SCIENTIFIC UPDATE
A Review of Recent Scientific Papers Related to Vegetarianism
Is There a "Vegetarian" Personality?
Are vegetarians and non-vegetarians similar in terms of personality traits and political views? That's what a German study of approximately 5,000 adults set out to investigate. In the first part of the study, participants were given a definition of vegetarian (do not eat meat or fish) and vegan (do not eat any product of animals) and asked if they were vegetarian or vegan. Using these definitions, 2.7% were vegetarian or vegan. In the second part of the study, another group, which included some people from the first study, was asked if they "predominantly or exclusively followed a vegetarian or vegan diet." Using these more lax criteria, 6% were classified as vegetarian or vegan. In both parts of the study, people classified as vegetarian or vegan were more likely to report openness, meaning a willingness to try new things. The vegetarians and vegans in the first part of the study were more likely to be interested in politics than the non-vegetarians. The non-vegetarians in both parts of the study were more likely to be politically conservative.
Pfeiler TM, Egloff B. 2018. Examining the "Veggie" personality: Results from a representative German sample. Appetite. 120:246-255.
Why Do Some People Stop Being Vegetarian or Vegan?
Little is known about factors that may help to predict who will stay with a vegetarian/vegan diet and who will lapse. Canadian researchers examined 1,313 current and former vegetarians and vegans in the U.S. There were 1,102 people who identified as former vegetarians and vegans and 211 who said they were currently vegetarian or vegan. Study participants were asked questions, including about their original motivation for becoming vegetarian or vegan, whether they craved meat, the extent of social support for their diet, and whether they felt their diet was convenient. Lapsed vegetarians and vegans were more likely to be politically conservative, report they did not have social supports, and have an initial motivation to be vegetarian/vegan that was not related to concerns about animals or the environment. Other factors, such as education level, meat cravings, and perceived inconvenience of being vegetarian/vegan, did not have a significant effect on the likelihood of stopping being vegetarian/vegan. The study authors propose that educating people about the benefits of a vegetarian/vegan diet for animals and the environment could be a way to motivate them to continue to follow a vegetarian/vegan diet. They also suggest that increasing social support for vegetarianism, such as emphasizing that others are eating less meat, could be a practical first step in encouraging people to stay vegetarian/vegan.
Hodson G, Earle M. 2018. Conservatism predicts lapses from vegetarian/vegan diets to meat consumption (through lower social justice concerns and social support). Appetite. 120:75-81.
What Do Vegetarians Eat?
We know the foods that vegetarians and vegans don't eat, but we may not be as certain about what they do eat. A recent large study of almost 200,000 middle-aged adults in the UK compared food choices of meat-eaters, vegetarians, and vegans. Study subjects' diets were determined based on their responses to a survey. Vegetarians (3,870 people) did not report eating meat or fish; vegans (248 people) did not report eating meat, fish, eggs, or dairy products. The researchers observed that vegetarians did not simply replace meat with other high-protein foods but that they ate a large variety of plant foods. Vegetarians and vegans ate more vegetables, fruits, whole-grain pasta, brown rice, dried beans, nuts, and breakfast cereals than did meat-eaters. The vegetarians and vegans consumed fewer fried potatoes and sugary drinks. Vegetarian men and women and vegan men had lower alcohol intakes than meat-eating men and women. Vegans got 2-3% of their calories from plant milks and 10% of their calories from dried beans, nuts, and vegetarian products such as tofu and soy burgers. In contrast, vegetarians got 11-14% of their calories from dairy products and eggs and 6-7% from dried beans, nuts, tofu, and soy burgers. Meat-eaters got 13% of calories from meat and fish and 11% of calories from dairy products and eggs. These differences among groups may help to explain the lower rates of a number of chronic diseases among vegans and vegetarians.
Bradbury KE, Tong TYN, Key TJ. 2017. Dietary intake of high-protein foods and other major foods in meat-eaters, poultry-eaters, fish-eaters, vegetarians, and vegans in UK Biobank. Nutrients. 9(12). pii: E1317.
Italian Society of Human Nutrition Issues Position Paper on Vegetarian Diets
Approximately a year ago, we reported that the Academy of Nutrition and Dietetics (AND), the world's largest organization of food and nutrition professionals, had published a new position paper about vegetarian diets. This position paper has been joined by a position paper from the Italian Society of Human Nutrition, a non-profit scientific organization. The Italian position paper was developed to provide the Italian public with sound advice about vegetarian diets. It provides current information about nutrients, including vitamin B12, calcium, iron, zinc, and vitamin D. The overall conclusion of the position paper is that "vegetarian diets that include a wide variety of plant foods, and a reliable source of vitamin B12, provide adequate nutrient intake." The paper encourages government agencies and other groups to provide more educational resources about vegetarian diets for Italians.
Agnoli C, Baroni L, Bertini I, et al. 2017. Position paper on vegetarian diets from the working group of the Italian Society of Human Nutrition. Nutr Metab Cardiovasc Dis. 27:1037-1052.
Biotin - Too Much Can Affect Lab Tests
The U.S. Food and Drug Administration (FDA) recently issued a safety alert about biotin supplements. Biotin, also called vitamin B7, is found in many multivitamins, as a stand-alone supplement, and in some supplements promoted as having hair, skin, and nail benefits. While there's usually no problem with taking a daily dose of biotin of 30 micrograms (0.03 milligrams), higher doses have been shown to interfere with some lab tests, causing falsely high or falsely low results. The kinds of lab tests affected include tests used to diagnose heart disease and some tests of hormone levels. Currently, the FDA does not have information about how long you should wait after taking a biotin supplement before having a lab test done.
When I heard about this safety alert, I checked my vegan multi-vitamin and learned that it contains 100 micrograms of biotin. I'll be looking for a new supplement. If you are taking biotin supplements or supplements containing biotin at levels above 30 micrograms (0.03 milligrams) per day, be sure to tell your health care provider. In fact, it's smart to inform your health care provider about any supplements that you use.
Food and Drug Administration. Biotin (Vitamin B7): Safety Communication - May Interfere with Lab Tests. https://www.fda.gov/Safety/MedWatch/Safety Information/SafetyAlertsforHumanMedicalProducts/ucm586641.htm. November 28, 2017.
What Aren't Adults in the USA Eating? Vegetables and Fruits
Dietary guidelines in the United States call for healthy adults to eat the equivalent of 2-3 cups of vegetables and 1 1/2 to 2 cups of fruit a day. It may help to picture a piece of most fruits as being equivalent to a cup of fruit. For more information about what counts as a cup of fruit, see https://www.choosemyplate.gov/fruit.
Overall, approximately 1 out of 8 adults meets the fruit recommendation, while fewer than 1 out of 10 adults meets the vegetable recommendation. These results are based on a survey of almost 320,000 adults living in the United States. Women, adults aged 51 and older, and those with higher income were most likely to meet the vegetable recommendation, while Hispanics, women, and people aged 31-50 were most likely to meet the fruit recommendation. West Virginia had the lowest percentage of people meeting the vegetable and the fruit recommendations. The District of Columbia had the highest percentage meeting the fruit recommendation, and Alaska had the highest percentage meeting the vegetable recommendation. Overall, the vast majority of adults in the United States are not eating enough vegetables and fruit.
Lee-Kwan SH, Moore LV, Blanck HM, Harris DM, Galuska D. 2017. Disparities in state-specific adult fruit and vegetable consumption - United States, 2015. MMWR Morb Mortal Wkly Rep. 66:1241-1247.
