Umbrella Study Finds Vegetarian Diets Associated with Lower Risk for Heart Disease, Cancer
Vegetarianism has existed for centuries—both the world’s oldest religion, Hinduism, and Buddhism, founded in 400 BCE, have recommended a plant-based diet since their inceptions, researchers said in a 2014 study.
In modern times, the term “plant-based diet” emerged in the 1980s, but it wasn’t until around 2015 that the idea began to spread quickly, according to marketing agency Mintel, which tracks consumer products and trends.
The growing popularity of plant-based foods is fueled by many reasons but especially health concerns related to eating meat, dairy, and other foods, as well as the environmental impacts of meat production. A 2019 survey reported that 40% of global consumers are trying to reduce their consumption of animal proteins. This, in turn, is attracting new plant-based foods to market—research from Mintel’s Global New Products Database predicts that the plant-based goods market could grow to $160 billion by 2030.
What Are the Different Types of a Plant-based Diet?
A plant-based diet primarily consists of foods made from fruits and vegetables, nuts, seeds, oils, whole grains, legumes, and beans. While this diet doesn't mean complete avoidance of animal products, its goal is to eat more of what comes directly from plants and less of what comes from animals.
Here’s how plant-based diets work, their potential benefits, and ways to incorporate plant-based concepts into a person’s eating habits.
The goal [of a plant-based diet] is to eat more of what comes directly from plants and less of what comes from animals.
Plant-based diets can take several forms. Probably best-known is the vegetarian diet, which excludes meat, fish, and poultry, but there are variations that are still considered vegetarian:
Lacto-vegetarian: Includes dairy products.
Ovo-vegetarian: Includes eggs.
Lacto-ovo vegetarian: Includes dairy products and eggs.
Some other popular plant-based diets include:
Vegan diet: Excludes all animal products, including dairy, eggs, and honey
Pescatarian diet: Includes fish and other seafood but excludes meat and poultry
Flexitarian diet: Primarily vegetarian with occasional inclusion of meat and fish
No matter how meat enters the equation, the standard foods included in a plant-based diet are:
Fruits and vegetables: Rich in vitamins, minerals, and antioxidants
Whole grains: Provide essential fiber and nutrients
Legumes: High in protein and fiber
Nuts and seeds: Offer healthy fats and protein
Just How Healthy Is a Plant-based Diet?
A recent umbrella study consolidated findings from 48 studies published between 2000 and 2023 on plant-based diets and their health impacts. The researchers cautioned that there are significant gaps in knowledge that must be addressed. However, their study indicates that plant-based diets are linked to better health outcomes, such as less risk of cancer, a better lipid profile and glycemic control, lower body weight, less inflammation, lower mortality from cardiovascular diseases, and a lower risk of ischemic heart disease.
The study indicates that plant-based diets are linked to better health outcomes, such as less risk of cancer, a better lipid profile and glycemic control, lower body weight, less inflammation, [and] lower mortality from cardiovascular diseases.
Vandana Sheth, RDN, CDCES, FAND, an award-winning registered dietician and public speaker on diabetes and plant-based diets, says that “key health markers” are used to assess health outcomes.
These markers “include lower blood pressure, lower body mass index, improved cholesterol levels, inflammation/pain, and improved blood glucose,” she says. “These positive benefits are mainly due to the high fiber, antioxidant and phytonutrient content found in plant foods.”
Here are some ways that a plant-based diet can improve health:
Obesity: Plant-based diets are typically lower in calories and higher in fiber, thus aiding weight management.
Blood Pressure: High potassium and low sodium content in plant foods help regulate blood pressure.
Cholesterol: Soluble fiber in legumes, fruits, and vegetables helps reduce levels of “bad” cholesterol.
Mental Health: Nutrient-rich plant foods support brain health, potentially reducing the risk of depression and cognitive decline. [See The Earth & I, Feb. 2024]
Inflammation: Anti-inflammatory properties of plant foods can alleviate symptoms of arthritis and asthma.
“[P]articipants following a plant-based diet might have other reasons for their positive health outcomes, such as ... being more health-conscious.”
Although the statistical associations between plant-based diets and improved health are robust, questions remain. “The research is complicated,” says Elizabeth Nix, Ph.D., RDN, an assistant professor of nutrition in Ohio Wesleyan's Department of Health and Human Kinetics. “For years, there have been observational studies that show an association between plant-based diets and health, but association does not mean causation, and many criticize these statistics citing that participants following a plant-based diet might have other reasons for their positive health outcomes, such as having a higher income, being more health-conscious, and eating more vegetables, fruits, and whole grains.”
Meat-based Diets and Health Outcomes
Nix explains that most studies compare vegan or plant-based diets to common low-fat, low-calorie diets, such as the Mediterranean or DASH diets. “It’s unclear what it is about meat products that might increase risks of disease,” says Nix. “For a long time, nutritionists and popular media villainized the saturated fat found in meat as being the unhealthy component, but a lot of new research doesn’t really support that saturated fat is unhealthy per se; it depends more on the food source.”
Besides saturated fats, other another suspected culprit are the nitrosamines found in meats—i.e., compounds developed during the curing and cooking of meats with nitrates.
