News & Research

Associations between dietary fiber and inflammation, hepatic function, and risk of type 2 diabetes in older men, by S. Gova Wannamethee and colleagues. Diabetes Care 32:1823–1825, 2009

What is the problem and what is known about it so far?

Eating foods that contain fiber, such as grains, fruits, and vegetables, can help protect people from getting type 2 diabetes. However, it is not clear exactly how eating fiber may help. Some studies have suggested that fiber can protect the liver, improve the body’s ability to respond to insulin, and reduce inflammation (the body’s response to infection, irritation, or injury). All of these factors have been linked to diabetes. However, their links to fiber have not been widely studied.

Why did the researchers do this particular study?

The researchers wanted to find out more about whether eating high-fiber foods can help people avoid diabetes by protecting the liver and reducing inflammation.

Who was studied?

The study included 3,428 nondiabetic British men who were 60–79 years old. The men participated in a heart disease study between 1978 and 1980 and received 20-year follow-up exams between 1998 and 2000.

How was the study done?

This study drew on information from the earlier heart disease study and continued to follow the participants for 7 more years. The men completed questionnaires at the 20-year follow-up of the heart disease study that included questions about their medical history and lifestyle behaviors. They also had their blood tested. The researchers looked at how much fiber the men ate and also at tests for diabetes, liver function, response to insulin, and inflammation levels.

What did the researchers find?

Men who ate the least fiber (no more than 20 grams each day) had the greatest chance of getting diabetes, after taking other factors into account. Men who ate more fiber had healthier livers and fewer signs of inflammation. Eating fiber was only slightly linked to how well the men responded to insulin and to their triglyceride (blood fat) level. Fiber was not related to their blood pressure, cholesterol, or blood glucose levels.

What were the limitations of the study?

The study design did not let researchers find out exactly how eating fiber may protect the liver or reduce inflammation. Also, the study was performed on a group of mostly white European men. More studies are needed to find links between fiber and diabetes among women and members of other ethnic groups.

What are the implications of the study

Eating a diet rich in fiber from grains, fruits, and vegetables may help older men avoid getting diabetes. This may be in part because fiber helps liver function and reduces inflammation in the body.

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