Fruit as a food choice has a caveat, says researcher: Quantity matters, here’s why

Fruit is widely regarded as a healthy food — but is there such a thing as too much?

In a recent video, a Harvard researcher sets out to explore the nutritional nuances of this popular food group.

Nick Norwitz — who has a PhD in metabolic health and is currently finishing his medical degree — weighs the benefits and risks of consuming large quantities of different types of fruit. (See the video at the top of this article.)

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“The blanket statements that fruit is ‘natural and therefore healthy’ and ‘contains sugar and therefore unhealthy’ are both harmful oversimplifications,” he told Fox News Digital.

“Different fruits have different properties that interact with unique features of individuals,” he went on. “I made this video so people could make more informed choices about their fruit intake.”

In the video, Norwitz focuses on fruit’s fructose content, noting that fructose can be “metabolically harmful” — but points out that its negative effects depend on how it’s metabolized in the body.

“All fruits, in moderation, can fit into a healthy diet.”

The highest-fructose fruit is mango, he noted, with a full mango having about 30 grams of fructose.

“Other high-fructose fruits include jack fruit, grapes and watermelon,” Norwitz noted.

Some lower-fructose fruits include berries, kiwi, citrus fruits, and non-sweet, low-carb fruits like coconut, avocado and olives.

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Norwitz noted that it’s “surprisingly difficult” to assess the impact of fruits on health.

“This is largely due to the fact that in large-scale epidemiological studies, there is healthy user bias, where those who eat more fruit tend to live overall healthier lifestyles,” he said in the video.

Context also matters, he pointed out.

“For example, an athlete or generally healthy person having a banana before a run or after a run is very different than a person with diabetes chopping a banana into their morning brown sugar oatmeal,” he said.

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If fresh fruit replaces unhealthy foods like fruit juice, candy and donuts, people can expect to see a benefit, Norwitz noted — “but that doesn’t mean fruit intake is metabolically optimal in all circumstances, nor does it mean that a bowl of fruit is a healthier breakfast than eggs and bacon, or a healthier dessert than cheese.”

Different fruits also have different vitamin and mineral profiles, the researcher pointed out.

Nutritionists weigh in

Theresa Gentile, a registered dietitian in New York and spokesperson for the Academy of Nutrition and Dietetics, stated that overall, fruit is a healthy food. 

“All fruits, in moderation, can fit into a healthy diet,” she told Fox News Digital. “In a diet that doesn’t exceed your calories for the day, the natural fructose in fruit is a positive, healthy component.”

The USDA guideline for fruit consumption is about 2 cups per day.

“Fruit has fiber, vitamins and minerals, which are often underconsumed in the American diet,” Gentile added.

The fructose in fruit is different from the fructose in many processed foods, according to the expert.

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“Natural fructose is absorbed from the gastrointestinal tract by a different mechanism than that of glucose — it does not require insulin that is released from the pancreas for it to be absorbed,” she said.

“This means fructose doesn’t immediately impact blood sugar levels the way glucose does.”

The dietitian noted, however, that consuming too much fructose may have other negative effects on metabolism. 

“Most of the fructose in the American diet doesn’t come from fresh fruit, but from added sugars like high-fructose corn syrup and table sugar.”

“Fructose is highly reactive and can contribute to the formation of harmful compounds in the body, which may play a role in aging and certain diseases,” she told Fox News Digital.

“Most of the fructose in the American diet doesn’t come from fresh fruit, but from added sugars like high-fructose corn syrup and table sugar, which are commonly found in soft drinks and sweets.”

Michelle Routhenstein, a New York City registered dietitian who specializes in heart disease, agreed that fruit is healthy. 

“It’s packed with essential nutrients like vitamin C, potassium, fiber and antioxidants, which support immune function and heart health and reduce inflammation,” she told Fox News Digital.

“Fruit also contains unique polyphenols, which have protective benefits against chronic diseases like heart disease.”

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Because fruit does contain natural sugars, Routhenstein said it’s important to be mindful of portion sizes, recommending that people stick to 1.5 to 2 cups per day.

New Jersey-based dietitian Erin Palinski-Wade, author of “2-Day Diabetes Diet,” echoed that fruit can provide numerous health benefits, with essential nutrients, fiber and antioxidants that may lower the risk of certain diseases.

“However, any food, if consumed in very high levels, can lead to an imbalance in overall diet,” she told Fox News Digital. 

“If you opt to consume only fruit at the expense of eating foods containing protein, good fats and other essential nutrients, this can lead to an unbalanced diet and potential nutrient deficiencies.”

Are some fruits healthier than others?

While all fruits offer health benefits, some can offer higher levels of beneficial nutrients and antioxidants, according to Palinski-Wade.

“For instance, berries contain a high level of antioxidants, with blueberries being linked with many cognitive health benefits,” she told Fox News Digital. 

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“Avocados are rich in good fats and have been linked with many benefits, including improved outcomes for those at risk of developing type 2 diabetes.”

Palinski-Wade also called out “miracle berries” as containing high levels of antioxidants as well as compounds that alter the taste of sour foods, which allows them to be preserved as sweet and makes it easier to reduce added sugar in the diet. 

“Any food, if consumed in very high levels, can lead to an imbalance in overall diet.”

“Kiwifruit and tart cherries have also been linked with improved sleep quality and quantity in those experiencing insomnia,” she added.

Routhenstein pointed out that some fruits may be more suitable for certain dietary needs.

“Fruit choices should be based on personal preferences, lifestyle and health needs,” she said.

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“The focus should be on variety, portion control and pairing fruits with other heart-healthy foods, rather than demonizing any specific fruit.”

See more of Nick Norwitz’s food research videos here.