Dr Martin Juneau, M.D., FRCPCardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.27 February 2020
OVERVIEW
- Plant-based proteins meet all the amino acid requirements if care is taken to vary the diet and include plants high in protein such as whole grains, legumes and oleaginous seeds.
- Excessive consumption of sulfur amino acids, which are found in greater amounts in animal proteins, has been associated with a higher risk of cardiometabolic diseases.
- In animal models, a limited supply of sulfur amino acids in the diet has the effect of delaying the aging process, inhibiting the onset of age-related diseases and disorders, and increasing life expectancy.
Proteins are essential macromolecules found in all living cells, in microorganisms as well as in plants and animals. Whatever their origin and function, proteins are linear chains of amino acids linked by peptide links, and whose sequence is encoded by a specific gene (DNA). Proteins have very diverse functions and are found in animal cells and organs in the form of structural proteins (e.g., collagen, keratin) and proteins with biological activity: enzymes, contractile proteins (e.g., muscle myosin), hormones (e.g., insulin, growth hormone), defence proteins (e.g., immunoglobulins, fibrinogen), transport proteins (e.g., hemoglobin, lipoproteins), etc.
From a nutritional point of view, the important parameters of dietary protein intake are quantity and quality, particularly with regard to the relative amino acid composition of proteins of plant or animal origin. Of the 20 amino acids, 8 are said to be “essential” or indispensable because they cannot be synthesized by our body and therefore must come from the diet. These are lysine, methionine, phenylalanine, tryptophan, threonine, valine, leucine and isoleucine. The proteins ingested during a meal are “cut” into peptides in the stomach, then into free amino acids during their passage in the intestine. It is these free amino acids and not the proteins that are absorbed in the intestine.
Does the origin of the protein contained in food, i.e., plant or animal, have an impact on health? This is an interesting question that is still being debated. Two questions caught our attention:
1) Does a vegetarian diet meet all the energy and amino acid needs?
2) Why are plant proteins better for health than animal proteins?
Nutritional value of plant protein
Do vegetarians eat enough protein? In developed countries, vegetable proteins from different plants are used in the form of mixtures, especially in vegetarian dishes, and the amount of protein consumed exceeds the recommended nutritional intake. According to data from the EPIC-Oxford study of 58,056 Europeans, all types of diet provide more protein than the Recommended Dietary Allowance (RDA: 0.83 g/kg of body weight/day for adults) and the Estimated Average Requirement (EAR: 0.66 g/kg/day) (see Figure 1 below). Even the vegan diet, with an average daily intake of 0.99 g of protein per kg of body weight, meets protein needs in most cases. However, experts have estimated that a small percentage of vegans may not be getting enough protein. It should be noted that children and adolescents and the elderly need more protein to support growth in the young and to compensate for loss of appetite in the elderly.
Figure 1. Daily protein intake by type of diet. According to data from the EPIC-Oxford study (Sobiecki et al., 2016.)
It is often said, incorrectly, that the vegetarian diet is deficient in amino acids (see this review article). In fact, plant proteins contain all 20 amino acids, including the 8 essential amino acids, but it is true that they generally contain less lysine and methionine than those of animal origin. However, by varying one’s diet and taking care to include legumes, nuts and whole grains (three types of protein-rich foods), it has been shown that the vegetarian diet provides ample amounts of each of the amino acids, including lysine and methionine. For example, in the EPIC-Oxford study, it was estimated that lacto-ovo vegetarians and vegans consume an average of 58 and 43 mg of lysine/kg of body weight every day, respectively, which is significantly higher than the estimated average requirement of 30 mg/kg. In rare cases, a deficiency could occur when a vegetarian person has a poor diet, consisting mainly of starchy foods (pasta, fries, pastries) or of a single food (rice or beans).
Why consume more plant protein?
