The importance of properly controlling your blood pressure

The importance of properly controlling your blood pressure


  • Hypertension is the main risk factor for cardiovascular disease and is responsible for 20% of deaths worldwide.
  • Early hypertension, before the age of 45, is associated with an increased risk of cardiovascular disease, cognitive decline and premature mortality.
  • Adopting an overall healthy lifestyle (normal weight, not smoking, regular physical activity, moderate alcohol consumption, and a good diet including sodium reduction) remains the best way to maintain adequate blood pressure.

According to the latest data from the Global Burden of Disease Study 2019, excessively high blood pressure was responsible for 10.8 million deaths worldwide in 2019, or 19.2% of all deaths recorded. This devastating impact is a direct consequence of the enormous damage caused by hypertension on the cardiovascular system. Indeed, a very large number of studies have clearly shown that excessive blood pressure, above 130/80 mm Hg (see box for a better understanding of blood pressure values), is closely linked to a significant increased risk of coronary heart disease and stroke.


Systolic and diastolic

It is important to remember that blood pressure is always expressed in the form of two values, namely systolic pressure and diastolic pressure. Systolic pressure is the pressure of the blood ejected by the left ventricle during the contraction of the heart (systole), while diastolic pressure is that measured between two beats, during the filling of the heart (diastole). To measure both pressures, the arterial circulation in the arm is completely blocked using an inflatable cuff, then the cuff pressure is allowed to gradually decrease until blood begins to flow back into the artery. This is the systolic pressure. By continuing to decrease the swelling of the cuff, we then arrive at a pressure from which there is no longer any obstacle to the passage of blood in the artery, even when the heart is filling. This is the diastolic pressure. A blood pressure value of 120/80 mm Hg, for example, therefore represents the ratio of systolic (120 mm Hg) and diastolic (80 mm Hg) pressures.

As shown in Figure 1, this risk of dying prematurely from coronary heart disease is moderate up to a systolic pressure of 130 mm Hg or a diastolic pressure of 90 mm Hg, but increases rapidly thereafter to almost 4 times for pressures equal to or greater than 150/98 mm Hg. This impact of hypertension is even more pronounced for stroke, with an 8 times higher risk of mortality for people with systolic pressure above 150 mm Hg and 4 times higher for a diastolic pressure greater than 98 mm Hg (Figure 1, bottom graph). Consequently, high blood pressure is by far the main risk factor for stroke, being responsible for about half of the mortality associated with this disease.

Figure 1. Association between blood pressure levels and the risk of death from coronary heart disease or stroke. From Stamler et al. (1993).

Early hypertension
Blood pressure tends to increase with aging as blood vessels become thicker and less elastic over time (blood circulates less easily and creates greater mechanical stress on the vessel wall). On the other hand, age is not the only risk factor for high blood pressure: sedentary lifestyle, poor diet (too much sodium intake, in particular), and excess body weight are all lifestyle factors that promote the development of hypertension, including in younger people.

In industrialized countries, these poor lifestyle habits are very common and contribute to a fairly high prevalence of hypertensive people, even among young adults. In Canada, for example, as many as 15% of adults aged 20–39 and 39% of those aged 40–59 have blood pressure above 130/80 mm Hg (Figure 2).

Figure 2. Prevalence of hypertension in the Canadian population. Hypertension is defined as systolic pressure ≥ 130 mm Hg or diastolic pressure ≥ 80 mm Hg, according to the 2017 criteria of the American College of Cardiology and the American Heart Association. The data are from Statistics Canada.

This proportion of young adults with hypertension is lower than that observed in older people (three in four people aged 70 and over have hypertension), but it can nevertheless have major repercussions on the health of these people in the longer term. Several recent studies indicate that it is not only hypertension per se that represents a risk factor for cardiovascular disease, but also the length of time a person is exposed to these high blood pressures. For example, a recent study reported that onset of hypertension before the age of 45 doubles the risk of cardiovascular disease and premature death, while onset of hypertension later in life (55 years and older) has a much less pronounced impact (Figure 3). These findings are consistent with studies showing that early hypertension is associated with an increased risk of cardiovascular mortality and damage to target organs (heart, kidneys, brain). In the case of the brain, high blood pressure in young adults has been reported to be associated with an increased risk of cognitive decline at older ages. Conversely, a recent meta-analysis suggests that a reduction in blood pressure with the help of antihypertensive drugs is associated with a lower risk of dementia or reduced cognitive function.

Figure 3. Change in risk of cardiovascular disease (red) or death from all causes (blue) depending on the age at which hypertension begins. Adapted from Wang et al. (2020).

Early hypertension should therefore be considered an important risk factor, and young adults can benefit from managingtheir blood pressure as early as possible, before this excessively high blood pressure causes irreparable damage.

