diet Archives - Sanford Burnham Prebys
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Are artificial sweeteners bad for your health?

AuthorJessica Moore
Date

October 25, 2016

These days, we’re fighting a war on sugar, and it might seem like we’re winning. Low-calorie, artificial sweeteners are added to 15% of the volume of foods and beverages purchased in the United States.1 And they’re in all sorts of products labeled “light” or “no added sugar,” from soda to yogurt to protein bars. By replacing sugar, they’re meant to help consumers take in fewer calories. But epidemiological data suggest they may do the opposite, elevating the risk of health problems like type 2 diabetes and cardiovascular disease. 

“Artificial sweeteners were approved for consumption by the U.S. Food and Drug Administration because they’re non-toxic and don’t cause cancer at the recommended daily intake,” said George Kyriazis, PhD, assistant professor in the Integrative Metabolism Program, who recently presented evidence of their possible health risks during a public lecture at the University of Central Florida. “But we’re only now figuring out whether and how they may affect metabolism.”

The potential impact of artificial sweeteners, including sucralose, aspartame, saccharin and acesulfame potassium, on American health could be huge. In large studies following the same group of people over 10-20 years, those who drank at least one artificially sweetened beverage every day were 40% to 60% more likely to develop type 2 diabetes or suffer a heart attack or stroke as those who didn’t.2 The jump in relative risk is roughly the same as that with one or more regular sugary sodas.

Why is consumption of low-calorie sweeteners associated with all these problems if they’re not metabolized by our cells? Kyriazis thinks a potential mechanism lies in their ability to activate sweet taste receptors, the focus of his research. Sweet taste receptors, despite their name, are actually found in many organs, including the intestine and pancreas, where they regulate sugar uptake and secretion of sugar-regulating hormones, respectively.

Kyriazis has shown that sweet taste receptors are essential for artificial sweeteners to wreak havoc on metabolism. For example, adding saccharin to the water of normal mice for a few months causes them to become pre-diabetic, but mice lacking sweet taste receptors are protected from this condition. Whether this is also true in humans is unknown, but Kyriazis is leading a proof-of-concept clinical study at the Translational Research Institute for Metabolism and Diabetes at Florida Hospital that will begin recruiting soon.

“We will give healthy participants an FDA-approved food additive that inhibits sweet taste receptors and see if it can prevent any of the anticipated negative metabolic effects of saccharin consumption,” Kyriazis explained. “These studies could further our understanding of the role of sweet taste receptors in metabolic disease, which will help determine their validity as a target for future drug development.”

 

References:

  1. Ng SW, Slining MM, Popkin BM. Use of caloric and noncaloric sweeteners in US consumer packaged foods, 2005–2009. J Acad Nutr Diet 2012.
  2. Swithers SE. Artificial sweeteners produce the counterintuitive effect of inducing metabolic derangements. Trends Endocrinol Metab 2013. Table 1, refs 25, 26, 30.
Institute News

Dietary restriction increases lifespan through effects on the gut

AuthorJessica Moore
Date

July 14, 2016

Dietary restriction, or limited food intake without malnutrition, has beneficial effects on longevity in many species, including humans. A new study from the Sanford Burnham Prebys Medical Discovery Institute (SBP), published today in PLoS Genetics, represents a major advance in understanding how dietary restriction leads to these advantages.

“In this study, we used the small roundworm C. elegans as a model to show that autophagy in the intestine is critical for lifespan extension,” said Malene Hansen, PhD, associate professor in SBP’s Development, Aging, and Regeneration Program and senior author of the study. “We found that the gut of dietary-restricted worms has a higher than normal rate of autophagy, which appears to improve fitness in multiple ways—preserving intestinal integrity and maintaining the animal’s ability to move around.”

Autophagy, or cellular recycling, is well known to play a role in lifespan extension. Autophagy involves breaking down the cell’s parts—its protein-making, power-generating, and transport systems—into small molecules. This both eliminates unnecessary or broken cell machinery and provides building blocks to make new cell components, which is especially important when starting materials are not provided by the diet.

In this study the research team wanted to understand how dietary restriction impacts autophagy in the intestine, whose proper function is already known to be important for long life.

“The strain of worms we used, called eat-2, is genetically predisposed to eat less, and they live longer than normal worms, so they provide an ideal model in which to investigate how dietary restriction extends lifespan,” said Sara Gelino, PhD, research associate in Hansen’s lab and lead author of the study. “We found that blocking autophagy in their intestines significantly shortened their lifespans, showing that autophagy in this organ is key for longevity.

“These results led us to examine how inhibiting autophagy impacts the function of the intestine. We found that while normal worms’ gut barriers become leaky as they get older, those of eat-2 worms remain intact. Preventing autophagy eliminated this benefit, which indicates that a non-leaky intestine is an important factor for long life.”

“How intestinal integrity relates to longevity is not clearly understood,” Hansen commented. “It’s possible that the decline in the gut’s barrier function associated with normal aging might let damaging substances or pathogens into the body.”

The research team also observed that turning off autophagy in the intestine made the slow-eating, long-lived worms move around less.

“The decrease in physical activity indicates that autophagy in one organ can have a major impact on other organs, in this case probably muscle or motor neurons,” said Hansen. “Finding the link between motility and autophagy in the intestine will require further research, but we speculate that inhibiting autophagy in the gut may impair the gut’s ability to metabolize nutrients or secrete hormones important for the function of other organs.”

While these results suggest that boosting autophagy in the gut is generally beneficial, Hansen cautions that further research is needed: “Before we can consider regulating autophagy to manage disease, we need to learn a lot more about how the process works both in a single cell as well as in the whole organism.”

Many of these future studies will also employ C. elegans. “Even though worms are much simpler than humans, many of the same basic mechanisms drive their biology. The knowledge we gain from this fast-paced research could eventually contribute to the development of new treatments that help people live longer, healthier lives,” added Hansen.

The paper is available online here.

Institute News

Why the “Biggest Losers” don’t win

AuthorJessica Moore
Date

May 12, 2016

Following a recent publication on the long-term effects of participation in TV’s “Biggest Loser” competition, Steven Smith, MD, professor in SBP’s Integrative Metabolism Program and director of the Translational Research Institute for Metabolism and Diabetes at Florida Hospital, was interviewed by NBC WESH TV Orlando reporter Amanda Ober. Smith explained why nearly all of the “Biggest Losers” regained large proportions of the weight they had lost, and sometimes even more. Continue reading “Why the “Biggest Losers” don’t win”

Institute News

How your organs ‘taste’ sugar

Authorjmoore
Date

April 18, 2016

You might be surprised to learn that the sensors for sweet-tasting molecules aren’t located only on your tongue—they’re also found in the gut, pancreas, fat tissue, and muscle. And new research from the laboratory of George Kyriazis, PhD, assistant professor in the Integrative Metabolism Program at Lake Nona, indicates just how important these sweet taste receptors are in regulating metabolism. Continue reading “How your organs ‘taste’ sugar”