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December 2006

Low Testosterone Increases Mortality in Older Men

A recent report in the Archives of Internal Medicine links reduced levels of testosterone in men to an increased risk of mortality during up to eight years of follow-up.5 Testosterone levels in men progressively decline after the age of 30, which can eventually result in a loss of muscle mass and bone density, diminished energy and libido, and symptoms of depression and irritability.

Scientists analyzed the association between testosterone levels and mortality in 858 male veterans over the age of 40. Testosterone levels were measured at least twice between 1994 and 1999. The subjects were followed through 2002. Nineteen percent of the participants had a low total testosterone level (less than 250 ng/dL) or a low free testosterone level, while 53% had normal levels and 28% had equivocal levels (an equal number of low and normal levels).

While 20% of the men with normal testosterone died during follow-up, deaths occurred among 25% of those with equivocal levels and 35% of those with low levels. After adjusting for age, illness, and other factors, men with low testosterone had an 88% higher risk of dying over the course of follow-up compared to men with normal levels. To reduce the effect of acute illness, the researchers then excluded men who died within the first year of follow-up, yet still found a 68% greater risk of death among men with low testosterone.

Larger prospective studies are needed to clarify the association between low testosterone and mortality risk, the scientists noted.

—Dayna Dye

DHEA May Delay HIV Disease Progression

Supplementing with DHEA elevates levels of sex hormones and may help arrest disease progression in HIV-positive men, according to a newly published report.1

DHEA (dehydroepiandrosterone) is a precursor to the sex hormones testosterone and estrogen. Previous studies have demonstrated that DHEA supplementation enhances immune function, improves bone mineral density and wound healing, reduces depression, increases muscle mass, and reduces low-density lipoprotein (LDL) levels.2 In HIV-infected individuals, lower blood levels of DHEA and DHEA-sulphate (DHEA-S) are associated with disease progression.3

In a randomized, placebo-controlled trial of 69 HIV-infected men with mild depression, 100-400 mg per day of oral DHEA therapy increased circulating levels of DHEA, DHEA-S, free testosterone, and androstenedione, while suppressing sex hormone-binding globulin. A separate report noted that DHEA supplementation elevated mood in HIV-positive individuals suffering from depression.4

The investigators concluded that DHEA supplementation of up to 400 mg per day is safe in HIV-infected men, and that it can help improve mood and elevate levels of sex hormones.1,4

—Penny Baron

Milk Thistle Compound Suppresses Prostate Cancer

Isosilybin B, an active constituent of silymarin found in milk thistle, suppresses the growth of prostate cancer cells far more effectively than other milk thistle compounds and extracts, according to a recently published report.7

Scientists have known for some time that milk thistle (Silybum marianum) offers protection against some forms of prostate cancer. Two extracts of milk thistle seed, silymarin and silibinin, have long been recommended for liver support and various other health benefits. Scientists recently tested several active constituents of silymarin and silibinin to determine which exerted the most powerful effects against prostate cancer.

Isosilybin B, which is present only in silymarin, was the most consistently potent suppressor of cell growth compared to other milk thistle constituents and extracts. Isosilybin B accounts for no more than 5% of silymarin and is not contained in silibinin. The researchers thus concluded that milk thistle extracts enriched for isosilybin B, or isosilybin B alone, may prove most effective in prostate cancer prevention and treatment.

—Dale Kiefer

Emotional Stability, Well-Being Improve with Age

As people grow older, they become “mellower” in their response to negative emotions, and emotional stability continues to improve over the course of the human life span, even into the seventh decade of life, according to a new report.6

Neuroscientists studied a group of healthy individuals between the ages of 12 and 79, using emotional well-being questionnaires as well as brain imaging studies. They found that neurotic tendencies decreased with advancing age, with those aged 12-19 reporting the highest level of neurosis, and those aged 50-79 reporting the lowest level. Using functional MRI testing and measurements of brain electrical activity, the scientists found that younger age groups were better able to recognize facial expressions of fear, but less accurate at identifying expressions of happiness. In older adults, the medial prefrontal cortex, an area of the brain that plays a role in coordinating thoughts and actions with internal goals, was more active when processing negative emotions than positive emotions.

These findings led the scientists to propose that life experience and changing motivational goals may help older adults to increase their control over both negative and positive emotions, helping them to maintain mental health, even in the face of difficult life events.

—Elizabeth Wagner, ND

Cystatin C Valuable in Detecting Kidney Dysfunction

Cystatin C is a more sensitive indicator of early kidney dysfunction than the currently used biomarker, according to a report in the Annals of Internal Medicine.8 This is a welcome finding, as kidney disease affects approximately 5% of adults over the age of 20 but is often undetected until its later stages.

Scientists compared the prognostic value of cystatin C and creatinine in detecting early kidney impairment. Creatinine, a normal by-product of muscle breakdown, is currently used to estimate glomerular filtration rate, an indicator of kidney function. Cystatin-C was found capable of detecting early kidney disease considerably sooner than creatinine or estimated glomerular filtration rate. Unlike creatinine, cystatin-C is not affected by variables such as age, gender, or race, and is thus a more sensitive and useful test for detecting kidney dysfunction.

Scientists have previously demonstrated that, among apparently healthy elderly people, cystatin C is a better predictor of mortality risk from various causes than either creatinine or estimated glomerular filtration rate.9

—Dale Kiefer

Lutein, Zeaxanthin Improve Skin Health

Compounds in leafy green vegetables known as lutein and zeaxanthin increase hydration, elasticity, and surface lipids of the skin while protecting against lipid oxidation, according to the results of a study presented at the Beyond Beauty Paris conference in September 2006.

Italian researchers studied women aged 25-50 who received 10 mg of an oral supplement of lutein and zeaxanthin, a 50-part-per-million topical lutein/zeaxanthin formula, a combination of oral and topical lutein and zeaxanthin, or a placebo for 12 weeks. Compared to placebo, lutein and zeaxanthin administered orally, topically, and both orally and topically were associated with improvements in skin elasticity, skin hydration, and superficial lipid levels, as well as a reduction in skin lipid oxidation. Combined oral and topical lutein provided the greatest overall benefit, resulting in a 60% increase in skin hydration, a 20% increase in skin elasticity, a 50% elevation in superficial lipid levels, and a 65% decrease in skin lipid peroxidation.

The study contributes to previous findings suggesting that regular ingestion of lutein may help improve the skin’s antioxidant defense system, which helps protect against damage caused by the sun and artificial light.11 Lutein and zeaxanthin are commonly ingested as nutritional supplements for eye health.

“This is the first study to determine the impact of lutein/zeaxanthin alone on the human skin,” noted Richard L. Roberts, PhD, senior manager of scientific affairs for Kemin Health, a leading manufacturer of lutein. “It provides strong new evidence of lutein’s positive role in promoting skin health and appearance by increasing hydration, elasticity, and lipid content.”

—Dayna Dye