Recent studies suggest an interesting avenue to explain why plant-based proteins are superior in preventing chronic diseases. Sulfur amino acids (cysteine and methionine) are present in greater quantities in animal proteins; however, the average consumption of an adult far exceeds the amount required to be healthy. Consuming these sulfur amino acids (SAAs) in excess has been associated with a higher risk of cardiometabolic diseases and certain cancers, regardless of the total amount of protein consumed.
The cohort studied was derived from the NHANES III study, conducted between 1988 and 1994 among 11,576 adult Americans. The participants’ average SAA consumption was more than 2.5 times higher than the estimated average requirement, i.e., 39.2 mg/kg/day vs. 15 mg/kg/day. Participants in the first quintile consumed an average of 20.1 mg/kg/day SAAs, while those in the last quintile consumed 62.7 mg/kg/day, or 4.2 times the estimated average requirement. Consumption of excess SAAs was associated with several individual risk factors, including blood levels of cholesterol, glucose, uric acid, urea nitrogen, insulin and glycated hemoglobin.
Several previous studies in animal models have illustrated the effect of a diet limited in SAAs to delay the aging process and inhibit the onset of ageing-related diseases and disorders (see this review article). Benefits of this type of diet on animals include increased life expectancy, reductions in body weight and adiposity, decreased insulin resistance, and positive changes in blood levels of several biomarkers such as insulin, glucose, leptin and adiponectin.
Several animal studies have reported that a diet low in methionine inhibits tumour growth. Indeed, a common feature of some cancers is that their growth and survival require an exogenous supply (from the diet) of methionine. In humans, certain types of vegetarian diets low in methionine could be a useful nutritional strategy for controlling tumour growth.
In summary, it seems beneficial for maintaining good health to reduce the consumption of animal proteins and replace them with plant-based proteins. There is no risk of a protein or essential amino acid deficiency for people who adopt a vegetarian diet, as long as they take care to vary their diet and include plants rich in protein such as whole grains (wheat, rice, rye), legumes (e.g., chickpeas, beans, lentils, soybeans, broad beans) and oilseeds (e.g., nuts, cashews, almonds, hazelnuts).
Dr Martin Juneau, M.D., FRCPCardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.1 July 2019
Red meat: An issue for human health and the health of the planet.
Consumption of red meat and processed meat is associated with an increase in all-cause mortality and mortality from cardiovascular diseases, diabetes, respiratory diseases, liver and kidney diseases, and certain cancers. On the contrary, consumption of white meat and fish has been associated with a decreased risk of premature death. Another troubling aspect with the production of red meat is that it is harmful to the global environment.
In traditional European agricultural societies, meat was consumed once or less than once a week, and annual meat consumption rarely exceeded 5 to 10 kg per person. In some rich countries (U.S.A., Australia, New Zealand), meat consumption now stands at 110–120 kg per person per year, > 10 times more than in traditional agricultural societies. Livestock farming occupies more than 30% of the world’s land area, and more than 33% of arable land is used to produce livestock feed. World consumption of red meat is rising sharply, especially in developing countries. This has adverse consequences for the environment and represents an unsustainable situation according to several experts.
The main harmful effects to our planet caused by meat production (Potter, BMJ 2017)
- Depletion of aquifers (producing 1 kg of meat requires more than 110,000 L of water).
- Groundwater pollution.
- Decrease of biodiversity.
- Destruction of rainforest for livestock and the production of greenhouse gases by livestock. Both combined contribute more to climate change than fossil fuels used for transport.
- Production of 37% of methane (CH4) from human activity (with 23 times the global warming
potential of CO2).
- Production of 65% of nitrous oxide (N2O) from human activity (almost 300 times the global
warming potential of CO2).
- Production of 64% of ammonia (NH3) from human activity, which contributes significantly to
acid rain and acidification of the ecosystem.
Other potential negative effects associated with red meat include accelerated sexual development, caused either by the consumption of meat and fat, or by the intake of growth hormones naturally present in meat or added to livestock feed; more extensive antibiotic resistance caused by their use to promote animal growth; a reduction in the food available for human consumption (for example, 97% of the world’s soybeans are used to feed livestock); and higher risks of infections (such as bovine spongiform encephalopathy or “mad cow disease”) due to faulty practices in intensive farming.
