Host‐related factors explaining interindividual variability of carotenoid bioavailability and tissue concentrations in humans
Age-related changes in nutrition can affect the nutritional status of the elderly in a number of ways. Food intake is affected by socio-economic, physiological and pathological factors. The major physiological age-related change is the decrease in the energy requirement due to a reduction in lean body mass and a reduction in physical activity leading to a compensatory decrease in macro- and micronutrient intake of approximately 30% by the age of 80 years. Morbidity and some types of medication, smoking and alcohol consumption also affect the absorption and metabolism of vitamins. The plasma levels of fat-soluble vitamins and carotenoids tend to increase with age with the exception of vitamin D, while certain water-soluble vitamin levels decrease, particularly vitamin B6 and vitamin B12. Many epidemiological studies have examined the vitamin intake and the plasma concentrations of large elderly populations in many regions of the world, but few have specifically determined the incidence of vitamin deficiencies. The criteria for defining deficiency varies between studies making it difficult to compare data from different studies. In the SENECA Study on European elderly evidence for biochemical vitamin deficiency was found in 47% for vitamin D, 23.3% for vitamin B6, 2.7% for vitamin B12 and 1.1% for vitamin E.