A Guide to Vegan Diet
Choosing to embrace a vegan diet requires careful consideration. Carrying out that decision is a thoughtful process as well. The healthy diner—vegan or otherwise—must know something about nutrition in order to plan nourishing and enticing meals. The information in this section will provide you with a wealth of information that you can use to make sound nutritional decisions.
The USDA introduced the food pyramid in 1992 as a graphic depiction of dietary guidelines. The latest version can be found at www.mypyramid.gov, where recommendations are given based on age, gender and activity level. There are specific suggestions in the Tips and Resources section for those following vegetarian diets.
Whatever the guidance, each plan is built on a strong foundation of complex carbohydrates, fruits, and vegetables.
Many of us are familiar with the term RDA, Recommended Dietary Allowance.
This was the intake level of a particular nutrient that was deemed adequate for all the known needs of healthy people. In 1995, this was expanded to incorporate a broader understanding of the role that nutrition has in preventing chronic disease, promoting health and performance.
So the RDA has been replaced by the DRI, Dietary Reference Intakes. This number is comprised of four different reference values and is thought to give more accurate guidelines for nutrients in a wider range of settings and personal circumstances.
In 1997 the American Dietetic Association officially endorsed vegetarian diets,
and vegan diets specifically, as being nutritionally sound and providing health benefits in the prevention and treatment of certain diseases. Vegans take in significantly higher amounts of fiber, vitamin C, potassium, magnesium, vitamin B-6, and folate than even lacto-ovo-vegetarians. A sound vegan diet, however, must be planned to meet specific nutritional requirements. Guidelines for vegans include 6 to 11 servings of grains (including bread, pasta, and cereals); 3 to 5 servings of vegetables; 2 to 4 servings of fruit; and 4 to 5 servings of beans, legumes, seeds, and nuts. The ADA recommends that special attention is paid to getting enough iron, vitamin B-12, vitamin D, calcium, and zinc. Iodine consumption may be a concern as well. While these nutrients may concern dietitians, the question most often asked by those considering changing to a vegan diet is, “Will I get enough protein?”
|What’s in a Serving?|
|For one serving of grain, you might eat . . .||1 slice bread||1⁄2 cup cooked pasta||1 ounce dry or 3⁄4 cup cooked cereal||2 tablespoons wheat germ|
|For one serving of vegetables,
you might eat . . .
|1 cup salad greens||1⁄2 cup cooked vegetable||1 medium carrot||3⁄4 cup vegetable juice|
|For one serving of fruit, you might eat . . .||1 medium orange, banana, or apple||2 apricots or plums||1⁄2 cup cooked or fresh fruit||3⁄4 cup juice|
|For one serving of beans or legumes, you might eat . . .||1 cup soymilk or 1⁄2 cup soft or medium tofu||1 cup lentil soup||1⁄2 cup hummus or cooked beans||2 tablespoons peanut
Getting All You Need
We all know how important proteins are: they build muscle, repair cells, and make the enzymes responsible for basic bodily functions like eating, breathing, and moving.
It is not necessary to consume animal products to get adequate protein into your diet. What many people don’t realize is that they get plenty of protein from grains, beans, and vegetables.
Between 23 and 54 percent of the calories in beans and legumes (lentils and tofu, for example) come from protein.
Spinach is 49 percent protein, and wheat germ, 31 percent. If you are eating enough calories and a varied diet, you are almost guaranteed to be getting enough protein.
Many plant foods, however, do not contain all the essential amino acids, the building blocks of proteins. Most grains, for example, lack the amino acids lysine and threonine, while many beans lack methionine. This is why a varied diet is so important. When all essential amino acids are consumed throughout the day, the body uses the protein more efficiently, meaning that less overall protein needs to be consumed.
The daily reference intake (DRI) of protein is 56 grams for men and 46 grams for women. Pregnant women are encouraged to increase their intake to 50 grams and lactating women to 60 grams per day. Your individual needs may vary depending on your body size and activity level. Considering the rich assortment of foods in the vegan diet, meeting protein needs is a snap.
Most of the iron in our bodies is found in hemoglobin, which ferries oxygen from our lungs to our cells. Anemia results when daily iron requirements are not met and the body’s iron stockpile is depleted. The DRI for iron is 8 milligrams for men and 18 milligrams for women (8 milligrams after menopause). The problem in vegan diets is not the amount of iron consumed, but the amount of iron the body absorbs. While “heme iron” from animal sources is readily absorbed by the body, nonheme iron is much more temperamental. For example, a cup of tea can cut iron absorption by half, whereas a glass of orange juice can increase absorption fourfold. Phytates, chemicals found in whole grains, bind iron so tightly that it is all but unavailable to the body, but vitamin C largely counteracts the action of phytates. Phytates are also destroyed by cooking or fermenting, as in yeast bread.
