A survey of human liver reserves of retinol in London

Abstract

1. The retinol content of human liver tissue, obtained at autopsy from mortuaries in the London area, was determined in a group of 364 subjects.2. Tissue samples from the central portion of the right lobe of the liver were saponified, extracted with light petroleum (b.p. 40–60°) and retinol assayed colorimetrically using the trifluoroacetic acid procedure.3. The frequency distribution of retinol reserves was skewed to the right (positive skewness). The mean retinol content for the entire group was 252 mg/kg, with a median of 198 mg/kg and a range of 0–1201 mg/kg. Of the subjects, 49% had reserves in the range 100–300 mg/kg (regarded as the‘normal range’ for liver retinol) while 5% had reserves below 40 mg/kg (the arbitrary ‘cut-off’ point below which individuals are considered to be at risk). Only one subject had no detectable retinol reserves. On the other hand, 11 % of the subjects had reserves exceeding 500 mg/kg.4. No sex-related differences were apparent, the median retinol reserves of male and female subjects being 190 and 202 mg/kg respectively.5. Median retinol reserves varied markedly with age. They were relatively low (121 mg/kg) in infancy. but were approximately three times greater in childhood, adolescence and young adulthood. Thereafter, reserves declined gradually with increasing age to a low of 113 mg/kg in subjects over the age of 90 years.6. When subjects were classified according to primary cause of death, the median reserves were as follows (mg/kg): accidental deaths 270, cancer 207, cardiovascular diseases 204, intestinal diseases 178, nervous diseases 164, hepatic diseases 158, respiratory diseases 141, sudden infant death syndrome 127.7. Retinol reserves in London are substantially higher than those reported from North America and are exceeded only by those reported from New Zealand and Ghana. It is therefore concluded, from the results of this survey and also from official estimates of the dietary intake of retinol and provitamin A carotenoids, that vitamin A status in London, and probably also in the rest of Britain, is quite satisfactory.