Smokers have worse quality diets than former smokers or non-smokers, according to a study published in the open access journal BMC Public Health.

Dr Jacqueline Vernarelli at Fairfield University, Connecticut and Dr R. Ross MacLean at Yale University evaluated data from 5293 US adults and found that smokers consumed around 200 more calories a day, despite eating significantly smaller portions of food, than non-smokers or former smokers.

Dr Vernarelli commented: "Smokers had diets that were high in energy density, meaning they consumed smaller amounts of food containing a greater number of calories. Non-smokers consumed more food which contained fewer calories."

The researchers found that people who had never smoked consumed around 1.79 calories per gram of food, daily smokers consumed 2.02 kcal/g and non-daily smokers consumed 1.89 kcal/g. The researchers also found that former smokers consumed more calories per gram of food (1.84kcal/g) than those who had never smoked, but the former smokers' dietary energy density was still significantly lower than that of current smokers. The finding suggests that any amount of cigarette consumption could be associated with poorer diet quality.

The calorie dense diets consumed by the smokers whose data was used in this study often included less fruit and vegetables, which means their intake of vitamin C was likely to be lower. The authors suggest that this deficiency could potentially put smokers at further risk of cardiovascular disease and cancer, presenting a major public health concern.

The researchers also suggest that a diet low in energy density could help prevent weight gain after quitting smoking.

Dr Vernarelli explained: "We know from the literature that concerns about weight gain are barriers to quitting smoking, and we know that diets high in energy density are associated with higher body weight. Our results suggest that addressing the energy density in diets of current smokers may be a good target for interventions as part of a larger smoking cessation plan"

The researchers used data from 5293 adults who took the National Health and Examination Survey, a program of studies designed to assess the health and nutritional status of adults and children in the US. The dietary data used in the study was based on participants recalling what they ate in the past 24 hours. The mean dietary energy density (kcal/g) was calculated after adjusting for age, sex, race, educational attainment, socioeconomic status, beverage energy density, physical activity and BMI.

The authors caution that the study's use of self-reported survey data may have introduced information and recall bias. The cross sectional nature of this study does not allow for conclusions about cause and effect between diet quality and smoking.