Drinks with added sugars linked to lipid imbalance, which increases CVD risk
February 26, 2020
Science Daily/American Heart Association
Drinking 12 ounces of sugary drinks more than once per day is linked to lower levels of high-density lipoprotein cholesterol (HDL-C), ("good" cholesterol), and higher levels of triglycerides, in middle aged and older adults, both of which have been shown to increase risk of cardiovascular disease. These results are from a new observational study published today in the Journal of the American Heart Association, the open access journal of the American Heart Association.
In previous studies, added sugars have been shown to increase cardiovascular disease risk. Beverages such as sodas, sports drinks and fruit-flavored drinks are the largest source of added sugars for Americans.
"For some time, we have known sugary drinks can have a negative effect on Americans' health status, yet the assumption for many is that they only contribute to weight gain," said Eduardo Sanchez, M.D., M.P.H., chief medical officer for prevention and chief of the Center for Health Metrics and Evaluation at the American Heart Association. "This research reinforces our understanding of the potential negative impact sugary drinks have on blood cholesterol, which increases heart disease risk. It is yet one more reason for all of us to cut back on sodas and other sugar-sweetened beverages."
Researchers hypothesized that dyslipidemia could be one pathway by which sugary drinks may increase cardiovascular disease risk. An estimated 40% to 50% of U.S. adults are affected by dyslipidemia, an unhealthy imbalance of cholesterol and triglyceride levels in the blood, which increases the risk of cardiovascular disease.
To determine the association between sugary drinks on triglyceride and cholesterol levels, researchers studied observational medical data of up to 5,924 participants from the Offspring and Generation 3 cohorts of the Framingham Heart Study, who were followed for an average of 12.5 years between 1991 and 2014. The Offspring cohort of the Framingham Heart Study includes the children of original participants in the Framingham Heart Study, and the Generation 3 cohort includes grandchildren of the original participants in the Framingham Heart Study.
For this study, the beverages were defined as: 12 ounces of sugary drinks, such as sodas, fruit-flavored drinks, sports drinks, presweetened coffees and teas; 12 ounces of low-calorie sweetened beverages, including naturally and artificially sweetened "diet" sodas or other flavored drinks; or 8 ounces of 100% fruit juices, including orange, apple, grapefruit and other juices derived from whole fruits with no added sugars. Study participants were classified into five groups according to how often they drank the different beverage types ranging from low intake (<1 serving per month) to high intake (>1 serving per day).
Researchers analyzed how the different drink types and their consumption levels correlated with changes in cholesterol and triglyceride levels over approximately four-year periods. They found that:
Drinking sugar-sweetened beverages (more than 12 ounces per day) was associated with a 53% higher incidence of high triglycerides and a 98% higher incidence of low HDL cholesterol (the "good" cholesterol) compared to those who drank less than one serving per month;
Drinking low-calorie sweetened beverages did not appear to be associated with increased dyslipidemia risk among the people who regularly drank low-calorie sweetened beverages; and
Regularly drinking up to 12 ounces of 100% fruit juice per day was not associated with adverse changes in cholesterol or dyslipidemia, though further research is needed to warrant this finding.
"Reducing the number of or eliminating sugary drink consumption may be one strategy that could help people keep their triglyceride and HDL cholesterol at healthier levels," said lead study author Nicola McKeown, Ph.D., a nutrition epidemiologist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston. "And, while our study didn't find negative consequences on blood lipids from drinking low-calorie sweetened drinks, there may be health consequences of consuming these beverages on other risk factors. Water remains the preferred and healthiest beverage."
While previous cross-sectional studies have had similar findings, this study reaffirms those findings with prospective data. One potential limitation of the study is that participants self-reported their dietary intake.
The American Heart Association recommends people eliminate sugary drink consumption to improve heart health and to reduce the risk of cardiovascular disease.
