RELATIONSHIPS BETWEEN MICRONUTRIENT INTAKE AND BIOCHEMICAL INDICATORSOF NUTRIENT ADEQUACY IN A FREE-LIVING ELDERLY UK POPULATION

Nutritional assessments are frequently based on amounts of nutrients c onsumed. In the present paper the usefulness of nutrient intake data f or assessing nutrient adequacy is examined in an elderly British popul ation. Subjects were 'free-living' elderly aged 68-90 years (sixty men , eighty-five women) in Norwich. Forty-two of forty-nine surviving mal es and sixty-seven of seventy-nine surviving females were reassessed a fter 2 years. With few exceptions, estimated micronutrient intake was not statistically predictive of biochemical measures of nutrient adequ acy. Initial biochemical measures of nutritional adequacy were compare d with those found 2 years later in an attempt to assess whether initi al biochemical assessment was predictive of the 'longer term' situatio n. Biochemical measurements at the start of the study were correlated to the same measurements made 2 years later for: serum ferritin, haemo globin and erythrocyte count, whole-blood Se-glutathione peroxidase (E C 1.11.1.9; males only), plasma Cu, alkaline phosphatase (EC 3.1.3.1), ascorbic acid, vitamin B-6 (pyridoxal-5-phosphate), folate and vitami n B-12, total erythrocyte thiamin (males only), riboflavin (erythrocyt e glutathione reductase (EC 1.6.4.1) activation coefficient): but not for: erythrocyte Cu-superoxide dismutase (EC 1.15.1.1) or plasma Zn. E ither only small changes, or no changes, in mean values were seen over the 2 years for most of the biochemical measures. One exception was a large increase in plasma folate. The only important 'negative' featur es seen at 2-year follow up were a large fall in serum ferritin concen tration and a large increase in the activity of two antioxidant defenc e enzymes, superoxide dismutase and glutathione peroxidase. As judged by currently accepted biochemical deficiency threshold values, a small proportion of subjects were possibly at risk of Fe (3 % men; 1 % wome n), folate (7 %, 3 %), thiamin (12 %; 3 %) and vitamin C (15 %; 17 %) deficiency. Many more appeared to be at risk of vitamin B-6 (42 %; 47 %) and riboflavin (77 %; 79 %) deficiency. It was concluded that the r equirements of the elderly for vitamins B-1, B-2 and C, and the bioche mical deficiency threshold values used to indicate vitamin B-6 deficie ncy, need review.