Adopting a vegan, vegetarian, or lacto-ovo vegetarian diet significantly lowers the risk of developing cancer, heart disease, and dying prematurely from cardiovascular disease, according to a comprehensive new analysis spanning over 20 years of research.
An umbrella review, which synthesizes findings from multiple meta-analyses to offer a broad perspective, revealed these benefits. The analysis showed that such diets not only reduce cardiovascular risk factors like blood pressure and cholesterol but also offer protective effects against specific cancers, including liver, colon, pancreas, lung, prostate, bladder, melanoma, kidney, and non-Hodgkin lymphoma.
“Reducing salt intake can decrease CVD deaths and reduce the occurrence of cardiovascular events such as heart attacks,” said Dr. Angelo Capodici, lead author and graduate student in health science, technology, and management at Scuola Superiore Sant’Anna in Pisa, Italy.
Vegetarian diets exclude all animal flesh, while lacto-ovo vegetarian diets include dairy products and eggs but exclude meat, poultry, and fish. Veganism, the strictest form, excludes all animal products and by-products.
However, the study authors warned that the health benefits of these diets could be undermined by poor dietary choices. “Diets that emphasize unhealthy plant foods, such as fruit juices, refined grains, potato chips, and sodas, might negate the health advantages of a plant-based diet,” said Dr. Federica Guaraldi, coauthor and medical director at the IRCCS Institute of Neurological Sciences of Bologna in Italy.
Guaraldi pointed out that fruit juices, often high in sugars or sweeteners, can have a detrimental impact on metabolism, sometimes even more than white sugar.
Researchers have long observed that individuals on plant-based diets tend to lead healthier lifestyles, often incorporating regular exercise and avoiding sugar-sweetened foods and beverages, refined grains, snacks, alcohol, and tobacco. However, lifestyle factors alone do not account for the health benefits seen with plant-based diets.
“What is attributed to diet here may be in part due to other lifestyle practices,” noted Dr. David Katz, a preventive and lifestyle medicine specialist who founded the nonprofit True Health Initiative. Despite this, he affirmed that the net effect of plant-predominant dietary patterns is favorable to health outcomes.
A recent study on twins by Christopher Gardner, coauthor of the umbrella analysis, showed that even without additional exercise, adopting a vegan diet yielded significant health benefits. Over an eight-week period, healthy twins on a vegan diet experienced lower LDL cholesterol, better blood sugar levels, and greater weight loss compared to those on a diet including meat and vegetables.
The nutritional advantages of plant-based diets are attributed to high levels of vitamins, minerals, antioxidants, and anti-inflammatory substances found in plants, coupled with reduced intake of inflammatory elements present in meat and processed foods.
“Plants have more fiber, less saturated fat, and zero cholesterol, while animal foods contain cholesterol and lack fiber,” Gardner explained. He also highlighted the importance of phytochemicals, unique to plant foods, which play a crucial role in health.
The umbrella review analyzed 48 meta-analyses, focusing on vegetarian and vegan diets excluding meat, poultry, and seafood. It considered lacto-vegetarian, ovo-vegetarian, and lacto-ovo-vegetarian diets but excluded diets like pesco-vegetarian and pollo-vegetarian that include some animal products.
Findings indicated that plant-based diets significantly reduce the risk of cardiovascular disease, diabetes, and inflammation, positively affecting factors such as body mass index, fasting glucose, and blood pressure.
However, no significant benefits were observed for pregnant women, an intriguing finding that warrants further research. Hormonal changes during pregnancy and potential supplement use could influence these results, noted Guaraldi.
Experts advise that vegetarians and vegans need to ensure adequate intake of certain vitamins and minerals typically found in animal products. Supplements for B12, calcium, iron, zinc, iodine, and vitamin D might be necessary to avoid deficiencies.
“Strictly vegan diets can be deficient in vitamin B12, easily resolved by consuming fortified foods,” Gardner stated. Iron, another challenging nutrient, is present in plant foods like legumes, but supplements can be helpful.
Protein from plant sources includes legumes, nuts, seeds, whole grains, and soy products. While processed meat substitutes are available, they can be high in sodium, so labels should be read carefully.
In summary, embracing a plant-based diet offers substantial health benefits, but careful dietary planning is essential to ensure nutritional adequacy.