Fortifying cereal grains has been effective in increasing serum folate levels, reducing neural tube defects and other fetal malformations.1 2 3 An examination of the 1994 edition of the National Health and Nutrition Examination Survey (NHANES) shows mean serum folate concentrations for all women of childbearing age increased from 6.3ng/mL in the time prior to fortification to 16.2ng/mL after fortification (NHANES, 1999). Neural tube defects and other birth defects have decreased by 20% since fortification began in 1998.4 However, folate adequacy not only reduces birth defects, it also reduces pregnancy complications such as pre-eclampsia (the most common cause of maternal death in Westernized countries).5
Folate has many roles, but transfer of methyl groups to amino acids and DNA are critical. Homocysteine's methylation to methionine is impaired even without overt folate deficiency, so homocysteine levels rise in the bloodstream. It is a marker of heart disease risk on par with elevated cholesterol and also is linked with cancer, dementia and Alzheimer's disease.
Folate and Chronic DiseaseNumerous studies show that those with the highest folate intakes had a 30%-60% reduction in risk of cardiovascular and related diseases, including stroke, when compared with those with the lowest intakes.6 7 8 9 10 Folate also reduced the risk of various cancers. Low folate intakes are associated with increased occurrence of colorectal cancer and precursors such as polyps, especially if alcohol intake is high.11 12 Low folate intakes were associated with increased risks of breast, lung (amongst former smokers), cervical, and mouth and throat cancers.13 14 15 16
Folate and Brain FunctionLow folate levels are related to depression.17 Young adults with major or mild depression had lower folate levels than those with no depression.
Elevated homocysteine levels may render the brain vulnerable to age-related neurodegenerative disorders by subjecting cerebral vessels and neurons to damage caused by oxidative stress seen in Alzheimer's and some dementias.18 19 20 Folate helps to protect against these destructive oxidations, and higher intakes were associated with improved brain function in the free-living elderly.21 Unfortunately, existing dementia was not impacted by folate supplementation.22 Folate deficiency in experimental animals makes them more prone to Parkinson's disease.23
SummaryThe health benefits of folate are exciting, as are the benefits derived from folate fortification.24 However, more research needs to be done because folate status at the time of conception is critical for preventing birth defects. Tragically, many young women and nearly 30% of the elderly are deficient in folate. Women of child-bearing age should be taught to ingest a variety of folic sources: broccoli, spinach, peas, Brussels sprouts, corn, beans, lentils, oranges, breads and folate-fortified cereals.
The preventative effects of folate in terms of chronic disease and dementia means that the entire population needs to be more folate-conscious in order to reap the B-vitamin's benefits. Further fortification of foods such as whole grains, as well as a general educational effort, also may be important industry steps.
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