Serum β-carotene and α-tocopherol in smokers and non-smokers—associations with food sources and supplemental intakes. A report from the Malmö Diet and Cancer cohort

Abstract

High blood concentrations of β-carotene (BC) and α-tocopherol (AT) are markers of lower risk of cancer and cardiovascular disease. However, it is not clear how well they serve as markers of food consumption in a general population setting, in a country with a traditionally low vegetable consumption, or if they work equally well in smokers and non-smokers. We performed a cross-sectional study of 366 non-smokers and 163 smokers of both sexes, aged 46-67 y, who participated in the Malmö Diet and Cancer study (Sweden). Serum concentrations of BC and AT were determined by HPLC. Food habits were assessed by a validated modified diet history method. Intake of dietary supplements was calculated from a 7-day self-registration. We found that non-smokers had higher serum BC concentrations than smokers (arithmetic means 550 ± 25 (SE) vs. 400 ± 27 nmol/l, p < 0.001), but serum AT concentrations were similar (27.2 ± 0.43 vs. 27.0 ± 0.65 μmol/l, p = 0.88). After adjustment for sex, serum cholesterol, obesity, and other sources of BC, consumption of carrots and leafy vegetables were moderately but positively associated with serum BC in non-smokers. In smokers, serum BC was positively associated with consumption of BC supplements only. The only AT sources associated with serum AT were vitamin E supplements. We also observed a positive association between serum BC and consumption of coffee in smokers. We conclude that serum BC concentration may not be a useful marker of vegetable consumption when vegetable consumption is low, that the foods associated with serum concentrations of BC differed by smoking status in this population, and that serum AT concentrations were only associated with dietary supplements, not with foods.