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Editor–Stefan Kiechl and colleagues claim that their study is the first to show a relation between alcohol consumption and plasma insulin concentrations in men.1 This is untrue. Over a year ago we published data on the relation between alcohol consumption and plasma insulin and lipoprotein concentrations in a large cross sectional study of men.2
Altogether 729 men aged 40-69 (75% of a stratified random sample) were recruited from general practitioners' lists in east Bristol, England. They comprised 354 men aged 40-49, 205 aged 50-59, and 170 aged 60-69. Our findings differed from those of Kiechl and colleagues. Increases in alcohol consumption were associated with increases in high density lipoprotein, high density lipoprotein-2 cholesterol, and high density lipoprotein-3 cholesterol concentrations and decreases in low density lipoprotein cholesterol concentrations and the total:high density lipoprotein cholesterol ratio (table 1). With insulin, however, there was a U shaped relation, with moderate drinkers (21-30 g/day) having the lowest concentrations. This was confirmed when a quadratic term was introduced into the analysis of covariance (P = 0.04).
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Table 1 Mean lipoprotein and insulin concentrations (mmol/l) according to daily alcohol consumption, adjusted for age, body mass index, smoking, and use of antihypertensive drugs
Compared with non-drinkers, moderate drinkers had a lower plasma insulin concentration (by 1.2 mU/l, P = 0.04), low density lipoprotein cholesterol concentration (by 0.4 mmol/l, P = 0.0001), and total:high density lipoprotein cholesterol ratio (by 0.9, P = 0.0001) but a higher high density lipoprotein cholesterol concentration (by 0.1 mmol/l, P = 0.02). Conversely, compared with moderate drinkers, heavy drinkers (>40 g/day) had a higher plasma insulin concentration (by 1.5 mU/l, P = 0.01) and high density lipoprotein cholesterol concentration (by 0.16 mmol/l, P = 0.0001). In this analysis the P value was derived from one way analysis of covariance after adjustment for age, smoking habits, body mass index, waist:hip ratio, and use of antihypertensive drugs.
Our data support Kiechl and colleagues' conclusion that moderate alcohol consumption improves insulin sensitivity, and this might at least partly explain its cardioprotective effect. We do not agree, however, that higher intakes have the same benefit. We also question whether up to 50 g/day should be called a low intake and up to 99 g/day a moderate intake.
Altogether 729 men aged 40-69 (75% of a stratified random sample) were recruited from general practitioners' lists in east Bristol, England. They comprised 354 men aged 40-49, 205 aged 50-59, and 170 aged 60-69. Our findings differed from those of Kiechl and colleagues. Increases in alcohol consumption were associated with increases in high density lipoprotein, high density lipoprotein-2 cholesterol, and high density lipoprotein-3 cholesterol concentrations and decreases in low density lipoprotein cholesterol concentrations and the total:high density lipoprotein cholesterol ratio (table 1). With insulin, however, there was a U shaped relation, with moderate drinkers (21-30 g/day) having the lowest concentrations. This was confirmed when a quadratic term was introduced into the analysis of covariance (P = 0.04).
View this table:
[in this window]
[in a new window]
Table 1 Mean lipoprotein and insulin concentrations (mmol/l) according to daily alcohol consumption, adjusted for age, body mass index, smoking, and use of antihypertensive drugs
Compared with non-drinkers, moderate drinkers had a lower plasma insulin concentration (by 1.2 mU/l, P = 0.04), low density lipoprotein cholesterol concentration (by 0.4 mmol/l, P = 0.0001), and total:high density lipoprotein cholesterol ratio (by 0.9, P = 0.0001) but a higher high density lipoprotein cholesterol concentration (by 0.1 mmol/l, P = 0.02). Conversely, compared with moderate drinkers, heavy drinkers (>40 g/day) had a higher plasma insulin concentration (by 1.5 mU/l, P = 0.01) and high density lipoprotein cholesterol concentration (by 0.16 mmol/l, P = 0.0001). In this analysis the P value was derived from one way analysis of covariance after adjustment for age, smoking habits, body mass index, waist:hip ratio, and use of antihypertensive drugs.
Our data support Kiechl and colleagues' conclusion that moderate alcohol consumption improves insulin sensitivity, and this might at least partly explain its cardioprotective effect. We do not agree, however, that higher intakes have the same benefit. We also question whether up to 50 g/day should be called a low intake and up to 99 g/day a moderate intake.
