Unexpectedly, Extra Folate is Unhelpful in Older People

Summarized by Robert W. Griffith, MD
August 3, 2005

Introduction

Vitamin B12 and folate have long been considered important factors in neurological function, and a relative lack of them has been associated with 'lower cognition', or reduced power of thinking. Insufficient levels of either of these substances can lead to increased blood homocysteine levels, which is itself linked to the occurrence of Alzheimer's.

Because of the risk to the unborn fetus in mothers with folate deficiency, it has been mandatory since 1998 for grain products (bread, cereal, etc) to be fortified with folic acid. Scientists from Chicago and the CDC (Center for Disease Control and Prevention) have now reported a study in which they examined possible effects of high folate intake in the elderly, with respect to their mental functioning. Their results are reported in the Archives of Neurology, and summarized here.

What was done

The participants, who were over 65, were enrolled in the Chicago Health and Aging Project (CHAP). In-home interviews were done where the volunteers completed a test of mental functioning and a food-frequency questionnaire. Follow-up interviews were done after 3 and 6 years. Only those who completed at least one of the two possible follow-up visits were used in the analyses.

The 4 mental tests used were the Mini-Mental State Exam (MMSE), the East Boston Tests of immediate and delayed recall, and the Symbolic Digit Modalities Test. The results were averaged for each subject to give an overall 'cognitive score'.

Additional information gathered included education (in years), smoking habits, depressive symptoms, and history of heart disease, high blood pressure, and diabetes.

What was found

A third of the participants took multivitamins. Folic acid (folate) and vitamin B12 supplementation was mostly through multivitamin preparations. The subjects were classified according to their folate intake (both from diet and supplements) into five equally-sized groups, or quintiles.

At baseline, those people in the highest folate intake quintile had a higher cognitive score than those with a low intake, as well as those with more years of education, and greater consumption of vitamins C and E. They were also less likely to have high blood pressure or heart disease.

The average cognitive score at baseline for the entire group of 3,700-plus people was 0.18. There was an average decline of 0.04 units per year during the follow-up period. As expected, the decline was slightly slower in the subjects with a high vitamin B12 intake.

After adjusting for various factors that might interfere with the analyses, it was found that the rate of decline in the cognitive score was greater in the two higher folate-intake quintiles; in the top quintile it was twice as fast as it was in the bottom quintile. This effect was similar for folate derived from food or from supplements.

What this may mean

As the authors of the report put it, "higher intake of folate may be associated with cognitive decline in older persons. These unexpected findings call for further study . . ."

This is quite an understatement. The changes seen with folate consumption were the opposite of those expected, and which we mentioned in the introduction to this article. Before one dismisses them just because they are different from those of earlier studies, it must be remembered that this study is the only one done after the introduction of folic acid fortification of grain foods.

One explanation offered is that a high folate intake may in fact mask a vitamin B12 deficiency, that itself can produce neurological defects. As already stated, more research is needed. In the meantime, it looks as if there is little need for older people to take extra folic acid in the form of supplements or multivitamins, provided they are eating a 'grainful' diet.

Source

• Dietary folate and vitamin B12 intake and cognitive decline among community-dwelling older persons. MC. Morris, DA. Evans, JL. Bienias,  et al., Arch Neurol, 2005, vol. 62, pp. 641--645

Related Links
Vitamins C and E Against Alzheimer's?
Fat Intake Appears to be Tied to Alzheimer's Risk
Diet to Prevent Alzheimer's?

Please take a moment to give us your comments. For questions about Health matters you may check our "Questions & Answers" Portal and Service.