Abstract
Serum samples from 341 males aged 10 to 59 years were obtained and stored at -40°C until examined for retinol and β-carotene concentrations by HPLC, and their relationships to smoking habit, alcohol drinking habit and vitamin A intake were studied.
In univariate analysis the serum β-carotene level was significantly lower in the smokers than in the non-smokers (smokers: 4.6μg/dl, non-smokers: 7.1μg/dl, p<0.01) and lower in the drinkers than in the non-drinkers (drinkers: 4.6μg/dl, non-drinkers: 7.3μg/dl, p<0.01). The serum retinol level was not different by smoking habit but was higher in the drinkers than in the non-drinkers (drinkers: 80.4μg/dl, non-drinkers: 67.0μg/dl, p<0.01). Serum β-carotene was higher in the group with a greater intake of vitamin A of vegetable origin (6.1μg/dl) than in the group with a smaller intake of it (4.7μg/dl) (p<0.01), but serum retinol was not different by the amount of vitamin A intake of animal food origin.
To estimate the respective effects and interactions of the above factors on serum β-carotene and retinol levels by adjusting for the confounding effects of age, serum total cholesterol, HDL-cholesterol and triglyceride, analysis of covariance was performed. For serum β-carotene, smoking habit (p<0.01), drinking habit (p<0.01) and the amount of vitamin A intake of vegetable food origin (p<0.05) had significant main effects. Interaction by the smoking and drinking habits was shown to be of borderline significance (p<0.10) and adjusted mean levels showed that the decrease in serum β-carotene caused by both smoking and drinking habits was strengthened in the group which had both habits.
For serum retinol interaction of smoking and drinking habits was significant (p<0.01). The direction of the effect of the smoking habit on serum retinol was opposite in the drinkers and in the non-drinkers. On the other hand, the drinking habit resulted in an increase of serum retinol in both smokers and non-smokers, but the increase was greater in the former than in the latter. The effect of the amount of vitamin A of animal food origin was not significant.
It was concluded that the effects of smoking and drinking habits on serum β-carotene and serum retinol levels became unpredictably strong when both habits coexisted.
