Folate and folic acid: friend or foe?
Folate deficiency is believed to be the most common vitamin deficiency in the world due to food processing, food selection and intestinal disorders. Yet in recent times, concerns have been raised around folate, or more particularly the synthetic form of folate, “folic acid”. To understand the latest on this vital nutrient it helps to know a bit of recent history.
Folate and folic acid
Folate is a generic term for a group of water-soluble B vitamins occurring naturally in food. Humans are unable to make their own folate, making it an essential nutrient obtained from the diet. Important sources of folate are leafy green vegetables, fruits, legumes, liver, eggs, dairy products and sprouts.
The terms “folic acid” and “folate” are often used interchangeably, but “folic acid” actually refers to the fully oxidised synthetic compound used in dietary supplements and in food fortification, while “folate” refers to the substances naturally present in foods. Folic acid was isolated from spinach in 1941 but it does not exist in the spinach when the spinach is growing. Since it is fully oxidised, however, the folic acid form of this nutrient is very stable and it can be added easily to foods. But its synthetic nature means humans had never ingested it until 70 years ago and this has led to concerns.
In the past few years, research has shown that people who take high doses of folic acid — above 400mcg a day — have unmetabolised folic acid in their blood. While this will eventually be converted into a natural folate form by the liver, there is concern over what may happen in the interim if folic acid is taken long term. Additionally, reports have emerged linking folic acid to an increase in the likelihood of developing some cancers. Fortunately, a study published in early 2013 in The Lancet has put some of those fears to rest.
In this new study, researchers examined the results of all large randomised trials of folic acid up to the end of 2010. In doing so, they were analysing data on more than 50,000 people. They found there was no notable increase in cancer of any type, even among people taking the highest levels of folic acid (much beyond what you would be taking in ordinary supplements and food).
So, while the concerns over folic acid may not be as serious as has been touted, a more “natural” form of folate, “folinic acid”, is generating some interest.
Folinic acid
The history is that folic acid does not occur naturally in foods but is stable when isolated and oxidised. If you could find one of these folate substances that is stable when isolated and occurs naturally, you might be onto something.
This is where folinic acid comes into play. It occurs naturally in food and as “calcium folinate” is stable, which is why you may be hearing more about folinic acid in the future. Essentially, it is a form of folate that occurs in food but is stable enough to be used as a supplement.
Folate actions
It seems then that, despite being synthetic, folic acid will not increase cancer risk in the short term at least. So what are the benefits of folate that have led to the widespread folic acid fortification of foods?
Birth defects
Pregnant women who don’t get enough folate are more likely to have children with birth defects. Women who plan to become pregnant should make sure they are getting adequate folate, as many neural tube defects can happen shortly after conception, before a woman even knows she is pregnant.
Studies show that women who take folic acid supplements before conception and during the first trimester may reduce their risk of having children with neural tube defects by 72–100 per cent.
Heart disease
Studies suggest that people with high levels of the amino acid homocysteine are almost twice as likely to develop coronary artery disease and are 2.5 times more likely to have a stroke than those with normal levels. B complex vitamins, especially folate, vitamin B6 and vitamin B12, help lower homocysteine levels.
Depression
The evidence about whether folate can help relieve depression is mixed. Studies show that up to 38 per cent of people with depression have low folate levels in their bodies, and those with very low levels tend to be the most depressed. One study found that people who did not get better when taking antidepressants had low levels of folate.
Another study found that taking 500mcg of folic acid daily helped the antidepressant Prozac work better in women, though perhaps not men. Yet another study found taking folic acid and vitamin B12 to be no better than placebo in relieving depression in older people. So the benefits of folate in depression do not seem to be universal but perhaps specific to individual cases.
Cancer
Folate in the diet seems to protect against the development of some forms of cancer, particularly of the colon as well as breast, cervix, pancreas and stomach. However, this evidence is based on population studies that show people who get enough folate in their diets have lower rates of these cancers.
It’s not clear exactly how folate might help prevent cancer. Some think folate keeps DNA healthy and prevents mutations that can lead to cancer. There is no evidence that taking folic acid supplements helps prevent cancer.
Dosage
Adults: 400mcg a day
Pregnant women: 600mcg a day
Breastfeeding women: 500mcg a day
Precaution
Use of folate supplements may mask a vitamin B12 deficiency by correcting an apparent anaemia without stopping nerve damage. In these cases of suspected anaemia, screening for B12 deficiency is a good idea.
References available on request.