The study of barbershops
In African-American culture, barbershops are gathering places that play a very important role in community cohesion. For health professionals, frequent attendance at these barbershops also represents a golden opportunity to regularly meet Black men to raise their awareness of certain health problems that disproportionately affect them. This is particularly the case with hypertension: African American men 20 years and older have one of the highest prevalence of high blood pressure in the world, with as many as 59% of them being hypertensive. Also, compared to whites, Black men develop high blood pressure earlier in their lives and this pressure is on average much higher.

A recent study indicates that barbershops may raise awareness among African Americans about the importance of controlling their blood pressure and promoting the treatment of hypertension. In this study, researchers recruited 319 African Americans aged 35 to 79 who were hypertensive (average blood pressure approximately 153 mm Hg) and who were regular barbershop customers. Participants were randomly assigned to two groups: 1) an intervention group, in which clients were encouraged to see, in the barbershops, pharmacists specially trained to diagnose and treat hypertension and 2) a control group, in which barbers suggested that clients make lifestyle changes and seek medical attention. In the intervention group, pharmacists met regularly with clients during their barbershop visits, prescribed antihypertensive drugs, and monitored their blood pressure.

After only 6 months, the results obtained were nothing short of spectacular: the blood pressure of the intervention group fell by 27 mm Hg (to reach 125.8 mm Hg on average), compared to only 9.3 mm Hg (to reach 145 mm Hg on average) for the control group. Normal blood pressure (less than 130/80 mm Hg) was achieved in 64% of participants in the intervention group, while only 12% of those in the control group were successful. A recent update of the study showed that the beneficial effects of the intervention were long-lasting, with continued pressure reductions still observed one year after the start of the study.

These reductions in blood pressure obtained in the intervention group are of great importance, as several studies have clearly shown that pharmacological treatment of hypertension causes a significant reduction in the risk of cardiovascular diseases, including coronary heart disease and stroke, as well as kidney failure. This study therefore shows how important it is to know your blood pressure and, if it is above normal, to normalize it with medication or through lifestyle changes.

The importance of lifestyle
This last point is particularly important for the many people who have blood pressure slightly above normal, but without reaching values ​​as high as those of the participants of the study mentioned above (150/90 mm Hg and above). In these people, an increase in the level of physical activity, a reduction in sodium intake, and body weight loss can lower blood pressure enough to allow it to reach normal levels. For example, obesity is a major risk factor for hypertension and a weight loss of 10 kg is associated with a reduction in systolic pressure from 5 mm to 10 mm Hg. This positive influence of lifestyle is observed even in people who have certain genetic variants that predispose them to high blood pressure. For example, adopting an overall healthy lifestyle (normal weight, not smoking, regular physical activity, moderate alcohol consumption, and a good diet including sodium reduction) has been shown to be associated with blood pressure approximately 3 mm Hg lower and a 30% reduction in the risk of cardiovascular disease, regardless of the genetic risk. Conversely, an unhealthy lifestyle increases blood pressure and the risk of cardiovascular disease, even in those who are genetically less at risk of hypertension.

In short, taking your blood pressure regularly, even at a young age, can literally save your life. The easiest way to regularly check your blood pressure is to purchase one of the many models of blood pressure monitors available in pharmacies or specialty stores. Take the measurement in a seated position, legs uncrossed and with the arm resting on a table so that the middle of the arm is at the level of the heart. Two measurements in the morning before having breakfast and drinking coffee and two more measurements in the evening before bedtime (wait at least 2 hours after the end of the meal) generally give an accurate picture of blood pressure, which should be below 135/85 mm Hg on average according to Hypertension Canada.

Insufficient dietary fibre intake harms the gut microbiota and the immune system’s balance

Insufficient dietary fibre intake harms the gut microbiota and the immune system’s balance


  • The typical diet in Western countries does not contain enough fibre.
  • This insufficient fibre intake adversely affects the bacteria in the gut microbiota and therefore the immunity and health of the host.
  • An abundant and varied consumption of dietary fibre helps maintain a diverse and healthy microbiota, which produces metabolites that contribute to human physiology and health.

Dietary fibre is made up of complex sugars that cannot be digested by human digestive enzymes, but is an important source of energy for gut bacteria, which have the ability to break it down. This fibre comes mainly from plants, but is also found in animal tissues (meat, offal), fungi (mushrooms, yeasts, moulds), and foodborne microorganisms. The main fibres are cellulose, lignins, pectin, inulin, starches and dextrins resistant to amylases, chitins, beta-glucans and other oligosaccharides. However, not all dietary fibre can be used by the intestinal microbiota (cellulose for example), so researchers are more particularly interested in “microbiota-accessible carbohydrates” or MAC, which are found in legumes, wheat and oats, for example.

