Potato-rich diet 'may increase pregnancy diabetes risk'

Eating potatoes or chips on most days of the week may increase a woman's risk of diabetes during pregnancy, say US researchers.  They say, this is probably because starch in spuds can trigger a sharp rise in blood sugar levels. The study in the BMJ tracked more than 21,000 pregnancies.  The study linked high potato consumption to a higher diabetes risk.  Swapping a couple of servings a week for other vegetables should counter this, say the authors.

Foods that contain carbohydrates affect blood sugar.  Some - high Glycemic Index (GI) foods - release the sugar quickly into the bloodstream.  Others - low GI foods - release them more steadily. Research suggests eating a low GI diet can help manage diabetes.

Pregnancy puts extra demands on the body, and some women develop diabetes at this time. Gestational diabetes, as it is called, usually goes away after the birth but can pose long-term health risks for the mother and baby.

The BMJ study set out to investigate what might make some women more prone to pregnancy diabetes. The study followed nurses who became pregnant between 1991 and 2001. None of them had any chronic diseases before pregnancy.

What is gestational diabetes mellitus?

  • It is a condition where there is too much glucose (sugar) in the blood
  • About three in every 100 pregnancies are affected in the UK
  • Symptoms include a dry mouth, tiredness and urinating frequently
  • Gestational diabetes can be controlled with diet and exercise, but some women will need medication to keep their blood glucose levels under control
  • If not managed properly, it could lead to premature birth or miscarriage

Every four years, the women were asked to provide information on how often potatoes featured in their diets, and any cases of gestational diabetes were noted.  Over the 10-year period, it found a 27% increased risk of diabetes during pregnancy in the nurses who typically ate two to four 100g (3.5oz) servings of boiled, mashed, baked potatoes or chips a week. In those who ate more than five portions of potatoes or chips a week, the risk went up by 50%.  The researchers estimate that if women swap their potatoes for vegetables or whole grains at least twice a week, they would lower their diabetes risk by 9-12%.

Cuilin Zhang, lead study author, from the National Institutes of Health in Maryland, US, said the findings were important.  "Gestational diabetes can mean women develop pre-eclampsia during pregnancy and hypertension," she said.  "This can adversely affect the foetus, and in the long term the mother may be at high risk of type-2 diabetes."

Simple swaps that can lower GI:

  • Switch baked or mashed potato for sweet potato or boiled new potatoes
  • Instead of white and wholemeal bread, choose granary, pumpernickel or rye bread
  • Swap frozen microwaveable French fries for pasta or noodles
  • Try porridge, natural muesli or wholegrain breakfast cereals

Dr Emily Burns, of Diabetes UK, said: "This study does not prove that eating potatoes before pregnancy will increase a woman's risk developing gestational diabetes, but it does highlight a potential association between the two.  What we do know is that women can significantly reduce their risk of developing gestational diabetes by managing their weight through eating a healthy, balanced diet and keeping active."