People who eat a plant-based diet live longer, have less cancer and heart disease, weigh less, and have healthier diets. They even have a lower carbon footprint. These were the impressive findings from the landmark study Adventist Health Study-2 (first announced at the International Congress of Vegetarian Nutrition at Loma Linda University, Loma Linda, CA., February, 2013).
What’s so special about the Adventist Health Study? AHS-2 is the culmination of more than 50 years of research conducted at Loma Linda University on members of the Seventh-day Adventist religious denomination. The Adventists garnered interest among researchers due to their healthful lifestyle, which includes abstinence from cigarettes and alcohol, and high rates of vegetarianism–35 percent are vegetarian, compared to about four percent in the general population.
Within this group is a wide range of dietary patterns, from strict vegan to non-vegetarian, making this group a researcher’s dream–scientists are able to study the effects of dietary patterns without the impact of other factors, such as smoking and alcohol.
The first Adventist Health Study (AHS-1, 1974-1988) examined risk of cancer and cardiovascular disease among 34,000 people. AHS-2, with 96,000 Adventist participants, was even more ambitious: Beginning in 2002, scientists at Loma Linda University compared the impact of various diet patterns within the same study population, making it one of the most comprehensive diet studies ever conducted. Data was gathered as subjects from all over the U.S. and Canada completed 50-page questionnaires about diet, lifestyle, and health.
MANY FORMS OF PLANT-BASED DIETS
The definition of a plant-based diet is not rigid; it simply means a diet that focuses on plants. Thus, someone who eats small amounts of animal foods can fit within this definition, as can someone who is a strict vegan and eats no animal foods. What makes AHS-2 unique is that scientists examined the effects of different plant-based diets within the study population. The five diet patterns in AHS-2 were broken down as follows:
1. Vegans who eat no animal products
2. Lacto-ovo vegetarians who eat no meat, but do eat eggs or dairy foods or both
3. Pesco-vegetarians who eat fish, but other meats one or fewer times per month
4. Semi-vegetarians who eat meats aside from fish occasionally, but less than weekly
5. Non-vegetarians who eat meats aside from fish at least one time per week
PLANT-BASED EATERS EAT DIFFERENTLY
Until this study, there was little knowledge about the daily intake of plant-based eaters. Gary Fraser, PhD, MPH, who led the AHS-2 research team at Loma Linda University, spoke about the study findings–both published and unpublished–at the Congress. He reported that for many years, researchers were convinced that various types of vegetarian diets were responsible for only moderate differences in health outcome, because there was inadequate research on plant-based diets.
But in AHS-2, “We saw huge differences in food intake among the different vegetarian dietary patterns,” said Fraser. Fraser reported many interesting observations about various dietary patterns, including:
— Plant protein. Soy protein and plant protein intake is much greater in vegans than in non-vegetarians.
— Omega-3 fatty acids. While the omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) intake is much lower among vegans and vegetarians, the plant omega-3 fatty acid ALA (alpha-linolenic acid) is higher in this group (about 2 grams per day), and higher levels of EPA and DHA are found in their body fat, suggesting high intake of plant omega-3s may result in higher levels in the body.
— Saturated fat. Intake is very low in vegans.
— Micronutrients. Beta-carotene and vitamin C intake is much higher in vegans. Vitamin B12 intake in vegans is low, but they often supplement this nutrient. Iron intake is good for vegans through the diet, as they don’t typically supplement this nutrient.
