Why might dried fruit consumption help lower type 2 diabetes risk?

Consuming more dried fruits is associated with a lower risk of type 2 diabetes in a newly published study. The study hopes to resolve conflicting evidence regarding their value for people hoping to keep their blood sugar levels under control, due to the fruits’ concentrated amounts of sugar.

The study — which appeared in BMC Nutrition & Metabolism — found that increasing dried fruit intake by about 1.3 pieces daily may lower the risk of type 2 diabetes by up to 60.8%.

Dried fruits are flavorful, convenient and healthful, and are less perishable, making them attractive snacks. The study looked at consumption of dried prunes, dried apricots, and raisins.

In addition to being rich in macro and micronutrients, dried fruits include plenty of fiber that may help control blood sugar levels and improve digestive health.

They also contain flavonoids that have been linked to improved insulin sensitivity and they have anti-inflammatory properties.

The concern is that they contain concentrated amounts of natural sugar that may result in rapid spikes in glycemia (blood sugar) shortly after eating.

This can undermine an individual’s attempts to maintain stable glucose levels. Until recently, their consumption was largely discouraged for people at risk of type 2 diabetes, although the authors of the study describe a recent shift in this view.

The study analyzed Genome-Wide Association Study (GWAS) data based on UK Biobank data for approximately 500,000 people.

These data included 421,764 participants’ responses to questionnaires regarding the number of dried fruits they habitually consumed daily. One prune, a single apricot, and 10 raisins were all considered one portion for the purposes of the questionnaire.

Additional response options included “less than one,” “do not know,” and “prefer not to answer.”

The GWAS study also included genotypic and various phenotypic data for participants. Their questionnaire answers were compared to type 2 diabetes statistics derived from the IEU OpenGWAS database, including 61,714 people with type 2 diabetes and 593,952 controls.

An analysis of, or comparison with, the health benefits of fresh fruits was beyond the scope of this study. Thus, the study does not suggest dried fruits are superior to fresh fruits for blood sugar control.

Michelle Routhenstein, MS, RD, CDCES, a preventive cardiology dietitian at EntirelyNourished.com, who was not involved in the study, explained what is nutritionally beneficial about dried fruits for Medical News Today.

“Dried fruits, through dehydration, concentrate sugars and nutrients, resulting in higher caloric density and sugar content compared to fresh fruits,” said Routhenstein.

In essence, dried fruits are compact versions of fresh ones. They retain most of the nutrients and natural sugars but in a smaller form with most of the water removed. So, by weight and volume, dried fruits may contain more calories and sugar than fresh ones.

Another expert not involved in the study, Jason Ng, MD, BA, of the Department of Medicine at the University of Pittsburgh, considered that “[t]his is a good step towards understanding these connections.”

“The evidence suggests that dried fruit in and of itself may have health benefits and decrease the risk of type 2 diabetes development,” said Ng, who specializes in endocrinology and metabolism.

He also described the issue with dried fruits, noting that:

“Dried fruits have a higher carbohydrate amount than fresh fruits [consumed] in the same amount [by volume and weight]. So eating too much dried fruit can really cause a higher amount of carb intake, causing your body to process more carbs, and may lead to increased sugars in the future.”

For example, if you take a quarter cup of raisins (dried grapes) versus a quarter cup of fresh grapes — the quarter cup of raisins will contain about seven times the carbohydrates because there are a lot more dried grapes than fresh grapes packed into the same space.

According to some dietary guidelines, one quarter cup serving of dried fruit is equivalent to a half-cup serving of fresh fruit in terms of a person’s daily fruit intake goals.

“Despite this,” Routhenstein noted, “[dried fruits] retain valuable fiber, and can offer concentrated vitamins, minerals, and antioxidants, making them a nutrient-dense option when consumed mindfully.”

Ng suggested a possible mechanism that might explain the link with a lower diabetes risk.

“Dried fruits may lower the risk of diabetes via having nutrients and substances that act to reduce stress in the body — oxidative stress or other mechanisms — overall which can help the body more easily regulate sugar,” he hypothesized.

He said the study begins to help us understand how that would work.

“Typically,” said Ng, “fresh fruits are preferred because they have a lesser concentration of carbs [by weight], and have other helpful nutrients — with water as well — so in that sense, most would say fresh fruits are still preferred.”

Of the study, Ng said that “[t]his is good evidence to suggest that eating a moderate amount of dried fruit in conjunction with a low-carb sensible diet can provide benefits in reducing the risk of developing type 2 diabetes.“

Routhenstein stressed the importance of emphasizing a balanced diet when discussing dried fruits with her clients, and she recommends their consumption in portion-controlled amounts.

Given dried fruits’ pleasing taste and ease of consumption, it is easy to eat too much of them.

“A small serving,” Routhenstein, advised “like a quarter of a cup, can still provide fiber and essential nutrients without causing significant spikes in blood sugar levels.”

In addition, Routhenstein advised pairing dried fruits with foods that have a lower glycemic load to offset the fruits’ higher levels of sugar, and to help ensure overall nutritional balance.

Glycemic load is a rating based on the amount of carbohydrate a food contains as well as how quickly it raises blood sugar levels.

Among the foods with the are green vegetables, most fresh fruits, raw carrots, lentils, chickpeas, and kidney beans.

Finally, “[w]hile dried fruits can be a convenient and accessible part of a healthy diet, it’s important to also prioritize the consumption of fresh fruits and vegetables as integral components of a nutrient-rich, balanced eating regimen for diabetes and heart disease risk reduction,” Routhenstein said.