Multivitamins and zinc

Studies have shown that most elderly patients fail to ingest the recommended daily allowance (RDA) of zinc. Supplementation with zinc could improve their immune responses to infection and thus prevent illness. Zinc supplementation for people aged 60–89 (defined as elderly) alone increased their in vitro lymphocytes' response to mitogens [9]. Their response to skin test antigens however, was not increased. When 15 mg of zinc was added to a multivitamin preparation and compared to a lactose placebo given to people aged 59–85 living in northern New Jersey, there was a significant increase in skin test responses to a panel of seven intradermal antigens [10]. The incidence of infectious diseases was not studied.

There is a considerable literature concerning the use of zinc as a therapy for the common cold. Marshall has reviewed 8 such studies and concludes that there is no convincing evidence as to zinc's efficacy in reducing the severity or duration of cold symptoms [11].

There is evidence that zinc supplementation significantly reduces the incidence of infections in people with sickle cell disease. Twenty-one of 32 sickle cell disease patients in the Detroit area were found to have zinc deficiency as determined by lymphocyte or granulocyte zinc levels. Zinc supplementation in those deficient reduced their documented infection rate by as much as 80% [12]. Their hospitalization rate, however, was unaffected.

Multivitamin and mineral supplementation has not been shown to affect illness or absenteeism rates in 158 adults (age >45 years old) living in North Carolina unless they had type II diabetes [13]. Diabetics taking a placebo reported a 93% incidence of infection (as opposed to an incidence in non-diabetics of 60%). Strangely, diabetics taking supplementation showed only a 17% incidence of infection-much lower than non-diabetics taking placebo. The infections did not result in hospitalizations. Elderly people (>60 years old) living in central France had no decrease in infection incidence when receiving a multivitamin supplementation as compared to a placebo [14]. A prospective study relating the intake of carotenoids, vitamins C and E and B-vitamins with the incidence of community acquired pneumonia in over 50,000 U. S. male health professionals aged 40–75 years old failed to show any correlation between pneumonia risk and vitamin intake [15]. This study looked at both food and supplement sources of vitamins. "Natural" vitamins therefore seemed to be no better than "pharmaceutical" vitamins in preventing pneumonia in this well-educated population of American men. Elderly nursing home residents in the Boston area were given multivitamins with either 4 IU of vitamin E (50% of the RDA) or 200 IU of vitamin E. High intake of vitamin E had no effect on the incidence or duration of lower respiratory tract infection [16]. There appeared to be a small, but significant effect on the incidence of upper respiratory tract infections (including otitis media), but not on their duration (risk ratio = 0.84 for incidence, but 1.53 for duration).

There are two studies which support the use of vitamin or micronutrient supplementation to prevent community-acquired infections. Chandra [17] showed that trace elements and multivitamins reduce the number of days with any sort of infection. The study enrolled 96 elderly Newfoundland residents and is apparently the only other study to show such an effect in those not institutionalized.

A French study gave a placebo, zinc and selenium supplements, or multivitamins with zinc and selenium to institutionalized people over the age of 65 [18]. The sample size was a total of 81 and over a two year follow-up period, they found that the number of pneumonias and UTIs decreased by about 50% in those who received the zinc and selenium with or without multivitamins. The multivitamins had no statistically significant effect alone.

If there is little or no effect of micronutrient and multivitamin supplementation on infection rates on apparently uninfected members of the community, how about those chronically infected with viruses? A small study from the era prior to the availability of effective anti-HIV therapy studied nutrient and vitamin intake in 56 HIV infected New Yorkers. Vitamin intake varied from 2% to 50,000% of the RDA. No correlation could be found between nutrient intake and CD4 lymphocyte count or absolute lymphocyte count [19].

A more intriguing study of HIV-infected people in Baltimore correlated their micronutrient intake as estimated by data from a questionnaire and the subsequent progression of HIV disease [20]. This study did not take any changing dietary habits into account. The study correlated any intake of zinc supplements with decreased survival. High intake of vitamins B1, B2 and B6 were correlated with increased survival. Studies of this nature always raise the question of whether the increased intake reflected a healthier life style or produced a healthier life. A review of fifteen studies utilizing vitamin and micronutrient supplementation in HIV-infected people concluded that such supplementation effected no reduction in mortality or morbidity in HIV-infected adults. HIV-infected children in under-developed countries could benefit from vitamin A supplementation, however [21].

Hepatitis C has a prevalence between 1% and 2% in the U. S. population. Could nutritional therapy affect the progression to cirrhosis or hepatoma? The only vitamin supplementation studies done with hepatitis C involve the use of vitamin E as an anti-oxidant to limit hepatic fibrosis [22]. Two studies which show decreased transaminase levels when patients with hepatitis C are given supplemental vitamin E [23,24] although there is no data on vitamin E's effect on the viral load.