Experts agree that we will have to reduce our consumption of red and processed meat in order to live longer, healthier lives, but especially so that our planet is in better condition and can support human activity long term. Eating mostly cereals, fruits, vegetables, nuts, and legumes, and little or no meat is probably the ideal solution to this environmental problem, but for many, red meat is a delicious food that is hard to replace. To satisfy meat lovers who still want to reduce their consumption, companies have recently developed products made only from plants whose appearance, texture and taste are similar to meat, whereas others are trying to produce artificial meat from in vitro cell cultures.
New plant-based patties: Beyond Burger and Impossible Burger
Plant-based burgers have long been available in grocery stores, but these meatless products are intended for vegetarians and consumed mainly by them. New products made from plants, but designed to have the same appearance, texture, and taste as meat have appeared on the market recently. These meat alternatives target omnivorous consumers who want to reduce their meat consumption. Among the most popular products, there is the Beyond Burger, available at the fast food chain A&W and recently in most supermarkets in Quebec, as well as the Impossible Burger, which will soon be on the menu at fast food chain Burger King under the name “Impossible Whopper.”
The main ingredients of Beyond Burger are pea protein isolate, canola oil and refined coconut oil. This food also contains 2% or less of other ingredients used to create a meat-like texture, colour and flavour, as well as natural preservatives (see box). It is an ultra-processed food that does not contain cholesterol, but almost as much saturated fat (from coconut oil) and 5.5 times more sodium than a lean beef patty. Nutrition and public health experts have suggested avoiding coconut oil in order not to increase blood LDL cholesterol (“bad cholesterol”) and maintain good cardiovascular health (see “Saturated fats, coconut oil and cardiovascular disease”). Moreover, the nutritional contribution of these two products is similar (calories, proteins, total lipids).
Beyond Burger ingredients: Water, pea protein isolate, canola oil, refined coconut oil, 2% or less of: cellulose from bamboo, methylcellulose, potato starch, natural flavour, maltodextrin, yeast extract, salt, sunflower oil, vegetable glycerine, dried yeast, gum arabic, citrus extract, ascorbic acid, beet juice extract, acetic acid, succinic acid, modified food starch, annatto.
Impossible Burger ingredients: Water, soy protein concentrate, coconut oil, sunflower oil, natural flavours, 2% or less of: potato protein, methylcellulose, yeast extract, dextrose, food starch modified, soy leghemoglobin, salt, soy protein isolate, mixed tocopherols (Vitamin E), zinc gluconate, thiamine hydrochloride (vitamin B1), sodium ascorbate (vitamin C), niacin (vitamin B3), pyridoxine hydrochloride (vitamin B6), riboflavin (vitamin B2), vitamin B12.
The Impossible Burger is made from soy protein, coconut oil and sunflower oil. It also contains ingredients that are used to create a meat-like texture, colour and flavour, as well as vitamins and natural preservatives. Among the ingredients added to mimic the colour and flavour of meat is soy leghemoglobin, a hemoprotein found in the nodules on the roots of legumes that has a similar structure to animal myoglobin. Rather than extracting this protein from the roots of soybean plants, the manufacturer uses leghemoglobin produced by yeast (Pichia pastoris) in which the DNA encoding for this protein has been introduced. The use of P. pastoris soybean leghemoglobin was approved by the US Food and Drug Administration in 2018. The fact that the leghemoglobin used is a product of biotechnology rather than from a natural source does not appear to pose a particular problem, but some researchers suspect that the heme it contains could have the same negative health effects as those associated with the consumption of red meat, i.e., an increased risk of cardiovascular disease and certain types of cancer. A causal link between heme and these diseases has not been established, but population studies (see here and here) indicate that there is a significant association between heme consumption and a rise (19%) in mortality risk from all causes. In contrast, non-heme iron from food (vegetables and dairy products) is not associated with an increased risk of mortality.