“However, history has taught us that trying to identify the one ‘bad’ component of a food often leads to confusion, misunderstanding, and ‘franken-foods’ as the food industry tries to counteract the one bad food component while trying to keep all the yummy things intact,” says Nix. “In fact, many commercially produced cured meats have stopped using isolated nitrites and nitrates, with the new, bold packaging of ‘uncured’ on things like turkey, ham, maybe even hot dogs. Don’t be fooled, these products still have nitrites and nitrates in the form of celery salt, a naturally occurring nitrate product. The truth is, we just eat too much meat, and we have developed the cheapest possible way of doing it.”
“The truth is, we just eat too much meat, and we have developed the cheapest possible way of doing it.”
Sheth takes a different view. She states that there are several factors that may be associated with meat-based diets leading to poor health outcomes:
High intake of red and processed meats has been linked to an increased risk of heart disease, cancer, and diabetes.
Quality matters. Low-quality meats often contain higher levels of unhealthy fats and are less nutrient-dense.
Processed meats often contain additives and preservatives that may be linked to cancer.
Grilling or frying meats can produce higher levels of harmful compounds.
“It's a combination of these factors that contribute to the negative health outcomes associated with meat-heavy diets,” says Sheth. “The problem is not just the meat itself, but the overall lifestyle factors and dietary patterns that contribute to the health outcomes.”
Limitations of Plant-based and Meat-based Diets
Both plant-based and meat-based diets have their limitations. Plant-based diets can lead to potential nutrient deficiencies without careful planning, while meat-based diets can lead to less fiber, vitamins, and minerals that are typically provided by vegetables and fruits.
Nix says that the nutritional limitations of a plant-based diet depend on what is eaten. A few micronutrients are often limited in a vegan diet, including iron, vitamin B12, calcium, and vitamin D. If someone is consuming dairy and eggs, though, these nutrients are likely not a concern. Iron deficiency anemia is particularly a problem—it is one of the most common nutrient deficiencies worldwide.
“Men are at a low risk of iron deficiency and are likely to have few problems with iron when adopting a plant-based diet,” says Nix. But “women who are menstruating or pregnant should be cautious when adopting a vegan diet and regularly check their iron levels.”
Despite the risk of these deficiencies, many researchers still believe the health benefits outweigh the potential risk of deficiency. Vitamin B12 is available in supplements, fortified foods, and as an injection. Many vegan food products are now fortified with B12, but it’s a good idea to get an annual injection of B12 for anyone adopting a fully plant-based diet, recommends Nix.
While there is concern that vegans don’t consume enough protein, Nix says, “This is a myth.”
“Most Americans are consuming way more protein than they actually need. A plant-based diet can provide enough protein, even for active individuals,” she says.
Plant proteins, with the exception of soy, are considered incomplete proteins, meaning they are missing one or more of the essential amino acids, explains Nix. However, if someone is getting a varied diet, they are likely getting the missing amino acids from something else. For example, grains often lack lysine, which are abundant in beans, but beans are a poor source of methionine, which is found in grains. These are called complementary proteins. It’s not crucial to pair these for every meal, but each day someone who is vegan should try to get a variety of grains and beans that complement each other. Vegans should consistently ensure they are eating good sources of plant protein.
Some great, minimally processed sources of protein include:
Tofu
Beans
Lentils
Peas
Nuts
Seeds
Plant-Based ‘Meats’: Yay or Nay?
Plant-based meats are becoming more and more popular as a convenient alternative for those transitioning away from animal products. However, they often contain processed ingredients and may not offer the same health benefits as whole plant foods; moderation is key.
“Many people want to ensure they are getting only these minimally processed foods, but if your lifestyle is complex and busy, these foods can be time-consuming,” says Nix. “While it’s less ideal, healthwise, the busy vegan may opt for some plant-based ‘meat’ products that may help with time or family tastes."
These options may not provide all the same health benefits as eating whole plant foods, but they are still a more planet-friendly option than meats.”
“While it’s less ideal, healthwise, the busy vegan may opt for some plant-based ‘meat’ products that may help with time or family tastes.”
“Some of the plant-based meat alternatives are fortified with essential nutrients, such as iron and vitamin B12, which are important for those following a plant-based diet,” says Sheth. “However, there are quite a few choices and it's important to read nutrition labels carefully to find those made from high-quality ingredients. Also, enjoy these as part of a well-balanced diet that is rich in plant foods.”
Strategies to Eat More Plant-Forward
When it comes to introducing plant-forward eating, Sheth offers these tips to get started:
Start slow, try one plant-based meal as part of the meal rotation.
Consider doing Meatless Mondays.
Be creative and try new recipes.
Start the day with a smoothie bowl (see image below), followed by lentil soup and salad for lunch, and a tofu and vegetable stir fry served over quinoa for dinner.
For snacks, enjoy some veggies with hummus or fruit with some nuts.
Transitioning to a plant-based diet can be a rewarding step towards better health. With careful planning, it’s now easier than ever to embrace plant-forward eating thanks to its growing popularity as the “it” diet.
*Alina Bradford is a safety and security expert who has contributed to CBS, MTV, USA Today, Reader’s Digest, and more. She is currently the editorial lead at SafeWise.com.
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