RESUMO
Caloric restriction has consistently been shown to extend life span and ameliorate aging-related diseases. These effects may be due to diet-induced reactive oxygen species acting to up-regulate sirtuins and related protective pathways, which research suggests may be partially inhibited by dietary anti-oxidant supplementation. Because caloric restriction is not sustainable long term for most humans, we investigated an alternative dietary approach, intermittent fasting (IF), which is proposed to act on similar biological pathways. We hypothesized that a modified IF diet, where participants maintain overall energy balance by alternating between days of fasting (25% of normal caloric intake) and feasting (175% of normal), would increase expression of genes associated with aging and reduce oxidative stress and that these effects would be suppressed by anti-oxidant supplementation. To assess the tolerability of the diet and to explore effects on biological mechanisms related to aging and metabolism, we recruited a cohort of 24 healthy individuals in a double-crossover, double-blinded, randomized clinical trial. Study participants underwent two 3-week treatment periods-IF and IF with anti-oxidant (vitamins C and E) supplementation. We found strict adherence to study-provided diets and that participants found the diet tolerable, with no adverse clinical findings or weight change. We detected a marginal increase (2.7%) in SIRT3 expression due to the IF diet, but no change in expression of other genes or oxidative stress markers analyzed. We also found that IF decreased plasma insulin levels (1.01 µU/mL). Although our study suggests that the IF dieting paradigm is acceptable in healthy individuals, additional research is needed to further assess the potential benefits and risks.
Assuntos
Envelhecimento/genética , Envelhecimento/metabolismo , Restrição Calórica , Metabolismo Energético/genética , Jejum/metabolismo , Comportamento Alimentar , Estresse Oxidativo/genética , Adulto , Fatores Etários , Antioxidantes/administração & dosagem , Estudos Cross-Over , Suplementos Nutricionais , Método Duplo-Cego , Metabolismo Energético/efeitos dos fármacos , Feminino , Florida , Regulação da Expressão Gênica , Voluntários Saudáveis , Humanos , Masculino , Estresse Oxidativo/efeitos dos fármacos , Cooperação do Paciente , Satisfação do Paciente , Sirtuína 3/genética , Sirtuína 3/metabolismo , Fatores de Tempo , Adulto JovemRESUMO
Ketogenic diets (KDs) are used for treatment of refractory epilepsy and metabolic disorders. The classic saturated fatty acid-enriched (SAT) KD has a fat:carbohydrate plus protein ratio of 4:1, in which the predominant fats are saturated. We hypothesized that a polyunsaturated fat-enriched (POLY) KD would induce a similar degree of ketosis with less detrimental effects on carbohydrate and lipid metabolism. Twenty healthy adults were randomized to two different weight-maintaining KDs for 5 d. Diets were 70% fat, 15% carbohydrate, and 15% protein. The fat contents were 60 or 15% saturated, 15 or 60% polyunsaturated, and 25% monounsaturated for SAT and POLY, respectively. Changes in serum beta-hydroxybutyrate, insulin sensitivity (S(I)), and lipid profiles were measured. Mean circulating beta-hydroxybutyrate levels increased 8.4 mg/dl in the POLY group (P = 0.0004), compared with 3.1 mg/dl in the SAT group (P = 0.07). S(I) increased significantly in the POLY group (P = 0.02), whereas total and low-density lipoprotein cholesterol increased significantly in the SAT group (both P = 0.002). These data demonstrate that a short-term POLY KD induces a greater level of ketosis and improves S(I), without adversely affecting total and low-density lipoprotein cholesterol, compared with a traditional SAT KD. Thus, a POLY KD may be superior to a classical SAT KD for chronic administration.