Carbohydrate restriction does not change mitochondrial free radical generation and oxidative DNA damage

Abstract

Many previous investigations have consistently reported that caloric restriction (40%), which increases maximum longevity, decreases mitochondrial reactive species (ROS) generation and oxidative damage to mitochondrial DNA (mtDNA) in laboratory rodents. These decreases take place in rat liver after only seven weeks of caloric restriction. Moreover, it has been found that seven weeks of 40% protein restriction, independently of caloric restriction, also decrease these two parameters, whereas they are not changed after seven weeks of 40% lipid restriction. This is interesting since it is known that protein restriction can extend longevity in rodents, whereas lipid restriction does not have such effect. However, before concluding that the ameliorating effects of caloric restriction on mitochondrial oxidative stress are due to restriction in protein intake, studies on the third energetic component of the diet, carbohydrates, are needed. In the present study, using semipurified diets, the carbohydrate ingestion of male Wistar rats was decreased by 40% below controls without changing the level of intake of the other dietary components. After seven weeks of treatment the liver mitochondria of the carbohydrate restricted animals did not show changes in the rate of mitochondrial ROS production, mitochondrial oxygen consumption or percent free radical leak with any substrate (complex I- or complex II-linked) studied. In agreement with this, the levels of oxidative damage in hepatic mtDNA and nuclear DNA were not modified in carbohydrate restricted animals. Oxidative damage in mtDNA was one order of magnitude higher than that in nuclear DNA in both dietary groups. These results, together with previous ones, discard lipids and carbohydrates, and indicate that the lowered ingestion of dietary proteins is responsible for the decrease in mitochondrial ROS production and oxidative damage in mtDNA that occurs during caloric restriction.

Reduced extracellular phagocyte oxidative activity, antioxidant level changes and increased oxidative damage in healthy human blood as a function of age

“…Some studies have established an inverse relationship between the lifespan potential and the intracellular levels of oxidative damage in different organisms. This is valid irrespectively of the factors that can change the maximum longevity, such as calorie restriction, mutations and levels of antioxidants (Sohal et al 1995;Sanz et al 2006). SOD, CTS and GSH-Px are the three main antioxidant enzymes that control the biological effects of the ROS produced in the organism.…”

Effect of 8.5% and 25% caloric restriction on mitochondrial free radical production and oxidative stress in rat liver

“…Thus, before ruling out a causal role for the calories, it is necessary to check whether 8.5% CR affects or not mitochondrial ROS production and oxidative stress. Analogously, the decreased carbohydrate intake during the carbohydrate restriction experiment (Sanz et al 2006a) unavoidably led to 25% CR, and in the case of lipid restriction (Sanz et al 2006b) the degree of CR was only 7%. Since only the carbohydrate restriction experiment lead to substantially different and much higher restriction of calories, 25% CR was also selected as the second level of calorie restriction in the present investigation.…”

“…Looking for the dietary factor responsible for the decreases in mitochondrial ROS production and oxidative stress, we have separately studied the effects of 40% protein restriction (Sanz et al 2004), 40% carbohydrate restriction (Sanz et al 2006a) and 40% lipid restriction (Sanz et al 2006b), without changing the amounts of the rest of dietary components, in male Wistar rats. The outcome of these studies was that neither 40% carbohydrate nor 40% lipid restriction modified mitochondrial ROS generation and oxidative stress, whereas 40% protein restriction did decrease those parameters in a very similar way to that observed in 40% CR, and the decrease in ROS generation during protein restriction specifically occurred, like in CR, at complex I.…”

Angiotensin II blockade: how its molecular targets may signal to mitochondria and slow aging. Coincidences with calorie restriction and mTOR inhibition

“…Among these, the most frequently used are intermittent fasting, food restriction, and food restriction with micronutrient supplementation, each of which displays specific effects and mechanisms of action (67). In this scenario, Sanz et al pointed out that lipid or carbohydrate restriction has no effect on mtROS production, whereas protein restriction reduces mtROS generation in rat liver independent of energy intake (356). In addition, methionine restriction, which increases longevity in rodents (280,337), reduces mtROS production and decreases oxidative damage in rat heart and liver mitochondria, suggesting that decreased methionine ingestion may contribute to the antiaging effects of CR (356).…”