The researchers from the University of Alberta showed that feeding 23-month-old rats with folic acid (35 mg per kg of feed) produced a dramatic increase in T-cell distribution and mitogen response (cell division to increase the immune response).
T-cells are a subset of lymphocytes that play a major role in the immune response. But as the body ages, their levels fall significantly.
When the researchers measured the levels of a kind of T-cell, CD8+, in the spleen and mesenteric lymph nodes of the supplemented rats after three weeks, the proportion was about the same as those measured in 12-months-old rats.
"The results of the current study suggest that, as the elderly population increases, public health measures aimed at significantly increasing folate intake should be considered," reported Catherine Field and colleagues in the January 2006 issue of the Journal of Nutritional Biochemistry (vol 17, pp 37-44).
Folate supplementation is a particularly hot topic at the moment. TheScientific Advisory Committee on Nutrition (SACN), a group of independentexperts that advises the UK's food authorities and health department,recently called for folic acid to be added to flour to increase pregnant women's levels of this nutrient and protect against birth defects.
But there has previously been some opposition to the initiative as folic acid can mask deficiency of another B vitamin in the elderly.
The new study however makes a case for the benefits of folic acid in the elderly as well as pregnant women. A recent study has also suggested that higher folic acid intake may improve memory in the older population.
Flour in the US and Canada is already fortified with folic acid and Ireland is also consulting on a similar programme.