.Covas et al. (2006)
Increase in HDL cholesterol only observed with EVOO.Estruch et al. (2006)
Blood glucoseEVOO improves postprandial glycemic profile (decrease in glucose levels and increased insulin).Violo et al. (2015)
Polyphenol-rich EVOO reduces fasting blood glucose and glycated hemoglobin (HbA1c) levels in diabetic patients.Santagelo et al. (2016)
InflammationEVOO, but not OO, induces a decrease in inflammatory markers (TXB(2) and LTB(4)).Bogani et al. (2017)
EVOO, but not OO, induces a decrease in IL-6 and CRP.Fitó et al. (2007)
EVOO, but not OO, decreases the expression of several inflammatory genes.Camargo et al. (2010)
EVOO, but not OO, decreases levels of inflammatory markers sICAM-1 and sVCAM-1.Pacheco et al. (2007)
Oxidative stressStrong in vitro antioxidant activity of phenolic compounds of olive oil.Owen et al. (2000)
Linear decrease in oxidized LDL levels as a function of the amount of polyphenols.Covas et al. (2006)
Lower levels of oxidized LDL after ingestion of EVOO compared to OO.Ramirez-Tortosa et al. (1999)
EVOO phenolic compounds bind to LDL particles and protect them from oxidation.de la Torre-Carbot et al. (2010)
EVOO induces the production of neutralizing antibodies against oxidized LDL.Castañer et al. (2011)
EVOO decreases urinary levels of 8-isoprostane, a marker of oxidative stress.Visioli et al. (2000)
EVOO positively influences the oxidative/antioxidant status of blood plasma.Weinbrenner et al. (2004)
Blood pressureEVOO causes a decrease in systolic and diastolic pressures in hypertensive women.Ruíz-Gutiérrez et al. (1996)
EVOO, but not OO, causes a decrease in systolic pressure in hypertensive coronary patients.Fitó et al. (2005)
EVOO improves postprandial endothelial dilation.Ruano et al. (2005)
EVOO increases the NO vasodilator and decreases systolic and diastolic pressures.Medina-Remón et al. (2015)
EVOO, but not OO, improves vessel dilation in pre-diabetic patients.Njike et al. (2021)
EVOO, but not OO, decreases systolic pressure by 2.5 mmHg in healthy volunteers.Sarapis et al. (2020)
Table 2. Examples of studies comparing the effect of EVOO and OO on several cardiovascular health parameters.

 

In addition to its multiple direct actions on the heart and vessels, it should also be noted that extra virgin olive oil could also exert an indirect beneficial effect, by blocking the formation of the metabolite trimethylamine N-oxide (TMAO) by intestinal bacteria. Several studies have shown that TMAO accelerates the development of atherosclerosis in animal models and is associated with an increased risk of cardiovascular events in clinical studies. Extra virgin olive oils (but not regular olive oils) contain 3,3-dimethyl-1-butanol (DMB), a molecule that blocks a key enzyme involved in TMAO production and prevents development of atherosclerosis in animal models fed a diet rich in animal protein. Taken together, these observations show that there are only advantages to favouring the use of extra virgin olive oil, both for its superior taste and its positive effects on cardiovascular health.

Some people may dislike the slightly peppery taste that extra virgin olive oil leaves in the back of the throat, but interestingly, this irritation is greatly reduced when the oil is mixed with other foods. According to a recent study, this attenuation of the pungent taste is due to the interaction of the polyphenols in the oil with the proteins in food, which blocks the activation of the heat receptors that are normally activated by these polyphenols. People who hesitate to use extra virgin olive oil because of its irritant side can therefore get around this problem and still enjoy the benefits of these oils simply by using it as the main fat when preparing a meal.