You probably naturally pair foods that optimize your body’s uptake of iron: cream of wheat with strawberries, five-bean chili with tomatoes, a soymilk smoothie made with pineapple and kiwi, whole grain bread with a slice of tomato. Eating these foods in combination, and saving your coffee and tea for other times, can help your body make efficient use of these iron-rich foods.
This water-soluble vitamin is unique because it is stored in the body. In fact, most of us are walking around with a five-year supply in our livers. Our bodies treat vitamin B-12 as a precious commodity, reabsorbing about 70 percent of what we use every day. (Vitamins are cofactors—they assist in chemical reactions but are not used up by them.) As a result, our vitamin B-12 requirements are very small—perhaps as little as 1 microgram a day, although the DRI is 2.4 micrograms. This is a good thing since neither plants nor animals can synthesize vitamin B-12.
Many plant-based foods—tofu, greens, legumes, seaweed, and tempeh—contain a form of B-12 slightly different from the one our bodies can use. To ensure optimum health, vitamin B-12 should be supplemented in the vegan diet.
The most reliable vitamin B-12 supplement is cyanocobalamin. The cyanide ion stabilizes the vitamin until we put it in our mouths, where enzymes remove the cyanide and attach to the cobalamin. Vitamin B-12 is then escorted through the digestive tract, changing partners along the way until it reaches the small intestine where it can be absorbed. This is why chewable and sublingual tablets are more effective supplements than pills that are swallowed.
You will need to choose a reliable source of vitamin B-12. Fortunately, many common foods are now supplemented. Check the nutrition labels of soymilk, veggie burgers, and breakfast cereals. It’s best if the label specifies cyanocobalamin so you know that you are getting an active form of the vitamin. (When checking nutritional labels on cereals, be sure to read the values for cereal alone, without milk.)
The most fun source of active vitamin B-12 is nutritional yeast. This handy kitchen helper has a toasted, nutty taste perfect for sprinkling on popcorn, stirring into hummus, mixing into lentil stew, or making into the mushroom gravy. Try mixing it with ground almonds and a little salt to make a Parmesan cheese substitute. Nutritional yeast is often used to impart a cheesy flavor (see, for instance, Macaroni and Cheeze, page 193).
Red Star Vegetarian Support Formula (T6635+) is the only brand of nutritional yeast that guarantees the active form of vitamin B-12. Half a tablespoon contains enough vitamin B-12 to meet the daily nutritional needs of two people. As a bonus, you’ll also get zinc, selenium, protein, and the full complement of B vitamins. The yeast is grown on cane and beet molasses and is certified kosher (except during Passover when no yeast may be consumed). For those concerned, Red Star nutritional yeast is inactive and guaranteed to contain no candida Albicans, a yeast that can cause debilitating infections.
If vitamin D worked in corporate America, its title might be CEO of Calcium Uptake and Relocation. There would be branch offices all over the body and corporate headquarters located in the intestines, regulating the absorption of calcium and phosphorus. The central office would then allocate the minerals to the branches for deposit in bones and teeth.
Vitamin D is produced in our skin when we are exposed to sunlight. A light- skinned person can meet vitamin D requirements with just ten to fifteen minutes of exposure two or three times a week in the summer. Darker skin requires up to six times more exposure for similar results. However, smog and sunscreen prevent vitamin D production. In high-fiber diets, the vitamin D found in fortified foods may be ushered right through our system without being absorbed. So even though we could theoretically store enough vitamin D in the summer to carry us through a long, dark winter, it’s best to look for supplementation.
While rickets is not as common as it once was, this vitamin D deficiency disease is still reported, especially in elders and home-bound individuals. A breakfast of fortified soymilk and granola would start your day off right by providing 5 micrograms, your entire day’s requirement, of vitamin D. Fortified breakfast cereals, are other good bets. If you choose to take a supplement, 200 IU (international units) will provide the 5- microgram requirement. Because vitamin D is fat-soluble and is readily stored in the body, you should be very careful not to exceed the Tolerable Upper Intake Level (UL) for Vitamin D, 50 micrograms or 2000 IU. Overloading on vitamin D can cause calcium deposits in soft tissues, including the kidneys (ouch! kidney stones) or the eardrum (which may cause deafness).
Calcium is well known as the builder of strong bones and teeth. But did you know that calcium is also necessary for the transmission of nerve impulses and for muscle movement? The good news is that vegans tend to absorb and retain calcium better than non-vegans do. Some good sources of calcium are green leafy vegetables (kale, mustard greens), tahini, tofu (when prepared with calcium salts), almonds, figs, and sunflower seeds. In addition, there are several calcium-fortified foods that make it easy to meet the RDA of 1,000 milligrams. Most soymilk is enriched with calcium, providing 300 to 400 milligrams in just 1 cup. Tofu processed with calcium salts can provide 300 milligrams in a 1⁄ 2 cup serving.
