Do You Need Multivitamin/Multimineral Supplements

By Joel Fuhrman, M.D.

Even The Best Diet Can Leave You Low In Certain Nutrients!

Is it true that “an apple a day keeps the doctor away”? Before you answer, remember that the average person in the United States does not eat even one whole serving of fresh fruit or vegetables daily (unless you consider french fries and ketchup a vegetable.) With that in mind, it is not likely that one apple by itself will keep the doctor away. But if Americans began eating at least 4 servings of fresh fruit and at least a pound of vegetables daily to get the antioxidants, vitamins, and minerals they need, it certainly would help keep the doctor away. Then, maybe most doctors could close their offices and become lawyers, pilots, scientists, educators, carpenters, electricians, plumbers... whatever else they truly are passionate about.

Multiple Considerations

There are multiple issues that need to be considered before making thorough and accurate recommendations about the advisability of taking a multivitamin/multimineral supplement (multi).The key questions that I will address are:

  • Should a person eating the standard diet take a multi?
  • Should a person eating a relatively healthy diet take a multi?
  • Who doesn’t need a multi?
  • Besides the cost, what is the downside of taking a multi?
  • What should a person look for when choosing a multi?

Vitamin & Mineral Essentials

There are 13 essential vitamins: vitamin A, vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin, includes nicotinic acid and nicotinamide), vitamin B5 (pantothenic acid), vitamin B6 (pyridoxine), vitamin B7 (biotin, vitamin H), vitamin B9 (folic acid, vitamin M, vitamin Bc), vitamin B12 (cobalamin), vitamin C, vitamin D, vitamin E, and vitamin K.

There are 15 essential minerals. The seven major (more than 100 mg needed daily) minerals are: calcium, phosphorus, magnesium, sulfur, potassium, sodium, and chloride. The eight trace (less than 100 mg needed per day) minerals are: iron, iodine, zinc, selenium, copper, chromium, manganese, and molybdenum.

Should A Person Eating The Standard Diet Take A Multi?

It is well established that Americans eat a nutritionally deficient, disease causing diet. A report entitled “What We Eat in America 2001-2002” from the dietary interview component of the U.S. Department of Health and Human Services’ National Health and Nutrition Examination Survey (NHANES) for 2001-2002 revealed that Americans are significantly deficient in a number of micronutrients, such as vitamin E, C, B vitamins, zinc, carotenoids, folate, and magnesium. The findings of the survey are disturbing given that many consider the Reference Daily Intake (RDI) as already too low to ensure optimal health. The report’s findings stand in sharp contrast with the too often heard statement that one can obtain all of one’s vitamin needs from one’s diet, when the reality is that the vast majority of Americans do not eat healthfully enough to do so.

The American Medical Association (AMA) now advises all adults to take at least one multivitamin per day. This is a reversal of their long-standing anti-vitamin policy, which came about as a result of advances in research on the effects of vitamins. It now appears that people who get enough vitamins may have a lower risk of some common chronic illnesses, such as cancer, heart disease, and osteoporosis.1 Eighty percent of Americans do not eat the recommended five servings of fruits and vegetables daily that are necessary to provide essential nutrients.

We need to get our vitamins and minerals from somewhere. For the vast majority of Americans who eat poorly, a multivitamin/multimineral is a smart first step. Taking a multi is not as good as eating healthfully. Real, nutrient-rich, natural foods supply much more than just vitamins and minerals, and processed foods supply harmful substances that should not be consumed at all. Nevertheless, taking a multivitamin is much better than doing nothing.

Do People Eating Relatively Healthful Diets Need A Multi?

I think they do. Even the high-nutrient, vegan version of my Eat To Live diet is deficient in vitamin B12 (due to the lack of a reliable, natural, dietary source) and on the low side for zinc and selenium. Are these amounts of selenium and zinc sufficient for health? Probably. But a little more on a regular basis would likely be better. The point is that it is easy to be a little low in essential nutrients—especially zinc, selenium, and iodine— unless the diet is extremely well planned. Practicing vegans need a reliable source of B12, so some form of supplementation is necessary to ensure adequate intake.

