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Getting your vitamins and minerals through diet

JUL 2009

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The benefits of multivitamins are looking doubtful. Can we do without them?

We all know that vitamin supplements are no substitute for a healthy diet, but nobody's perfect when it comes to healthful eating. It can be particularly challenging to get the nutrients you need if you're dieting or if you avoid animal or dairy products. So, many of us take a daily multivitamin as nutritional insurance. But research suggests that multivitamins may not be all they're cracked up to be. Moreover, many multivitamins contain some micronutrients in amounts in excess of those recommended in the government's Dietary Guidelines for Americans (www.health.gov/dietaryguidelines). In some cases, these levels may result in unsafe intakes.

In February 2009, a study involving 161,808 postmenopausal women in the Women's Health Initiative (WHI) concluded that those who took multivitamins did not have a lower death rate than others and were just as likely to develop cardiovascular disease or cancers of the lung, colon/rectum, breast, and endometrium — the kinds that are most common in women. Granted, WHI participants were healthy to begin with, but these results are consistent with findings from other studies. There's been little or no evidence of protection against cardiovascular disease or cancers from a number of vitamin supplements, including vitamin E, vitamin C, beta carotene, and the B-vitamin trio — B6, B12, and folic acid. And in 2006, the National Institutes of Health (NIH) said there wasn't enough evidence for a recommendation about taking multivitamins.

Now research suggesting potential harm has been added to the mix. In 2008, a Cochrane Collaboration review found that people in trials who were given supplements of vitamin A, vitamin E, and beta carotene had a higher death rate. And there's some evidence that excess folic acid (the synthetic version of folate, a vitamin found abundantly in vegetables, fruits, and grains) may be contributing to an uptick in colorectal cancer. Multi vitamins contain the recommended daily amount — 400 micrograms (mcg) — but folic acid is also added to breakfast cereals and enriched grain and cereal products, including breads, rice, and pasta. A person taking a multivitamin can easily exceed the recommended total intake, and maybe even the safe upper limit of 1,000 mcg. (Excess isn't a problem with folate found naturally in foods.)

These findings raise questions about the use of multivitamins as a safety net. Experts agree that the best way to get the nutrients we need is through food. A balanced diet — one containing plenty of fruits, vegetables, and whole grains — offers a mix of vitamins, minerals, and other nutrients (some yet to be identified) that collectively meet the body's needs. Maybe what counts is the synergistic interactions of these nutrients — which might also help explain why trials of single nutrients often don't pan out.

But many of us doubt whether we can get all the nutrients we need from food alone. For one thing, the "percent daily values" featured on food labels are based on a 2,000-calories-a-day diet. Many of us can't eat that much without gaining weight. What if your energy needs are closer to 1,500 calories a day? What if you're dieting? Can you eat enough to take in the recommended micronutrients without falling back on a multivitamin? To find out, we consulted two nutrition experts, clinical dietitian Ellen di Bonaventura, R.D., at Massachusetts General Hospital in Boston, and Helen Delichatsios, M.D., nutrition educator at Harvard Medical School and Massachusetts General Hospital. Dr. Delichatsios is also on the editorial board of the Harvard Women's Health Watch.

Some nutrient-dense foods*

  • Avocados

  • Chard, collard greens, kale, mustard greens, spinach

  • Bell peppers

  • Brussels sprouts

  • Mushrooms (crimini and shiitake)

  • Baked potatoes

  • Sweet potatoes

  • Cantaloupe, papaya, raspberries, strawberries

  • Low-fat yogurt

  • Eggs

  • Seeds (flax, pumpkin, sesame, and sunflower)

  • Dried beans (garbanzo, kidney, navy, pinto)

  • Lentils, peas

  • Almonds, cashews, peanuts

  • Barley, oats, quinoa, brown rice

  • Salmon, halibut, cod, scallops, shrimp, tuna

  • Lean beef, lamb, venison

  • Chicken, turkey

*Foods that have a lot of nutrients relative to the number of calories.

