People adopt vegetarian diets for various reasons, such as protecting animal welfare, reducing their carbon footprint, affordability, personal food preferences and religious dietary requirements. But maintaining good health is one of the primary motives.
Eating a plant-focused diet has been shown to benefit weight control, blood pressure, heart health and immunity, as well as lower the risk of type 2 diabetes and cancer.
Now, a large-scale study adds to existing evidence that following such an eating pattern guards against chronic disease, in particular coronary heart disease and cancer.
Here’s a rundown of the study findings, vegetarian styles of eating, plus simple ways to transition to a plant-based diet.
About the research
The study, published May 15 in the journal PLOS ONE, analyzed results from 49 reviews and meta-analyses published between 2000 and 2023. (A meta-analysis combines data from many studies.)
This extensive review, called an umbrella review, is one of the highest levels of evidence recognized by the academic community.
Studies included in the umbrella review had investigated the links between vegetarian and vegan diets, and cardiovascular health and cancer risk. Semi-vegetarian diets (e.g., flexitarian, pescatarian) were excluded.
Defining vegetarian and vegan diets
Lacto-ovo vegetarians eat dairy and eggs but avoid meat, poultry and fish. Lacto-vegetarian diets include dairy but omit meat, poultry, fish and eggs. Ovo-vegetarians eat eggs but no other animal foods.
Vegan diets exclude all animal products – meat, poultry, fish, eggs and dairy.
The findings
The results showed, compared to non-vegetarian diets, vegetarian and vegan diets were associated with significantly lower body weight, LDL (low-density lipoprotein) cholesterol, blood pressure and fasting blood glucose, as well as lower levels of inflammation.
Vegetarian and vegan diets were also tied to a significantly lower risk of coronary heart disease and cancer, especially colorectal and prostate cancers.
The risk of dying from cardiovascular disease was significantly lower in vegetarians compared to non-vegetarians. There weren’t any studies that investigated mortality risk in vegans.
Overall, the new findings suggest that plant-based diets have notable health benefits.
The researchers cautioned, however, against making large-scale recommendations for such diets.
Because of the many differences between the original studies included in the umbrella review, such as sample size, study duration, geographical location, cooking methods, diet adherence and other lifestyle factors, the findings are more difficult to interpret. More research is needed.
How vegetarian diets protect health
Still, there are many ways in which plant-based diets may lower disease risk.
Vegetarian and vegan diets made up of a wide variety of whole plant foods provide plenty of vitamins, minerals and fibre along with thousands of anti-inflammatory and antioxidant phytochemicals. Phytochemicals don’t exist in animal foods.
At the same time, vegetarian and vegan diets exclude red and processed meats, high intakes of which are tied to a greater risk of heart disease and colorectal cancer.
Research also suggests that vegetarians consume fewer refined grains, sweets, snack foods and sugary beverages than non-vegetarians.
Plant-based diets may also protect health by preventing obesity, a risk factor for heart disease and certain cancers.
Transitioning to a vegetarian diet
If you’re considering adopting a vegetarian lifestyle, ease into it by gradually adding more plant foods to your daily diet.
At lunch and dinner, for example, replace half of your usual portion of meat or chicken with plant protein such as chickpea salad, edamame, grilled tofu, lentil pasta or a handful of nuts.
Or consider giving up animal foods a few days a week. Try a tofu scramble, black bean tacos, chickpea curry, bean pasta, edamame stir-fry, black bean burgers or bell peppers stuffed with lentils and brown rice or farro. Gradually, increase your weekly target for vegetarian days.
Eliminate animal foods you seldom eat; you’ll be less likely to miss them. For many people, red meat is the first to go.
Reach for plant-based snacks such as fruit and nuts, vegetables and hummus, whole grain crackers with almond butter or fruit smoothies.
Set a goal to make one new vegetarian recipe each week. You can find loads of recipes online.
Pay attention to vitamin B12
Vitamin B12, used to make DNA and red blood cells, occurs naturally only in animal foods.
People who follow a vegan diet can get B12 by consuming foods fortified with vitamins such as non-dairy milk (e.g., soy, almond, oat, etc.), some meat alternatives (check ingredient lists) and nutritional yeast and/or by taking a daily multivitamin with 25 to 100 mcg of B12.
If you are planning to adopt a vegan diet, consider consulting a dietitian to help ensure you are meeting your daily needs for B12, as well as protein, iron, zinc, iodine and omega-3 fatty acids.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD
Leslie Beck