According to a new Australian study, eating at least two servings of whole fruit each day helps guard against type 2 diabetes.
The study, from Edith Cowan University, examined data from 7,675 Australians participating in the Australian Diabetes, Obesity and Lifestyle study. The researchers assessed participants’ intake of fruit and fruit juice intake and the prevalence of type diabetes after five years of follow-up. They also administered blood tests to measure insulin resistance.
Insulin resistance occurs when cells in the body don’t respond properly to the blood-sugar-lowering hormone insulin. As a result, the pancreas has to make more insulin to allow glucose to enter cells.
The researchers found that participants who ate least two daily servings of fruit (versus less than one-half) were 36% less likely to be diagnosed with type 2 diabetes over the next five years.
They also found that people who ate at least two fruit servings each day had higher measures of insulin sensitivity than those who ate less than half a serving. In other words, people whose diets included fruit used less insulin to lower blood sugar levels.
Having high levels of insulin circulating in the bloodstream can damage blood vessels and is tied to a greater risk of diabetes, obesity and heart disease.
The researchers did not find the same beneficial relationship for fruit juice. Higher insulin sensitivity and a lower risk of diabetes was observed only for people who consumed whole fruit, not fruit juice, likely because juice tends to be much higher in sugar and lower in fibre.
The researchers said that it's unclear exactly how fruit contributes to insulin sensitivity, but it is likely to be multifaceted.
As well as being high in vitamins and minerals, fruits are a great source of phytochemicals which may increase insulin sensitivity. Fibre in fruit helps regulate the release of sugar into the bloodstream and also helps people feel fuller for longer.
As well, most fruits have a low glycemic index, which means the fruit's sugar is digested and absorbed into the body more slowly.
This study was observational in nature, so it can’t prove that eating whole fruit lowers diabetes risk. Still, its findings are consistent with previous large studies that investigated fruit intake and diabetes risk.
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