Life Extension - Treatment using Supplements

Caloric Restriciton - updated: 16 December 2008

Metabolic reprogramming in dietary restriction

Interdiscip Top Gerontol. 2007;35:18-38

Anderson RM, Weindruch R.

It is widely accepted that energy intake restriction without essential nutrient deficiency delays the onset of aging and extends life span. The mechanism underlying this phenomenon is still unknown though a number of different, nonmutually exclusive explanations have been proposed. In each of these, different facets of physiology play the more significant role in the mechanism of aging retardation. Some examples include the altered lipid composition model, the immune response model and models describing changes in endocrine function. In this paper we propose the hypothesis that metabolic reprogramming is the key event in the mechanism of dietary restriction, and the physiological effects at the cellular, tissue and organismal level may be understood in terms of this initial event.

Publication Types:

• Review

Overview of caloric restriction and ageing

Mech Ageing Dev. 2005 Sep;126(9):913-22

Masoro EJ.

It has been known for some 70 years that restricting the food intake of laboratory rats extends their mean and maximum life span. In addition, such life extension has been observed over the years in many other species, including mice, hamsters, dogs, fish, invertebrate animals, and yeast. Since this life-extending action appears to be due to a restricted intake of energy, this dietary manipulation is referred to as caloric restriction (CR). CR extends life by slowing and/or delaying the ageing processes. The underlying biological mechanism responsible for the life extension is still not known, although many hypotheses have been proposed. The Growth Retardation Hypothesis, the first proposed, has been tested and found wanting. Although there is strong evidence against the Reduction of Body Fat Hypothesis, efforts have recently been made to resurrect it. While the Reduction of Metabolic Rate Hypothesis is not supported by experimental findings, it nevertheless still has advocates. Currently, the most popular concept is the Oxidative Damage Attenuation Hypothesis; the results of several studies provide support for this hypothesis, while those of other studies do not. The Altered Glucose-Insulin System Hypothesis and the Alteration of the Growth Hormone-IGF-1 Axis Hypothesis have been gaining favor, and data have emerged that link these two hypotheses as one. Thus, it may now be more appropriate to refer to them as the Attenuation of Insulin-Like Signaling Hypothesis. Finally, the Hormesis Hypothesis may provide an overarching concept that embraces several of the other hypotheses as merely specific examples of hormetic processes. For example, the Oxidative Damage Attenuation Hypothesis probably addresses only one of likely many damaging processes that underlie aging. It is proposed that low-intensity stressors, such as CR, activate ancient hormetic defense mechanisms in organisms ranging from yeast to mammals, defending them against a variety of adversities and, when long-term, retarding senescent processes.

Publication Types:

• Review

Reduced energy intake: the secret to a long and healthy life?

IBS J Sci. 2007 Sep;2(2):35-39

Martin B, Golden E, Egan JM, Mattson MP, Maudsley S.

Reduced energy intake, or caloric restriction (CR), is known to extend life-span and to retard age-related health decline in a myriad of species, including nematode worms, flies, fish, mice and rats. The exact mechanism whereby CR exerts its life-extending and health-extending effects is unclear. CR however has been shown to improve insulin sensitivity, reduce oxidative stress and alter neuroendocrine responses and central nervous system (CNS) function in animals. In this review article we provide a comprehensive overview of the effects of CR on animal physiology and we discuss some of the potential molecular mechanisms and pathways whereby reduced energy intake can increase health-span and life-span. A better understanding of how energy intake can influence the aging process could lead to new strategies and therapeutics to reduce age-related decline and increase health-span.

Publication Types:

• Review

Calorie restriction and aging: review of the literature and implications for studies in humans

Am J Clin Nutr. 2003 Sep;78(3):361-9

Heilbronn LK, Ravussin E.

