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June 2009
Science in Society

What are folates and folic acid?

The term folate(s) describes a family of naturally occurring water soluble B-group vitamins. There are large numbers of folates, but methyl- and formyl-tetrahydrofolate are the main forms found in foods. Folic acid is the synthetic form of folate, which is easily absorbed. It is more stable than food folate making it easy to include in fortified foods and dietary supplements.

What is their biological role in the body and why are they important? See http://en.wikipedia.org/wiki/Folic_acid

What foods provide folate?

Folates are found in a wide variety of foods. Rich sources include liver, yeast extract and green leafy vegetables such as spinach, kale and Brussels sprouts. Significant amounts are found in other vegetables and fruit including broccoli, spring greens, cabbage, parsnips and oranges.

Bread Fruit and Vegetables
Broccoli and Cabbage Breakfast Cereals

The main sources of folic acid are supplements and fortified foods. In the UK, fortification of foods with folic acid is voluntary and unregulated. It includes breakfast cereals and some brands of reduced or low fat spread.

Do women of childbearing age and pregnant women have a special need for folate?

Neural tube defects (NTDs) including spina bifida are thought to arise through a failure of the neural tube (which forms the brain and spinal cord as well as the surrounding tissue and bone) to close properly within the first 28 days after conception. There is conclusive evidence that folic acid supplementation can prevent NTDs (MRC Vitamin Study Research Group, 1991).

Public health advice recommends all women of childbearing age supplement their diet with folic acidBecause low folate is associated with a high risk for NTD-affected pregnancy (Daly et al, 1995) and the consumption of folic acid prevents NTDs, women planning a pregnancy are recommended to take 400 micrograms (µg) of folic acid per day, from the time contraception is stopped until the  to 12 weeks pregnancy.

As more than half of all pregnancies in the UK are unplanned, many women are unaware they are pregnant during the crucial first 28 days. This has led to the public health advice recommending all women of childbearing age supplement their diet with folic acid.

Taking folic acid supplements prior to conception and during pregnancy is not only safe for the mother and child, but positively beneficial for the baby!

Who else may need extra folic acid?

Fortified foods and supplements make up a large proportion of total folate intake for some individuals because they do not like or do not include folate-rich foods in their diet. Current estimates reckon this to be more than 13 million people in the UK. Not eating enough folate is associated with increased risk of cardiovascular disease including heart attack and stroke as well as some cancers, particularly colon cancer.

Our understanding of the relationship between folate/ folic acid intake and protection from chronic age-related diseases, together with a lack of understanding about absorption and the behaviour of folate in the body, has led to much debate about folate/ folic acid requirements for optimal health and function.

What are some current issues and controversies about folate?

No adverse effects have been reported with consumption of high amounts of food folates (Butterworth and Tamura, 1989). Concerns regarding the safety of prolonged high intakes (> 5 mg per day) are restricted to folic acid.

Evidence emerging from the US and Canada, where folic acid fortification has been carried out for the last ten years, suggests potential hazards of over-consumption of folic acid include: changes in the immune system, blockage of coronary stents, and an increased rate of cognitive decline in the elderly, particularly in those who have low B12 levels (Wright et al, 2007).

Other potential problems include an increased risk of reproductive and developmental abnormalities, promotion of DNA replication which may increase the risk of existing cancers progressing (Mason et al, 2007), and reduced intestinal zinc absorption. Many of these risks are theoretical or have yet to be demonstrated conclusively.

References

  • Butterworth CE Jr & Tamura T (1989) Folic acid safety and toxicity: a brief review. Am J Clin Nutr 50: 353-8
  • Daly S, Kirke PN, Molloy AM, Weir DG & Scott JM (1995) Folate levels and neural tube defects, implications for prevention. JAMA 274:1696-1702
  • MRC Vitamin Study Research Group (1991) Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet 338: 131-137
  • Mason JB, Dickstein A, Jacques P, Haggarty P, Selhub J, Dallal G & Rosenberg IH (2007) A Temporal Association between Folic Acid Fortification and an Increase in Colorectal Cancer Rates May Be Illuminating Important Biological Principles: A Hypothesis. American Association for Cancer Research. Cancer Epidemiology Biomarkers & Prevention 16, 1325,
  • Wright AJA, Dainty JR, & Finglas PM (2007) Folic acid metabolism in human subjects revisited: potential implications for proposed mandatory folic acid fortification in the UK. Br J Nutr 98: 667–675

Additional links regarding folic acid:

  • UK Scientific Advisory Committee on Nutrition (SACN) www.sacn.gov.uk > Working Group Meetings > Folate-Cancer.
  • UK Food Standards Agency (FSA) www.food.gov.uk ; using ‘folic acid’ as a search term.
  • European Food Standards Agency (EFSA) www.efsa.europa.eu ; using ‘folic acid’ as a search term.
  • International Federation (IF) for Spina Bifida and Hydroencephalus www.ifglobal.org ; look under ‘folate’ banner menu, or click on Flour Fortification Initiative (FFI)
  • The following 2 publications are more scientific and generally not for the layman. Nevertheless, they spell out questions and issues that are being addressed currently.
    1. Examination of selected national policies towards mandatory folic acid fortification. Lawrence et al. DOI:10.1111/j.1753-4887.2009.00164.x - a 2009 scientific publication which examines the contrasting policies towards mandatory folic acid fortification in six countries from different regions of the world (Australia, China, Finland, Ireland, United Kingdom and United States). Three questions are addressed: 1) What is the policy of the country? 2) Why was the policy adopted? 3) What lessons have been learned? ;  
      It was concluded that mandatory folic acid fortification is a complex policy topic, and that rather than a case of one size (mandatory folic acid fortification policy) fits all (national circumstances), the policy should be determined on a country-by-country basis, taking into account the national circumstances and a national authority’s assessment of potential risks and benefits.
    2. Nutritional interpretation of folic acid interventions. Omar D DOI:10.1111/j.1753-4887.2009.00193.x - a 2009 scientific publication that reviews recent key publications on folic acid interventions (particularly the question of mandatory fortification) and attempts to ascertain: 1) What minimum efficacious dose reduces the Neural Tube Defect rate? 2) How can the population’s need for additional folate intake, be determined based on biomarkers? 3) How can the probable impacts (beneficial and negative) of folic acid interventions be predicted

Revised and Compiled by:

Ellen Mitchell
IFR Communications
Institute of Food Research,
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