but poor in omega-3 fatty acids, may contribute to decreased production of EPA and DHA in vegetarians. Apart from fish and eggs, omega-3 fatty acids can be obtained from microalgae, which is now available as a dietary supplement.
The Dietary Reference Intake (IOM, 2002/2005) recommendation for an adequate intake (AI) of 1.6 and 1.1 grams of ALA per day for men and women, respectively, assumes some intake of EPA and DHA to meet targeted omega-3 levels. However, since vegetarians may not consume adequate levels of preformed EPA and DHA from seafood, and ALA is not efficiently converted to EPA/DHA, this recommendation may not be adequate for their needs. The joint World Health Organization/Food and Agriculture Organization Consultation on Diet, Nutrition and the Prevention of Chronic Disease (WHO/FAO, 2003) recommendation of an intake of 5–8 percent of daily calories from omega-6 and 1–2 percent from all omega-3 (EPA, DHA, and ALA) sources also falls short of vegetarians’ needs if an algal source is not included in the diet.
The position of the American Dietetic Association is that vegetarians should include good sources of ALA, such as flaxseed, flaxseed oil, soy, or walnut oil in their diets. In addition, for those with increased requirements, including pregnant and lactating females, direct sources of EPA and DHA such as microalgae should be included in the diet.
The levels of different toxic compounds in seafood vary within and among species due to the chemical properties of the contaminant and the characteristics of the seafood. For example, compounds such as dioxins and polychlorinated biphenyls (PCBs) accumulate in fat tissue and are found predominantly in fatty fish and fish that live in fresh or coastal waters, including striped bass, bluefish, American eel, lake trout, and farmed Atlantic salmon. Heavy metals such as methylmercury accumulate in lean tissue and are found in the muscle tissue of older, predatory fish such as shark, swordfish, king mackerel, and tilefish.
The Food and Drug Administration (FDA) of the US Department of Health and Human Services announced in 2001 its advice to pregnant females and those of childbearing age who may become pregnant on the hazard of consuming fish that may contain high levels of methylmercury. In 2004, the advice was jointly reissued by FDA and the US Environmental Protection Agency (US EPA), and was updated to include the message that seafood makes an important contribution to the diet (US EPA/FDA, 2004).