Protein restriction or caloric restriction?

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The below article indicates that protein restriction without caloric

restriction may confer many of the benefits of caloric restriction:

J Bioenerg Biomembr. 2004 Dec;36(6):545-52. Related Articles, Links

Protein restriction without strong caloric restriction decreases

mitochondrial oxygen radical production and oxidative DNA damage in

rat liver.

Sanz A, Caro P, Barja G.

Department of Animal Physiology-II, Faculty of Biological Sciences,

Complutense University, Madrid, 28040, Spain.

Previous studies have shown that caloric restriction decreases

mitochondrial oxygen radical production and oxidative DNA damage in

rat organs, which can be linked to the slowing of aging rate induced

by this regime. These two characteristics are also typical of long-

lived animals. However, it has never been investigated if those

decreases are linked to the decrease in the intake of calories

themselves or to decreases in specific dietary components. In this

study the possible role of the dietary protein was investigated.

Using semipurified diets, the ingestion of proteins of Wistar rats

was decreased by 40% below that of controls while the other dietary

components were ingested at the same level as in animals fed ad

libitum. After seven weeks in this regime the liver of the protein

restricted animals showed 30-40% decreases in mitochondrial

production of reactive oxygen species (ROS) and in oxidative damage

to nuclear and mitochondrial DNA. The decreases in ROS generation

occurred specifically at complex I. They also occurred without

changes in mitochondrial oxygen consumption. Instead, there was a

decrease in the percent free radical leak (the percentage of total

electron flow leading to ROS generation in the respiratory chain).

These results are strikingly similar to those previously obtained

after 40% caloric restriction in the liver of Wistar rats. Thus, the

results suggest that part of the decrease in aging rate induced by

caloric restriction can be due to the decreased intake of proteins

acting through decreases in mitochondrial ROS production and

oxidative DNA damage. Interestingly, these tissue oxidative stress-

linked parameters can be lowered by restricting only the intake of

dietary protein, probably a more feasible option than caloric

restriction for adult humans.

PMID: 15692733 [PubMed - indexed for MEDLINE]