An all-vegan diet for the US would not solve problems, scientists find
Completely switching the United States to a plant-based food system would not be able to support the population's nutritional requirements, according to two animal scientists. Their findings were just published in the Proceedings of the National Academy of Sciences.
Mary Beth Hall, a scientist with the U.S. Department of Agriculture and the U.S. Dairy Forage Research Center, and Robin White, professor of animal and poultry science at Virginia Tech, wrote that converting land now used for animal-based food production to a plant-based foods would mean a 23% increase in total U.S. supply, but the nutritional quality would not be as high. "In all simulated diets, vitamins D, E and K were deficient," they reported. "... In the plants-only diets, a greater number of nutrients were deficient, including [calcium], vitamins A and B12, and EPA, DHA and arachidonic acid."
The scientists also wanted to test the theory that limiting animal-based food consumption would reduce greenhouse gases and enhance food security, according to Food Navigator. They concluded that gas emissions would slightly decrease but not disappear.
According to HealthFocus data, 17% of U.S. consumers aged 15 to 70 currently claim to eat a predominately plant-based diet, while 60% report to be cutting back on meat-based products. Of those who are reducing their intake of animal-based proteins, 55% say the change is permanent, and 22% hope that it is.
People reduce or eliminate animal products from their diet for a variety of reasons. Some want to cut back on cholesterol, others may be concerned about animal welfare, and still others may worry about the effect of animal agriculture on the environment. Whatever the reason, more people are shifting to a vegetarian diet — or a vegan one that includes no animal-sourced products at all. According to a recent Top Trends in Prepared Foods in 2017 report, 6% of the U.S. population identifies as vegan, which is up from just 1% in 2014.
The USDA's Economic Research Service reported last year that the per capita share of calories in the American diet from animal-based and plant-based foods in 2000 and 2010 stayed the same — at 30% and 70%, respectively. Grains were the main contributor to daily calories, followed by added plant-based fats and oils — such as salad and cooking oil, margarine and shortening. Meat, poultry and fish came in third.
It's difficult to prescribe an ideal diet that perfectly balances animal and plant sources since demographics, health status, dietary preferences and restrictions and individual tastes all come into play. Most experts recommend eating a variety of foods from all food groups and limiting calories from sugar, saturated fat and sodium. Their main message is to make sure that total nutritional content is adequate, calories are within reasonable limits and protein requirements are met.
Last December, the Academy of Nutrition and Dietetics released a position paper stating that diets without animal products can be nutritionally adequate and also have far-reaching health and environmental benefits. "Compared to nonvegetarian diets, vegetarian diets can provide protection against many chronic diseases, such as heart disease, hypertension, type 2 diabetes, obesity, and some cancers. Furthermore, a vegetarian diet could make more conservative use of natural resources and cause less environmental degradation," the academy wrote.
Every dietary choice carries environmental implications — from how a product is produced, to its processing and even its packaging — and it's a complex and challenging matter to balance all these elements and manage to be healthy, ethical and green all at the same time.
- Proceedings of the National Academy of Sciences Nutritional and greenhouse gas impacts of removing animals from US agriculture
- Food Navigator Eliminating animal-based food production might not be panacea for improved health