Some dark leafy greens (spinach, beet greens, Swiss chard) contain oxalates that bind calcium (and iron), making it unavailable to the body. Salt, caffeine, and phosphorus can also inhibit the assimilation of calcium. While clearly there is value to spinach, going easy on salt, salty snacks, and caffeinated beverages is a good general practice.
Zinc, a trace mineral, is involved in the metabolism of carbohydrates, proteins, and fats, and the basic processes of bodily repair and maintenance: cell reproduction and tissue growth and recovery. Children have a particularly critical need for zinc in order to maintain normal growth and development.
The USDA’s recommended daily allowance of zinc is 11 milligrams for men, 8 milligrams for women (11–12 milligrams during pregnancy and lactation), and 3 milligrams for toddlers, 5 for children 4 to 8 years old and 8 milligrams after 9 years of age).
Eating foods high in zinc is just the beginning of getting enough. The amount of zinc your body actually absorbs can vary from 8 to 38 percent of what makes it to your belly. The zinc intake of the average person with a diet including animal and dairy products is 8.6 to 14 milligrams per day. In such a diet, 70 percent of the zinc comes from animal sources. Furthermore, with a diet high in animal products and low in fiber, a large percentage of the zinc that is consumed is absorbed.
Plant-based diets, emphasizing whole grains, may actually contain more than the recommended amount of zinc, but much of it is not in a form that the body can use.
Phytates, a compound found in whole grains, and fiber both bind zinc and other minerals, making them inaccessible to the body.
You may say to yourself, “I’ll just keep eating dairy if animal sources are a good source of zinc.” Actually,
a diet high in calcium makes phytates bind minerals more effectively, so Lacto-Ovo vegetarians may need more zinc than vegans.
Zinc lozenges aren’t the answer, either. Zinc is more effectively absorbed in small doses. Large doses of zinc may elevate cholesterol by affecting the balance of LDL and HDL proteins, the bad and good lipo-proteins that regulate cholesterol. Excess zinc can also cause copper deficiency by out-competing copper for its binding sites, which in turn can impair immune function. Besides, many zinc lozenges contain compounds such as mannitol, sorbitol, and citrate that actually bind the zinc, keeping it inaccessible.
Many high-fiber foods contain a correspondingly high amount of zinc, so while much of the zinc isn’t available, a reasonable amount makes it to the bloodstream. Also, phytates are fairly easy to circumvent. Cooking and fermentation destroy phytates, making the zinc available to the body. So yeasted whole grain bread are excellent sources of zinc. Only 5 percent of the zinc may be absorbed from an unprocessed whole grain cereal, but once two-thirds of the phytates are destroyed through fermentation, 20 percent of the zinc is absorbed. Some cereals also may be malted, increasing the availability of the minerals in the grains. Fermented soy foods— miso, tempeh, soy sauce—are good sources of trace minerals with high bio- availability.
To be safe, the USDA is now recommending that vegetarians get one-and-a-half times the RDA of zinc—making the requirements 22 milligrams for men, 18 milligrams for women, and 15 milligrams for children—since we don’t know precisely how the body handles zinc from plant sources. What a great excuse to eat some of the great- tasting and satisfying foods high in zinc.
Since the introduction of iodized salt in 1924, little notice has been given to this essential trace mineral. The incidence of endemic goiter, an iodine-deficiency disease, had dropped dramatically in this country. Infant formulas were supplemented with iodine beginning in the 1960s. Iodized oils have been introduced in countries where salt isn’t commonly used. The RDA for iodine, set at 150 micrograms, is well below the 250 and 170 micrograms that American men and women, respectively, consume every day.
All was quiet on this salty front until the USDA was deciding whether foods containing soy proteins could make special health claims. Soy contains compounds that can prevent the body from using iodine, an integral part of thyroxin, a thyroid hormone that helps regulate your body’s energy usage.
After careful consideration, the USDA observed that no link has been demonstrated between soy consumption and thyroid disorders, as long as sufficient quantities of iodine are included in the diet. Persons with low thyroid function or marginal iodine intake may want to consult a doctor, dietitian, or nutritionist.
Raw flaxseeds also contain a substance known to inhibit the use of iodine by the thyroid. Cooking inactivates these compounds, so baked goods containing flaxseeds are not a cause for concern. It is advised that no more than 3 tablespoons of raw flaxseeds be consumed each day.
The most secure way to address these health concerns is to make sure you are eating an iodine-rich diet. One-half teaspoon of iodized salt provides 200 micrograms of sodium or 133 percent of the RDA. Sea vegetables have very high levels of iodine—and they are tasty, too. Kelp powder is widely available in natural foods markets. Gomaiso, a Japanese blend of seaweed and sesame seed, can be found in Asian markets.