It’s best known for the important role it plays before and during pregnancy to prevent birth defects. But folate, sometimes called folic acid or vitamin B9, is also essential for the health of the brain, so we don’t want to be short of it at any time of life.
While evidence points to folate deficiency as posing a risk for dementia, studies have been small and lacked rigor. Researchers needed a large, comprehensive study to root out whether the risk is real, so that’s what scientists from the U.S. and Israel carried out. What they found is disturbing.
Scientists agree that harm to the brain can continue for a long time, possibly for as long as twenty years, before symptoms of dementia become apparent.
This makes it difficult for scientists to determine whether folate deficiency is a risk factor for dementia or whether the damage to brain cells that leads to dementia causes a deficiency in the uptake of folate (or any other nutrient). This latter effect is called reverse causation.
Scientists at the Icahn School of Medicine, New York, and the University of Haifa, Israel, carried out a large study to investigate.
Deficiency Triples the Risk of Death
The researchers recruited 27,188 men and women between the ages of 60 and 75 living in Israel. All were free of dementia for at least ten years before the study began in 2013, when the researchers measured blood folate levels. At the end of 2017 researchers checked to see how many of the participants had been diagnosed with dementia or had died.
Over the four-year study period they found 3,418 participants were deficient in folic acid with blood levels below 4.4 ng/ml. They also found that the deficiency substantially increased the risk of both dementia and death.
After taking additional factors into account, researchers found those deficient in folate were 88 percent more likely to be diagnosed with dementia, and their risk of death from any cause tripled.
But the team conceded that even this sizable and robust study couldn’t rule out reverse causation entirely. Even so, when they published their findings in the journal Evidence-Based Mental Health in March, they wrote, “Serum concentrations of folate may function as a biomarker used to modify the risks of dementia and mortality in old age.” Because of this, they believe older adults should be routinely screened and deficiencies treated.
How Does Folate Deficiency Harm the Brain?
The authors point to several reasons why low folate levels might harm the brain.
First of all, folate is needed to prevent a buildup of homocysteine, which is formed from the amino acid methionine. Elevated levels are linked to many health problems including dementia and Alzheimer’s disease.
Low folate levels may also interfere with the repair of DNA in brain cells, making them vulnerable to oxidative damage, which in turn might accelerate brain cell damage and aging.
The findings of this study are not surprising as they reinforce previous research.
The Folate-Dementia Link Goes Back Over Half a Century
In 1967 a paper was published in the Quarterly Journal of Medicine entitled Dementia and Folate Deficiency. The authors describe cases of two elderly women with dementia. After supplementation with folic acid the condition of one improved while the other returned to normal.
Forty years on, a study was conducted among 965 individuals with an average age of 76 and who were free of dementia. After six years, 192 developed Alzheimer’s disease. The risk of Alzheimer’s was lower in participants with higher intakes of folate from food and supplements.
More than Three Times More Likely to Get Dementia
Another study published in 2008 involved 518 people over the age of 65. After two years 45 participants developed dementia. The researchers found those who were folate deficient at the start of the study were almost 3½ times more likely to develop dementia.
Although earlier studies aren’t as robust as the current study, being deficient in this nutrient is clearly problematic. Yet even with mandatory fortification of cereal-grain products since 1998, it’s estimated that one in five Americans are getting insufficient amounts of folate from their diet.
To avoid falling into this category, eat dark green leafy vegetables. Spinach, asparagus, and Brussels sprouts also contain high levels. Other sources include peas, fresh fruits, nuts, beans, seafood, eggs, dairy, meat, poultry, and whole grains. Liver also contains healthy amounts of folate. Supplements of folic acid are also readily available.