Careful planning and extra D

Both di Bonaventura and Dr. Delichatsios say that a woman can meet her nutrient needs through food alone even if she eats 1,500 calories (or less) per day. "It's not an issue of food quantity but rather food quality. Even a low-calorie diet can have the needed vitamins and minerals," says Dr. Delichatsios. The only exception is vitamin D. Most experts now recommend a daily intake of 1,000 international units (IU), an amount that's difficult to get through foods or sun exposure (unless you live in the lower half of the United States and spend time outdoors). So plan to take a vitamin D supplement.

Getting the rest of your micronutrients through diet requires planning, patience, and knowledge about the foods that will help you meet your daily requirements. Such nutrient-dense foods, as they're called, are packed with vitamins and minerals and have relatively few calories. (See examples above.)

Nutrient-dense foods are the foundation of the sample menu (see box below) that di Bonaventura devised at our request to meet the daily vitamin and mineral needs of a healthy postmenopausal woman consuming 1,500 calories or less a day. "You'd probably eat more salmon on this diet than most people. You'd have an occasional egg, because that's the easiest way to get a lot of vitamins for a low number of calories," says di Bonaventura. Our menu covers all the bases at about 1,200 calories. This leaves some discretionary calories for additional nutrient-dense foods and a treat — say, a piece of chocolate, a dish of sorbet, or a glass of wine. Notice that the menu provides more than 1,200 mg of calcium, the amount recommended for women over age 50 — thanks to the calcium in nutrient-dense foods such as nonfat dairy products and bok choy (Chinese cabbage).

1,200-calorie sample menu that meets the daily DRIs* for a woman 51 to 70 years of age

Breakfast

8 oz nonfat yogurt

½ cup sliced papaya

½ cup sliced kiwi

1 oz (14 halves) walnuts

4 oz skim milk

Lunch

1 small whole-wheat pita

Green salad:

  • 1 cup dark green lettuce

  • 1 red or orange pepper

  • 1 cup grape tomatoes

  • ½ cup edamame beans

  • 1 tbsp. unsalted sunflower seeds.

Salad dressing made with 1 tbsp. olive oil, balsamic vinegar, and pepper

Dinner

4 oz broiled wild salmon and yogurt sauce (1 tbsp. Greek-style nonfat yogurt, 1 tsp. lemon juice, 1 clove chopped garlic)

¼ cup cooked barley and ¼ cup cooked lentils with spices to taste

1 cup steamed baby bok choy

* Dietary reference intakes.

Menu provides 1,155 calories:

  • 33% of calories from fat,

  • 40% from carbohydrate, and

  • 27% from protein

Vitamins and minerals and their amounts in the sample menu, above (DRIs are listed in parentheses)

  • Vitamin A, 1,031 mcg (700 mcg)

  • Vitamin C, 383 mg (75 mg)

  • Vitamin D, 12 mcg (10 mcg)

  • Vitamin E, 11 mg (15 mg)

  • Vitamin K, 156 mcg (90 mcg)

  • Thiamin, 1.3 mg (1.1 mg)

  • Riboflavin, 1.8 mg (1.1 mg)

  • Niacin, 14 mg (14 mg)

  • Vitamin B6, 2.23 mg (1.5 mg)

  • Folate, 556 mcg (400 mcg)

  • Vitamin B12, 10.6 mcg (2.4 mcg)

  • Pantothenic acid, 5.5 mg (5 mg)

  • Calcium, 1,222 mg (1,200 mg)

  • Copper, 900 mcg (1,156 mcg)

  • Iron, 11 mg (8 mg)

  • Magnesium, 355 mg (320 mg)

  • Manganese, 2.8 mg (1.8 mg)

  • Phosphorus, 1,530 mg (700 mg)

  • Selenium, 90 mcg (55 mcg)

  • Zinc, 8.6 mg (8 mg)

  • Potassium, 4.7 g (4.7 g)

Note: Biotin, choline, and chromium are not precisely measured in foods and thus not included in our analysis.

Source: Ellen di Bonaventura, R.D., clinical dietician, Massachusetts General Hospital, Boston, MA.

