PROTEIN RESTRICTION (PR) AND CALORIC RESTRICTION (CR) COMPARED - EFFECTS ON DNA-DAMAGE, CARCINOGENESIS, AND OXIDATIVE DAMAGE

Protein restriction (PR) and caloric restriction (CR) similarly imping e upon various physiological factors that can significantly inhibit th e growth of DNA-damaged tissue and, therefore, carcinogenesis. Whether this effect is largely, or only in part, due to simple inhibition of body weight gain is examined. Among their many other health-improving effects, PR and CR delay the onset of puberty. It has been suggested t hat animals have developed mechanisms to cope with lean periods and th at, when food is limited, resources are diverted from those physiologi cal functions that offer no benefit for immediate survival (e.g., repr oductive capacity) to thereby support an increase in the maintenance f unctions that prolong life. PR has also been shown to affect numerous other varied mechanisms that can affect carcinogenesis, including gene expression and metabolism of xenobiotics. The effects of PR on initia tional and promotional growth of DNA-damaged tissue is also discussed. PR also seems to boost antioxidant defenses and inhibit the accumulat ion of oxidative damage (as does CR). Protein restricted animals have been shown to accumulate more calories, but develop fewer preneoplasti c lesions and tumors than their high-protein counterparts. This observ ation seems quite counter to most ideas about dietary restrictions and CR. Despite the fact that both PR and CR induce many beneficial physi ological effects in common, it is possible that PR is the more feasibl e option for human consideration. The levels of PR likely to improve h ealth without negative side effects are discussed.