Some women, particularly if they gain lots of weight during pregnancy, can develop gestational diabetes – high blood sugars. They usually return to normal after the baby is born but it does make you more prone to developing diabetes later on. If it’s not controlled by diet you end up having a big baby (ouch!)and he or she has a higher risk of being overweight and developing diabetes when older. Now here’s a study, just published in the British Journal of Nutrition, that has found taking specific probiotics may reduce gestational diabetes by 20%.

What did they do? It was a double-blind, randomised controlled study which means the study participants (256 healthy pregnant women) were randomly assigned to one of three groups: dietary counselling plus a daily probiotic capsule, dietary counselling plus a placebo capsule (looked and tasted the same but had no probiotics in it) or just the placebo capsule.

Double-blind means that neither the study participants nor the study organisers knew which group was which. Actually the control group who had no dietary counselling and just took the placebo capsule were single-blinded which means they didn’t know it didn’t contain probiotics but the study organisers did.

When assessing a study, clinical trials carry more clout than a pure association study such as ‘people who eat more vegetables have less heart disease’. Association studies give researchers a hint of what might be worth investigating further. Then they do a more specific trial – like this one.

Why did they do it? To test a theory that the composition of gut microflora influences glucose metabolism and obesity. One study found that women with lower weight gain in pregnancy had higher numbers of bifidobacteria in their gut. The number and type of bacteria in an infant’s gut is determined by the mother’s diet and lifestyle. It’s thought the more numbers and variety of bifidobacteria, the healthier and more resilient the gut. This may determine overweight risk as the infant grows.

What were the results? The women who took probiotics had substantially lower blood glucose and insulin levels both during pregnancy and for 12 months after pregnancy.

So what? Lower glucose and insulin levels reduces the chance of having an overweight baby. Babies who have developed in a womb of excess sugar (glucose) grow big and are more at risk of being overweight and developing diabetes when they are older. From this study the researchers think that probiotics may reduce glucose absorption and also promote anti-inflammatory and immune strengthening effects in the gut.

Will eating yoghurt keep my blood sugar levels down? Not necessarily. It depends which bacteria are in the yoghurt. This study used two specific bacteria – Lactobacillus rhamnosus GG and bifidobacterium lactis.

What do I do? If you are pregnant, and particularly if you are overweight, ask your doctor or dietitian to check out this study. Taking these bacteria doesn’t replace eating a healthy diet but it may enhance the effects.