Beyond Burger and Impossible Whopper, served with mayonnaise and white bread, are not suitable for vegans (eggs in mayonnaise) or a particularly healthy option because of the saturated fat and salt they contain. However, the manufacture of these products requires much less energy and has a much smaller environmental footprint than real red meat, which is their strong selling point. According to one study, the production of a Beyond Burger patty generates 90% less greenhouse gas emissions and requires 46% less energy, 99% less water and 93% less arable land than a beef patty.
We believe that it is preferable, as much as possible, to obtain unprocessed fresh plant products and to do the cooking yourself, in order to control all the ingredients and thus avoid ingesting sodium or saturated fat in excessive amounts, as is the case with most ultra-processed products, including these new meatless patties. Fatty and salty foods taste good to a large majority of human beings, and the food industry takes this into account when designing the ultra-processed food products it offers on the market. If you want to eat a “burger” without meat, why not try to prepare it yourself with black beans (recipes here and here), oats, lentils or quinoa?
Production of “meat” in the laboratory
In vitro “meat” production involves culturing animal muscle cells (from undifferentiated cells or “stem cells”) in a controlled or laboratory environment. The first beef patty produced in a laboratory in 2013 cost 215,000 pounds (Can$363,000), but the price has dropped considerably since then. However, this product is not yet ready to be commercialized, as there are still several technological problems to solve before it can be produced on a large scale. Moreover, if the current experimental product can be used to successfully mimic ground meat, we are still far from being able to grow cells in a three-dimensional form that looks like a steak, for example.
The technology could be used to produce, for example, “Fugu” (puffer fish) meat, a delicacy prized by the Japanese, but which can be deadly if the chef or specialized companies do not prepare the fish properly. Indeed, tetradoxine contained in the liver, ovaries and skin of the fugu is a powerful paralyzing poison for which there is no antidote. Laboratory-made fugu meat would not contain any poison and would be safe for consumers.
Another example of an advantageous application would be the production of duck foie gras. A majority of the French (67%) are against the traditional method of production by gavage, which makes the animals suffer. One company (Supreme) is developing a method to obtain fatty liver from isolated duck egg cells.
Other companies are developing methods to produce egg white and milk proteins by fermentation rather than using animals. Although this “cellular agriculture” still seems a little “futuristic”, it could become increasingly important in the food industry and help reduce the production of meat that is harmful to our planet.
Dr Martin Juneau, M.D., FRCPCardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.14 February 2018
Updated May 21, 2018
More and more people, especially young adults, are choosing to become vegans, i.e., to eat an exclusively plant-based diet (vegetables, fruits, oilseeds, legumes, whole grains) and not consume any product of animal origin (meat, eggs, dairy products). The most common motivations for adherence to veganism are the ethical aspects of animal husbandry and slaughter, environmental issues (pollution associated with the production of animal products), and the benefits of plant-based diets on human health in general, particularly with respect to cardiovascular diseases.
Despite all these benefits, abstinence from any form of animal products means that vegans are at greater risk of deficiencies in certain micronutrients found exclusively in the animal kingdom. This is especially true for vitamin B12, which plays an important role in the functioning of the human body, so a deficiency of this vitamin can cause very serious health problems. The purpose of this article is to convince vegans that vitamin B12 supplementation is the only way to effectively counteract this deficiency and that these supplements are absolutely essential to maintaining good health.
A complex vitamin
Vitamin B12, also known as cobalamin, has several unique characteristics that give it a special status in the large family of vitamins. First, it is distinguished from other vitamins by its extremely complex chemical structure (see below) including a corrin ring similar to that found in haemoglobin and chlorophyll and to which is attached a cobalt atom (hence the name cobalamin). This structure is the culmination of a series of biochemical reactions using thirty different enzymes that, collectively, transform a very simple molecule (the amino acid glutamate) into B12 (to grasp the scale of this transformation, it is important to mention that it took more than 10 years for a group of about 100 chemists to successfully synthesize this vitamin in a test tube).
