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Megadoses of Vitamins: Healthy or Hype?

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Glancing at the back of multivitamin bottles, energy or health drinks, or vitamin packets, I’m always a bit perplexed. Many of the vitamin and mineral amounts exceed the Recommended Daily Allowance (RDA) and not just by a little. Supplements often provide double, triple, or even upwards of 1,000 to 2,000 percent of our RDA, making me wonder if I’m getting extra-nutrified or overdosed. Yes, we’re used to supersizing our homes, cars, and portions sizes, but should our vitamins necessarily follow suit? Are we preventing disease or wasting money while putting our health at risk?

More Produce, Less Pill
The some-is-good, more-is-better attitude has resulted in a three billion dollar vitamin and supplement industry, which constantly advertises how easy it is to get your vitamins in a pill. Why bother with spinach, oranges, and broccoli when popping a pill gives you what you need? The food industry has also latched on to this trend, augmenting nutrient deficient items, like 7UP, with vitamins.

While it may seem as if augmenting our diet with vitamins is a good thing, there is scant evidence showing that extremely high doses of vitamins do any good at all. And as anyone who’s taken these supplements knows, many of them are merely excreted in our bright yellow urine hours later.

And while no one would dispute that vitamins and minerals are necessary for good health and disease prevention, where we get these necessary nutrients is a case of food versus pharmacology.

Why We Need ’Em
Vitamins and minerals play crucial roles in everyday biological functions. They act as co-enzymes, helping the large proteins responsible for all our biochemical reactions keep doing what they’re doing. The micronutrients assist in tissue repair, bolster the immune system, and help in DNA repair and synthesis. While we associate certain vitamins with certain roles—vitamin C and zinc for our immune system, for instance—they all play crucial roles that are intertwined, connected, and nuanced.

Thanks to fortification of common foods, like milk and bread, diseases like scurvy, beriberi, rickets, and pellagra (all due to vitamin and mineral deficiencies) are rare in the United States and in most developed countries.

In fact, the American Dietetic Association states that because of the diversity and quality of the American diet, most of us can, by eating a range of foods, get all the nutrients we need. Individual pills cannot recreate the multitude of beneficial compounds—some of which haven’t even been identified yet—found in fruits, vegetables, and whole foods like grains, nor can they supplant the fiber, protein, or micronutrients found in these foods. Most scientists agree that food is the best and the most bioavailable (better absorption and utilization) source of nutrients.

Disease Prevention
Yet there are still those claims that supplementing one’s diet with certain nutrients can prevent cancer, heart disease, and other diseases and there has been research to support some of these claims. In 1993, two large epidemiological studies showed an association between high levels of vitamin E intake and reduced risk of heart disease.

Other studies, looking at things like selenium, vitamins C and E, and certain antioxidants like lycopene are inconclusive as to whether they help prevent cancer, heart disease, and other ailments. In 2007, a study published in the Journal of the American Medical Association reviewed sixty-eight studies that dealt with antioxidant supplementation—like vitamins A, C, and E—and found that supplementation does not lead to longer lives. However, many studies support the conclusion that eating a diet rich in antioxidants, such as those that incorporate green vegetables, citrus fruits, and orange-and red- colored produce, is associated with a reduced risk of cancer and heart disease.

Adverse Effects
It’s alluring to think that because supplements are on the market and sold in health food stores and pharmacies, they’re safe. But the supplement industry is largely unregulated and many claims made on bottle labels are bogus, if harmless.

However, megadoses of vitamins do have very real consequences. When taken in high potency form, vitamins and minerals act less like a nutrient and more like a drug. This includes negative, and sometimes toxic, side effects.

For instance, fat soluble vitamins (A, E, D, and K), because they are not readily excreted, can be toxic in high amounts. Excess vitamin A can lead to nausea, diarrhea, headache, and scaling skin; at extremely high doses, it can be fatal. However, plant-derived sources, because they contain a provitamin compound, are only made into vitamin A if physiologically necessary; there is no way to overdose on vitamin A from vegetables and fruits.

Water-soluable vitamins used to be considered harmless because our body excreted the excess. However, recent research indicates that high amounts of vitamin B6 can cause nerve damage and that large amounts of vitamin C can cause diarrhea and nausea.

Sometimes megadoses of minerals and vitamins can backfire. Although many people believe that zinc helps the immune system, this claim is unproven. At high doses, like those found in some cold remedies, zinc can actually impair immunity.

Single nutrient supplementation also takes a reductionist approach to getting our vitamins, ignoring the subtle reactions they have with each other. Excess doses of one vitamin may increase or decrease the absorption of others and cause nutritional imbalances.

While taking a multivitamin with normal levels of nutrients isn’t going to hurt, megadosing might. However, some populations can benefit from dietary augmentation. Those with reduced food intake, such as the elderly or those with specific diseases, might not meet their nutritional needs through diet alone. Pregnant women and breastfeeding women may require higher levels of folate, iron, and calcium. Heavy drinkers, smokers, people with malabsorption conditions, and other people with special needs may benefit from supplementation.

While all of the potential effects of high-dose vitamins may sound alarming, it really is good news. No longer do you have to spend money on pills that aren’t doing anything for you. Instead of hitting up the drugstore to pop a pill, you can hit up the farmer’s market to buy an apple. It’s much more fun to swallow.

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