In the news: Potential Pitfalls of Too Little Zinc, Vitamin D & Vitamin E

Zinc Boosts Immune Function in Older People

The ability of our immune system to respond efficiently often declines as we grow older. A number of nutrients play a role in supporting healthy immune function, and zinc is among them.

Marginal intakes of zinc among adults 60 or older are fairly common according to survey data. Inadequate zinc levels are thought to be a risk factor for respiratory illnesses including pneumonia in the elderly (1). In fact, an analysis of the AREDS trial found lower mortality in participants who received zinc – either alone or with antioxidants, possibly due to a protective effect against respiratory causes of death.

A new study from Tufts and Harvard Medical School underscores the need to get enough of this important mineral with advancing age (2).

The researchers gave elderly people with low blood levels of zinc, either a supplement of 30 mg zinc daily or a placebo. After 3 months, blood zinc levels had increased, though they were still not adequate in some participants who had very low levels initially. The improvement in zinc levels was associated with enhanced T-cell function, mainly from more T-cells being produced.

Different cells of the immune system contribute to the impaired immunity that can occur with age, but T cells have been shown to be the major contributor. T-cells attack and destroy cells inflected with a foreign invader such as a virus.

Suboptimal Vitamin E Levels Common

If zinc intake can be a problem for older adults, low intakes of vitamin E appear to be widespread among younger and middle-aged adults.

Using the most recent biomarker data available from the National Health and Nutrition Examination Survey, researchers found that only 1% of participants were clinically deficient in vitamin E (serum alpha-tocopherol concentration under 12 μmol/L) (3). Despite the lack of clear-cut deficiency, however, a large portion of people had inadequate blood levels of vitamin E (serum alpha-tocopherol concentration less than 30 μmol/L):

•  87% of persons 20-30 years of age
•  68% of those 31-50
•  43% of those 51 and older

The findings aren’t that surprising since the 2015 US Dietary Guidelines Advisory Committee identified vitamin E as a ‘shortfall nutrient’ with greater than 90% of American adults not getting recommended amounts.

What do these findings mean for health? Since vitamin E plays a vital role in supporting healthy pregnancy and development, the authors find the suboptimal levels among those of reproductive age to be concerning. Low vitamin E has also been associated with age-related changes in brain function, and vitamin E may help maintain liver function as well.

Vitamin D Linked to Dry Eye Risk

New findings of a small study conducted at a research hospital in Turkey add to the body of evidence linking low vitamin D blood levels to dry eye (4).

Researchers evaluated 50 premenopausal women with vitamin D deficiency comparing them with 48 women with adequate vitamin D levels. Both objective tests of dry eye (Schirmer’s and tear break-up time) and subjective measures (OSDI) showed dry eye to be more common in those with vitamin D deficiency.

Vitamin D may help protect against dry eye by enhancing tear film stability and reducing ocular surface inflammation, according to the study’s authors.

References:

1. Barnett JB. Zinc: a new risk factor for pneumonia in the elderly? Nutr Rev 68: 30–37, 2010.
2. Barnet JB, et al. Effect of zinc supplementation on serum zinc concentration and T-cell proliferation in nursing home elderly: a randomized, double blind, placebo-controlled trial. Am J Clin Nutr [EPub ahead of print Jan 27, 2016].
3. McBurney MI, et al. Suboptimal serum α-tocopherol concentrations observed among younger adults and those depending exclusively upon food sources, NHANES 2003-2006. PLoS One Volume 10, Number 8:e0135510.
4. Yildrim P, et al. Dry eye in vitamin D deficiency: More than an incidental association. Int J Rheum Dis 19:49-54, 2016.