One of the few proven methods for extending life spans is to keep calorie intake to a bare minimum, but new studies suggest that even moderate calorie restriction could have substantial health benefits.
Separate new studies suggest cutting calories, especially carbohydrates, might ward off or alleviate symptoms of Alzheimer's disease and diabetes.
In one study done on mice, researchers found that restricting caloric intake can calm or even reverse symptoms associated with Alzheimer's.
People afflicted with Alzheimer's have elevated levels of a protein called beta-amyloid. The protein builds up as a plaque inside the brain and disrupts brain cell activity.
Putting mice on caloric restriction diets reduced the amount of beta-amyloid in their brains. The reverse was also true: Eating foods high with calories and saturated fats was found to increase beta-amyloids.
The researchers think that caloric restriction promotes the activity of SIRT1, a protein known to influence a variety of functions, including metabolism and aging. SIRT1 is believed to activate other proteins, such as alpha-secretase, which are known to inhibit beta-amyloid buildup.
The study, led by Giulio Maria Pasinetti at the Mount Sinai School of Medicine, will be detailed in the July issue of the Journal of Biological Chemistry.
In another study, albeit a small one, researchers in Sweden report that a low-carbohydrate diet in humans can improve symptoms associated with type 2 diabetes and reduce the need for medication.
The researchers found that seven diabetic patients who switched from a low-fat diet to a low carbohydrate diet (20 percent carbs) for 22 months showed improvement in hemoglobin A1C, a marker for long-term blood-sugar levels in diabetes.
The study, led by Jorgen Vesti Nielsen from the Department of Medicine at Blekingesjukhuset in Sweden, is detailed online in the journal Nutrition and Metabolism.
The U.S. Food and Drug Administration recommends that out of a 2,000 calorie diet, 60 percent of the calories should come from carbohydrates, 30 percent from fat and10 percent from protein.