Designing a nutritionally balanced vegetarian diet can be challenging because some essential nutrients are found primarily in meat sources. Oysters, beef, lamb and poultry, for example, are rich in zinc. Iodine, found in fish and seafood, is another micronutrient that might be lacking in a vegetarian diet. With careful meal planning and attention to detail, it is certainly possible to obtain adequate amounts of these micronutrients from a vegetarian or even a vegan diet.
Iodine for Heath
Iodine is essential for the production of thyroid hormone. Your body cannot make iodine, so it must be obtained from your diet. Iodine deficiency may cause enlargement of the thyroid gland in the neck, a condition known as a goiter. Low thyroid hormone levels, known as hypothyroidism, affect every organ system in your body and cause your metabolism to slow. You may have trouble staying warm and become fatigued easily. Your mental functioning may be affected and you may have difficulty concentrating or feel depressed. Digestion slows as well, often leading to constipation. Iodine is critical to growth and development; iodine deficiency is a leading cause of mental retardation among populations with low iodine consumption. Low iodine intake in pregnant women can birth defects, including hearing and speech problems, mental retardation and cretinism, a condition marked by short stature and brain damage. Adults need 150 micrograms of iodine each day to meet the recommended dietary allowance established by the Institute of Medicine. During pregnancy and while breast-feeding, women need to increase their iodine intake to 220 micrograms and 290 micrograms daily, respectively.
Iodine for Vegetarians
Iodine is essential for maintaining good health and is especially important during pregnancy. While meat and seafood are rich sources of iodine, vegetarians can get ample amounts of this element from non-meat sources. Dairy products and eggs contain significant amounts of iodine. Eight fluid ounces of milk provide 56 micrograms of iodine, more than one-third of the recommended dietary allowance for adults. Individuals who do not eat any animal products can choose iodine-rich plant foods, such as potatoes and beans. One medium baked potato with the peel provides 60 micrograms of iodine and a 1/2-cup serving of navy beans contains 32 micrograms. It is important, however, to be aware that the iodine content of plant foods fluctuates, depending on the amount of iodine in the soil in which they were grown. Seaweed is another excellent plant source of iodine, containing up to 4,500 micrograms of the element in a quarter of a cup of dried plant matter. Although the amount of iodine in seaweed varies, depending on the type and source of the seaweed, do not overdo it with seaweed. The safe upper limit of intake for iodine is 1,100 micrograms daily; excess consumption may cause thyroid problems.
Most people in developed nations consume iodized salt. In the United States, a gram of iodized salt contains approximately 45 micrograms of iodine. Unless you have been advised to adhere to a low-salt diet, using iodized salt in your cooking is a good way to boost your consumption of this micronutrient. Talk to your doctor if you have concerns about your iodine intake or your thyroid hormone levels. Blood tests help your doctor assess your thyroid function and whether you need additional iodine. Supplements are available for individuals who struggle with iodine deficiency.
Zinc from Plant Sources
Zinc is an essential mineral that plays important roles in cell formation and metabolism, wound healing and normal growth and development. It also supports immune function and deficiency has been associated with higher rates of pneumonia and infectious diarrhea. Zinc may help protect the eye from cell damage that results in age-related macular degeneration, a leading cause of vision loss worldwide. Zinc is a component of many enzymes and is involved in numerous metabolic processes. The recommended dietary allowance for zinc is 11 milligrams for adult males and 8 milligrams for adult females. During pregnancy and breast-feeding, women need 11 milligrams and 12 milligrams, respectively.
Approximately 45 percent of the zinc in the typical American diet comes from meat, poultry or seafood. However, grains, grain products, nuts, beans and legumes are good non-meat sources of the mineral. A 1/2-cup serving of baked beans provides 1.7 milligrams and 1 ounce of dry, roasted cashews contains 1.6 milligrams. Lacto-ovo vegetarians can boost zinc intake with yogurt and cheese; these add approximately 1.6 and 1.2 milligrams of zinc per serving, respectively. If you are concerned that your zinc intake may be too low, ask your doctor whether zinc supplements are right for you.
An eight-week study by the U.S. Department of Agriculture of women following a carefully designed, zinc-rich vegetarian diet found that zinc absorption is another critical factor for vegetarians to consider. The work was published in the "American Journal of Clinical Nutrition" in March 1998. Plant foods that provide zinc are often high in fiber and phytic acid. Although these components are beneficial for overall health, they reduce the intestinal absorption of certain minerals. Consumption of a lacto-ovo vegetarian diet led to a 21 percent reduction in zinc absorption compared to a nonvegetarian diet. There is some good news for vegetarians, however; the body seems capable of adapting well to different sources of zinc. Study participants maintained zinc balance on the lacto-ovo vegetarian diet. In other words, they consumed enough zinc to balance the amounts lost in urine, sweat and other bodily fluids, and did not develop a deficiency.
- Linus Pauling Institute: Oregon State University: Iodine
- USDA; Vegetarians, Watch Your Zinc!; March 1998
- National Institutes of Health Office of Dietary Supplements; Zinc; June 2011
- American Thyroid Association: Iodine Deficiency
- "American Journal of Clinical Nutrition"; Zinc Absorption, Mineral Balance and Blood Lipids in Women Consuming Controlled Lactoovovegetarian and Omnivorous Diets for 8 Weeks; J.R. Hunt, et al.; 1998
- National Institutes of Health Office of Dietary Supplements; Iodine; June 2011