New research from the University of Warwick has found that a plant-based diet—which includes fruits, vegetables, whole grains, legumes, nuts and seeds—can lower blood pressure, even if small amounts of meat and dairy are consumed too. Published online in the Journal of Hypertension (July 25, 2020), the study reports that any effort to increase plant-based foods and limit animal products may benefit blood pressure levels and reduce the risk of heart attack, stroke and cardiovascular disease.
The researchers conducted a systematic review of previous controlled clinical trials to compare seven plant-based diets, several of which included animal products in small amounts, to a control diet and their impact on subjects' blood pressure.
"We reviewed 41 studies involving 8,416 participants, in which the effects of seven different plant-based diets (including DASH, Mediterranean, Vegetarian, Vegan, Nordic, high fiber and high fruit and vegetables) on blood pressure were studied in controlled clinical trials," explained lead author Joshua Gibbs, a student in the University of Warwick School of Life Sciences. "A systematic review and meta-analysis of these studies showed that most of these diets lowered blood pressure. The DASH diet had the largest effect, reducing blood pressure by 5.53/3.79 mmHg compared to a control diet, and by 8.74/6.05 mmHg when compared to a 'usual' diet.
"A blood pressure reduction of the scale caused by a higher consumption of plant-based diets, even with limited animal products would result in a 14% reduction in strokes, a 9% reduction in heart attacks and a 7% reduction in overall mortality," Gibbs continued. "This is a significant finding, as it highlights that complete eradication of animal products is not necessary to produce reductions and improvements in blood pressure. Essentially, any shift towards a plant-based diet is a good one."
Added senior author Francesco Cappuccio, professor at the Warwick Medical School: "The adoption of plant-based dietary patterns would also play a role in global food sustainability and security. They would contribute to a reduction in land use due to human activities, to global water conservation and to a significant reduction in global greenhouse gas emission."
The plant-based diets examined included:
- Healthy Nordic diet: Higher content of plant foods, fish, egg and vegetable fat; lower content of meat, dairy, sweets and alcohol
- High-fruit and vegetable diet: Increased consumption of fruit and vegetables; some studies included regular dark chocolate content
- High-fiber diet: Although fiber can be present in all plant foods, it's most prevalent in whole grains and legumes, so most high-fiber diets focus on increasing whole grain and legume consumption
- Lacto-ovo vegetarian diet: These exclude all meat, poultry and fish, but include dairy and eggs. Fruit, vegetables, whole grains, legumes, nuts and seeds are the main components
- DASH diet: Encourages the consumption of fruits, vegetables, whole grains, nuts, seeds and low-fat dairy products, while limiting the intake of sweets, saturated fat and sodium
- Mediterranean diet: Daily consumption of vegetables, fruit, whole grains and olive oil, plus weekly consumption of legumes, nuts, fish, dairy, and eggs, with a limited intake of meat
- Vegan diet: Consists of plant foods exclusively, with no animal flesh or other animal-derived products (including dairy and eggs). It's mostly low fat and focuses on whole plant food consumption, like fruits, vegetables, whole grains, legumes, nuts and seeds
The researchers do point out, that there are often socio-economic challenges to putting this new knowledge into practice, not to mention perceived difficulties like resistance to change and issues with palatability that may affect a person's adherence to any plant-based diet. "To overcome these barriers, we ought to formulate strategies to influence beliefs about plant-based diets, plant food availability and costs, multisectoral actions to foster policy changes focusing on environmental sustainability of food production, science gathering and health consequences," noted Cappuccio.