The study, published in the Journal of Internal Medicine, looked at 42,000 women in the Uppsala area. The women answered regular questions about their diets and were followed up over a twelve year period, according to Uppsala Nya Tidning.
The results showed that the more energy that women obtained from protein and the less energy obtained by carbohydrates the more likely the women were to die. The most common cause of death was cardiovascular disease.
The study was carried out by researchers at Harvard and at Swedish universities including the Karolinska Institute.