Heavy smokers consuming more than 20 cigarettes per day have a diet of worse quality than people who smoke less or not at all, and this amplifies their risk for cardiometabolic diseases. This is the original finding from a recent study published in the Clinical Nutrition journal by the Epidemiology and Public Health Research Unit at LIH’s Department of Population Health together with international collaboration partners.

Smoking is proclaimed as the most preventable cause of disease and premature death by the World Health Organisation. There are many studies showing a relationship between tobacco smoking and food habits or nutrient intake. However, the overall diet quality of smokers with regards to smoking intensity has not been assessed before.

In this study, data was analysed from the cross-sectional ORISCAV-LUX study (Observation of Cardiovascular Risk Factors in Luxembourg) carried out with more than 1300 participants aged between 18 and 69 years and living in Luxembourg. About one quarter of them were smokers. Participants reported on their smoking status, filled in a questionnaire about the type of food they consume (134 food items), the portion size and the frequency of consumption, and were taken blood samples.

By looking at 8 diet quality indices assessing different attributes of diet quality such as energy density and food diversity, the researchers identified a clear association between smoking status and diet quality, and found that smoking intensity plays a role. Heavy smokers (> 20 cigarettes/day) have a poorer diet quality than non- and former smokers, as well as light to moderate (≤ 20 cigarettes/day) and occasional smokers (< 1 cigarette/day). ‘We found that heavy smokers are less compliant with general dietary recommendations and have a less diverse food regime’, tells principal investigator Dr Ala’a Alkerwi. ‘They also consume more of so-called pro-inflammatory food that contributes to increase the risk of cardiovascular disease’, she points out.  

Strikingly, heavy smokers suffered more from metabolic disorders such as obesity (34%), dyslipidaemia (83%) (abnormal amount of lipids in the blood) and high levels of glycaemic biomarkers (risk for diabetes). The group of heavy smokers was mostly composed of men (70%) with lower level of education compared to the other groups.

‘The poorer diet quality in heavy smokers could be explained in several ways’, tells Dr Alkerwi. ‘Firstly, there is a proven link between education level and health and nutritional awareness. Consequently, heavy smokers that are more likely to be less educated may have a poorer diet quality because they are not aware of or do not care about food recommendations. Smoking has also been associated with mood function. Our mood can have an effect on our appetite and attitude towards food. Moreover, smoking leads to a modification of taste and could make us prefer certain unhealthy food types’, she explains.

From a public health standpoint, the scientists propose that diet quality of smokers should be considered in smoking cessation programmes and when emitting prevention messages on the negative effects of tobacco consumption.

The present study was carried out in collaboration with the University of Maastricht, the Netherlands, and the University of South Carolina, Columbia, US. The work was supported by a grant from the National Research Fund Luxembourg (FNR) for the project DIQUA-LUX.

Link to publication:  http://www.clinicalnutritionjournal.com/article/S0261-5614(16)30212-6/abstract