Vegetarian Diet (Page 2 of 3)

The Vegan Diet

The vegan diet is not recommended for children under 18-years-old, because of the high nutrient demands for growth and the volumes of food which is needed to support metabolism. The nutrients most likely to be deficient in the vegan diet of adults include protein, calcium, vitamin B2, Vitamin B12, iron, zinc, and calories.

The vegan diet must be planned carefully to include adequate amounts of protein. The nine essential amino acids are found in protein-rich foods, such as lean meat, chicken, fish, eggs, milk, cheese, and yogurt. These foods provide all the essential amino acids in the proper ratio for optimal absorption and use. The vegan diet excludes these foods and individuals following this diet must use complementary proteins to obtain the essential amino acids.

Calcium needs are more difficult to meet on the vegan diet than on less restrictive diets that include dairy products. A glass of milk provides 36% of adult RDA for calcium; a cup of legumes provides 12%; and nuts, seeds, and grains provide even less. Daily calcium needs can be met by consuming dark green leafy vegetables, such as mustard greens, beet green, collards, kale, and broccoli. These vegetables are excellent sources of calcium and contain between 50% to 100% of the calcium in a glass of milk (300 mg). Some greens, such as spinach, contain calcium but the mineral is not well absorbed because of other calcium-binding substances, called oxalates, in spinach. Calcium fortified soymilk is the best source of calcium for the vegan. Powdered calcium carbonate can be added to flour for baking or calcium supplements can be taken. A source of Vitamin D also must be identified, since fortified milk is the only reliable source of this essential vitamin.

A main source of Vitamin B2 is dairy products. The vegan must be particularly careful in diet planning to meet daily needs for this water-soluble vitamin. The foods of plant origin in the list below supply approximately the same amount of Vitamin B2 as does one cup of milk (0.395 mg). A minimum of three servings each day should be consumed to meet the adult RDA.

• Avocado 1 medium
• Fortified cereal 1 ounce
• Fresh mushrooms 1-1/4 cups
• Cooked turnip greens 1-1/4 cups
• Winter squash 1-1/2 cups
• Cooked broccoli 1-1/3 cups
• Cooked htmlaragus 1-3/4 cups
• Cooked spinach 1-3/4 cups
• Brussels sprouts 2 cups
• Okra 2-1/4 cups

The only reliable dietary sources of Vitamin B12 are foods of animal origin. A few kinds of algae and some fermented soybean products (i.e. tempeh and miso) are the only plant sources of this vitamin. These products contain varying amounts of Vitamin B12. Vegans should consider Vitamin B12 fortified soymilk or supplements to prevent deficiencies.

Although many foods of plant origin are high in iron, the iron from these sources is not as well absorbed as the iron in meat (called "heme" iron). In addition, the high fiber content of the vegan diet might interfere with optimal absorption of some trace minerals, such as iron and zinc. To increase absorption of iron, the vegan should consume a Vitamin C-rich food with meals, cook in cast iron pots, and include several servings each day of iron-rich foods.

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