Including Folate in the Diet May Reduce the Risk of Alzheimer's Disease: Findings from the Nun Study.

March 31, 2000
Snowdon DA, Tully CL, Smith CD, Riley KP, Markesbery WR

SUMMARY: A study conducted on a group of 30 nuns who lived together, shared meals and had similar lifestyles tested for a variety of factors and found low serum folate to be strongly associated with atrophy (wasting) of the cerebral cortex (brain) and Alzheimer's disease. At autopsy, several indicators of Alzheimer disease due to low folate intake were determined, including the degree of atrophy of 3 lobes of the neocortex (frontal, temporal, and parietal lobes of the brain) and the number of neocortical Alzheimer disease lesions (i.e., neurofibrillary tangles, which are abnormalities in the cytoplasm/fluid of the cells in the neurons in the brain). Researchers attributed atrophy to low folate because none of the 18 other nutrients, lipoproteins, or nutritional markers measured in the blood had significant negative correlations with atrophy. This study suggests it is important and beneficial to include folate rich foods (leafy dark green vegetables, orange juice, beans and peas, etc.) in your diet.

BACKGROUND: Previous studies suggested that low concentrations of folate in the blood are related to poor cognitive function, dementia, and Alzheimer disease-related neurodegeneration of the brain.

OBJECTIVE: Our aim was to determine whether serum folate is inversely associated with the severity of atrophy of the neocortex.

DESIGN: Nutrients, lipoproteins, and nutritional markers were measured in the blood of 30 participants in the Nun Study from one convent who later died when they were 78-101 y old (f1.gif" BORDER="0">: 91 y). At autopsy, several neuropathologic indicators of Alzheimer disease were determined, including the degree of atrophy of 3 lobes of the neocortex (frontal, temporal, and parietal lobes of the brain) and the number of neocortical (upper surface of the brain) Alzheimer disease lesions (i.e. neurofibrillary tangles) as assessed by a neuropathologist (studies diseases of the nervous system).

RESULTS: The correlation between serum folate and the severity of atrophy of the neocortex was -0.40 (P = 0.03). Among a subset of 15 participants with significant numbers of Alzheimer disease lesions in the neocortex, the correlation between folate and atrophy was -0.80 (P = 0.0006). Atrophy may be specific to low folate because none of the 18 other nutrients, lipoproteins, or nutritional markers measured in the blood had significant negative correlations with atrophy.

CONCLUSIONS: Among elderly Catholic sisters who lived in one convent, ate from the same kitchen, and were highly comparable for a wide range of environmental and lifestyle factors, low serum folate was strongly associated with atrophy of the cerebral cortex. Definitive evidence for this relation and its temporal sequence awaits the findings of other studies.

Source: Am J Clin Nutr 2000 Apr;71(4):993-998