from Harvard School of Public Health (HSPH), Press Releases January 25, 2012 Study appears in January 25, 2012 issue of Science Translational Medicine
Study was supported by the National Institute on Aging and the National Institute of Diabetes and Digestive and Kidney Diseases (part of the National Institutes of Health), Ellison Medical Foundation, the American Federation for Aging Research, and the William F Milton Fund.
Over the past few decades, numerous studies on animals showed that long-term dietary restriction can improve health and lengthen life. But researchers were uncertain as to whether the benefits derived are from the source of calories or the total calories. HSPH launched a new study to provide further clarity to the subject.
Results of the study suggests that limiting certain essential nutrients, either protein or amino acids, for several days before surgery may reduce the risk of heart attack or stroke. It confirms the results of recent studies on the benefits of restricting protein in fruit flies.
“Food restriction as a way to increase stress resistance may seem counterintuitive, but in fact our data indicate that the well-fed state is the one more susceptible to this kind of injury,” said James Mitchell, HSPH assistant professor of genetics and complex diseases.
Mitchell and a former HSPH postdoctoral fellow, Wei Peng, led researchers in analyzing two groups of mice. One group ate normally for 6-14 days. The other group ate a diet free of protein or lacking a single amino acid—the building blocks of proteins.
Both groups of mice experienced surgical stress that could potentially harm the kidneys or liver. Forty percent of the mice in the first group died. No mice from the second group died.
In humans, stroke risk related to cardiovascular surgery ranges from 0.8%-9.7%. Heart attack risk is 3% to 4%.
Clarification of the process opens the door to targeting drugs to the activating pathway.
The next step for Mitchell and his colleagues is to determine whether dietary preconditioning works as well in humans to lower surgery-related risks as it did in mice. Accordingly, they’re in the early planning stages with colleagues at Brigham and Women’s Hospital in Boston on a clinical trial of patients on protein-free diets before surgery.
It may be possible to significantly lower humans’ surgical risks if the collaboration confirms the same beneficial results as documented from the animal study.