A new study published in The American Journal of Clinical Nutrition has revealed a diet high in refined carbohydrates may lead to an increased risk of depression in postmenopausal women.
Carbohydrates are found in a wide variety of foods and have often been the focus of new weight-loss diets. However, the emphasis should not be on how many carbohydrates we eat, but the type.
Refined carbohydrates are contained in refined grains, such as white flour, white bread and white rice. They differ from whole-grain foods because they have been milled – a process that increases the texture and shelf life, but that also removes much of the nutritional value which includes important fiber and vitamins.
Once carbohydrates are eaten, some of the sugar is broken down into glucose that then proceeds to enter the bloodstream.The glycemic index (GI) is a metric tool used to measure and rank the extent to which our body’s sugar levels are raised after eating.
Foods with a low GI take longer to digest and break down and, therefore, enter the blood stream slowly. This causes the blood’s glucose level to be raised more slowly over a longer period of time.
In contrast, foods with a high GI cause a more rapid rise of the blood’s glucose level. Refined grains fall into this category, and it is this reason why a high-GI diet can lead to a host of health problems, such as diabetes and obesity.
Foods that have some of the highest GI scores include:
- White bread
- Corn flakes, puffed rice, bran flakes, instant oatmeal
- Shortgrain white rice, rice pasta, macaroni and cheese from mix
- Pretzels, rice cakes, popcorn, saltine crackers.
James Gangwisch, PhD, and colleagues, from the Department of Psychiatry at Columbia University Medical Center (CUMC), NY, set out to investigate the relationship between a diet high in refined carbohydrates and depression.
High-GI diet increased depression risk by 22%
Researchers analyzed data from more than 90,000 postmenopausal women who participated in the National Institutes of Health’s Women’s Health Initiative Observational Study that was conducted between 1994-1998. The observational study enlisted postmenopausal women between the ages of 50-79 and tracked their health over an average of 8 years.
They examined the levels of depression reported, the types of carbohydrates consumed, the GI rank and the glycemic load.
It was found high-GI diets increased the risk of depression in postmenopausal women by 22%. Also, a higher consumption of lactose, fiber, non-juice fruits and vegetables was significantly associated with a lower chance of developing depression.
The study concludes that further research should be done to see if a low-GI diet could serve as a treatment or primary preventive measure for postmenopausal women suffering from depression.