Researchers have found a link between low blood folate levels, allergic reactions, and asthma; suggesting folic acid supplements may benefit sufferers.
According to findings of a study conducted at John Hopkins Childrens Center, folic acid or vitamin B9, which is essential for red blood cell health, replication of genetic material, and prevention of birth defects, may also suppress allergic reactions and reduce the sevrity of allergy and asthma symptoms.
This large study of over 8000 people is believed to be the first to examine the relationship between blood folate levels and the incidence and severity of allergic conditions in humans. Folate is the naturally occuring form of folic acid found in the human body.
Researchers at Johns Hopkins say the results add to growing evidence that folate plays a role in the regulation of inflammation. Recent studies have found links between folate levels and inflammatory conditions, including cardiovascular disease.
Elizabeth C. Matsui, M.D. and William Matsui, M.D analysed information from the National Health and Nutrition Examination Survey and the findings are published online in the Journal of Allergy & Clinical Immunology.
In total, findings for, 8,083 individuals, ages 2 to 85, were examined. All participants had serum folate and total immunoglobulin E (IgE) measurements taken in the 2005-2006 as part of the National Health and Nutrition Examination Survey. IgE is the type of antibody associated with allergic reactions. It binds to allergens and triggers the release of histamine from mast cells. Histamine being the major contributor to the symptoms of allergy.
Of the participants, 14% had physician-diagnosed asthma, 15.7% reported wheeze in the prior 12 months, 27% had high total IgE of more than 100 kU/L, and 32% were classified as atopic, with at least one positive test for IgE-mediated allergy.
The results of the study showed that higher folate levels were associated with a decreased risk for each of these and were also linked to reduced severity of symptoms in sufferers.
Pediatric allergist and lead researcher, Elizabeth Matsui, said "Our findings are a clear indication that folic acid may indeed help regulate immune response to allergens, and may reduce allergy and asthma symptoms."
The Johns Hopkins research team is now planning a study that will compare the effects of folic acid supplements to placebo in people with allergies and asthma.
Good dietary sources of folic acid include green leafy vegetables (e.g. spinach, kale), nuts, and seeds. In many countries, cereals and grains are also commonly fortified with folic acid. The current recommendation for daily dietary intake of folic acid is 400mcg for men and non-pregnant women, in both the US and UK.
Specific Study Findings
- Those with the lowest folate levels had 16% higher risk of having asthma than people with the highest folate levels.
- People with the lowest folate levels had 31% higher risk of atopy (allergic symptoms) than people with the highest folate levels.
- People with the lowest folate levels (below 8 nanograms per millilitre) had 40% higher risk of wheezing than people with the highest folate levels (above 18 ng/ml).
- People with the lowest folate levels had a 30% higher risk than those with the highest folate levels of having elevated IgE antibodies, markers of allergy predisposition.
- Blacks and Hispanics had lower blood folate levels - 12 and 12.5 ng/ml, respectively - than whites (15 ng/ml), but the differences were not due to income and socio-economic status.