What makes a vegetarian diet healthy?

Thirty years after dietitians warned against vegetarianism and veganism, it is now clear that this is a healthy, good way of life. So, what are the benefits of this diet and what should one be wary of?

In recent years, there has been an increase in the number of vegetarians across the world. People adopt this lifestyle for many different reasons: religious beliefs, moral considerations, environmental protection and health benefits. But does it really have such health benefits?

Starting with a history lesson, three decades ago the American Dietetic Association, which is considered the leading body in setting dietary recommendations, expressed doubt about the ability of a vegetarian diet to satisfy one’s nutritional needs, and also questioned its health benefits. But the research evidence collected over the past thirty years has demonstrated its advantages and convinced the organization to change its views. The knowledge accumulated since then has allowed us to better understand the link between nutrition and morbidity and ultimately promote vegetarianism.

Under the umbrella of “vegetarianism” there exists a variety of diets: pescetarians who eat fish, dairy products and eggs but avoid red meat and poultry; lacto-ovo vegetarians who eat dairy products and eggs but avoid red meat, chicken and fish; as well as vegans who abstain from any animal product including milk, eggs and sometimes even honey. Despite the differences between the options, the current article will treat all of the above as a vegetarian diet, to avoid any misconceptions.

The latest position presented by the Dietetic Association on this issue, published in 2009, states that well-planned vegetarian and vegan diets that meet all nutritional needs are considered healthy and have advantages in preventing and treating certain diseases. A good diet plan can be adapted to the entire population, including pregnant and lactating women, toddlers and adolescents and even athletes. The Association developed these recommendations following a review of extensive research literature that only included articles that met very strict methodological and technical standards, which ensured their validity.

The Benefits of a Vegetarian Diet?

Vegetarian diets are usually based on cereals, fruits and vegetables, legumes and nuts. Such diets tend to contain less saturated fat and cholesterol, and more dietary fiber, magnesium, potassium, vitamin C and E, folic acid, natural antioxidants (carotenoids and flavonoids) and other active plant ingredients (phytochemicals).

Most of the health benefits of vegetarian diets appear to stem from their effect on our body weight. Many studies show that vegetarians have a lower BMI (Body Mass Index – a measure of body fat) compared to non-vegetarians, which increases as meat consumption increases, as seen in both men and women. The low body weight of vegetarians probably stems from the high consumption of food rich in dietary fiber but low in calories, such as fruits and vegetables.

Obesity is a major risk factor for type 2 diabetes, cardiovascular disease, and certain types of cancer. Studies have found that the incidence of type 2 diabetes is lower in vegetarians than meat consumers. In addition, it was found that consumption of red meat and processed meat (mainly sausages and bacon) is a major risk factor for type 2 diabetes, beyond the effect of obesity itself.

In terms of cardiovascular disease, vegetarians have a lower chance of dying from heart disease than meat eaters, regardless of obesity. In other words, the vegetarian diet has other aspects that influence morbidity and mortality.

The beneficial effect of a vegetarian diet is probably due to polyunsaturated dietary fiber, the antioxidant folic acid and phytochemicals, all of which are found in vegetables, whole grains, legumes (mainly soybean) and nuts. Their association with reducing the risk of type 2 diabetes has been well documented.

A vegetarian diet is also associated with lower levels of “bad” cholesterol (LDL) because dietary fiber lowers cholesterol. Soy contains substances called flavonoids, which also reduce bad cholesterol levels and function as antioxidants. Legumes, nuts, whole grains and vegetable oils all contain substances called sterols, which reduce the absorption of cholesterol from food. In addition, flavonoids and other phytochemicals positively affect the body at various stages of development of cardiovascular disease. Also, plant foods are rich in potassium and magnesium, as well as in certain fatty acids and antioxidants that can all lower high blood pressure and thus fight against cardiovascular disease.

The findings also suggest that vegetarians have a significantly lower risk of colon and prostate cancers compared to non-vegetarians. In other common cancers, however, there were no differences between vegetarians and meat eaters. Many studies have found the consumption of red meat and processed meat increases the likelihood of colon cancer. High consumption of fruits and vegetables reduces this risk, probably due to their high dietary fiber.

It is also known that fruits and vegetables contain antioxidants that make it difficult for cancer cells to thrive. Among them are vitamin C, carotenoids, flavonoids, onions and garlic, or lycopene from red fruits.

Vegetarians, then, are less likely to die from cardiovascular disease and certain types of cancer. But there is other evidence to show vegetarians differ from meat eaters in other ways that may also affect their health. Among other things, vegetarians tend to adopt a healthy and active lifestyle, are less overweight, smoke less and drink less alcohol. It is also important to emphasize that most of the studies that examined the benefits of vegetarian diets were epidemiological studies that are based on a correlation between different factors, and do not examine cause and effect. Therefore, they can only point out a relationship between two things, without proving that one caused the other.

To date, it has been scientifically proven that consuming high amounts of red meat, especially processed, increases the risk of mortality over time, cardiovascular disease, colorectal cancer and other cancers, and type 2 diabetes. And today’s bottom-line recommendation is to reduce their consumption.

It is important to ensure an adequate intake of proteins from plant sources as well | Photo: Shutterstock

And what are the dangers?

Avoidance of meat has certain risks, especially for vegans who don’t consume any animal products at all. Meat is an excellent source of protein, vitamins A, B1, B6, and especially vitamin B12, as well as iron and zinc. The iron found in meat is better absorbed than that from a plant source.

It is very important for vegetarians and vegans to ensure they get an adequate intake of B12, as a supplement or from enriched foods, as this vitamin is only found in animals. Vitamin B12 deficiency is common in vegetarians and vegans and poses a great danger to them. The danger is even greater because the vegetarian diet is rich in folic acid, which may mask a B12 deficiency. A deficiency of this vitamin may increase levels of homocysteine, which can increase the risk of cardiovascular disease and dementia. B12 deficiency is related, among other things, to other neurological problems, especially in children with vegan mothers who did not take supplements.

Beyond strict adherence to a B12 intake, people who opt for a vegetarian or vegan lifestyle should make sure they consume enough protein, omega-3 fatty acids, iron and zinc (which are better absorbed from animal foods), iodine (from fish sources), calcium and vitamin D (especially for vegans who do not consume milk and its products).

To summarize, the discussion of the superiority of one diet versus another does not achieve anything for the general public. Perhaps not all health authorities agree on the proportion of meat in the diet, but all agree that the consumption of sugar, processed grains and large amounts of saturated and trans fat should be limited. In addition, today there is general consensus that proper nutrition should include many fruits and vegetables, whole grains, legumes and nuts. Achieving these goals is more important than whether proper nutrition should include moderate amounts of dairy products, eggs, fish, and meat. Vegetarian diets are generally healthy and in many ways preferable to meat diets. Many studies have proven the associated significant reduction in the incidence of serious diseases, some of which can be fatal. However, like any good thing, you should also be realistic and considered in maintaining a balanced diet that includes all the substances the body needs, especially vitamin B12. Naturally, it is always good to maintain a healthy lifestyle.