An interest in investigating the long term
effects of dietary advice

According to Kerstin Brismar, diabetes doctor of 40 years and chair of the Dietary Science Foundation’s scientific advisory board, the dietary advice given to people with conditions such as type 2 diabetes, cardiovascular disease, dementia and cancer is based on inadequate scientific evidence. She sees a need for well-constructed scientific studies that answer important questions.

When Kerstin Brismar diagnoses people with type 2 diabetes, she usually gives them a choice:

“I tell them they can choose; they can either change their lifestyle or start taking medicine. Most of them choose to change their diet and start exercising more. Many people want to avoid medication,” says Kerstin Brismar, Professor of Diabetes Research at Karolinska Institutet.

As a doctor, her ambition is to give her patients the tools they need to make lifestyle changes. But when it comes to diet, the advice to give is unsure.
“For example, the conventional advices has been to tell people they should eat sandwiches every day. I’ve always thought that was wrong; it raises the blood sugar too much,” says Kerstin Brismar.

Among other things, she has shown that high blood sugar can lead to local oxygen starvation in the tissue, which may be the cause of chronic foot ulcers, a common problem for diabetics. High blood sugar and high insulin levels are also linked to an increased risk of cardiovascular disease, dementia and some types of cancer, such as breast, colon, uterine and liver cancer.

Food and fasting affect blood sugar

When blood sugar rises to excessively high levels, free radicals are formed in the cells. Kerstin Brismar’s research suggests that antioxidants offer protection from these free radicals. Therefore, it’s likely that antioxidants can prevent foot ulcers.

“That’s why I believe it’s important for the diet to contain a lot of antioxidants, which are mainly found in berries, fruit and vegetables, but also in olive and rapeseed oil,” she says.

The results of her studies also show that it’s possible to avoid high blood sugar by eating fewer simple carbohydrates, or by reducing calorie intake using intermittent fasting like the 5:2 diet, where for a few days a week you eat only a quarter of your normal intake.

Lower blood sugar is a good sign; it suggests that people with type 2 diabetes can prevent serious complications such as cardiovascular disease, dementia, cancer, kidney damage, eye problems and chronic foot ulcers. But proving that a particular way of eating produces such effects requires clinical trials where participants are followed for many years, and this is where research is lacking.

A shaky foundation for dietary guidelines for type 2 diabetes

In 2010 a group of experts evaluated the science supporting the dietary advice given to people with type 2 diabetes on behalf of the Swedish Agency for Health Technology Assessment and Assessment of Social Services (SBU). They concluded that there was a lack of high-quality studies, and that the scientific evidence was weak. SBU also identified a number of areas on the subject of food for diabetes where knowledge is deficient.

To fill some of these knowledge gaps, the Dietary Science Foundation wants to prioritize a long-term study investigating the effect of different diets on type 2 diabetes. Kerstin Brismar’s opinion is that people who want to change their lifestyle have a right to know what to eat to stay healthy. Is eating a sandwich every day good or bad, and for whom? It’s also important for healthcare professionals to feel confident they’re giving their patients the best possible care.

Photo of Kerstin Brismar: Joachim Bergström