From bacteria to humans
Another very particular characteristic of vitamin B12 is that the enzymatic machinery necessary for its production is exclusively found in certain bacteria. During evolution, plants and animals have “lost” these enzymes and therefore the ability to produce vitamin B12 by themselves. For plants, this is not a problem as they do not need it to survive (with the exception of some algae, see below); however, for animals the situation is quite different. Humans, for example, absolutely need small amounts (about 1 μg per day) of vitamin B12 to ensure the functioning of two enzymes (methionine synthase and -methylmalonyl-CoA mutase) that play an essential role in metabolism and cell growth.
It is the food chain that allows this transfer of vitamin B12 of bacterial origin to animals. Products derived from ruminants (cows, sheep), for example, are excellent sources of vitamin B12, because their stomachs contain bacteria that produce this vitamin and then carry it in the liver and muscles, or secrete it into their milk (see Table 1). Consumption of liver, red meat or dairy products therefore allows an adequate intake of vitamin B12. For people who do not like to eat liver or who prefer to limit their consumption of red meat, some fish and seafood are an excellent alternative because the B12 synthesized by bacteria living in aquatic environments is ingested by marine plankton, which is assimilated by these organisms. For example, molluscs such as bivalves (mussels, oysters, clams) filter large volumes of water to extract plankton and accumulate large amounts of B12 at the same time. Carnivorous fish such as tuna or oily fish such as sardines and salmon (rich in omega-3 fatty acids) are also major sources of vitamin B12, with levels 10 to 20 times higher than those found in poultry or pork. Fish and seafood are therefore major sources of vitamin B12 and in some countries, such as Japan, make up to 85% of the total intake of this vitamin.
Table 1. Examples of dietary sources of vitamin B12. From Dieticians of Canada.
| Food | Portion | Vitamin B12 content (μg) |
| Veal liver | 75 g | 53-66 |
| Clams/mussels/oysters | 75 g | 13-18 |
| Tuna (bluefin) | 75 g | 8-9 |
| Sardines (canned) | 75 g | 7 |
| Beef (ground) | 75 g | 2.3-2.7 |
| Salmon (Atlantic) | 75 g | 2.3 |
| Eggs | 2 large | 1.6 |
| Milk | 250 mL | 1.2-1.4 |
| Yogurt | 175 g | 0.5 |
| Chicken | 75 g | 0.2 |
Plant sources of B12?
Although there is a broad consensus that vitamin B12 is absent from the plant kingdom, it is interesting to note that several studies have nevertheless managed to detect the presence of this vitamin in certain plants. For example, seaweeds of the genus Porphyra (e.g., nori seaweed used in sushi) can contain up to 60 μg/100 g of vitamin B12, which is similar to that found in calf liver. This is consistent with recent data showing that more than half of the algae species require vitamin B12 for growth and are closely associated with bacterial species producing this vitamin. Significant amounts of vitamin B12 have also been measured in some species of wild mushrooms (black trumpet, golden chanterelle) and in Paris mushrooms, as well as in some fermented vegetable preparations.
However, the bioavailability of vitamin B12 present in these foods, especially algae, remains uncertain. On the one hand, it has been shown that the addition of nori algae to the diet of vitamin B12-deficient rats caused a 2-fold increase in the amount of B12 present in the liver, suggesting that the vitamin is well assimilated. In the same vein, it is interesting to note that a study of children who adhered for a period of 4 to 10 years to a strict vegan diet, based on the consumption of brown rice and nori seaweed (genmai-saishoku), showed no symptoms of vitamin B12 deficiency. It was also reported that vegans who consumed nori seaweed (2.4 μg B12/day) and dried wild mushrooms (0.7 μg B12/day) for 8 months had normal blood levels of vitamin B12 and adequate blood count.
