Artificial Versus Naturally Occurring Sweetness and Metabolic Syndrome

A new review examines the weight-loss benefits of whole fruit, yogurt, and even juice in limited amounts

 

No one would suggest that sugary sodas and juices are healthy. Indeed, there is ample science suggesting that sugary drinks can lead to weight gain and obesity, risk of type 2 diabetes, and cardiovascular disease. A single increased serving of sugary drinks per day was associated with an 18% higher risk of type 2 diabetes in one study.

Despite this, intake of sugar sweetened beverages is high, and in some groups exceeds recommendations of both the United States government and the World Health Organization. These drinks – sodas, fruit flavored drinks, sports drinks – account for the largest share of added sugar in Western diets, as much as 15-17% of total calories.

But there are also many other sources of fructose that come from natural foods such as fruit, juice, and fruit varieties of yogurt. Their impact on metabolic syndrome – a condition that afflicts nearly a quarter of adults in the United States – is what is still under investigation. A new review looked at multiple studies to determine the differences in the way fructose in sugar-sweetened drinks, ice cream, and other sweets impact weight and metabolic syndrome versus natural sources such as fruit and yogurt.

Review details

Examining prospective cohort studies that lasted a year or more, the research team assessed study quality and looked at the pooled risk ratio of metabolic syndrome. They also noted if there was a dose response relationship between the food and metabolic syndrome to see how important portion-size was compared to eliminating certain high-fructose foods and drinks altogether.

There were 13 studies included in the analysis, with a total of nearly 50,000 study participants. Fructose containing foods included among the research analyzed included: sugar-sweetened beverages such as soda, mixed fruit juices, pure fruit juices, whole fruit, yogurt, honey, and desserts including ice cream, cake, candies, chocolate, and cookies.

Results

A clear adverse relationship was found between sugar-sweetened beverages and metabolic syndrome, quantifying it at a 14% increased incidence per 355-ml serving a day of sugar-sweetened drinks.

However, fruit and yogurt had a positive protective association with reducing metabolic syndrome. Fruit had the most protective impact at the equivalent of about three to five servings each day.

For yogurt, the most protection seems to come from a daily dose of 60 to 80 grams, plateauing at about 85 grams per day. Fruit juices, both mixed and 100% fruit based, had a positive protective effect at moderate doses of less than 200 ml per day, but an adverse impact at higher amounts.

Expert analysis

In discussing possible reasons why some types of food have a protective benefit, the authors note that yogurt has calcium, which inhibits fat absorption, and dairy fat has anti-inflammatory properties. Fruit can have beneficial impacts on waist circumference and blood pressure, both aspects of metabolic syndrome. With juices, there are nutrients that can benefit health, while at higher doses, the excess calories and sugar outweigh the protective benefits.

The review authors concluded that “the small beneficial effects of some foods might be driven by catalytic doses of fructose intake. Second, the food composition is important. Sugar sweetened beverages are without beneficial nutrients, thus offer an unchecked source of fructose-containing sugar, whereas in other foods, nutrients other than sugars such as polyphenols, minerals, and fiber may offer protection that might overcome harms from added sugars.”

“The harm identified with sugar sweetened beverages and metabolic syndrome was consistent with many previous studies,” notes lead author Zhila Semnani-Azad, a PhD candidate in the department of nutritional sciences at the University of Toronto School of Medicine. Sweet drinks tend to be less satisfying than eaten calories, she adds, which can lead to overeating, weight gain, and other issues that increase the risk of metabolic syndrome.

“We need more high-quality data to improve our estimates and to be able to make recommendations,” says Semnani-Azad. This is especially true for sweets, ice cream, and honey, where there was just a single study for each that met the qualifications of her analysis. And they found no studies on grain products and foods that contain grains, which are leading sources of sugar once broken down during digestion. “Furthermore, the complexity in the nutritional composition of other foods such as yogurt, fruit, and even mixed- or 100% fruit juice may be the reason for the protective association observed at all or low to moderate doses of intake with metabolic syndrome.”

She’d like to see more clinical trials that assess association of sources of fructose-containing sugars and how they impact the risk of developing metabolic syndrome. Having more data would help researchers to better estimate dose-response associations.

Portions and sources of food matter, she continues. Advice emphasizing that patients should avoid added sugar may need to be amended, since it’s clear from this analysis that the harm caused by sugar-sweetened drinks cannot be extrapolated to other foods that contain fructose-based sugars. “Sugar-reduction strategies that aim to limit foods such as fruit, yogurt, and mixed or 100% fruit juices, which were associated with a reduced risk of metabolic syndrome, may have unintended harm if replaced with other potentially less healthy foods,” she says.

Although there is still work to be done, there is some information in this work that providers can use, says Semnani-Azad. “It's critical for providers to recognize that although fructose in and of itself is not beneficial, other components of foods may contain nutritious ingredients, such as certain vitamins and minerals, that are beneficial to health and weight loss.” Small amounts of foods that have fructose can be benign or even beneficial, if they contain other nutrients that outweigh the potential harm of the fructose. “It is important to be mindful of what patients are consuming and to emphasize the need for a varied diet.”

Continue Reading:
Eliminating Fructose Promises Improved Lipids in At-Risk Children
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