Nutrition Hotline

By Reed Mangels, PhD, RD

Thirty-five years ago, scientific research about vegetarian diets was limited; research about vegan diets was even less common. In 1982, 48 articles related in some way to vegetarian nutrition were published in scientific and medical journals; six mentioned vegan diets. The vegan articles had titles like "Rastafarianism and the Vegans Syndrome" and "Vitamin B12 Deficiency in Vegans" and were mainly concerned with getting adequate amounts of nutrients on a vegan diet. Over the next 35 years, much more research was conducted on people choosing vegetarian diets and more attention was paid to the health benefits of vegetarian and vegan diets. In 2016, 75 articles were published about vegan diets and 176 about some aspect of vegetarianism. Many of these articles focused on the use of vegetarian and vegan diets to prevent and treat chronic diseases like obesity, heart disease, and diabetes.

The limited attention paid to vegan and vegetarian diets 35 years ago is reflected in the first edition of Dietary Guidelines for Americans, which was in effect in 1982 and made no mention of vegetarian or vegan diets.1 In contrast, the most recent Dietary Guidelines for Americans 2015-2020 endorses "a healthy vegetarian eating pattern" as one of three "healthy eating patterns that can be adapted based on cultural and personal preferences."2 The past two editions of Dietary Guidelines for Americans have included vegetarian and vegan adaptations of USDA food patterns.2,3 It's clear that increased research on vegetarian diets and increased interest has led to policy changes on the national level. There have been changes in nutrition research in general over the past 35 years. Some changes affect the way we think about nutrition, others lead to use of different kinds of research, others open up new areas of focus or research interests.

In 1982, researchers were just beginning to explore the importance of fiber in a healthy diet. Research on phytochemicals — naturally occurring chemicals in plants that offer health benefits — was in its early stages. Now we know that there are different kinds of fiber and that some types of fibers can help to prevent heart disease and control blood glucose. We know that there are thousands of phytochemicals. Their beneficial activities include inhibiting cancer cell growth, improving immune response, and preventing DNA damage. Of course, the more prominent plant foods are in your diet, the more likely you are to benefit from their fiber and phytochemical content.

Over the past 35 years, we've seen shifts in nutrition advice. In the 1980s, low-fat diets were the order. Unfortunately, food manufacturers flooded the market with low-fat and fat-free processed foods, where fats were often replaced with sugar. The pendulum swung — the emphasis on low-fat was replaced with an emphasis on low-carbohydrate and high-protein diets. Today, there are calls to avoid or markedly limit sugar.

Nutritional epidemiology was a new area of research in 1982. Epidemiology uses studies of large groups of people to help to understand health and how to prevent diseases. Nutritional epidemiology focuses on people's diets. For example, epidemiologists might ask people about what they're eating today and then follow them to see how their food choices change and whether or not they get common diseases like diabetes over the next 20 or more years. This powerful branch of nutrition research has provided much information about the benefits of vegetarian diets.

Another fascinating area of research that has developed since 1982 is epigenetics. Simply put, epigenetics involves the regulation of the activity of genes. All sorts of factors including food choices, exercise, the environment, and aging can affect gene function. Scientists are studying epigenetics to learn more about causes of cancer, Alzheimer's disease, and other conditions.

Increasingly, nutrition researchers are calling for a more holistic approach to replace the reductionist approach that is commonly used in human nutrition research.4 Instead of focusing on a single nutrient, vitamin A, for example, and examining the effect of this nutrient in isolation, scientists are encouraged to look more at overall patterns of diet and exercise. Since 1982, there has been increased interest in specialized areas of nutrition. There is more research on sports nutrition, including dietary modifications to improve athletic performance and enhance recovery. With the aging of the Baby Boomers comes more research into the effects of diet on aging healthily. The connection between food choices and the environment has become an increasingly common area of research.

The past 35 years have seen big changes in the treatment of many diseases. Cancer treatments are more sophisticated and are targeted at specific tumor types. Gene therapy is on the horizon as a means of treating a number of diseases. Despite many advances in treatment and in nutrition research, some hanges in the health of the American public have not been positive ones. In 1982, about 15% of adults in the United States were obese.5 The most recent report finds that in 2013-2014, 37.7% of adults were obese.6 Childhood and adolescent obesity has also increased from 7% in the early 1980s7 to 17% today.8 Not surprisingly, type 2 diabetes is much more common, as is hypertension.

What is the future of nutrition science? Here are a few thoughts: Over the next 35 years, I expect that we'll see many advances. By 2052, diets may be customized to meet your genetic fingerprint. Tracking devices for exercise and food intake will allow researchers to collect much more information about our diets, lifestyle, and health. More research will be conducted on the effect of prenatal and early childhood diet on chronic disease risk in adulthood. Hopefully these studies will examine the effects of early use of vegetarian and vegan diets. Increased attention will be paid to the connection between diet and the environment. Prevention and treatment of obesity, cancers, heart disease, diabetes, Alzheimer's disease, and other chronic diseases will continue to be areas of active research.

Over the next 35 years, some things will change; some won't. Despite the ups and downs of protein, carbs, and fats, the basis of a healthy diet will remain whole grains, beans, nuts, fruits, and vegetables.


  1. U.S. Department of Agriculture and U.S. Department of Health and Human Services. 1980. Nutrition and Your Health. Dietary Guidelines for Americans. Available at
  2. U.S. Department of Health and Human Services and U.S. Department of Agriculture. December 2015. 2015-2020 Dietary Guidelines for Americans. 8th Edition. Available at
  3. U.S. Department of Agriculture and U.S. Department of Health and Human Services. December 2010. Dietary Guidelines for Americans, 2010. 7th Edition. Available at
  4. Fardet A, Rock E. Toward a new philosophy of preventive nutrition: from a reductionist to a holistic paradigm to improve nutritional recommendations. Adv Nutr. 2014; 15:430-46.
  5. Fryar CD, Carroll MD, Ogden CL. Prevalence of overweight, obesity, and extreme obesity among adults: United States, 1960-1962 through 2011-2012. NCHS Health E-Stats. Available at
  6. Flegal KM, Kruszon-Moran D, Carroll MD, Fryar CD, Ogden CL. Trends in obesity among adults in the United States, 2005 to 2014. JAMA. 2016; 315:2284-91.
  7. Centers for Disease Control and Prevention (CDC). 2011. CDC grand rounds: childhood obesity in the United States. MMWR Morb Mortal Wkly Rep; 60:42-6.
  8. Ogden CL, Carroll MD, Lawman HG, et al. Trends in obesity prevalence among children and adolescents in the United States, 1988-1994 through 2013-2014. JAMA.