These results are interesting, but it should nevertheless be mentioned that a study carried out on children with a vitamin B12 deficiency showed that even if algae consumption made it possible to increase blood levels of vitamin B12, it did not succeed in correcting anemia, which suggests that the ingested vitamin B12 was not bioavailable. In the current state of knowledge, it seems premature to recommend that vegans consume algae to avoid a B12 deficiency.
Overall, these observations indicate that vitamin B12 is absent from plants, with the possible exception of some algae, mushrooms and fermented vegetables. Recent observations, however, indicate that several plants have the capacity to passively absorb this vitamin when it is present in the surrounding soil, which could eventually allow the production of plants containing vitamin B12. In the meantime, the only proven way to get this vitamin from food is to eat foods of animal origin, whether meat, fish and seafood, eggs or dairy products. Unless you add insects to your eating habits! (See box.)
Soil … and insects
As vitamin B12 is found exclusively in animal products, many people may wonder how our primate ancestors, who were vegetarians, were able to obtain enough to ensure their survival and allow the evolution of the human species. Firstly, simply through contamination of the foods consumed: monkeys do not wash the fruits, shoots and other vegetables they eat and the presence of soil (and therefore bacteria) on these foods can provide small amounts of vitamin B12 needed to live. Since early humans were also vegetarians and mainly ate fruits and tubers, it is likely that much of the B12 intake of our distant ancestors was achieved in a similar fashion. However, the contribution of insects should not be ignored: it has long been known that great apes spend a lot of time hunting a wide variety of insects (termites, ants, bees, etc.), larvae and worms, even if these animals represent only a tiny fraction (<1%) of their daily food intake. But it is an energy expenditure that is really worthwhile given the very high nutritional value of these insects, especially for their high content of vitamin B12 (termites, for example, contain up to 970 μg/100 g). It can be assumed that insect consumption helped ensure adequate vitamin B12 intake during the early stages of human evolution, particularly before meat became a part of our diet. It is interesting to note that this consumption of insects (entomophagy) still exists today, with no less than 2 billion humans who regularly eat insects. Moreover, insects are increasingly seen as a viable alternative to traditional meats because of their many health and environmental benefits. There are, however, significant cultural barriers to the consumption of insects, larvae or other “bugs” and, unless there is a drastic (and unlikely) change in our dietary habits, vitamin B12 supplements remain the best solution to compensate for the lack of animal foods.
B12 deficiency
The absence of vitamin B12 in plants necessarily implies that people who adhere to a strict vegan diet, which completely excludes all animal products, are at high risk of vitamin B12 deficiency. This is indeed the case: studies to date indicate that a large number of vegans have blood levels of vitamin B12 lower than recommended, a proportion that can reach 86% in some studies. This is a dangerous situation because the main consequence of vitamin B12 deficiency is pernicious anemia, caused by disruption of DNA synthesis. In this disease, the decrease in DNA synthesis causes megaloblastic anemia (very large red blood cells), the appearance of various gastrointestinal symptoms (loss of appetite, constipation), and certain neurological symptoms (numbness, loss of balance, depression, memory loss). At the cardiovascular level, vitamin B12 deficiency leads to an increase in blood levels of homocysteine, a derivative of the amino acid methionine that has long been recognized as a risk factor for cardiovascular disease. When present in excessive amounts, homocysteine promotes clot formation and prospective studies show an association between elevated levels of homocysteine and the risk of coronary heart disease and stroke. The negative consequences of a vitamin B12 deficiency are numerous, and it is therefore extremely important to ensure that adequate blood levels of this vitamin are maintained.
Blood tests are usually used to diagnose a lack of vitamin B12, because anemia is the main sign of a B12 deficiency. It should be noted, however, that this criterion is not infallible, especially for vegans: in people who eat a lot of vegetables, folate (vitamin B9) intake is very high and can “mask” the B12 deficiency by eliminating the signs and symptoms of anemia. However, the damage to the nervous system caused by B12 deficiency is not reversed by folate and neurological problems can continue to worsen and cause irreversible damage (dementia, paralysis). Again, the best way to avoid this type of problem is vitamin B12 supplementation.
