A diet with clear potential to benefit the environment is still highly contested when it comes to nutrition.
American farmers require 10-16 pounds of grain and 2,5000 gallons of water to produce one pound of beef; and with the same inputs, could grow “16 pounds of broccoli, 25 pounds of potatoes, enough soybeans for three pounds of tofu or enough wheat for nearly five pounds of whole wheat bread”, according the Sierra Club.
And compared to a vegetarian diet, an average meat-inclusive diet required 2.9 times more water, 2.5 times more primary energy, 13 times more fertilizer, and 1.4 times more pesticides, according to a study in the American Journal of Clinical Nutrition. The greatest contribution to the difference? Beef.
The environmental arguments for a plant-based diet seem clear, but eaters have resisted this lifestyle for a number of reasons. For many, it is just a matter of taste: beef is hard to give up. But others, even nutritionists, are hesitant to declare plant-based diets a healthy alternative to those that rely on meat for protein.
Several members of the Department of Agriculture’s Dietary Guidelines Advisory Committee, that influential board of nutritionists behind the food pyramid and its recently updated reincarnation, “Choose My Plate”, have recently discussed advocating the American public increases plant food consumption toward vegetarianism; but researchers at the American Society of Nutrition, the organization that publishes America’s pre-eminent nutrition journals, challenged the prudence of such a suggestion, claiming insufficient literature on the health risks of vegetarianism.
In David R Jacobs Jr,Ella H Haddad, Amy Joy Lanou, and Mark J Messina’s “Food, plant food, and vegetarian diets in the US dietary guidelines: conclusions of an expert panel”, the American Society of Nutrition researchers concluded more research should be done to create a firm scientific base for plant-based diets before the Dietary Guidelines Committee officially endorses meat-free diets.
Barnard biology professor Hilary Callahan argues that this reluctance is unfounded and doesn’t reflect the scientific nutritional knowledge to date: “Really, in our society, where almost everyone has more than enough food, quantity and variety, there is no reason to be concerned about this issue. Even if following a vegan diet, there are plenty of nutrients include protein and the full complement of amino acids”
Calahan labels concerns such as those voiced by the American Society of Nutrition researchers as “a huge and unjustified fixation in US of a vegetarian diet being ‘deficient’”, going on to say that it is “this focus on protein-combining or protein-complementing that makes a vegetarian diet seem difficult to follow”
And this misunderstanding is of particular concern to those who hope vegetarians can help have a positive impact on the environment: “health” is the main reason 53% of America’s vegetarians choose their diet, according to surveys completed by Vegetarian Times. But without the expert backing of the country’s top nutritionists, scores of potential vegetarians may be shying away from the lifestyle.
The Vegetarian Resource Group’s John Cunningham sees the nutritional benefit of vegetarianism is “not really a controversy,” citing a medical study titled “American Dietetic Association Endorses Vegetarian Diets”, published by the American Dietetic Association.
And not only are the keys to a healthy vegetarian diet very similar to recommendations for diets that include meat, vegetarians, on average, have lower average body mass indexes, lower cholesterol, and lower incidences of cancer, and are less likely to die of ischaemic heart disease.
Yet the American dietary guidelines fail to reflect the evidence that an environmentally friendly vegetarian diet can be healthy, if not healthier, than the diet currently suggested. The American Society of Nutrition found that the public had an even less complete understanding of vegetarian diets than academic and research communities, but in withholding their endorsement they appear to be, in part, culpable. Though emphasizing that “information must be transmitted to the public”, the place to start might be at the American Society of Nutrition.