Study: Low-fat diets decrease testosterone in men

A recent research review conducted in the United Kingdom has determined that low-fat diets can reduce testosterone in men.

The study, published earlier this month in the Journal of Steroid Biochemistry and Molecular Biology, looked at six studies of low-fat diet and sex hormones with 206 participants.

The studies included in the systematic review started men on a high fat diet (40% fat), measured their testosterone, then put them on a low fat diet (20%) and did the same. Testosterone levels decreased 10-15% on average with the low-fat diets, and vegetarian diets decreased testosterone as much as 25%.

The authors determined that compared to high-fat diets, low-fat diets created small to moderate decreases in testosterone that could not be explained by changes in bodyweight.

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The decreases in testosterone noted in persons on a vegetarian diet, the authors suggested, were likely related to a reduction of dietary zinc, but mostly the diet.

The authors speculated a mechanism behind the drop in testosterone, one stemming from increased consumption of seed and vegetable oils frequently used in foods marketed as low fat, lipids known to cause oxidative cell damage capable of decreasing testosterone production.

Testosterone is a sex hormone produced by the body which is involved in the production of muscle and bone. Aging, alcohol, stress, steroids, bodyfat and opioids all lower testosterone.

Average testosterone levels have been falling since the 1980s, giving rise to concerns of environmental factors at play, but a specific level of testosterone known to be healthy has not been identified.

The authors believed large randomized trials are necessary to confirm their findings before practical recommendations can be made.

Report: CPAP therapy research fails to show hard outcomes

CPAP masks like these help with sleep apnea but may not help with other health outcomes. Derek Murray / WDAY
CPAP masks like these help with sleep apnea but may not help with other health outcomes. Derek Murray / WDAY

There are 18 million Americans with Obstructive Sleep Apnea, leaving them feeling unrested and tired. Of these, 8 million are believed to be users of Continuous Positive Airway Pressure (CPAP) machines, nighttime medical devices that slip over the nose and mouth and which combat breaks in breathing by keeping the airway open with continuous forced air.

The devices are covered by Medicare and can cost from $500 to $3,000.

The Centers for Medicare and Medicaid Services recently asked the Agency for Health Research and Quality (AHRQ), the federal government's treatment effectiveness review panel, to review the machines. After examining 47 clinical trials of CPAP treatment for six to 12 months of use, the results of that investigation were made available for review and are now concluding a period for public comment.

Notably, the AHRQ report determined that the treatments, while effective in reducing the symptoms of sleep apnea, are not shown as of yet to translate into meaningful outcomes from a health policy standpoint: reductions in stroke, heart attack, diabetes and depression. The report also noted that the medical literature on the machines was lacking in consistent outcome terminology.

Compliance remains a primary drag on CPAP usage and long term compliance issues are believed to have limited the data for long-term outcomes. A 2008 Canadian study of 80 patients found that a third never tried the therapy, and another 15% abandoned it after 10 months.

More than half of Medicare recipients are candidates for the machines, however, and public payers spend hundreds of millions of dollars annually on the treatments. The devices require maintenance and upkeep, and federal insurance will not pay for that outlay without demonstrated compliance.