We know that just because some of a nutrient is a good thing, more is not necessarily better. Recent studies of supplemental vitamin E, for example, suggest it may increase the risk of both heart disease and cancer at doses above 400 IU per day.

Vitamin Fortified Everything

If you like the idea of getting plenty of vitamins and minerals every day,
eat foods that are naturally nutritious. Take a multivitamin for added insurance.

By: Dr. David L. Katz*

The era of vitamin-fortified soda has arrived. Coca Cola has introduced Diet Coke Plus: Diet Coke with additions of niacin, vitamins B6 and B12, magnesium and zinc. PepsiCo is scheduled to follow soon with Diet Pepsi containing niacin, vitamins B6 and E, and chromium. We already have Glaucea's "Vitamin Water." Food fortification has clearly crossed into uncharted territory, so I'm here with my compass.

My suggestion is to divide the territory of foods and their nutrients into three -- best, beneficial and balderdash -- and to avoid the last one. I'll define each category shortly, but first some context.

Back in the early decades of the 20th century, many of the most important public health problems of the time were due to micronutrient deficiencies. Fortifying milk with vitamin D to prevent rickets and adding B vitamins to grains to prevent beriberi and pellagra was sensible and effective preventive medicine.

Occasionally we still have opportunities to use nutrient fortification in such a targeted manner to fight illness and infirmity. Inadequate calcium intake is common, and may contribute to osteoporosis risk. So adding calcium to orange juice to help out those who don't drink milk is very reasonable. The same is true of fortifying grains with folate, now that we know the higher levels needed to prevent most cases of neural tube defect -- a congenital anomaly.

But once we leave the realm of using nutrient supplements to treat known deficiencies, the benefits of supplementation are increasingly suspect. Personally, I favor the use of a multivitamin/mineral supplement as an insurance policy for getting nearly optimal levels of all major nutrients each day, and most of my colleagues seem to concur.

We also know that just because some of a nutrient is a good thing, more is not necessarily better. Recent studies of supplemental vitamin E, for example, suggest it may increase the risk of both heart disease and cancer at doses above 400 IU per day. Much the same is true of beta-carotene, which large trials also suggest may increase cancer risk at high doses.

But even if we could say with confidence that more micronutrients are always good, the value of those nutrients is highly dependent on the company they keep in two ways.

First, nutrients interact with one another and exert effects on the body in concert. When we try to isolate the "active ingredient" responsible for the health benefits of any fruit or vegetable, we are actually guessing. It may be there is no one active ingredient that promotes health, but the sum of a food's parts working together. This may explain why our studies of isolated nutrients are so often disappointing.

The other issue is that foods naturally rich in nutrients are markedly different from processed foods used as vitamin vehicles. Imagine the extreme case of putting a multivitamin into chewing tobacco. Such an addition would certainly not eliminate the toxic influences of the delivery system!

Soda is, of course, less extreme in its adverse health effects than tobacco, but nutritionally it has nothing to recommend it. Tossing a few vitamins and minerals into the mix does not meaningfully change that.

Here, then, are my categories for separating foods into a distinct nutritional hierarchy.

The first and best choice is always an unprocessed food that is naturally rich in nutrients. Fruits and veggies are standouts in this top tier.

The second-most beneficial group consists of "functional" foods. These are foods that are fairly nutritious and wholesome to begin with, and then enhanced with nutrients of known and specific value. Good examples are the active cultures/probiotics in yogurt; the vitamin D in dairy products; and calcium added to orange juice. Don't go out of your way to eat the foods in this category, but choosing them won't do you any harm and may do you some good.

The third category -- balderdash -- is where hype, not health, rules. This bottom tier is populated by foods of negligible nutritional value that seek nutritional legitimacy through association with vitamins and minerals. Vitamin-fortified soda belongs here. So do many children's cereals that are really glorified candy (the first ingredient in a cereal grain product should not be sugar!) with added salt and even trans fat. A few vitamins thrown in cannot salvage such a concoction. Steer clear of this entire category.

If you like the idea of getting plenty of vitamins and minerals every day, eat foods that are naturally nutritious. Take a multivitamin for added insurance. But when it comes to health claims for vitamin-fortified soda, my advice is don't swallow them -- or the soda either.

David L. Katz, MD, MPH, FACPM, FACP; Director, Prevention Research Center,

Yale University School of Medicine  and medical contributor for ABC News.

He may be reached at www.davidkatzmd.com.)