Effects of lifestyle on plasma levels of the IGF system and the antioxidants coenzyme Q10 and vitamin E in Kenyan rural and urban populations.

Abstract

OBJECTIVE: Overnight fasting blood plasma insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein-1 (IGFBP-1), coenzyme Q10, (CoQ) vitamin E and plasma lipids were compared between a semi-nomadic Samburu population and relatively urbanized cohorts from Nairobi, Kenya. RESEARCH DESIGN AND METHODS: 143 middle aged subjects without known diabetes were included. IGF-I and IGFBP-1 were analyzed by RIA, and CoQ and vitamin E by HPLC. Plasma lipid levels were analyzed by standard laboratory methods routinely used in the clinics. RESULTS: The age adjusted IGF-I serum levels were low in the Samburu male and female populations, ranging from 0 to -4 IGFSD-score (SDS), and a minor part of the investigated population reaching as low as -5 and -7 SDS. The Nairobi cohorts showed significantly higher values reaching from -2.5 to +1 SDS (P<0.0001). The nomadic Samburu population showed fasting IGFBP-1 values ranging from 30-100 μg/l, while that of the urbanized Nairobi cohorts was considerably lower (25-60 μg/l) (P<0.0001). CoQ concentrations of the Nairobi cohorts were 1.5-2.0 nmol/ml similar to the levels found in several European countries. The Samburu population on the other hand showed extremely high CoQ values ranging from 2 to 9 nmol/ml (P<0.0001). Vitamin E levels of the Nairobi group were low (5-20 nmol/ml), but the Samburu population had even lower levels ranging from 3 to 15 nmol/ml (P<0.0001). Plasma lipid levels such as cholesterol, triglycerides, LDL/HDL, ApoB/ApoA ratios as well as BMI and weight were significantly higher in the Nairobi population (P<0.0001). CONCLUSIONS: Low IGF-I and high IGFBP-1 levels of the Samburu cohorts indicate malnutrition. High lipid levels of the Nairobi cohorts indicate that these groups have several risk factors for cardiovascular diseases and diabetes type2.