Abstract and Introduction
Abstract
Background. There is emerging debate over the effect of Helicobacter pylori infection on body mass index (BMI). A recent study demonstrated that individuals who underwent H. pylori eradication developed significant weight gain as compared to subjects with untreated H. pylori colonisation.
Aim. To elucidate the association between H. pylori colonisation and the prevalence of overweight and obesity in developed countries.
Methods. The literature was searched for publications reporting data on H. pylori prevalence rates and obesity prevalence rates. Studies selected reported H. pylori prevalence in random population samples with sample sizes of more than 100 subjects in developed countries (GDP >25 000 US$/person/year). Corresponding BMI distributions for corresponding countries and regions were identified. Nonparametric tests were used to compare the association between H. pylori and overweight and obesity rates.
Results. Forty-nine studies with data from 10 European countries, Japan, the US and Australia were identified. The mean H. pylori rate was 44.1% (range 17–75%), the mean rates for obesity and overweight were 46.6 (±16)% and 14.2 (±8.9)%. The rate of obesity and overweight were inversely and significantly (r = 0.29, P < 0.001) correlated with the prevalence of H. pylori infection.
Conclusions. There is an inverse correlation between H. pylori prevalence and rate of overweight/obesity in countries of the developed world. Thus, the gradual decrease of the H. pylori colonisation that has been observed in recent decades (or factors associated with decrease of) could be causally related to the obesity endemic observed in the Western world.
Introduction
In Western countries, the prevalence of those people classified as overweight (BMI >25 > 30) and obese (BMI >30) has substantially increased. The WHO in 2008 estimated that over 500 million adults have obesity, representing 10–14% of the world's population. In this context, there is emerging debate over the effect of Helicobacter pylori (H. pylori) infection on body mass index (BMI). While several cross-sectional studies have observed an association of H. pylori infection with BMI, the National Health and Nutrition Examination Survey (NHANES III) did not find an association. Other studies have evaluated the impact of H. pylori eradication on BMI. Kamada et al. demonstrated that Japanese patients who underwent H. pylori eradication developed significant weight gain as compared to subjects with untreated H. pylori colonisation. This has since been confirmed in a larger population-based randomised controlled trial in England where people gained more than 3 kg of weight in the intervention (19%) as compared to placebo (13%), although follow-up of this study was limited to 6 months. In addition, animal studies have shown that H. pylori colonisation decreased fasting blood glucose levels, increased levels of leptin, improved glucose tolerance, and suppressed weight gain. All this may indeed suggest a role of the reduction of the H. pylori prevalence as a contributing factor for the obesity endemic.
It is widely accepted that environmental factors such as the availability and the characteristics of food and dietary habits play a role, while there are also genetic factors that influence the manifestation of obesity. On the other hand, it is interesting to note that some cohort studies do not find an association between nutrition and obesity suggesting that factors other than caloric intake are important for the obesity endemic. Nevertheless, there are overwhelming data supporting that the endemic of obese patients is linked to an increased incidence of cancer and liver disease.
While the obesity epidemic has been observed for prolonged periods of time in the Western World, there is now emerging evidence that the obesity epidemic is spreading to the developing world. Interestingly, there is now a substantial decrease in the H. pylori prevalence. However, it is as yet unknown if on a larger scale (e.g. across different populations and countries) there might be an association between H. pylori and obesitas. In the Western World, the prevalence of H. pylori is decreasing. H. pylori infection is prevalent worldwide, with a large disparity between developed and developing countries. This decreasing prevalence of H. pylori may represent a risk or contributing factor to the world-wide endemic of obesity with all its complications. However, as yet there are no systematic analyses that aim to assess a potential association between the prevalence of H. pylori and the prevalence of obesity across various geographical regions of the world. Thus, this study aimed to elucidate the potential link between H. pylori and the prevalence of obesity and people who are overweight in developed countries.