Which supplements to choose?
The recommended daily intake of vitamin B12 is 2.4 μg, a quantity that can be easily achieved with supplements on the market. In most cases, vitamin B12 is in the form of cyanocobalamin, which is rapidly converted to methylcobalamin and 5-deoxyadenosylcobalamin, the active forms of the vitamin. In some cases, the supplements already contain the active form of B12 (methylcobalamin), but this does not seem to influence the absorption of the vitamin or its bioavailability.
It should be noted that several foods available on the market are fortified with B12, including breakfast cereals, several soy products, as well as some types of yeast (RedStar, for example). In the last example, it is important to ensure that the vitamin has been added to the preparation because the yeast does not produce B12. Finally, cyanobacterial preparations such as spirulina are not valid sources of vitamin B12. This alga instead contains pseudovitamin B12, a form of vitamin that is biologically inactive and may even hinder the absorption of B12.
Dr Martin Juneau, M.D., FRCPCardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.19 September 2017
Updated on March 15, 2019
Life expectancy at birth in Canada in 2015 was 84.1 years for women and 80.2 years for men. It has been steadily rising for half a century: in 1960 life expectancy was 74.1 years for women and 71.1 for men. However, it is far from the exceptional longevity observed in specific areas of our planet where we find a large proportion of centenarians. These regions, named “Blue Zones”, have been identified by two demographers, Gianni Pes and Michel Poulain, and journalist Dan Buettner, author of the article The Secrets of Long Life in National Geographic magazine and the book The Blue Zones.
The five Blue Zones identified in the world.
Sardinia, Italy
By studying the longevity of the inhabitants of Sardinia, an Italian island in the Mediterranean Sea, the demographers Gianni Pes and Michel Poulain and their collaborators have located the areas where morecentenarianslive. These longevity hot spots, or Blue Zones (the researchers initially used a blue marker to delineate these areas on a map), are located in a mountainous area of the island, the Barbagia, which was still difficult to access a few decades ago. This geographical situation discouraged immigration and promoted consanguinity, reducing the diversity of the genetic heritage. In the area of exceptional longevity, in the southeast of the Province of Nuoro, 91 people have become centenarians among the 18,000 people who were born in the region between 1880 and 1900. In one village in particular, Seulo, 20 centenarians were identified between 1996 and 2016. In comparison, according to Statistics Canada, there were 17.4 centenarians per 100,000 inhabitants in Canada in 2011.
The analysis of genes involved in inflammation, cancer and heart disease did not reveal any significant difference that could be related to the exceptional longevity of the Sardinians. Researchers therefore suspect that environmental characteristics, lifestyle and diet are much more important than genetic predispositions for a long and healthy life. Many of these Sardinian centenarians are shepherds or farmers who have been doing a great deal of outdoor physical activity throughout their lives. The Sardinian diet, which is part of the Mediterranean diet, could play an important role in the longevity of the inhabitants of this Blue Zone. Indeed, the Sardinian diet consists of homegrown vegetables (mainly beans, tomatoes, eggplants), whole-grain bread, Pecorino cheese made from whole milk from grass-fed sheep, and local red wine particularly rich in polyphenols. The traditional Sardinian diet included meat once a week at most.
When journalist Dan Buettner asked some of these centenarians the reason for their exceptional longevity, many mentioned the importance of family and social ties; in Sardinia, elderly people live with their family rather than in retirement homes. The elderly who live in the Sardinian Blue Zone believe they have excellent mental well-being and report few symptoms of depression. An Italian study of 160 elders of the Sardinian Blue Zone reports that the trait of resilience was significantly associated with markers of good mental health. For these seniors, resilience and satisfaction derived from social ties are predictors of all markers of good mental health.
