Vitamin B3 in pregnancy

If you’re pregnant (or thinking about becoming pregnant) and have been keeping an eye on the media recently you may have noticed there’s been a fair bit of talk about vitamin B3 and miscarriage.

A recently published Australian study has found a possible association between vitamin B3 (niacin) and some rare birth defects. The study discovered that supplementing vitamin B3 in pregnancy may help to prevent the development of these birth defects.

So, should all pregnant women start taking vitamin B3 supplements? Not so fast! While this study is interesting, the researchers didn’t actually give vitamin B3 to any humans, so we need a lot more information before we can recommend it.

The media love a good headline, and unfortunately the claim that vitamin B3 (or even Vegemite on toast for us Aussies), prevents miscarriage and birth defects is slightly misleading.

The researchers were looking into causes for a rare constellation of birth defects called VACTERL association. VACTERL stands for vertebral defects, anal atresia (problems with the tissue closing the anus), cardiac defects, tracheo-esophageal fistula (an abnormal connection between the windpipe and the foodpipe), renal anomalies (kidney defects), and limb abnormalities. Affected babies have anomalies in at least three of these.

Around one in 20 000 pregnancies are affected by this, so the condition is very rare.

Our Aussie researchers identified genetic mutations in some families they were studying with a history of VACTERL. They then genetically engineered mice and found that by giving vitamin B3 (niacin) to mice with these genetic mutations while pregnant prevented the development of these birth defects and resulted in healthy normal offspring.

While these findings are interesting, they don’t apply to every woman who is or is thinking about getting pregnant.

In fact while the researchers suggest  that vitamin B3 supplementation may prevent recurrence of these birth defects  in the families they identified with the mutation, they did not draw any conclusions in relation to vitamin B3 supplementation in the population as a whole.

Since this study was released all we’ve heard is that vitamin B3 may prevent miscarriage and birth defects. The truth is, this conclusion wasn’t reached by the researchers and in fact miscarriage isn’t mentioned in the article at all.

So what does this mean for you?

This does NOT mean that taking vitamin B3 in pregnancy prevents miscarriages and all birth defects.

There is currently no recommendation for supplementation with vitamin B3 in pregnancy to minimise the risk of miscarriage or birth defects. There is no convincing proof of benefit, and we also don’t understand what recommended dosages, or even unsafe levels, may be.

Vitamin B3 deficiency isn’t exactly common in Australia. Vitamin B3 is found in meat, whole grains and most breakfast cereals—most of us are getting sufficient vitamin B3 in our diet without even thinking about it.

So, for now the recommendations remain the same—pregnant women (and women considering pregnancy in the next few months) are advised to take folic acid (500mcg daily for most women, or higher dose folic acid at 5mg per day for women with additional risk factors) and 150mcg of iodine daily. 

Some women may choose to take a pregnancy multivitamin and this is definitely worthwhile if you’re concerned about a balanced diet. But as for vitamin B3, more research is needed before a recommendation can be made.