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What foods are highest in antioxidants? Answer

Antioxidants can be a vitamin, mineral or phytochemical. Antioxidants can protect cells in the body from damage. Foods that are high in antioxidants are usually easy to identify because they are usually brightly colored. For example, orange vegetables such as carrots contain beta-carotene; red produce such as strawberries and tomatoes contain vitamin C and tomatoes and watermelon contain lycopene.

Phytochemicals are literally plant chemicals. Research has shown that phytochemicals can affect chemical processes in the human body. Consuming foods containing phytochemicals may reduce the risk of developing certain cancers as well as heart disease. Fruits and vegetables are usually high in phytochemicals. Diets rich in fruits, vegetables, whole grains and beans appear to be the healthiest diets for reducing the risk of cancer and some other serious diseases.

Fruits and vegetables contain both antioxidants and phytochemicals. No one fruit or vegetable contains more important antioxidants than another. It is important to eat a variety of fruits and vegetables to consume a variety of antioxidants and pytochemicals.

Reference: A closer look at antioxidants. (2005). Washington, DC: American Institute for Cancer Research. Retrieved May 14, 2010

Reference: A closer look at phytochemicals. (2001). Washington, DC: American Institute for Cancer Research. Retrieved May 14, 2010

Kristi Chipman, MS, RD, LD

My teenage daughter wants to try a vegan diet. What can I do to make sure she’s getting the nutrition she needs? Answer

The American Dietetic Association (ADA) states that vegetarian diets, including total vegetarian or vegan diets, are nutritionally adequate if planned appropriately. Vegetarian diets do not include meat, poultry, seafood, or products containing these foods. Eight nutrients that are important for vegetarians to monitor include protein, n-3 fatty acids, iron, zinc, iodine, calcium, vitamin D and vitamin B-12.

Protein: Protein from plants can meet a person’s protein requirements and provide all the essential amino acids necessary for a healthy person. Complementary proteins do not need to be consumed in the same meal. When a person does not consume any animal protein and the diet is low in protein, lysine should be monitored. Since cereals tend to be low in lysine, it is important to increase beans and soy products or increase dietary protein from all sources to ensure an adequate intake of lysine.

n-3 Fatty Acids: Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are fatty acids that are important for cardiovascular health and brain and eye development. EPA and DHA are mainly found in fish and eggs. Vegetarians, especially vegans, who do not consume these products may have low intakes of n-3 fatty acids and tend to have lower n-3 fatty acid bloods levels than nonvegetarians. The conversion of α-linolenic acid (ALA), a plant-based n-3 fatty acid, to EPA is less than 10 percent in humans and the conversion of ALA to DHA is considerably less. To help with n-3 fatty acid intake, vegetarians can consume soy milk and breakfast bars that are fortified with DHA. ALA sources include flaxseed, walnuts, canola oil and soy.

Iron: Iron is the key component of metabolism. Heme (iron containing compound) is part of hemoglobin, which is used to transfer oxygen throughout the body. Nonheme iron is found in plant foods. Nonheme iron absorption is inhibited by phytates, calcium and the polyphenolics in tea, coffee and cocoa. Nonheme iron absorption can be enhanced by vitamin C. Because of the bioavailability of iron found in vegetarian diets, the recommended iron intake for vegetarians is 1.8 times that of nonvegetarians.

Zinc: Zinc plays a role in growth and development as well as a person’s immune response. Due to the higher phytic acid content of vegetarian diets, the bioavailability of zinc from vegetarian diets is lower than that from nonvegetarian diets. Zinc sources include soy products, legumes, grains, cheese and nuts. Citric acid may enhance zinc absorption.

Iodine: Iodine is essential for normal thyroid function. Some studies suggest that vegans, who do not consume iodized salt or sea vegetables, may be at risk for iodine deficiency, because plant-based diets are usually low in iodine.

Calcium: Calcium is important for bone health. Calcium intakes of vegans tend to be lower than nonvegetarians as well as lacto-ovo-vegetarians. Many vegans find it is easier to meet calcium needs if calcium-fortified foods or dietary supplements are consumed. Fortified foods such as fruit juices, soy milk and breakfast cereals contribute significant amounts of dietary calcium for a person following a vegan diet. Oxalates found in foods such as spinach reduce calcium absorption, which makes them a poor source of usable calcium.

Vitamin D: Vitamin D is important for bone health. A person’s vitamin D status depends both on the amount of sunlight a person is exposed to as well as their intake of vitamin-D containing foods. Low vitamin D intakes, low serum 25-hydroxyvitamin D and reduced bone mass have been seen in some vegans who do not consume vitamin D-fortified foods or take vitamin D supplements. Cow’s milk, some brands of soy milk, rice milk and orange juice, as well as breakfast cereals and margarine can be fortified with vitamin D. If sun exposure and intake of fortified foods are insufficient to meet a person’s needs, vitamin D supplements are recommended.

Vitamin B-12: Vitamin B-12 is important for methoinine synthase, an enzyme required for the synthesis of methionine from homocysteine. A buildup of homocysteine has been associated with increased risk for cardiovascular disease. Vitamin B-12 is found in animal products and fortified foods. If a person is a vegan, vitamin B-12 must be obtained from regularly consuming vitamin B-12 fortified foods or a daily vitamin B-12 supplement. There are no unfortified plant foods that contain any significant amount of active vitamin B-12 and fermented soy products are not considered a reliable source of active B-12. Folic acid may mask a vitamin B-12 deficiency. Since vegetarian diets are typically high in folic acid, a vitamin B-12 deficiency may go undetected until neurological signs and other symptoms begin to develop.

Reference: Craig, W & Mangels, A. (2009). Position of the American Dietetic Association: vegetarian diets. Journal of the American Dietetic Association, 109 (7), 1266-1282.

Kristi Chipman, MS, RD, LD

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