It seems highly likely that flour could be fortified with folic acid in the UK, a decision that has lagged behind other European countries for years. Yet did we hold back for good reason and what are the potential pros and cons of this? This insight post discusses.
First before we delve into the ins and outs of fortification strategies it’s important to recognise that there are several different folate forms.
- Folate – this is a general term for a group of water soluble B-vitamins, and is also known as B9. Dark green leafy vegetables such as broccoli, spinach, kale and whole grains can provide folate though the bioavailability of these tends to be poor.
- Folic acid – this refers to the oxidized synthetic compound used in dietary supplements and food fortification.
- 5-methyltetrahydrofolate (5-MTHF) or L-methylfolate – this is the pure stable crystalline form of the naturally-occurring predominant form of folate. This type of water-soluble B-vitamin plays a key role in central metabolic pathways, e.g., cell division and repair.
Requirements May be DIFFERENT
This is very important to consider. For example, individuals who have previously had a neural-tube defect (NTD) affected pregnancy or those with diabetes may require up to 5 mg per day. There is also growing evidence that obese women could have higher requirements of this nutrient. Equally, women with underlying polymorphisms in genes related to folate metabolism could benefit from 5-MTHF instead of folic acid
- Healthy women – 0.4 mg/day
- Women with diabetes – 5mg/day
- Women who have had a previous NTD-affected pregnancy – 5mg/day
- Women with obesity – 0.4mg/day ↑
Other recent work suggests that 0.4mg-0.8mg per day could be enough, as intake above ∼1 mg does not show an increase in absorption. However, in this work it is recommended that maternal folate status should be assessed. Bearing this in mind, should requirements first be updated become fortification strategies go ahead? – the last report was in 2006.
Years 1 to 9 of the UK National Diet and Nutrition survey show a downward trend in folate intakes – especially amongst girls aged 11 to 18 years. Again for red blood cell folate there was a 19 percentage point increase amongst those aged 11 to 18 years – indicating risk of anaemia. Results also showed that folate intakes increased with income.
Amongst women of childbearing age the proportion with a red blood cell folate concentration suggestive of increased risk of neural tube defects (should pregnancy occur) increased from around 2/3s in 2008/9 to almost 90% in 2016/17. The outstanding question here is why?
Genetic Polymorphisms Should be Considered
The MTHFR 677TT genotype polymorphism (when the base code in DNA changes) is present in 10-22% of the European population. These individuals have an increased risk of delivering infants with neural tube defects. Obviously, the key issue here is screening to make women aware that they have this polymorphism. These individuals have lower folate levels and are less responsive to folic acid.
- Will supplementation strategies become confused? One concern is that if flour is fortified with folic acid women may disregard supplements.
- Would young girls and women of childbearing age eat enough of these flour fortified foods to generate an effect? Models are yet to be developed so we are not sure about this at present.
- What about those with higher requirements and with polymorphisms? For some individuals with higher requirements, the amount of folic acid delivered via flour may not be enough. Carriers of certain polymorphisms in genes related to folate metabolism or absorption appear to have an increased benefit from 5-methylTHF intake instead of folic acid.
- What about the masking of vitamin B12 deficiency? Using 5-MTHF instead of folic acid also reduces the potential for masking haematological symptoms of vitamin B12 deficiency.
- And what about ‘unmetabolised folate?’ – do we know enough? Use of 5-MTHF also prevents the potential negative effects of unconverted folic acid in the peripheral circulation also known as ‘unmetabolised folate’.
Scaglione F & Panzavolta G (2014) Folate, folic acid and 5-methyltetrahydrofolate are not the same thing. Xenobiotica 44(5):480-8.
Obeid R et al. (2013) Is 5-methyltetrahydrofolate an alternative to folic acid for the prevention of neural tube defects? J Perinat Med 41(5):469-83.
Derbyshire (2011) Nutrition in the Childbearing Years. Wiley Blackwell, West Sussex. pp. 34-36.
SACN (Scientific Advisory Committee on Nutrition) (2006) Folate and Disease Prevention. The Stationary Office: London.