The impact of diet on long-term health is evident from the literature, with many studies highlighting the benefits of improved diet quality on reductions in mortality and morbidity. Much of the damage from a poor quality diet is caused by increase systemic inflammation and oxidative stress that results in damage to cells and tissues. Telomere length is a potential biomarker that may reflect biological ageing based on cumulative damage to cells. Telomeres are regions at the end of chromosomes that protect the chromosomes from damage and from fusion to other chromosomes. As telomeres are replicated they are cumulatively shortened and this shortening may eventually trigger the cell to undergo apoptosis. Evidence suggests that erosion of telomere length may result from the burden of poor quality diet and this may in turn lead to a number of diseases such as cancer, cardiovascular disease and diabetes.
The association between telomere length and diet quality, body composition and lifestyle factors has been investigated1. Polymerase chain reaction analysis of the leukocyte telomeres of 2284 female subjects revealed that a number of factors were associated with telomere length. Dietary fibre was positively associated with telomere length, with particularly strong associations being shown with cereal fibre and whole grains. Intakes of polyunsaturated fatty acids showed an inverse association with telomere length, with the strongest association being shown by linoleic acid. Vitamin E intakes showed a tend towards associations with telomere length but the data did not reach statistical significance. In terms of body composition, an inverse association was demonstrated between waist circumference and telomere length, but no association was found for physical activity. Smoking also showed no association with telomere length, which contradicts data some of the previous studies.
The fact that whole grain cereals improve the overall quality of the diet has been shown in numerous studies looking at many aspects of human health. Research suggests that those with high intakes of cereal fibre have a reduced risk of developing obesity, diabetes, cardiovascular disease and some cancers. The fact that cereal fibre showed the strongest association to telomere length in not therefore surprising. High intakes of polyunsaturated fatty acids can increase oxidative stress, because of the structurally chemistry of the fatty acid chains. The double bonds are particularly susceptible to oxidation and require high intakes of vitamin E in order to prevent cellular damage. Many commercially available polyunsaturated fatty acids are damaging to the health because of heat treatment and chemical alteration during manufacture. This research supports evidence to show that high intakes of such oils are detrimental to telomere length.
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