Some scientists believe that some diets (such as the standard American diet) are detrimental to health, and they believe that a vegan diet represents an improvement, in part because vegan diets are often high enough in fruit and vegetables to meet or exceed the recommended fruit and vegetable intakes. According to the American Dietetic Association and Dietitians of Canada, diets that avoid meat tend to have lower levels of saturated fat, cholesterol, and animal protein, and higher levels of carbohydrates, fiber, magnesium, potassium, folate, and antioxidants, such as vitamins C and E, and phytochemicals.
People who avoid meat are reported to have lower body mass index. From this follows lower death rates from ischemic heart disease; lower blood cholesterol levels; lower blood pressure; and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer.
The authors of The China Study argue that osteoporosis is linked to the consumption of animal protein because animal protein, unlike plant protein, increases the acidity of blood and tissues which is then neutralized by calcium pulled from the bones. However, just not eating meat isn’t enough; it is recommended that vegans eat three servings per day of a high calcium food, such as fortified soy milk, and take a calcium supplement as necessary. American Dietetic Association has said that “appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases.” Poorly planned vegan diets can be deficient in nutrients such as Vitamin B, Vitamin D, Calcium, Iodine, and Omega-3 fatty acids.
A 2006 study found that in people with type 2 diabetes a low-fat vegan diet reduced weight, BMI, cholesterol, and LDL cholesterol and did so to a greater extent than the diet prescribed by the American Diabetes Association.
Physicians Committee for Responsible Medicine recommends what they call the “Four New Food Groups.” They suggest that vegans and vegetarians eat at least three servings of vegetables a day, including dark green, leafy vegetables such as broccoli, and dark yellow and orange such as carrots; five servings of whole grains (bread, rice, pasta); three of fruit; and two of legumes (beans, peas, lentils).
