DRINKING SUGAR SWEETENED BEVERAGES DURING ADOLESCENCE IMPAIRS MEMORY

Research to be presented at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB) finds that daily consumption of beverages sweetened with high-fructose corn syrup or sucrose can impair the ability to learn and remember information, particularly when consumption occurs during adolescence

Both adult and adolescent rats were given daily access to sugar-sweetened beverages that mirror sugar concentrations found in common soft drinks. Adult rats that consumed the sugar-sweetened beverages for one month performed normally in tests of cognitive function; however, when consumption occurred during adolescence the rats were impaired in tests of learning and memory capability.

The lead author, Dr. Scott Kanoski from the University of Southern California, says, "It's no secret that refined carbohydrates, particularly when consumed in soft drinks and other beverages, can lead to metabolic disturbances. However, our findings reveal that consuming sugar-sweetened drinks is also interfering with our brain's ability to function normally and remember critical information about our environment, at least when consumed in excess before adulthood."

In addition to causing memory impairment, adolescent sugar-sweetened beverage consumption also produced inflammation in the hippocampus, an area of the brain that controls many learning and memory functions.

"The hippocampus is such a critical brain region for memory function," says Kanoski. "In many ways this region is a canary in the coal mine, as it is particularly sensitive to insult by various environmental factors, including eating foods that are high in saturated fat and processed sugar."

NEW GENETIC VARIANTS ASSOCIATED WITH COFFEE DRINKING

A new, large-scale study has identified six new genetic variants associated with habitual coffee drinking. The genome-wide meta-analysis, led by Harvard School of Public Health and Brigham and Women's Hospital researchers, helps explain why a given amount of coffee or caffeine has different effects on different people and provides a genetic basis for future research exploring the links between coffee and health.

Coffee and caffeine have been linked to beneficial and adverse health effects. Our findings may allow us to identify subgroups of people most likely to benefit from increasing or decreasing coffee consumption for optimal health," said Marilyn Cornelis, research associate in the Department of Nutrition at Harvard School of Public Health and lead author of the study.

The study appears online October 7, 2014 in Molecular Psychiatry.

Genetics have long been suspected of contributing to individual differences in response to coffee and caffeine. However, pinpointing the specific genetic variants has been challenging.

The researchers, part of the Coffee and Caffeine Genetics Consortium, conducted a genome-wide meta-analysis of more than 120,000 regular coffee drinkers of European and African American ancestry. They identified two variants that mapped to genes involved in caffeine metabolism, POR and ABCG2 (two others, AHR and CYP1A2 had been identified previously). Two variants were identified near genes BDNF and SLC6A4 that potentially influence the rewarding effects of caffeine. Two others -- near GCKR and MLXIPL, genes involved in glucose and lipid metabolism -- had not previously been linked to the metabolism or neurological effects of coffee.

The findings suggest that people naturally modulate their coffee intake to experience the optimal effects exerted by caffeine and that the strongest genetic factors linked to increased coffee intake likely work by directly increasing caffeine metabolism.

"The new candidate genes are not the ones we have focused on in the past, so this is an important step forward in coffee research," said Cornelis.

"Like previous genetic analyses of smoking and alcohol consumption, this research serves as an example of how genetics can influence some types of habitual behavior," said Daniel Chasman, associate professor at Brigham and Women's Hospital and the study's senior author.

DRINKING TOO MUCH WATER CAN BE FATAL TO ATHLETES

The recent deaths of two high school football players illustrate the dangers of drinking too much water and sports drinks, according to Loyola University Medical Center sports medicine physician Dr. James Winger.

Over-hydration by athletes is called exercise-associated hyponatremia. It occurs when athletes drink even when they are not thirsty. Drinking too much during exercise can overwhelm the body's ability to remove water. The sodium content of blood is diluted to abnormally low levels. Cells absorb excess water, which can cause swelling -- most dangerously in the brain.

Hyponatremia can cause muscle cramps, nausea, vomiting, seizures, unconsciousness, and, in rare cases, death.

Georgia football player Zyrees Oliver reportedly drank 2 gallons of water and 2 gallons of a sports drink. He collapsed at home after football practice, and died later at a hospital. In Mississippi, Walker Wilbank was taken to the hospital during the second half of a game after vomiting and complaining of a leg cramp. He had a seizure in the emergency room and later died. A doctor confirmed he had exercise-associated hyponatremia.

And in recent years, there have been more than a dozen documented and suspected runners' deaths from hyponatremia.

Winger said it's common for coaches to encourage athletes to drink profusely, before they get thirsty. But he noted that expert guidelines recommend athletes drink only when thirsty. Winger said athletes should not drink a predetermined amount, or try to get ahead of their thirst.

Drinking only when thirsty can cause mild dehydration. "However, the risks associated with dehydration are small," Winger said. "No one has died on sports fields from dehydration, and the adverse effects of mild dehydration are questionable. But athletes, on rare occasions, have died from over-hydration."

Winger is co-author of a 2011 study that found that nearly half of Chicago-area recreational runners surveyed may be drinking too much fluid during races. Winger and colleagues found that, contrary to expert guidelines, 36.5 percent of runners drink according to a present schedule or to maintain a certain body weight and 8.9 percent drink as much as possible.

"Many athletes hold unscientific views regarding the benefits of different hydration practices," Winger and colleagues concluded. Their study was published in the British Journal of Sports Medicine.