June 26, 2008

Unhealthy Meals Dull Older Diabetics' Memory

THURSDAY, June 26 (HealthDay News) -- Older adults with type 2 diabetes are apt to have memory problems after eating a meal loaded with fat, but a new study has found the damage can be undone if they take antioxidant vitamins along with the unhealthy food.

However, the researchers emphasize, it is better to eat healthy foods and not rely on vitamins to undo the cognitive harm.

"What we are aiming for is for people to actually eat healthier meals," said study author Michael Herman Chui, a third-year medical student at the University of Toronto. His report is published in the July issue of Nutrition Research.

"From this study, we could conclude that if people continue to eat this kind of meal long-term, the memory impairment would potentially be long-lasting," he said. His co-author is Dr. Carol E. Greenwood, a senior scientist at Baycrest Centre for Geriatric Care, a research and care facility affiliated with the University of Toronto.

In 2003, Greenwood published a paper finding that memory problems occurred after type 2 diabetics ate a meal of rapidly absorbed carbohydrates -- in this case, half a bagel and white grape juice.

In the recent study, Greenwood and Chui added fat to the meal. They looked at the effects of the meal on the cognitive performance of 16 adults with type 2 diabetes, average age 63. The meal included 3,356 calories and had more than 50 grams of fat, more than 63 grams of carbs and more than 25 grams of protein. It included Danish pastry, cheddar cheese and yogurt with whipped cream.

They tested their cognitive performance on various tests 60 minutes and 105 minutes after eating the meal. On a second occasion, the researchers conducted the same tests after the participants ate the same meal but also took 1,000 milligrams of vitamin C and 800 IUs of vitamin E. On a third occasion, they tested the participants again after they had only water.

Eating the high-fat meal without vitamins caused performance to fall in verbal recall and working memory when tested 105 minutes later, compared to the water-only meal. After eating the high-fat meal, participants showed more forgetfulness of words and paragraph information in recall tests.

But when they ate the high-fat meal and took the vitamins, their performance was as good as after the water-only session, Chui said.

The vitamins are thought to work by reducing oxidative stress, which is triggered when levels of free radicals, unstable molecules that can damage brain and other tissues, are elevated. Eating unhealthy foods induces oxidative stress. Having type 2 diabetes is also associated with oxidative stress, which in turn is associated with vascular problems.

The study produced interesting results, said Lona Sandon, an assistant professor at the University of Texas Southwestern Medical Center at Dallas. But she offered several caveats: The study was small, with only 16 participants. Comparing performance after a meal with vitamins to performance after having only water is not the best idea, she said.

"Of course, they would perform poorly with water only; there is no glucose getting to their brains," she explained.

"Type 2 diabetics are encouraged to avoid high-fat meals and choose plenty of fruits and vegetables high in antioxidants," she said.

More study is definitely needed, said Connie Diekman, director of university nutrition at Washington University in St. Louis. Among the unanswered questions: "The meal consumed was not a typical meal, so would the vitamins have similar effect on a more typical meal?"

If anything, Sandon said, the study reinforces standard advice that those with type 2 diabetes should avoid high-fat, rapidly absorbed carbohydrate meals for heart health, blood sugar control, and possibly brain health.

More information

To learn more about healthy eating with diabetes, visit the American Diabetes Association.

SOURCES: Michael Herman Chui, medical student, University of Toronto; Connie Diekman, M.Ed., R.D., director, university nutrition, Washington University, St. Louis; Lona Sandon, M.Ed., R.D., assistant professor, University of Texas Southwestern Medical Center at Dallas; July 2008, Nutrition Research
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