In this nationally representative study, diet quality was poorer among women who were current drinkers than among women who had never consumed alcoholic beverages. Among both men and women who were current drinkers, diet quality declined with increasing consumption of alcoholic beverages.
Although higher levels of alcoholic beverage consumption were associated with higher intakes of energy, protein, and some vitamins and minerals among current drinkers, they were also associated with lower diet quality scores, due in part to the higher energy intakes attributable to alcoholic beverages. The higher intakes of alcoholic beverages contributed to both higher energy intakes and higher percentages of energy from alcoholic beverages, which in turn resulted in lower scores for energy from SoFAAS, the discretionary energy component of the HEI-2005. It appears that solid fats did not contribute much to the decreasing scores for energy from SoFAAS because intakes of saturated fats (in grams), which are highly correlated with solid fats, did not increase as alcoholic beverage consumption increased. The extent to which added sugars contributed is unknown.
Alcoholic beverages are a significant source of energy. The ethanol in alcoholic beverages provides about 7 kcal/g (34
). A 5-oz glass of red wine provides 125 kcal; a jigger (1.5 oz) of 80-proof gin or vodka, 97 kcal; and a 12-oz can of beer, 153 kcal (28
). Energy in mixed drinks can be considerably higher. For example, a 4.5-oz Piña Colada cocktail contains 245 kcal. In 1994-1996, alcoholic beverages provided 3.3% of the US adult population's energy intake (35
Alcoholic beverages do contain certain nutrients. In 1994-1996, alcoholic beverages provided 2% to 3% of adult intakes of folate, niacin, and vitamin B-6, and at least 1% of riboflavin, phosphorus, potassium, and copper (35
). (Note that this was before grain products were fortified with folate.) However, alcoholic beverages have been shown to interfere with absorption and metabolism of some nutrients in studies of alcoholics (4
). The higher protein intakes at higher alcohol consumption levels are surprising and cannot be accounted for by the alcoholic beverages, suggesting other dietary differences. All of the HEI-2005 food-group component scores decreased or remained unchanged with increasing alcohol consumption.
Optimal classification of nondrinkers in epidemiologic studies of alcoholic beverage consumption and chronic disease outcomes could be facilitated by information about the dietary intakes of never and former drinkers. Previous studies of alcoholic beverage consumption and dietary intakes (12
) generally combined never and former drinkers into a single nondrinker group; however, these groups could have different dietary intakes. The sick quitter hypothesis (23
) posits that some former drinkers may have quit consuming alcoholic beverages because they were ill (for reasons including alcohol consumption). Illness could also alter their diets. This study found more differences in nutrient intakes between former and never drinkers among women than men. However, the lower vitamin C intakes found in men who were former drinkers could be important in some studies. Furthermore, associations between drinking status and dietary intakes may vary between studies. In terms of clinical practice and nutrition education, the results suggest that former drinkers may be an overlooked, important target group.
The results of this study suggest that the HEI-2005 is a useful indicator of diet quality according to drinking status and drinking levels. It reveals information about dietary patterns that is not readily apparent from nutrient intake data. For example, in men and women, fruit intake declined with increasing consumption of alcoholic beverages. This specific dietary difference would not be easily determined from the nutrient data as all foods, including fruit, are comprised of a mixture of macro- and micronutrients and other important constituents not necessarily captured in a food composition database. In addition, the HEI-2005 adjusts for energy intake and, by doing so, controls for variation in energy intake across levels of alcoholic beverage consumption. Therefore, the HEI-2005 enables identification of key aspects of dietary behavior that differ among alcohol-use subgroups and may be useful in formulating educational messages understandable by consumers in terms of the foods they consume.
The diet quality of Americans is poor in general. A recent report from the US Department of Agriculture found that the mean total HEI-2005 score of the US population in 2003-2004 was 57.5 out of 100, indicating that diets are far from the recommendations of the 2005 DGA and need improvement (36
). In our study, mean total HEI-2005 scores (adjusted for age, race/ethnicity, education, smoking status, and body mass index) ranged from 41.5 for men who drank the most to 63.2 for women who had never consumed alcoholic beverages. Among men who were current drinkers, as alcoholic beverage consumption increased from <1 to ≥5 drinks per day, on average, total HEI-2005 scores significantly declined from 55.9 to 41.5; and among women who were current drinkers, as alcoholic beverage consumption increased from <1 to ≥3 drinks per day, on average, total HEI-2005 scores significantly declined from 59.5 to 51.8. This suggests that increasing levels of alcoholic beverage consumption may lead to increased nutrition risk (although causality cannot be inferred from these cross-sectional results).
This study had numerous strengths. The dataset used, NHANES 1999-2006, had relatively high response rates and provided a population-based sample much larger than used in earlier research. The study used the current US Department of Agriculture method of diet quality assessment, the HEI-2005. Appropriate analytic methods were used, including the Bonferroni technique to test statistical significance in the presence of multiple comparisons. Had this technique not been used, numerous additional associations would have been significant. The study estimated a population ratio for the HEI-2005 component scores adjusted for covariates that might differ according to drinking status (never, former, current drinker) and drinking level. This is an extension of the unadjusted population ratio for HEI-2005 proposed by Freedman and colleagues (32
). A jackknife method is provided for estimating standard errors for the HEI-2005 component scores from complex survey data, such as the NHANES. The method can be used to construct 95% confidence intervals and to conduct statistical testing. The methods used in this study are general and can be applied to analyses examining relationships between HEI-2005 total and component scores and exposures other than alcoholic beverage consumption.
The study updates and expands upon tabulations found in the 2005 Dietary Guidelines Advisory Committee's report by using a larger sample size, including results by drinking status, adjusting for covariates, and performing statistical testing. By controlling various characteristics of the groups studied, the differences in intakes related to alcoholic beverage consumption per se were evident. Earlier NHANES data are linkable to mortality data to create cohort studies (37
). The differences in nutrient intakes and diet quality found here may inform such studies.
This study also had limitations. Results were based on a 1-day recall of dietary intake; however, the mean nutrient intakes of a group are estimates of the mean long-term, or usual, intakes of each subpopulation studied if one assumes that the sampling of recalled days was balanced over the days of the week and seasons of the year. Although dietary data were collected on all days of the week and in all seasons, the distribution by day of week was uneven. The extent to which this affects the estimates of group usual nutrient intakes is unknown. Dietary supplements and physical activity were not accounted for. It would have been possible to remove energy from alcohol in the calculation of total energy intake, but we chose not to do so because our interest was in total nutrients consumed, including from alcoholic beverages; and, with regard to diet quality, it was important to capture all the major sources of discretionary calories, including those from alcoholic beverages as well as solid fats and added sugars. Finally, cause and effect cannot be inferred from cross-sectional results.