Alzheimer’s disease, the most common type of neurodegenerative disease in older adults, causes a progressive deterioration of cognitive function. Recent research indicates that folate (vitamin B9) deficiency may play a role in Alzheimer’s pathology along with other micronutrients, such as vitamin A. A recent systematic review and meta-analysis reports that folate deficiency increases the risk for Alzheimer’s disease.
Folate is an essential nutrient used by the body to create new DNA and RNA and to metabolize amino acids, all of which are necessary for cell division. Good sources of folate include legumes, such as peanuts and chickpeas, and green vegetables such as spinach and asparagus. Previous research has shown that folate supplementation improves cognitive function in older adults through mechanisms that are not well-understood, but likely involve reduced inflammation. Because dose, population characteristics, and testing methods often vary among clinical trials, coming to a consensus about the efficacy of an investigational treatment presents challenges; however, review articles can be a valuable way to combine and report existing data in a new and helpful way. This study is a systematic review and meta-analysis, meaning that the authors searched existing literature for studies related to folate and Alzherimer’s disease, collected studies based on a set of criteria meant to select for high-quality design, and then combined the data and reanalyzed it.
The authors selected 59 studies that met their criteria for high-quality design. In a sample of more than 2,000 participants from a collection of case-control studies, participants with folate deficiency (less than 13.5 nanomoles per liter) were more than twice as likely to develop Alzheimer’s disease compared to participants with normal folate status (greater than 13.5 nanomoles per liter). Likewise, data from a collection of five cohort studies revealed that participants with folate deficiency were 88 percent more likely to develop Alzheimer’s disease compared to individuals with sufficient folate status. Finally, in a sample of 11 cohort studies, participants who consumed less than the recommended dietary allowance (400 micrograms) were 70 percent more likely to develop Alzheimer’s disease than those who consumed 400 micrograms of folate per day or more.
This review of the evidence supports a relationship between folate intake and serum folate concentration in reducing risk for developing Alzheimer’s disease. Future studies should utilize an interventional design to investigate the mechanisms of folate in Alzheimer’s pathology.
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