The response of serum apolipoprotein H to an oral fat load.

BACKGROUND: We tested the hypothesis that serum apolipoprotein H (apo H) concentration increases after an oral fat load. Such a study would give valuable insight into whether apo H was influenced by the postprandial state. METHODS: Ten male subjects aged 24-48 years were fed 62.5 g of total fat (saturates 12 g, monounsaturates 35.3 g, polyunsaturates 12.5 g). Venous blood was sampled hourly for 5 h post-oral fat load. RESULTS: No significant change in serum apo H concentration occurred following the oral fat load. However, serum apo H in the baseline samples correlated significantly with subject body mass index (r = 0.683, P < 0.05), body fat mass (r = 0.778, P < 0.01), lean body mass (r = 0.693, P < 0.05), serum triglyceride (r = 0.732, P < 0.02), serum insulin (r = 0.808, P < 0.01) and insulin resistance index (r = 0.794, P < 0.01). In stepwise multiple linear regression model, with serum apo A1, apo B, lipoprotein(a), total cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol, plasma glucose and insulin and apo H as the dependent variable, insulin remained in the model (r = 0.81, P < 0.01). Conversely, with body mass index, body fat mass, lean body mass and waist/hip ratio in the model and apo H as dependent variable, only body fat mass remained in the model (r = 0.78, P < 0.01). CONCLUSIONS: Serum apo H may be involved in insulin resistance and relates to various indices of adipose tissue, including body fat mass. However, serum apo H concentrations do not significantly change postprandially.

The response of serum sialic acid and other acute phase reactants to an oral fat load in healthy humans.

BACKGROUND: Elevated serum total sialic acid (TSA) has been shown to be associated with increased cardiovascular mortality. It has been postulated that atherogenesis is a postprandial phenomenon. We tested the hypothesis that serum TSA and other acute phase proteins, namely C-reactive protein (CRP) and fibrinogen, may be related to the postprandial state. METHODS: Ten healthy male subjects, aged 24-48 years, were fed 62.5 g of total fat (saturates 12 g, monounsaturates 35.3 g and polyunsaturates 12.5 g) in the form of strawberry flavoured Calogen. Venous blood was sampled hourly for 5 h. Concentrations of serum triglyceride, TSA and acute phase proteins were measured. RESULTS: Serum triglyceride concentration increased postprandially, peaking at 240 min. Serum CRP and plasma fibrinogen did not significantly increase after the oral fat load. However, serum TSA did increase from baseline (0.599+/-0.051 g/l) in response to the oral fat load, peaking at 120 min post-oral fat load (0.633+/-0.066 g/l, P<0.02). There was a significant correlation between serum TSA and plasma fibrinogen at baseline (rho=0.62, P=0.05) but not for serum CRP (rho=-0.22) or triglyceride (rho=0.21). CONCLUSIONS: We conclude that serum TSA increases postprandially and this finding gives further insight as to why the former is considered to be a cardiovascular risk factor.