Okinawa, Japan
Japan has one of the largest concentrations of centenarians in the world, more than 34.7 per 100,000 inhabitants in 2010. The inhabitants of the islands of the Okinawa archipelago in southwestern Japan have a particularly high life expectancy, and 66.7 centenarians per 100,000 inhabitants have been recorded in this prefecture. Women living in Okinawa are 3 times more likely to live to age 100 than North Americans. The Okinawa diet is plant-based, and includes many leafy green vegetables, sweet potatoes, fish and seafood. The majority of Okinawa’s centenarians maintained a vegetable garden during their lifetime and moderate physical activity, which helps reduce stress and stay in shape. The people of Okinawa traditionally practice self-restraint when it comes to food, by following the Confucian teaching hara hachi bu, which recommends eating so as to be 80% satiated at the end of a meal. Older people in Okinawa are very active and maintain strong family and social ties, for example through regular meetings called moai. It is very important for them to make sense of their life. To have an ikigaiis to have a reason to get up every morning.
Nicoya, Costa Rica
Life expectancy is relatively high in Costa Rica (82.1 for women and 77.4 for men), especially in the region of the Nicoya Peninsula where men aged 60 are 7 times more likely to become centenarians than other Costa Ricans. Like Sardinia, Nicoya is a region that has been relatively isolated for hundreds of years. The cancer mortality rate is 23% lower than in the rest of the country, and Nicoya residents have a plant-based diet (squash, black beans, corn tortillas, plenty of local fruits), but that also includes eggs and meat (chicken and pork). The centenarians of Nicoya are very physically active, have strong family ties as well as strong religious faith, and like to work. Their stress level is low and they are generally very positive and happy.
Loma Linda, United States
The only identified Blue Zone in North America is located in Loma Linda, a city in Southern California, located 100 km east of Los Angeles, where there is a community of 9,000 members of the Seventh-day Adventist Church. In California, a 30-year-old Adventist man will live on average 7.3 years longer than a white Californian of the same age. A 30-year-old Adventist woman will live on average 4.4 years longer than a Californian of the same age. Knowing that about two thirds of Americans die from cardiovascular disease or cancer, it is not surprising that Adventists are living longer as their way of life means they are less at risk of developing these diseases. About half of Adventists are vegetarians or rarely eat meat, and non-vegetarian Adventists are twice as likely to develop cardiovascular disease. The majority of Adventists are non-smokers and do not drink alcohol. As a result, they have a lower incidence of lung cancer than Americans in general. Adventists are physically active and have a very developed community spirit, as they are very religious and their church encourages its members to help one another.
Icaria, Greece
Icaria is a Greek island in the Eastern Aegean Sea where one in three inhabitants will reach the age of 90. The incidence of cancer, cardiovascular disease, diabetes and dementia is significantly lower than the rest of the world. As in Sardinia, Okinawa and other Blue Zones, Icarians maintain a vegetable garden at home and lead a low-stress life. Their diet, of the Mediterranean type, is composed of vegetables (potatoes, peas, lentils, green leafy vegetables), fruits, olive oil, fish, goat milk, dairy products, and a little meat. Icarians eat little sugar and drink coffee, red wine and herbal teas made from rosemary, sage, oregano and artemisia daily. Icarians who observe the calendar of the Greek Orthodox Church must fast regularly, and caloric restriction is known to slow down the aging process in mammals.
The inhabitants of the Blue Zones, Okinawa, Sardinia, Nicoya, Icaria and Loma Linda, share characteristics in their lifestyle that contribute to their longevity. In his book The Blue Zones, Dan Buettner lists 9 common features:
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- Moderate and regular physical activity, throughout life.
- Caloric restriction.
- Semi-vegetarianism, food largely sourced from plants.
- Moderate alcohol consumption (especially red wine).
- Give meaning and purpose to life.
- Reduced stress.
- Engagement in spirituality or religion.
- Family is at the centre of life.
- Social commitment, integration in the community.
