Ask any pregnant woman about folate and she will vouch for this group B vitamin known as folic acid – that has proven itself as an essential cornerstone of good pregnancy nutrition. But a new finding by Pune-based diabetologist is bound to create ripples in the obstetric world. Dr C S Yajnik, diabetologist and head of Pune KEM hospital's diabetes unit states that babies born to mothers with high folate levels and low vitamin B-12 levels are more insulin resistant.

Insulin resistance is the body's inability to respond to or use the insulin it produces. It may be linked to obesity, hypertension and high levels of fat in the blood. Dr Yajnik, in his paper — Vitamin B-12 and folate concentrations during pregnancy and insulin resistance in the offspring- the Pune Maternal Nutrition study – published in the January 2008 issue of Diabetologia has concluded that low maternal vitamin B-12 and high folate may contribute to the epidemic of adiposity and type II diabetes in India.

Says Yajnik, "We studied the association between the maternal vitamin B-12, folate and total homocysteine (tHcy) status during pregnancy and offspring adiposity and insulin resistance at six years. Raised maternal plasma total homocysteine concentrations predict small size at birth which is a risk factor for type II diabetes mellitus," says Yajnik.

The Pune Maternal Nutrition Study researched over 700 consecutive eligible pregnant women in six villages. The offspring of mothers with a combination of high folate and low vitamin B12 concentrations were the most insulin resistant.

Why this study is important
"India has the largest number of diabetic patients in the world," says Yajnik and this may be related to the fact that Indian babies are amongst the smallest in the world. "The Pune study was the first to demonstrate that low birth weight of Indian babies predicts insulin resistance and adiposity in childhood. These babies grow into shorter, thinner (low BMI) but more adipose (higher body fat per cent and higher central fat) adults compared with whites, and have a many times higher risk of type 2 diabetes," he points out.

Apart from genetic and modern day lifestyle factors, the intrauterine environment may also influence the risk of type 2 diabetes mellitus. The Pune Maternal Nutrition Study (PMNS) is the first study in India to investigate the relationship between maternal nutrition and offspring risk of type 2 diabetes and cardiovascular diseases.

Among rural mothers in Pune, energy and protein intakes are lower than the recommended daily allowance, vitamin B12 status is poor but folate status is adequate. Higher maternal folate concentrations predicted greater adiposity (fat mass and body fat per cent) and higher insulin resistance, and lower vitamin B12 concentrations predicted higher insulin resistance. Children born to mothers with low vitamin B12 concentrations but high folate concentrations were the most insulin resistant.

Thus, early-mid pregnancy may be a critical period for the programming of adiposity and insulin resistance, says Yajnik, pointing out that the results suggest a need for caution in designing nutritional strategies to improve fetal growth and future health based on relationships with birth size alone.