The National Institutes of Health, the American Heart Association and the U.S. Department of Agriculture's Agricultural Research Service supported the study.
https://www.sciencedaily.com/releases/2020/02/200226072110.htm
Fat fruit flies: High-sugar diet deadens sweet tooth; promotes overeating, obesity in flies
May 7, 2019
Science Daily/University of Michigan
Some research suggests that one reason people with obesity overeat is because they don't enjoy food -- especially sweets -- as much as lean people.
But it's not understood if obesity itself or eating certain foods causes taste changes, or how those changes impact appetite and obesity.
For clues, University of Michigan researchers turned to Drosophila melanogaster -- fruit flies -- in a study appearing May 7 in Cell Reports.
They discovered that after feeding fruit flies a high-sugar diet, the flies' taste neurons triggered a molecular chain-reaction that hampered their ability to taste sweets, which in turn fueled overeating and obesity. Further, eating sugar caused the taste changes, not the metabolic consequences of obesity or the sweet taste of food.
The fly findings are significant because if people respond similarly to sugar, researchers are closer to understanding how too much sugar contributes to overeating and obesity. And, because these are molecular changes, it supports the idea that overeating is at least partly beyond our control.
While it's impossible to measure fruit flies' "enjoyment" of food, they certainly ate more on the high-sugar diet, said principal investigator Monica Dus, U-M associate professor of molecular, cellular, and developmental biology.
And yes -- fruit flies do become obese, said Christina May, first author of the study and a doctoral student in Dus' lab. Flies and humans share other surprising similarities: Both love sugar and fat and produce dopamine upon eating it, and their brain cells use many of the same proteins and molecules humans do, for the same things.
The researchers tested their findings in several ways. First, they fed flies that were genetically obese but never exposed to high dietary sugar, and their taste didn't change. However, when they fed sugar equivalent to a cookie to flies unable to store fat, they stayed thin but still lost the ability to taste sweets.
"That's really amazing because it tells you their ability to taste sweets changed because of what they're eating, not because they're becoming obese," May said.
To find out if the sugar or the sweet taste of food caused taste changes, the researchers fed flies a diet similar to artificially sweetened diet soda. Only the files eating real sugar lost their sweet-tasting ability.
"We know it's something specific about the sugar in the diet that's making them lose their taste," Dus said.
The researchers identified the molecule O-GlcNAc transferase, a sugar sensor located in the flies' taste buds that keeps track of how much sugar is in the cells. OGT has previously been implicated in obesity-related conditions like diabetes and heart disease in humans.
They also manipulated flies' taste cells so that even on a high-sugar diet they wouldn't lose taste, and those flies didn't overeat despite loads of sugar.
"This means the changes in taste, at least in flies, are pretty important to drive overconsumption and weight gain," Dus said. "Do changes in taste also play a role in the overconsumption that we see when humans and other animals find themselves in food environments high in sugar?"
Study co-author Anoumid Vaziri, a doctoral student in Dus' lab, said the findings "not only shed light on sugar-diet-dependent neural mechanisms of overeating and obesity, but provide a platform to study the underlying molecular mechanisms that drive changes in neural activity."
So what's this mean for people who are overweight, dieting or feel addicted to sugar? It's possible that in the long-term, a drug or other intervention that corrects dietary sweetness and preserves the sweet taste sensation could someday help curb obesity and the associated chronic diseases. But that is years away, May said.
More importantly, if humans respond the same way as the flies, the research suggests that changing the amount of sugar in the diet can help regulate our food intake, Dus said. Much of the sugar we eat is hidden in processed food, and it's important to keep it to a minimum, she added.
"I think if you try to keep added sugars out of your diet, you'll probably be totally fine, you won't have problems with changing taste and overeating," May said. "All of us try to avoid the added sugars. That's important."
Dus said that future research will examine sugar's impact on the brain's reward circuits to learn what causes overeating, and how sugar changes the brain on a molecular level.
https://www.sciencedaily.com/releases/2019/05/190507121423.htm