Multivitamin Supplements

Multivitamin Supplements

All nutrients play some role in immune system function. With nutrient deficiency, supplementation can certainly strengthen the immune system, but we should not expect that, with adequate nutrient status, additional intake will further improve the immune system. Many seemingly healthy older people, however, have a micronutrient deficiency. So does it help to take multivitamin and mineral supplements?

Some of the most prestigious professional journals spoke of an extraordinary health benefit, leading reviewers to the conclusion: “All these reports confirm that the immune response of older people can be improved by taking micronutrient supplements.” Then most of these papers were retracted, one after another. An older article by one of the lead authors had put reviewers on the trail. “Impossible” results from a study that purported to show a positive effect of multivitamin and mineral supplements on cognitive performance led to the official investigation that uncovered scientific misconduct, which then led to the cascade of retractions.

Since that debacle, there have been three large randomized controlled trials on multivitamin and mineral supplements for the prevention of infections. One of them, on acute respiratory infections in older people not living in institutions, could not find any effect on frequency or severity. In another study on general infections in nursing home residents, the infection rate did not fall, although those randomized to receive multivitamin and mineral supplements had to take antibiotics on fewer days over the course of the 18-month study. The third study examined multivitamin and multimineral supplements separately and found that with minerals, the antibody response to flu vaccines was better than with placebo, but with vitamins it was worse than with placebo. Neither added minerals nor vitamins brought a significant reduction in infection rates.

Vitamin C

Since its discovery almost 100 years ago, vitamin C has been recommended for the treatment of respiratory infections. In 1970, Nobel Prize winner Linus Pauling published the influential book Vitamin C and the Common Cold (published in German in 1972), which sparked enormous public interest and undoubtedly helped lead to dozens of randomized, placebo-controlled, double-blind trials being conducted subsequently to test whether his recommendation was justified. Details on the results are available at see.nf/c4colds, but in short, people exposed to extreme physical exertion, such as marathon runners or soldiers in subarctic maneuvers, appear to benefit from regular intake of vitamin C supplements, cutting their cold risk in half. In the general population, however, taking vitamin C daily does not appear to significantly reduce the infection rate, but if someone who regularly takes vitamin C gets sick, they suffer less severely and recover about 10 percent faster. If you start taking vitamin C only after cold symptoms begin, it appears to reduce neither the severity nor the duration of the cold.

The downside is that vitamin C supplements appear to double the risk of kidney stone formation. Anyone taking about 1000 milligrams of vitamin C daily gets a kidney stone with an annual probability of 1 in 300, rather than 1 in 600 without vitamin C—hardly a trivial risk given the pain the stones can cause.

Vitamin D and E

In children and adolescents, daily vitamin D supplementation appears to reduce the risk of acute respiratory infections, but not in adults, and the antibody response to a flu vaccination is not enhanced by vitamin D. Vitamin E, on the other hand, was able to clearly boost immunity with hepatitis B and tetanus vaccinations, but not with vaccinations against diphtheria or pneumonia. As I report in detail in see.nf/immunevitamins, the data on the effects of vitamin E are inconsistent, and some studies find a worsening of infections. However, that is irrelevant, because randomized controlled trials show that vitamin E increases cancer risk and overall mortality risk. In other words, anyone who buys vitamin E supplements might end up spending money to live a shorter life.

Zinc

In February 2020, a well-known virologist advised friends and family for the coming pandemic: “Stock up on zinc lozenges now.” His recommendation was based on the effectiveness of zinc for colds, which are caused by coronaviruses 29 percent of the time. There is a heartwarming backstory to this discovery that I tell in see.nf/zinc, about a three-year-old girl with cancer who inspired her father to conduct the first randomized, placebo-controlled, double-blind trial of zinc lozenges for colds.

In the video I cover all the studies, but essentially, zinc lozenges shorten colds by about three days and bring about a marked reduction in runny nose (by 34 percent), nasal congestion (by 37 percent), hoarseness (by 43 percent), and cough (by 46 percent). Zinc for colds is best taken as lozenges with about 10 to 15 milligrams of zinc; start at the first symptoms and, for a few days, dissolve one lozenge every two hours while awake—either zinc acetate or zinc gluconate without excipients such as citric acid, tartaric acid, glycine, sorbitol, or mannitol.

For more severe infections such as pneumonia, such a preparation may work only in the case of zinc deficiency. Surprisingly, zinc’s indispensability for humans was not demonstrated until the 1960s and was not officially recognized until 1974. About 40 percent of US men and women over 60 do not meet the recommended daily allowance in their diets. Unlike other minerals, such as iron, you cannot simply do a blood test to determine a possible deficiency, because the zinc level in the blood is not a good indicator of the body’s total zinc stores. The best thing is to make sure you get enough through your diet. The healthiest sources are probably legumes, nuts, and seeds, even though the highest concentration by far is likely found in oysters. (A single oyster contains more zinc than a cup of baked beans.)

Taking zinc supplements does not reduce the risk of getting sick, and long-term use can even impair certain parts of the immune system in older people. This is presumably because high doses of zinc can interfere with the absorption of other nutrients important for immune defense, such as copper and folic acid. One month of supplementation with zinc enhanced the antibody response to a tetanus vaccination, but no effect was seen with the flu vaccination—not even when zinc was taken for two months beforehand. Short-term supplementation is considered safe, but supplements and lozenges can cause gastrointestinal problems and, especially when taken on an empty stomach, nausea. Never put zinc up your nose. Pharmacies sell all kinds of intranasal zinc gels, sprays, and swabs, but they can lead to permanent loss of the sense of smell.

By the way, there was a happy ending: The three-year-old beat the cancer, had no relapse, and became a scientist herself.

Vaccination

Vaccines are among the greatest medical achievements of the last century; they eradicated smallpox—a scourge of humanity that killed several hundred million—and greatly reduced other serious diseases such as measles and polio. To this day, vaccines save millions of lives every year.