What you can do

One way to set up a plan that precisely meets your nutritional needs is to work with a registered dietitian, who can take into account your food preferences and allergies or other health issues (such as lactose intolerance). Many dietitians have access to computer programs and databases that ease the most difficult calculations, such as nutrient analyses of menus. You can ask your clinician for a referral (check to see if your insurance covers the cost of nutritional counseling), or ask at a local hospital or medical center. But if you have the time and the inclination to do the work yourself, there are free tools and calculators on the Web that can help. Here are some questions you'll need to ask and some of the Web sites where you can find the answers:

How much of what vitamins and minerals do I need? Most healthy postmenopausal women ages 51 to 70 require the same amounts of vitamins and minerals. The government's nutrient recommendations are called dietary reference intakes (DRIs); these replace the old RDAs, or Recommended Dietary Allowances. The quantities listed on the label of a multivitamin bottle may be more than you need, so don't use them for guidance. Instead, consult the DRI tables found at www.iom.edu/Object.File/Master/21/372/0.pdf.

How many calories do I need? It depends on your age, height, weight, and activity level. You can calculate the number of calories you need per day at several Web sites, including these: www.caloriecontrol.org/healthy_calculators.html, www.calorieking.com/tools, and www.bmi-calculator.net/bmr-calculator. (The last of these Web sites takes a two-step approach, first calculating your basal metabolic rate — the number of calories you'd need if you did nothing but rest — then linking you to a second page that takes your activity level into account.)

What do I eat? For a list of nutrient-dense foods you can incorporate into your meal plan, go to www.whfoods.com/foodstoc.php. To look up the nutrient and calorie content of specific foods — or to find out which foods contain specific nutrients — go to the U.S. Department of Agriculture (USDA) National Nutrient Database for Standard Reference, www.nal.usda.gov/fnic/foodcomp/search. Another good source of information on specific foods (including brand-name and fast-food items) is Calorie King, www.calorieking.com. To get an idea of how much you'll need daily from each of the basic food groups, see the chart below.

Daily amounts of basic food groups meeting recommended nutrient intakes at four different calorie levels

Calorie level

1,200

1,400

1,600

1,800

Fruits+

1 cup

1.5 cups

1.5 cups

1.5 cups

Vegetables+

1.5 cups

1.5 cups

2 cups

2.5 cups

Grains

4 ounce equivalents*

5 ounce equivalents

5 ounce equivalents

6 ounce equivalents

Lean meat and beans

3 ounce equivalents**

4 ounce equivalents

5 ounce equivalents

5 ounce equivalents

Dairy (choose fat-free or low-fat)

2 cups***

2 cups

3 cups

3 cups

Oils

17 g

17 g

22 g

24 g

Discretionary calories

171

171

132

195

+Choose a wide variety of colorful fruits and vegetables.

*1 ounce equivalent = ½ cup cooked rice, pasta, or cooked cereal; 1 ounce dry pasta or rice; 1 slice bread; 1 small muffin; 1 cup ready-to-eat cereal flakes.

**1 ounce equivalent = 1 ounce of lean meat, poultry, or fish; 1 egg; ¼ cup cooked dry beans or tofu; 1 tablespoon peanut butter; ½ ounce nuts or seeds.

***1 cup = 1 cup milk or yogurt; 1.5 ounces natural cheese or 2 ounces processed cheese.

Source: USDA Food Guide, Appendix A-2, Dietary Guidelines for Americans, 2005, www.health.gov/dietaryguidelines.

How do I know if my diet provides what I need? You can track your daily intake and have it analyzed at the USDA's My Pyramid Tracker, www.mypyramidtracker.gov. (This program is free, but you'll need to register first.) Entering everything you eat can be cumbersome, but if you try it for just a few days, you'll learn a lot about food quality and how to get the best nutritional return on the calories you consume. All in all, if you avoid saturated and trans fat, take a daily 1,000 IU vitamin D supplement, and eat a balanced diet — one that contains a variety of colorful fruits and vegetables, whole grains, legumes, and nonfat diary products — you probably don't need a multivitamin on your plate.