Calorie restriction (CR) extends life span and retards age-related chronic diseases in a variety of species, including rats, mice, fish, flies, worms, and yeast. The mechanism or mechanisms through which this occurs are unclear. CR reduces metabolic rate and oxidative stress, improves insulin sensitivity, and alters neuroendocrine and sympathetic nervous system function in animals. Whether prolonged CR increases life span (or improves biomarkers of aging) in humans is unknown. In experiments of nature, humans have been subjected to periods of nonvolitional partial starvation. However, the diets in almost all of these cases have been of poor quality. The absence of adequate information on the effects of good-quality, calorie-restricted diets in nonobese humans reflects the difficulties involved in conducting long-term studies in an environment so conducive to overfeeding. Such studies in free-living persons also raise ethical and methodologic issues. Future studies in nonobese humans should focus on the effects of prolonged CR on metabolic rate, on neuroendocrine adaptations, on diverse biomarkers of aging, and on predictors of chronic age-related diseases.

Publication Types:

• Review

Ageing free radicals and cellular stress

Med Sci (Paris). 2006 Mar;22(3):266-72

Barouki R.

A number of theories have attempted to account for ageing processes in various species. Following the << rate of living >> theory of Pearl, Harman suggested fifty years ago that the accumulation of oxidants could explain the alteration of physical and cognitive functions with ageing. Oxygen metabolism leads to reactive species, including free radicals, which tend to oxidize surrounding molecules such as DNA, proteins and lipids. As a consequence various functions of cells and tissues can be altered, leading to DNA instability, protein denaturation and accumulation of lipid byproducts. Oxidative stress is an adaptive process which is triggered upon oxidant accumulation and which comprises the induction of protective and survival functions. Experimental evidence suggests that the ageing organism is in a state of oxidative stress, which supports the free radical theory. A number of other theories have been proposed ; some of these are actually compatible with the free radical theory. Caloric restriction is among the best models to increase life span in many species. While the relationship between caloric restriction and corrected metabolic rate is controversial, the decrease in ROS production by mitochondria appears to be experimentally supported. The ROS and mitochondrial theories of ageing appear to be compatible. Genetic models of increased life span, particularly those affecting the Foxo pathway, are usually accompanied by an increased resistance to oxidative insult. The free radical theory is not consistent with programmed senescence theories involving the cell division dependent decrease in telomere length ; however, oxidants are known to alter telomere structure. An appealing view of the role of oxidative stress in ageing is the trade-off principle which states that a phenotypic trait can be evolutionarily conserved because of its positive effects on development, growth or fertility, and despite its negative effect on somatic functions and ageing. It is likely that most cellular stresses which comprise adaptive and toxic functions follow such a rule.

Publication Types:

• Review

Caloric restriction and immunosenescence: a current perspective

Front Biosci. 2000 Jun 1;5:D580-7

Pahlavani MA.

The age-related decrease in immunologic function is believed to be the major predisposing factor contributing to increased morbidity and mortality with age. Hence, the restoration of immunologic function is expected to have a beneficial effect in reducing pathology and maintaining a healthy condition in advanced age. Among various intervention strategies, caloric restriction (CR) has been shown to be the most powerful modulator of aging process. It is the most efficacious means of increasing longevity and reducing pathology. Several mechanisms have been proposed to explain its beneficial and robust action on various physiological systems, including the immune system. Experimental evidence suggests that CR increases longevity and reduces pathology through its action on the immune system. The observation that CR attenuates immunosenescence has provided a rationale for studying whether CR exerts its action through modulation of gene expression. The available data indicate that the effect of CR on signal transduction and gene expression can vary considerably from gene to gene and from one signaling molecule to another. This review summarizes the studies on the influence of CR on aging immune system and discusses the current state of knowledge on the molecular mechanisms responsible for the immunomodulatory action of caloric restriction.

Publication Types:

• Review

Influence of caloric restriction on aging immune system

J Nutr Health Aging. 2004;8(1):38-47

Pahlavani MA.

Nutrition has been shown to have a significant impact on aging. Caloric Restriction (CR), i.e., undernutrition not malnutrition, significantly increases the survival of laboratory animals by retarding/delaying the aging process. CR has beneficial effects on various physiological systems, including the immune system. Overall, the immunological status of rodents fed a restricted diet is superior to the immunological status of the non-restricted animals. It is believed that CR might retard aging and immunosenescence through a mechanism involving changes in signal transduction and gene expression. Recent studies from our laboratory support the view that the mechanism of CR involves changes in the activation of the upstream signaling molecules and cytokine gene expression that are altered with age.