One difficulty in designing an optimal diet is the fact that the government’s RDI levels used on food labels to establish the Percent Daily Value (DV) for vitamins and minerals were established years ago, and much of the science that governs their determination is soft. Furthermore, the original research focused on preventing deficiency disease, not optimizing long-term health and longevity. The numbers also are biased toward what a decent standard diet would supply. The Recommended Daily Allowance (RDA) levels that were used previously on labels have similar problems.

Recent science suggests that the RDAs and the RDIs for vitamins C, E, and D, magnesium, folate, zinc, and iodine might be too low for optimal health. The bottom line is that for most of these nutrients, the research is poor, and it is still controversial whether adding a multivitamin with some extra nutrients to a good diet is a health advantage or not. I think it is important that those eating healthfully utilize a multivitamin/multimineral in addition to their healthful eating style for reasons I will explain below.

Importance Of Zinc

Diets high in animal products and iodinated salt may supply optimal amounts of B12, zinc, and iodine, but there is overwhelming evidence that as the consumption of animal products increases above minimal level, the risk of developing certain diseases increases and the likelihood of long life decreases. The fact that we can handle small amounts of animal- based foods on a regular basis and large amounts on an occasional basis does not mean that we can handle large amounts on a regular basis. If you want to maximize your health and longevity, you need to be nutritionally sophisticated, putting into practice all that is known about nutritional science in the modern world.That means designing an eating style that contains large amounts of vegetables and little or no animal products. Since this level of animal product consumption is generally too low to maximize B12 and zinc intake, supplementation for these nutrients makes sense.

Vegetarians, vegans, and flexitarians require more zinc, compared with those who regularly consume animal products, because the zinc from animal products is more easily absorbed than the zinc from plant sources.Only about 20% of the zinc present in the diet is typically absorbed by the body. Dietary fiber and phytates found in grains, legumes, and nuts inhibit zinc absorption. Phytates form a highly insoluble complex with zinc that the body cannot absorb, although cooking can reduce the adverse effects of both phytates and dietary fiber on zinc absorption. Still, your body will absorb less zinc from plant sources than from animal sources.

Animal sources of zinc include king crab (3oz.) 6.5mg,broiled sirloin (3oz.) 5.5mg,oysters (3 med.) 2.4 mg, lowfat plain yogurt (8 oz.) 2.2 mg,and light meat chicken (3 oz.) 1.7mg.

Plant sources of zinc include pumpkin seeds (1/4 cup) 4.0 mg, almonds (1/4 cup) 2.0 mg, tofu firm (1/2 cup) 2.0 mg, sunflower seeds (1/4 cup) 1.7 mg, chickpeas (4 oz.) 1.6 mg, steamed spinach (1 cup) 1.4 mg, and frozen peas (5 oz.) 1.2 mg.

The RDI for zinc is 15 mg. It is not easy to design a vegan diet that includes this level of zinc unless you pick the very highest zinc-containing foods (such as beans and pumpkin seeds) and eat lots of them. Clearly, it makes sense for vegetarians, vegans, and flexitarians to take a little extra zinc from a multi.


Zinc Deficiency

Zinc is vital for the healthy working of many of the body’s systems. It is particularly important for healthy skin. It also is essential for a healthy immune system and resistance to infection. The first signs of zinc deficiency are impairment of sense of taste, a poor immune response, and skin problems. Other symptoms of zinc deficiency can include impairment of sense of smell, hair loss, diarrhea, fatigue, impotence, difficulty seeing in the dark, delayed wound healing, growth retardation in children, loss of appetite, and mental lethargy.

Since many of these symptoms are general and are associated with other medical conditions, do not assume they are due to a zinc deficiency. That should be determined with appropriate testing.

