Findings that appear in the journal Aging appear to suggest a calorie-restricted diet over an extended period of time, appears to reduce the onset of chronic conditions as long as adequate protein, vitamin, and mineral intake is maintained.
Calorie restriction (CR) without malnutrition has long been established as an effective intervention in lengthening lifespan in rodents. It is believed CR decreases inflammation, which is believed to protect against age-related diseases.
Despite this knowledge, little is known about the long-term effects of moderate CR with adequate intake of nutrients on inflammatory markers and cell-mediated immune response of healthy adults.
Study parameters
The study, carried out by researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, used a randomised clinical trial design that involved 218 healthy non‐obese adults aged between 20‐50 years old.
These individuals were placed either in a calorie-reduced diet group (n=143) or a no limit calorie (AL) diet of which 75 subjects were enrolled.
The control group stuck to their normal diet for the study’s duration, while the test group was provided with support to maintain a high-satiety diet that restricted their calories by 25% including behavioural advice.
The test group was also given multivitamin and mineral supplements to prevent micronutrient malnutrition. To maintain a 25% calorie reduction the test group’s calorie intake was reduced three times through the two-year study to account for their weight loss.
Data was collected at the start of the research and at 12, and 24 months of CR.
Results indicated that CR promoted a 10.4% weight loss over the 2-year period. In comparison to the to AL group, the calorie-restricted group saw a reduction of systemic inflammatory markers, indicative of disease onset.
These markers included total white blood cell (WBC) and lymphocyte counts as well as intercellular adhesion molecule‐1 (ICAM‐1) and leptin. ICAM-1 is a protein that plays a central role in the immune response.
“This may be one of the most powerful non-genetic intervention to slow aging, increase our health span and the quality of our lives,” said lead author Dr Simin Nikbin Meydani, director of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts (HNRCA).
Inflammation implicated
Low-grade chronic inflammation is characteristic of multiple age-associated chronic diseases and even in the biology of aging itself.
While research from observational human studies demonstrate that CR without malnutrition inhibits inflammation, the study’s researchers believe this trial is the first to show a causal relationship in humans.
The WBC count has been broadly used as a non-specific marker of systemic inflammation, with higher levels, even when within the clinical reference range, associated with an increased risk of developing insulin resistance, hypertension and cardiovascular disease.
“These calorie restricted changes suggest a shift toward a healthy phenotype given the established role of inflammation in the development of cardiovascular disease, cancer and aging,” said co-author Luigi Fontana, professor of medicine and nutrition at Washington University in St. Louis and Brescia University.
“With all of today’s fitness and biometric measurement technology available to the public, it is certainly feasible for the average person to maintain a 10-15% calorie restriction as a strategy for long-term health benefits.”
Source: Aging
Published online ahead of print, 10.18632/aging.100994
“Long‐term moderate calorie restriction inhibits inflammation without impairing cell‐mediated immunity: a randomized controlled trial in non‐obese humans.”
Authors: Simin Meydani et al.