An Apple a Day Keeps the Diabetes Away?

Type 2 diabetes risk and fruit consumption associated in new study

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Should the saying really be, "An apple a day keeps diabetes away?" A new study hints that maybe so.

Results of the study showed that eating more whole fruits was associated with a lower risk for type 2 diabetes. Blueberries, grapes and apples showed a particularly strong association.

On the other hand, the study also showed that consuming more fruit juice was associated with an increased risk of developing the disease. 

"Eat fruit everyday."

In type 2 diabetes, the body does not use insulin properly and, as a result, blood glucose (sugar) levels are high. Based on the latest available data, the US Centers for Disease Control and Prevention (CDC) estimated that around 25.8 million people in the US (around 8.3 percent of the population) have some form of diabetes. 

This study, led by Isao Muraki, PhD, MD, of the Department of Nutrition at the Harvard School of Public Health, relied on data from several long-term US studies, including the Nurses’ Health Study (1984–2008), the Nurses’ Health Study II (1991-2009) and the Health Professionals Follow-up Study (1986–2008).

In total, these studies accounted for 187,382 participants. The participants did not have a diagnosis of diabetes, cardiovascular disease or cancer at the beginning of the study. There were 151,209 women and 36,173 men.

The researchers looked at a variety of data on the participants — gathered in the form of questionnaires — including information like physical activity, family history of diabetes, weight and questions on specific foods eaten. Questionnaires on food frequency were completed by participants every four years. 

Participants were asked how often they consumed certain fruits, including grapes or raisins, peaches, plums or apricots, prunes, bananas, cantaloupe, apples or pears, oranges, grapefruit, strawberries and blueberries. Participants were also asked about apple juice, orange juice, grapefruit juice and other fruit juices. 

By the end of the studies, 12,198 participants (6.5 percent) had developed type 2 diabetes. 

After analyzing the data, Dr. Muraki and team wrote, "Greater consumption of specific whole fruits, particularly blueberries, grapes, and apples, is significantly associated with a lower risk of type 2 diabetes, whereas greater consumption of fruit juice is associated with a higher risk."

The authors also found that if three servings a week of fruit juice were replaced with three servings a week of whole fruit, the risk of developing type 2 diabetes was reduced by 7 percent. 

"Overall, these results support recommendations on increasing consumption of a variety of whole fruits, especially blueberries, grapes, and apples, as a measure for diabetes prevention," the study authors concluded.

In an interview with dailyRx News, Craig Weingrow, MD, of Valhalla Medical Associates in Las Vegas, explained, "Recent studies in clinical nutrition suggest that consuming two servings of fresh fruit per day could assist type 2 diabetics in reducing waist size, body weight and blood sugar levels over time."

"The fiber and mineral content in fresh fruit could prove to be beneficial for type 2 diabetics. Ongoing research will be enlightening," said Dr. Weingrow.

Food frequency information was self-reported for this study, and errors could be present. It is also important to note that the research merely found a relationship between fruit and diabetes risk, and does not necessarily indicate cause. Other factors might be at play, and further research is needed to confirm these findings. 

This article was published in BMJ on August 28. The study received funding from the National Institutes of Health. 

No conflicts of interest were reported.

Review Date: 
August 28, 2013
Last Updated:
August 29, 2013