INFLUENCE OF NUTRITION

The influence of Nutrition on Epigenetic Change in Elderly People

The influence of Nutrition on Epigenetic Change in Elderly People

1. Introduction

During ageing there is a progressively reduced ability to cope with physiological challenges (Johnson et al., 1999). This reduced capacity for homeostasis appears to be due largely to aberrant gene expression. For example, reduced stress tolerance in the elderly might accompany a blunted ability to synthesise protective intracellular stress proteins (Zhang et al., 2004). Nutrition is believed to be an important modulator of the ageing trajectory but, with the exception of energy (caloric) restriction (CR), there is as yet no proof of the role played by any particular dietary factor in influencing longevity. However, it is now becoming clear that nutritional factors have a profound influence on gene expression and that the application of high throughput genomics tools in nutrition research (nutrigenomics) in the context of a systems biology approach ([Van Ommen and Stierum, 2002], [Muller and Kersten, 2003], [Mathers, 2004] and [Oommen et al., 2005]) offers exciting new opportunities to explore the role of diet in influencing the biology of ageing.

Micronutrients

Approximately 40 micronutrients (the vitamins, essential minerals and other compounds required in small amounts for normal metabolism) are required in the human diet (Saltman et al., 1993). For each micronutrient, metabolic harmony requires an optimal intake (i.e., to give maximal life span); deficiency disrupts metabolism in numerous and complicated ways. The recommended daily allowance (RDA) of a micronutrient is currently based on information on acute effects, rather than long-term health, an area which has been little studied; however, for many micronutrients, a sizable percentage of the population is deficient relative to the current RDA. Remedying these deficiencies, which can be done at low cost, is likely to lead to a major improvement in health and an increase in longevity. The optimum intake of a micronutrient can vary with age and genetic constitution and be influenced by other aspects of diet. Determining these optima, and remedying deficiencies, and in some cases excesses, will be a major public health project for the coming decades. Long-term health is also influenced by many other aspects of diet, including caloric intake, the amount and type of fat consumed, macronutrients, phenolics, fiber (Platz et al., 1997); and other active compounds in plants (Ames et al., 1995), which are outside the subject of this review.

Micronutrient deficiency can mimic radiation (or chemicals) in damaging DNA by causing single- and double-strand breaks, oxidative lesions, or both. Those micronutrients whose deficiency mimics radiation are folic acid, B12, B6, niacin, C, E, iron, and zinc, with the laboratory evidence ranging from likely to compelling. The percentage of the population that is deficient for each of these eight micronutrients ranges from 2% to =20%, and may comprise in toto a considerable percentage of the US population. Micronutrient deficiency is a plausible explanation for the strong epidemiological evidence that shows an association between low consumption of fruits and vegetables and cancer at most ...