Tag: testosterone

Categories : Gender GeneticsTags :

Study Finds Testosterone’s Importance for Success Overrated

On By ModernMedia
Ball-and-stick model of the testosterone molecule, C19H28O2, as found in the crystal structure of testosterone monohydrate. Credit: Ben Mills, Wikimedia Commons.

With the Olympics underway, testosterone is again in the spotlight over its role in enhancing physical performance, with rules about its natural level being once again debated. It has also been popularly thought to be involved in success in other endeavours – but its importance in this regard may be overrated.

New research has found little evidence that testosterone exerts a meaningful influence on successes in life for men or women. The study in fact suggests that testosterone’s importance outside of physical endeavours could be even less important than previously believed.

In men, it is known that testosterone is linked to socioeconomic position, such as income or educational qualifications.  Researchers from the University of Bristol’s Population Health Sciences (PHS) and MRC Integrated Epidemiology Unit (IEU) set out to determine whether this is because testosterone has an influence on socioeconomic position, as opposed to socioeconomic circumstances affecting testosterone levels, or if it was a case of health affecting both. The findings are published in Science Advances.

To isolate effects of testosterone itself, the investigators used Mendelian randomisation in a sample of 306,248 UK adults from UK Biobank. They explored testosterone’s influence on socioeconomic position, including income, employment status, neighborhood-level deprivation, and educational qualifications; on health, including self-rated health and BMI, and on risk-taking behaviour.  

Dr Amanda Hughes, Senior Research Associate in Epidemiology in Bristol Medical School: Population Health Sciences (PHS), said: “There’s a widespread belief that a person’s testosterone can affect where they end up in life. Our results suggest that, despite a lot of mythology surrounding testosterone, its social implications may have been over-stated.”

First, the team identified genetic variants linked to higher testosterone levels, and explored their links to outcomes. Since genetic variations are essentially fixed throughout a lifetime, it is highly unlikely that they are affected by socioeconomic circumstances, health, or other environmental factors.

In common with prior studies, multivariate analysis showed men with higher testosterone had higher household income, lived in less deprived areas, and were more likely to have a university degree and a skilled job. Higher testosterone in women was linked to lower socioeconomic position, including lower household income, living in a more deprived area, and lower chance of having a university degree. Consistent with previous evidence, higher testosterone was associated with better health for men and poorer health for women, and greater risk-taking behaviour for men.

In contrast, the Mendelian randomisation method showed there was little evidence that the testosterone-linked genetic variants were associated with any outcome for men or women. The research team concluded that there is little evidence that testosterone meaningfully affected socioeconomic position, health, or risk-taking in men or women. The study suggests that – despite the mythology surrounding testosterone – its importance is much less than previously held.

Since the results for women were less precise than the men’s, the influence of testosterone in women could be further explored with larger sample sizes.  

Dr Hughes added: “Higher testosterone in men has previously been linked to various kinds of social success. A study of male executives found that testosterone was higher for those who had more subordinates. A study of male financial traders found that higher testosterone correlated with greater daily profits. Other studies have reported that testosterone is higher for more highly educated men, and among self-employed men, suggesting a link with entrepreneurship.

“Such research has supported the widespread idea that testosterone can influence success by affecting behaviour. There is evidence from experiments that testosterone can make a person more assertive or more likely to take risks – traits which can be rewarded in the labor market, for instance during wage negotiations. But there are other explanations. For example, a link between higher testosterone and success might simply reflect an influence of good health on both. Alternatively, socioeconomic circumstances could affect testosterone levels. A person’s perception of their own success could influence testosterone: in studies of sports matches, testosterone has been found to rise in the winner compared to the loser.”

Source: University of Bristol

Journal information: Testosterone and socioeconomic position: Mendelian Randomization in 306,248 men and women in UK Biobank’, Science Advances (2021).

Categories : Diet and NutritionTags :

Low Fat Diets Reduce Testosterone

On By ModernMedia

A new study has found that low fat diets decrease men’s testosterone levels by 10-15%, with important considerations for health.

Optimal testosterone levels are a crucial part of men’s health, with higher risks of heart disease, diabetes, and Alzheimer’s disease resulting from low levels of the hormone. Healthy testosterone levels are also key for men’s athletic performance, mental health, and sexual health. Clinically low testosterone rates are referred to as hypogonadism.

Men’s testosterone levels have been falling since the 1970s but low risk dietary strategies could be a useful treatment for low testosterone.

In a systematic review and meta-analysis, the researchers analysed the results of six well-controlled studies with a total of 206 participants. Men were first put on a high fat diet (40% fat), and then switched to a low fat diet (20% fat), with testosterone levels decreasing by 10-15% on average. Particularly bad were vegetarian low fat diets causing decreases in testosterone up to 26%.

Previous studies conducted in humans and mice found that high intakes of monounsaturated fats found in olive oil, avocados, and nuts may boost testosterone production. However, omega 6 polyunsaturated fats predominantly found in vegetable oils, may in fact damage the cells’ ability to produce testosterone. This is because highly unsaturated fats such as polyunsaturated fats are more prone to oxidation, causing damage to the cells.

“Low testosterone levels are linked to a higher risk of heart disease, diabetes, and Alzheimer’s disease.”

More research needs to be done in this area, said the researchers.

“Ideally, we would like to see a few more studies to confirm our results. However, these studies may never come, normally researchers want to find new results, not replicate old ones. In the meantime, men with low testosterone would be wise to avoid low fat diets.” said lead researcher Joseph Whittaker.

A controversial topic in nutritional science, dietary fibre has proponents of various diets often in stark disagreement over low fat versus low carbohydrates. Low fat diets have benefits such as reduced cholesterol levels, which should be weighed up against the potential downsides, such as decreased testosterone levels.

Traditionally, dietary guidelines have focused on limiting fat intake, with the current UK and US guidelines limiting fat intake to less than 35% of total calories. However, as more research on the benefits of high fat, low carbohydrate diets is done, this traditional view is coming under increasing scrutiny. Recent research has shown that high fat diets can decrease triglycerides, decrease blood pressure, increase HDL cholesterol (aka ‘good cholesterol’), and now it was found that it can increase testosterone levels.

Source: News-Medical.Net

Journal information: Whittaker, J & Wu, K (2021) Low-fat diets and testosterone in men: Systematic review and meta-analysis of intervention studies. The Journal of Steroid Biochemistry and Molecular Biology. doi.org/10.1016/j.jsbmb.2021.105878.