Media ReleaseFrom: Cell Press
Peer-reviewed Observational & Experimental Studies People & Animals/Mice
Three studies show caloric restriction’s varying effects on the immune system
Three studies about caloric restriction appearing in the journal Cell on August 22 show that more specificity is needed when discussing the effects of fasting and fasting-like diets. The diets studied in the three papers used different lengths and types of fasting and resulted in distinct and sometimes opposite effects on the immune system.
Jordan et al. studied the effect of one round of short-term fasting on circulating monocytes.
- By comparing blood drawn in an “eating state” from day 1 to a “fasting state” on day 2, Jordan et al. found that the short water-only fast reduced the number of pro-inflammatory monocytes in the blood.
- This study was conducted in humans and mice.
Collins et al. studied the effect of dietary restriction on memory T cells.
- Collins et al. cut calorie consumption in mice by 50 percent, instead of absolute water-only fasting used in the other two studies.
- In contrast to the findings of Jordan et al., dietary restriction resulted in increased protection against infections or tumors.
Nagai et al. studied how multiple rounds of water-only fasting affect the gut immune response.
- Researchers found that mice experienced attenuated immune response after oral immunization.
Because each paper tests the effects of a different kind of fasting, a Preview by Roberta Buono and Valter Longo in the same issue argues that it is time to establish a more specific vocabulary than ‘fasting’ or ‘intermittent fasting,’ for example, 24-hour alternate day fasting (24H ADF) or 12-hour time restricted feeding (12H TRF). They write, “Without these more precise definitions, it will be difficult to generate sufficient data to enhance our understanding of the biology of fasting responses and begin to translate this knowledge into randomized clinical trials.”