Researches say in the Journal of Gerontology, Biological Sciences, that volunteers who followed a low-calorie diet or a very low-calorie diet not only lost weight, but also significantly enhanced their immune response. The study may be the first to demonstrate the interaction between calorie restriction and immune markers among humans, they say.
The lead researcher, Simin Nikbin Meydani, is director of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. The study is part of the "Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy" trial.
As people age, their immune response generally declines. Calorie restriction has been shown to boost these immune responses in animals.
For the study, the researchers looked at specific biologic markers. A skin test used called DTH (delayed-type hypersensitivity) is a measure of immune response at the whole body level. The researchers also examined effects of calorie restriction on function of T-cells--a major type of white blood cell--and other factors on the volunteer's immune system.
DTH and T-cell response indicate the strength of cell-mediated immunity. One positive was that DTH and T-cell proliferative response were significantly increased in both calorie-restrained groups. These results show for the first time that short-term calorie restriction for six months in humans improves the function of T-cells, say the researchers.