Cross-sectional association of Toxoplasma gondii exposure with BMI and diet in US adults

Toxoplasmosis gondii exposure has been linked to increased impulsivity and risky behaviors, which has implications for eating behavior. Impulsivity and risk tolerance is known to be related with worse diets and a higher chance of obesity. There is little known, however, about the independent link between Toxoplasma gondii (T. gondii) exposure and diet-related outcomes. Using linear and quantile regression, we estimated the relationship between T. gondii exposure and BMI, total energy intake (kcal), and diet quality as measured by the Health Eating Index-2015 (HEI) among 9,853 adults from the 2009–2014 National Health and Nutrition Examination Survey. Previous studies have shown different behavioral responses to T. gondii infection among males and females, and socioeconomic factors are also likely to be important as both T. gondii and poor diet are more prevalent among U.S. populations in poverty. We therefore measured the associations between T. gondii and diet-related outcomes separately for men and women and for respondents in poverty. Among females <200% of the federal poverty level Toxoplasmosis gondii exposure was associated with a higher BMI by 2.0 units (95% CI [0.22, 3.83]) at median BMI and a lower HEI by 5.05 units (95% CI [-7.87, -2.24]) at the 25^th percentile of HEI. Stronger associations were found at higher levels of BMI and worse diet quality among females. No associations were found among males. Through a detailed investigation of mechanisms, we were able to rule out T. gondii exposure from cat ownership, differing amounts of meat, and drinking water source as potential confounding factors; environmental exposure to T. gondii as well as changes in human behavior due to parasitic infection remain primary mechanisms.

Toxoplasmosis gondii (T. gondii) is a parasite that infects over 10 percent of the US population. T. gondii infection can cause serious health problems for some people, but most infections remain undiagnosed and subclinical. When an individual is infected, T. gondii can chronically reside in muscle and central nervous system (including brain) tissue. Previous studies have found that individuals with prior exposure to T. gondii may engage in more risky and impulsive behaviors, and risk tolerance and impulsivity may be related with individual’s diet. Our study examines whether individuals with T. gondii exposure have higher body mass index (BMI) and worse diets. We further discuss and test for alternative explanations that prevent us from establishing a causal relationship between T. gondii and BMI/diet. Overall, our results show that T. gondii exposure is related with higher BMI and worse diets among lower-income females in the US. Our results uncover a novel correlate of BMI and diets, and suggest the importance of investigating the broader public health impacts of chronic T. gondii infection.

Metabolic syndrome and obesity in an insect

Dragonflies infected with noninvasive gregarine gut parasites (Apicomplexa: Eugregarinorida) [corrected] have reduced flight-muscle performance, an inability to metabolize lipid in their muscles, twofold-elevated hemolymph carbohydrate concentrations, and they accumulate fat in their thorax in a manner analogous to mammalian obesity. Gregarine infection is associated with inappropriate responses of hemolymph carbohydrate concentration to insulin and with chronic activation in the flight muscles of p38 MAP kinase, a signaling molecule involved in immune and stress responses. Short-term exposure to gregarine excretory/secretory products caused elevated blood carbohydrate and p38 MAPK activation in healthy individuals. These characteristics comprise a set of symptoms and processes that are known in mammals as metabolic syndrome but which have not previously been described in other animal taxa. In addition to expanding the known taxonomic breadth of metabolic disease, these results indicate that insects may be useful experimental models for studying its underlying biology and mechanisms.

Obesity, adipose tissue distribution and health in women--results from a population study in Gothenburg, Sweden

The associations between generalized obesity measured as body mass index (BMI), or adipose tissue distribution, measured as the waist/hip circumference ratio (WHR), on one hand, and a number of socioeconomic, somatic as well as psychologic and mental health variables on the other, were analysed in a population study of women (1462 participants, aged 38-60 years, participation rate 90.1%). The anthropometric measurements were adjusted for their influence on each other. BMI, but not WHR, was negatively associated with socioeconomic status and education. Increased WHR correlated to a number of somatic diseases from different organ systems, including diabetes mellitus, infectious respiratory and abdominal diseases. Even more striking were strong correlations to a number of variables indicating accident proneness as well as mental disorder, and increased use of antidepressants and tranquilizers. BMI and WHR were also associated to different personality profiles. Furthermore, the use of alcohol and smoking were positively correlated to the WHR. In contrast, most of these associations were not seen with the BMI--sometimes even negative correlations were found. Exceptions were, however, varicose veins, joint problems and surgery for gall bladder disease, which were positively correlated to BMI only. Blood pressure, plasma triglycerides and uric acid were positively correlated to both BMI and the WHR, plasma cholesterol, however, only to the WHR. Obesity (high BMI) and abdominal adipose tissue distribution (high WHR) clearly show differences in their associations to various health variables. It is hypothesized that an arousal syndrome might be a contributing factor to cause symptoms of psychological maladjustment, including psychosomatic disease. Hypothetically, in parallel, an accumulation of depot fat in the abdominal depot, might follow as a consequence of neuroendocrine dysregulation of endocrine secretions.