Self & Other
14. The Things That Sound Like They Help (But Mostly Don’t)
In 1970, Linus Pauling published a small book called Vitamin C and the Common Cold. Pauling was, at that point, the only person in history to have won two unshared Nobel Prizes — Chemistry in 1954, for his work on the structure of molecules, and Peace in 1962, for his campaigning against nuclear weapons testing. He was one of the most brilliant minds of the twentieth century.
By the late 1960s, Pauling had become convinced that taking very large doses of vitamin C — grams per day, instead of the few dozen milligrams the body actually needs — would prevent and cure the common cold. He proposed that megadose vitamin C could also prevent cancer, treat heart disease, and substantially extend human life. He took eighteen grams a day himself, mixed into orange juice each morning. He argued for it the rest of his life.
The evidence, as it accumulated through the 1970s and 1980s in carefully controlled trials done by other researchers, did not support him. Vitamin C, taken at Pauling’s doses, has at best a small effect on the duration of a cold (perhaps half a day shorter) and essentially no effect on whether you catch one. The larger claims about cancer and longevity could not be replicated. The science settled into a clear picture: real deficiency causes scurvy, small amounts are sufficient, very large amounts are mostly excreted in your urine. People who take megadose vitamin C are, in the most literal sense, manufacturing very expensive pee.
Pauling died in 1994, at ninety-three, of prostate cancer. His admirers said this proved his theory. His critics noted that ninety-three was hardly a victory for someone who had claimed his protocol could push human lifespans toward a hundred and fifty.
The cautionary tale is not that Pauling was a fool. He was not. He was a brilliant person who became personally convinced of a hypothesis and then — like many brilliant people — found it very difficult to update on evidence that contradicted him. The reason we have evidence-based medicine is precisely that any single brilliant person, no matter how brilliant, can be wrong.
This chapter is about things people sometimes recommend for immunity that are not, by the available evidence, doing what they are claimed to. Some are harmless and may produce small effects through mechanisms that are mostly placebo. Some are expensive without being effective. A few are actively dangerous in specific circumstances. The goal is not to mock anyone for buying any of these — the marketing is sophisticated, the cultural pressure is real, and many of the people promoting these products are themselves convinced. The goal is to be honest about what the evidence supports.
Vitamin C, Continued
Since we started with Pauling, we should finish the vitamin C question.
Severe deficiency is real and serious. Sailors used to die of it on long voyages, and the British Navy’s discovery in the 1750s that limes prevented the disease (giving us the slang “limey”) was one of the great early triumphs of evidence-based medicine. If you eat almost no fresh produce for months, you can develop scurvy, and the cure is straightforward: a small amount of vitamin C, far less than the supplements people buy.
In ordinary life, in most wealthy countries, deficiency is rare. Any normal diet that includes fresh fruit or vegetables provides enough. Taking more than the body needs does not allow it to do its job better; the extra is excreted. The exceptions are some specific clinical situations — intensive care patients, malabsorption conditions, extremely poor diets — where supplementation can be appropriate. For ordinary healthy people taking supplements during cold and flu season, the effect is small to nothing.
Some studies suggest that very large doses, taken at the very beginning of a cold, may shorten its duration by a small amount. The effect, if real, is on the order of half a day in a five-to-seven-day illness. Whether that is worth a closet full of pills, year-round, is up to you. Vitamin C is not magic, and your immune system is not waiting for you to provide it.
The Herbal Pharmacy
A whole shelf in your local drugstore, and a much larger section of any natural-foods store, is dedicated to herbal supplements that promise to support, boost, or strengthen your immune system. Echinacea. Elderberry. Astragalus. Andrographis. Garlic capsules. Olive leaf extract. Reishi mushroom. Cordyceps. The list is long.
What the evidence shows, taken across the most carefully done trials of the most popular of these, is that the effects are generally small, often inconsistent, and almost always smaller than the marketing claims.
Echinacea has been studied extensively for prevention and treatment of the common cold. The pooled evidence suggests, at best, a small effect on duration or severity, and many studies have found no effect at all. The variation is partly because echinacea is not a standardized product — different preparations contain different plant species, different parts of the plant, and different concentrations of various compounds. The product you buy may have nothing in common, biochemically, with the product that was tested. This is a general problem with herbal supplements: no enforced standard for what is actually in the bottle.
Elderberry has a small body of evidence suggesting it may modestly reduce cold or flu duration. The studies are mostly small, mostly funded by manufacturers, and mostly done with specific commercial preparations. The effect, if real, is small. Elderberry is also worth knowing about because raw elderberries are mildly toxic, and there have been documented cases of poisoning from improperly prepared products. Cooked, it is fine. “Natural” does not mean “harmless.”