13.3: The Difference Between Vitamins and Medicines

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The confusion between the roles of vitamins and medicines is an understandable one. Vitamins were discovered through studying and trying to relieve true deficiency diseases. When the early reports of vitamins appeared, scientists really didn’t understand how they served in body processes. They only knew they made people well. Decades were to pass before questions of their precise functions could be answered—before, for example, anyone knew how B-vitamins did their work as coenzymes.

Yet even the early vitamin researchers realized what the modern public rarely seems to comprehend—that, with few exceptions, vitamins can work their curative magic only when vitamins have been missing from the diet.

Medicines, on the other hand, usually function by causing body changes of their own, changes which are somehow helpful to patients in a disease state. Aspirin and antibiotics are examples. Aspirin can, for example, reduce the inflammatory reactions of arthritis. Antibiotics serve by killing disease-causing bacteria. In doing so, medicines act very differently from vitamins.

Where Medicines and Vitamins Overlap

The confusion between vitamins and medicines is made worse by the overlap in ways certain medicines and large doses of certain vitamins are used. Some medicines are given for the same reason that vitamins are given for a vitamin deficiency. That is, they are used to correct a deficient supply of a normal body chemical. Thyroid hormone is given when the thyroid gland can’t make enough, and insulin is given to diabetics whose pancreatic production of insulin is inadequate.

But note that, like vitamins, such drugs only cure when there’s a deficiency. And when these drugs are used to replace body chemicals, the physician takes care to prescribe only what’s needed. Excesses—as well as deficiencies—of these body chemicals can be hazardous. The same can be said of vitamins.

Vitamins are sometimes prescribed for reasons other than correcting a vitamin deficiency. In these cases, huge doses of water-soluble vitamins are used—water-soluble so that the excess can be excreted in the urine, and a dose that far exceeds the amount the body can use or store as a vitamin.

It’s crucial to keep in mind that, except when used to relieve a true deficiency, the huge dose isn’t being given for its vitamin effect, but rather for a pharmaceutical effect. In other words, most drug-like applications of vitamins have nothing to do with nutritional problems. As an example, a particular form of niacin is used in huge doses to improve blood-cholesterol levels and can have serious side effects. Its role here is as a drug rather than a vitamin.

There are two forms of niacin—nicotinic acid and nicotinamide. Both forms function the same as a vitamin, but huge doses of nicotinic acid (e.g., 2,000 mg/day) can improve blood cholesterol, whereas huge doses of nicotinamide do not. (The adult RDA for niacin is 14 to 16 mg/day.)

Let’s look a little more at this failure to understand that vitamins taken in large doses function as medicines rather than vitamins. Vitamin C is a useful example since it’s taken so commonly in large doses. Vitamin C plays an important role in the immune system, but there’s no good evidence that extra C enhances immunity. Controlled studies have failed to show that large doses of vitamin C are helpful in treating cancer or in reducing the frequency of the common cold.

Some Hazards of Using Vitamins as Medicines

Drugs have side effects, and vitamins used as drugs are no exception. Consider large doses of vitamin B₆. The ease with which excesses are excreted in the urine offers much protection against toxicity, but huge doses—particularly doses of 2000 milligrams or more—can cause permanent nerve damage.

Herbal supplements add to the food-medicine confusion because, for regulatory purposes, they are classified as food rather than drugs, yet are commonly used as medicine.

The special danger of vitamins used as medicine is that vitamins can be purchased freely without prescription. So there’s nothing to keep people from diagnosing and treating themselves—and they do.

In treating themselves, people sometimes get confused as to which form of niacin is the one that works in high doses to improve blood cholesterol, and take the wrong form. Also, many of them fail to understand that in taking large doses they are really taking a drug, rather than a “harmless vitamin,” and have suffered from serious liver damage, as well as milder side effects like flushing of the skin. When physicians use high doses of niacin as a drug, they check and monitor their patients’ liver function.

As with drugs, some of the side effects of large doses of vitamins/supplements are identified only when their use becomes widespread. If only a few people take a vitamin in large doses, their experience doesn’t provide enough of a statistical base to establish that the vitamin supplement is, for example, causing a side effect of a headache, tremor, rash, or kidney stones. It’s only as large doses of a vitamin or certain dietary supplements become popular that previously unknown side effects are uncovered. Most of the side effects of large doses of vitamin B₆ became apparent only as its use became widespread.

Vitamin	Adult RDA	Adult UL
Vitamin A	0.7-0.9 mg	2.8-3.0 mg
Vitamin D	5-15 μg	50 μg
Vitamin B₆	1.3-1.7 mg	80-100 mg
Vitamin C	75-90 mg	1800-2000 mg

*UL is the maximum daily intake that is not likely to have adverse effects.
1000 μg (microgram) = 1 mg (milligram); 1000 mg = 1 gm (gram)

Table 13-1: Examples of Tolerable Upper Intake Levels (UL*)

Health scientists had long advocated that dietary supplements be classified as drugs. They were out-matched by those who sell supplements and those who buy them—billions of dollars worth. This culminated in the 1994 Dietary Supplement Health and Education Act (DSHEA)¹, after which sales of dietary supplements skyrocketed. In effect, DSHEA classifies dietary supplements as food, enabling supplements to be sold without having to prove safety, purity, effectiveness, etc.

Classifying dietary supplements as drugs would mean that, like drugs (e.g., aspirin), they’d have to meet certain standards of purity, safety, etc., and consumers would be warned of side effects.

Dietary supplements include much more than vitamins, of course. More than half the adult population in the U.S. take dietary supplements.² The Food and Drug Administration (FDA) maintains a publicly available database of the labels of more than 71,000 dietary supplements.^3,4

The popularity of supplements began with the view that vitamins are good for you and that we all should play it safe by taking them. Those selling supplements have carefully reinforced this view. What’s the harm in such thinking?

First, because dietary supplements were thought of as “good” and “harmless,” they became stock-in-trade for promotion by shopkeepers, marketers, and others who weren’t licensed to prescribe drugs. Such uses of supplements quickly built up a store of testimonials. It’s well known that many ailments tend to take care of themselves, without medical treatment. Thus, in many cases, when a person recovered after taking a dietary supplement, the supplement got the credit, whether or not any credit was due.

Second, believing that supplements might be the answer to ailments, many people delayed in getting proper diagnosis and treatment. It’s much easier to accept the idea that one has a vitamin shortage or a problem that a supplement might “cure,” than to face the threatening reality of disease. Of course such false reassurance and delay in treatment can be dangerous if medical attention is really needed.

Finally, the popular belief in some or all of these ideas has led people to waste astonishing amounts of money. Using vitamins and supplements in the search for health is too-often pointless. Yet such thinking is now entrenched in our culture: “I’ve been feeling run-down lately; maybe I need some vitamins,” is a lamentably common idea.

Look at some popular websites, and you’ll find vitamin and/or supplement relief suggested for an astonishing array of physical problems—from insomnia to anxiety, from baldness to itches. Yet many of these disorders have only the vaguest relationship, if any, to vitamin chemistry.