In a recently published study European Journal of Clinical Nutritionresearchers investigated the relationship between dietary fatty acid consumption and serological steroid hormone binding globulin (SHBG) and testosterone levels in middle-aged male residents of Eastern Finland.
Study: Dietary fat quality and serum androgen concentrations in middle-aged men. Image Credit: val lawless / Shutterstock
Background
Serum testosterone levels in men have been decreasing in recent years, and the reasons for this are unclear. Low testosterone levels are linked to obesity, sexual dysfunction, metabolic syndrome and type 2 diabetes. That’s why normal testosterone levels are so important for men’s health. Age, body mass index (BMI), alcohol intake, physical activity and smoking status affect testosterone levels.
Studies have shown that changes in the quality of dietary fats can also affect serum testosterone levels. In particular, increased intake of polyunsaturated fatty acids (PUFA) has been associated with decreased serum testosterone. Although studies have investigated the link between the type of dietary fat consumption, namely PUFA, monounsaturated fatty acids (MUFA), saturated fatty acids (SFA) consumption, and androgen levels, findings are conflicting. Further research may inform strategies and nutritional interventions to improve men’s reproductive health.
About the study
In the current cross-sectional study, researchers investigated the effect of individual dietary fatty acid consumption on androgen levels in middle-aged men.
The population-based study included 2,546 men (mean age, 53 years) who participated in the Kuopio Ischemic Heart Disease Risk Factor Study (KIHD). Data were obtained at baseline KIHD examinations between 1984 and 1989 from 2,682 men who were 42, 48, 54, or 60 years old at the start of the study and resided in the city of Kuopio or neighboring communities.
The team excluded 59 people with missing data on serological androgen levels, 26 people with inadequate nutrition data, 50 cancer patients, and one person receiving hormone therapy. Blood samples were taken from all participants. Educational level and household income were assessed using self-administered questionnaires.
The KIHD annual Leisure Time Physical Activity Survey was used to determine physical activity levels. SHBG and testosterone concentrations were determined using time-resolved fluoro-immunoassays. Dietary intake was assessed at baseline using four-day food records, one on a weekend and three on a weekday.
Linear regression modeling was performed to determine relationships between dietary MUFA, PUFA, SFA, and trans fatty acid (TFA) intake and serological SHBG and free and total testosterone levels. Multivariate nutrient density modeling was also performed to determine the relationship between isocaloric nutrient changes and androgen levels.
Results
Among 2,546 men, after adjusting for age, caloric intake, and year of examination, increased SFA consumption was associated with higher serological SHBG concentrations, free and total testosterone levels, and increased PUFA consumption with lower levels. However, after adjusting for other potential confounding factors, the relationships weakened and became nonsignificant. TFA and MUFA consumption was not associated with androgen levels.
In isocaloric replacement models, dietary protein replacement with saturated fatty acids was associated with higher serological SHBG and total testosterone levels. Specifically, replacing calories from protein with those from SFA was associated with 1.0 nmol/L higher SHBG levels and 0.3 nmol/L higher total testosterone in serum. Similar relationships were obtained using energy-adjusted fatty acid consumption in grams per day. Excluding 1,021 men with a previous history of diabetes or cardiovascular disease revealed nonsignificant associations. Multivariate adjusted isocaloric replacement analysis showed that replacing calories from proteins with those from saturated fatty acids increased SHBG levels by 0.7 nmol/L and testosterone concentrations by 0.1 nmol/L.
Individuals with increased SFA consumption had higher MUFA intake and lower PUFA, vegetables, fruits and nut consumption. Higher SFA intake was also associated with lower educational attainment and physical activity. Increased PUFA consumption was linked to lower SFA consumption, less smoking, higher consumption of MUFAs, vegetables, fruits and berries, higher education level, and more physical activity. Individuals with increased MUFA intake increased their PUFA and SFA consumption, decreased their consumption of vegetables, fiber, fruits and nuts, and became less physically active.
Overall, study findings showed no independent association between dietary fats and serological androgen concentrations in middle-aged men. However, replacing caloric intake from proteins with saturated fatty acids may increase serological androgen levels. Further studies are needed to determine causal relationships between dietary fat intake and serological androgen concentrations. Future studies, such as randomized controlled trials, may include different populations to increase the generalizability of study findings. Well-controlled studies with observational designs that take into account dietary changes may also provide valuable information.