Publication Types:

• Review

Anti-inflammatory mechanisms of dietary restriction in slowing aging processes

Interdiscip Top Gerontol. 2007;35:83-97

Morgan TE, Wong AM, Finch CE.

Dietary restriction (DR) remains the most powerful and general environmental manipulation of aging processes in laboratory animals with strong beneficial effects on most age-related degenerative changes throughout the body. Underlying the beneficial effects of DR is the attenuation of system-wide inflammatory processes including those occurring within the central nervous system. During normal aging a progressive neuroinflammatory state builds in the brain involving astrocytes and microglia, the primary cellular components of neuroinflammation. DR attenuates the age-related activation of astrocytes and microglia with concomitant beneficial effects on neurodegeneration and cognition. Increasing evidence suggests that common pathways are emerging that link many normal aging inflammatory processes with age-related diseases such as Alzheimer, cancer, diabetes and cardiovascular disease.

Publication Types:

• Review

Caloric restriction and intermittent fasting: two potential diets for successful brain aging

Ageing Res Rev. 2006 Aug;5(3):332-53.

Martin B, Mattson MP, Maudsley S.

The vulnerability of the nervous system to advancing age is all too often manifest in neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. In this review article we describe evidence suggesting that two dietary interventions, caloric restriction (CR) and intermittent fasting (IF), can prolong the health-span of the nervous system by impinging upon fundamental metabolic and cellular signaling pathways that regulate life-span. CR and IF affect energy and oxygen radical metabolism, and cellular stress response systems, in ways that protect neurons against genetic and environmental factors to which they would otherwise succumb during aging. There are multiple interactive pathways and molecular mechanisms by which CR and IF benefit neurons including those involving insulin-like signaling, FoxO transcription factors, sirtuins and peroxisome proliferator-activated receptors. These pathways stimulate the production of protein chaperones, neurotrophic factors and antioxidant enzymes, all of which help cells cope with stress and resist disease. A better understanding of the impact of CR and IF on the aging nervous system will likely lead to novel approaches for preventing and treating neurodegenerative disorders.

Publication Types:

• Review

Dietary restriction initiated in late adulthood can reverse age-related alterations of protein and protein metabolism

Ann N Y Acad Sci. 2002 Apr;959:50-6

Goto S, Takahashi R, Araki S, Nakamoto H.

Many reports have been published on the effects of lifelong dietary restriction (DR) on a variety of parameters such as life span, carcinogenesis, immunosenescence, memory function, and oxidative stress. There is, however, limited available information on the effect of late onset DR that might have potential application to intervene in human aging. We have investigated the effect of DR initiated late in life on protein and protein degradation. Two months of DR in 23.5-month-old mice significantly reduced heat-labile altered proteins in the liver, kidney, and brain. DR reversed the age-associated increase in the half-life of proteins, suggesting that the dwelling time of the proteins is reduced in DR animals. In accordance with this observation, the activity of proteasome, which is suggested to be responsible for degradation of altered proteins, was found increased in the liver of rats 30 months of age subjected to 3.5 months of DR. Thus, DR can increase turnover of proteins, thereby possibly attenuating potentially harmful consequences by altered proteins. Likewise, DR in old rats reduced carbonylated proteins in liver mitochondria, although the effect was not observed in cytosolic proteins. Fasting induced apoA-IV synthesis in the liver of young mice for efficient mobilization of stored tissue fats, while it occurred only marginally in the old. DR for 2 months from 23 months of age partially restored inducibility of this protein, suggesting the beneficial effect of DR. Taking all these findings together, it is conceivable that DR conducted in old age can be beneficial not only to retard age-related functional decline but also to restore functional activity in young rodents. Interestingly, recent evidence that involves DNA array gene expression analysis supports the findings on the age-related decrease in protein turnover and its reversion by late-onset DR.

Publication Types:

• Animal Study