Michael Klaper, M.D., Director, Institute of Nutrition Education and Research, Manhattan Beach, CA, who collected blood tests for nutrient levels on hundreds of American vegans for a vegan health study, confirmed that many vegans were low in zinc. Dr. Klaper speculates that zinc deficiency may account for some of the “failure to thrive” vegans. 2 The same results were found with British vegans.3

These tests offer support to my recommendation to take a multivitamin to get a little extra zinc security. Individuals who experience chronic diarrhea should make sure they include sources of zinc in their daily diet and may benefit from zinc supplementation. There are no specific storage sites in the body for zinc, so a regular supply in the diet is required. Men need more zinc than women because male semen contains 100 times more zinc than is found in the blood. The more sexually active a man is, the more zinc he will require.

Importance Of Iodine

Iodine is needed for healthy thyroid function, which regulates metabolism. Both too much and too little iodine can result in abnormal thyroid metabolism. Iodine deficiency during pregnancy and early infancy can result in cretinism (irreversible mental retardation and severe motor impairments).

Iodine is found inconsistently in plant foods, depending on the iodine content of the soil. Food grown near the ocean tends to be higher in iodine. Iodine is consistently found in only a few foods, such as dairy products (iodine solutions used to clean the cows’ teats and the dairy equipment end up in the milk) and seafood (including seaweed).

Hypothyroidism is not usually caused by iodine deficiency in the United States because almost everybody eats lots of iodinated salt in this country. It is more of a problem in Europe where the salt contains less iodine. However, it may be more important to make sure we get sufficient iodine in the United States because there is a legitimate concern about perchlorate contamination of water used on fresh vegetables. Some of the irrigation water used in farmlands in western states is contaminated with perchlorate from rocket fuel. Perchlorate interferes with thyroid function, especially among people with low iodine intakes. This makes it even more important to ensure that iodine levels are adequate.

Symptoms of hypothyroidism or low thyroid function include low energy levels; dry, scaly skin; tingling and numbness in extremities; weight gain; personality changes; forgetfulness; depression; anemia; carpal tunnel syndrome; Reynaud’s phenomenon; and prolonged and heavy periods in women.

Adequate Iodine Intake

The RDI for iodine is 150 mcg per day for an adult. The safe upper limit is about 1000 mcg per day. If you eat some type of seaweed (multiple times a week) or sprinkle kelp or dulse on your salad, you probably will get adequate iodine from the seaweed. However, the availability of iodine from seaweed is variable, and it can provide too much iodine.

Cases of iodine toxicity cited in scientific journals were mostly from excessive amounts of kelp and kelp tablets. Avoid excess intake of iodine, and use kelp sparingly. It makes more sense to just take a small amount of iodine daily in a multivitamin/multimineral. A goiter (enlarged thyroid gland) can be caused by eating both too little and too much iodine.

In the United States, you can get 75 mcg of iodine from 1/4 teaspoon (500 mg of sodium) of iodized salt. But the consumption of excess salt causes elevated blood pressure and increases heart attack risk. These risks seem to me to be too high a price to pay for adequate iodine intake. If manufacturers want to iodinate something, why not iodinate fruit or some other healthful food? We shouldn’t be adding salt—iodinized or not—to anything.

Benefits Of Taking A Multi

The most important reason why a person on an excellent diet still should choose to take a multi is that it is the most convenient way to ensure optimal intake of iodine, selenium, zinc, vitamin B12, and vitamin D.


1. Fairfield KM, Fletcher RH. “Vitamins for Chronic Disease Prevention in Adults.” Scientific Review. JAMA 2002; 287:3116-3126.

2. Klaper, M. Personal communication.

3. Lightowler HJ, Davies GJ.“Iodine intake and iodine deficiency in vegans as assessed by the duplicate-portion technique and urinary iodine excretion.” Br J Nutr 1998 Dec; 80(6):529-35I.  

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