January 19, 2017
By: Anna Pashkova, ACSM EP-C
Vegetarian and Vegan Diets
Just last month, the Academy of Nutrition and Dietetics (AND) released an updated position paper on vegetarian diets. The paper explores the nutrition of vegetarian and vegan diets, in various stages of life, in chronic disease, as well as some helpful information for RDNs and NDTRs for clinical practice. The Academy also noted an environmentally beneficial aspect of vegetarian diets.
The position statement of the Academy is as follows:
“It is the position of the Academy of Nutrition and Dietetics that appropriately planned vegetarian, including vegan, diets are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. These diets are appropriate for all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence, older adulthood, and for athletes. Plant-based diets are more environmentally sustainable than diets rich in animal products because they use fewer natural resources and are associated with much less environmental damage.”
As long as calorie needs are met, protein intake in a vegetarian diet is typically adequate and not a nutrient of concern. Additionally, a diet rich in a variety of foods will ensure that all of the essential amino acids are consumed. Legumes and soy products are good sources of protein and other essential nutrients for vegetarians.
Omega-3 Fatty Acids:
Dietary intakes of ALA are similar in vegetarians and non-vegetarians, while EPA and DHA intake is lower in vegetarians. The health effects of the lower intakes are not yet known, although vegetarian children have not shown any issues with vision or mental development and adults continue to have lower risks of cardiovascular disease. It may be a good idea for vegetarians to eat concentrated sources of ALA, which the body converts to EPA and DHA at a low rate, which include various seeds, walnuts and their oils.
The intake is similar between vegetarians and non-vegetarians, although iron stores are much lower in vegetarians. Although this may seem like a bad thing, it could actually be advantageous as higher levels have been “independently associated with a risk of developing metabolic syndrome.” Additionally, plant sources of non-heme iron are absorbed at a lower rate than animal sources, but research highlighted in the position paper shows that vegetarians can actually adapt to absorb non-heme iron more efficiently over time and lower iron losses.
Intake of zinc is similar between vegetarians and non-vegetarians and may be lower in some vegetarians. Serum zinc concentrations are also typically lower in vegetarians, but are still considered to be in the normal range. There haven’t been any noticeable effects of the lower zinc levels, which may be due to the body’s natural ability to adapt to the diet. Some good sources of zinc include legumes, soy products, grains, cheese, seeds and nuts.
Vegetarian diets may be slightly low in iodine, especially in vegan diets. Vegans are recommended to consume iodine-rich foods such as iodized salt or sea vegetables to avoid deficiency. Additionally, women who are vegan and are of child-bearing age are recommended to take supplements of 150 micrograms of iodine per day to avoid a deficiency.
Lacto-ovo-vegetarians generally get enough calcium in their diet, while vegans may vary and sometimes fall below the recommended amount. The bioavailability of calcium in some plant foods is a concern because it can be influenced by oxalate, phytate and fiber, which may reduce absorption of calcium. Several high oxalate foods include spinach, beet greens, and Swiss chard. Because of this, other high sources of calcium should be consumed as well such as low oxalate vegetables including kale, turnip greens, Chinese cabbage, and bok choy. Fortified milks, calcium-containing tofu, and foods such as white beans, almonds, tahini, figs and oranges also contain calcium but at a lower bioavailability.
Levels can vary greatly in vegetarians because of the individual variability in sun exposure, consumption of vitamin D fortified foods and supplement intake. Low vitamin D intakes and low 25-hydroxyvitamin D blood levels have been seen in vegetarians and vegans, more prominently in the winter and spring and also those who live at higher latitudes. Sources of vitamin D fortified food include cow’s milk, some nondairy milks, fruit juices, breakfast cereals. Eggs and mushrooms treated with UV light can also contain vitamin D. Depending on individual factors; it may be beneficial to supplement vitamin D.
Of all nutrients, it may be most difficult to get vitamin B12 in a vegetarian diet because it is not in any plant foods. While there may be some B12 in fermented foods, nori, spirulina, chlorella algae and unfortified nutritional yeast, this may not be adequate. Some options of getting enough B12 include either consumption of B12 fortified foods or supplements. It is best to eat the fortified foods twice per day because of the absorption mechanisms involved. Some examples of fortified food include breakfast cereals, fortified milks, and fortified meat replacements.
For more information on vegetarian diets including the beneficial effects on overweight and obesity, cardiovascular disease, diabetes, cancer, and osteoporosis, as well as recommendations in various life stages and environmental impacts, you can check out the entire position paper article here.