Resurgence of allergies and inflammatory and autoimmune diseases
Non-communicable diseases, such as allergies and inflammatory and autoimmune diseases have been on the rise in Western countries over the past century. Although we do not know all the causes of these increases, it is quite plausible that they have an environmental component. The transition from the traditional diet to the Western diet that occurred after the Industrial Revolution is often called into question. The typical Western diet consists primarily of processed foods high in sugar and fat, but low in minerals, vitamins, and fibre. The recommended daily intake of dietary fibre is at least 30 grams (1 ounce), while followers of the Western diet consume only 15 grams on average. In addition, people living in traditional societies consume up to 50–120 g/day of fibre and have a much more diverse gut microbiota than Westerners. A diverse microbiota is associated with good health in general, while a poorly diversified microbiota has been associated with chronic diseases common in Western countries, such as type 2 diabetes, obesity, inflammatory bowel disease (ulcerative colitis, Crohn’s disease), colorectal cancer, rheumatoid arthritis and asthma.

Metabolites of the gut microbiota
The gut microbiota contributes to human physiology by producing a multitude of metabolites. The most studied are short-chain fatty acids (SCFAs), which are organic compounds such as acetate, propionate and butyrate that together constitute ≥95% of SCFAs. These metabolites are absorbed and find their way into the bloodstream via the portal vein and act on the liver and then, via the peripheral blood circulation, on other organs of the human body. SCFAs play key roles in the regulation of human metabolism, the immune system, and cell proliferation. SCFAs are metabolites produced by microorganisms in the intestinal microbiota from dietary fibres, which are complex sugars. The microbiota produces other metabolites from amino acids derived from dietary protein, including indole and its derivatives, tryptamine, serotonin, histamine, dopamine, p-cresol, phenylacetylglutamine, and phenylacetylglycine.

A lack of dietary fibre leads to the generation of toxic metabolites by the microbiota
Insufficient fibre intake not only leads to reduced microbiota diversity and a reduction in the amount of SCFAs produced, but also causes a shift in the metabolism of microorganisms towards the use of substrates less favourable for human health. Among these alternative substrates, amino acids from food proteins are fermented by the microbiota into branched-chain fatty acids, ammonia, amines, N-nitroso compounds, phenolic compounds such as p-cresol, sulphides, and indole compounds. These metabolites are either cytotoxic and/or pro-inflammatory and they contribute to the development of chronic diseases, particularly colorectal cancer.

Effects on mucus production that protects the intestinal lining
The main substrates used by the microbiota when fibre intake is low are mucins, glycoproteins contained in the mucus that cover and protect the epithelium of the intestinal lining. Maintaining this layer of mucus is very important to prevent infections; however, a diet low in fibre alters the composition of the gut microbiota and leads to a significant deterioration of the mucus layer, which can increase the susceptibility to infections and chronic inflammatory diseases (see figure, below). Transcriptomic analyses have revealed that when there is a lack of MAC-type fibres, the enzymes that break down the mucus are expressed in greater quantities in the microorganisms of the microbiota. The consequences of the deterioration and thinning of the mucus layer are a dysfunction of the intestinal barrier, i.e. increased permeability, which increases susceptibility to infection by pathogenic bacteria. A diet rich in fibre has the opposite effect: the microbiota is diverse and the abundant production of SCFA metabolites stimulates the production and secretion of mucus by specialized epithelial cells, known as goblet cells.

Figure. Effect of a high- or low-fibre diet on the composition and diversity of the gut microbiota and the impact on human physiology. MAC: microbiota-accessible carbohydrates. From Makki et al., 2018.

Immune system
A healthy gut microbiota contributes to the maturation and development of the immune system (see this review article). For example, short-chain fatty acids (SCFAs) produced by the microbiota stimulate the production of regulatory T-cells. SCFAs have many effects on the function and hematopoiesis of dendritic cells as well as on neutrophils, which are the first leukocytes to be mobilized by the immune system in the presence of a pathogen.

Inflammation and colon cancer
The incidence of inflammatory bowel disease has increased dramatically in the West over the past few decades. A diet low in fibre has been correlated with an increased incidence of Crohn’s disease. On the contrary, a sufficient intake of dietary fibre seems to protect against the development of ulcerative colitis, an effect which has been associated with a decrease in SCFAs produced by the microbiota, butyrate in particular, which has anti-inflammatory properties. Inflammatory bowel disease can lead to the development of colon cancer. Additionally, reduced dietary fibre intake has been linked to an increased incidence of colorectal cancer.

Dietary fibre plays a much more complex role than was believed a short time ago, when it was thought that it had a purely mechanical role in intestinal transit, by an increase in the volume of the alimentary bolus and by its emollient properties. Adequate dietary fibre intake helps maintain a diverse and healthy gut microbiota, which can prevent the development of allergies as well as inflammatory and autoimmune diseases. The gut microbiota is the subject of intense research efforts, as evidenced by the numerous scientific articles published each month, and it certainly has not revealed all of its secrets!