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Raloxifene: anti-oestrogen that boosts lean body mass and reduces fat

Tamoxifen, an effective anti-oestrogen that’s popular among doping users, has a drawback. For women at least, in the longer term, its use reduces lean body mass and leads to an increase in fat mass. Another anti-oestrogen, raloxifene [structural formula on the right], does not have these disadvantages. A Dutch study suggests that it actually improves body composition.

Chemical athletes use tamoxifen to counteract the oestrogenic side effects of the anabolic steroids they take, but also to boost their testosterone levels and reduce the effects of estradiol between courses of steroids.

Very few scientific studies have been published on the exact effects of tamoxifen on chemical athletes. More is known about the effects of tamoxifen in women who have survived breast cancer.

Tamoxifen boosts these women’s chances of survival considerably, and reduces the chance of estradiol-sensitive forms of breast cancer returning. That’s why doctors often prescribe tamoxifen for years after initial breast cancer treatment.

The price that these women pay for their increased chance of survival is worsening of their body composition, however. [Breast Cancer Res Treat. 2012 Oct;135(3):663-80.] Their lean body mass – or in other words their muscle mass – reduces and their body fat increases. Strength training can counteract this effect though.

Tamoxifen, an effective anti-oestrogen that’s popular among doping users, has a drawback. For women at least, in the longer term, its use reduces lean body mass and leads to an increase in fat mass. Another anti-oestrogen, raloxifene [structural formula on the right], does not have these disadvantages. A Dutch study suggests that it actually improves body composition.
In 2010 geriatricians in Utrecht published a study from which it’s possible to deduce that raloxifene does not have a negative effect on body composition. Raloxifene is marketed under the name of Evista by Eli Lilly. The manufacturer provided the medicines used in the study, but did not sponsor the study. The researchers were funded by the Dutch government.

In the study one group of 70 women aged between 70 and 80 took 60 mg raloxifene daily. Another group of 73 women were given a placebo.

The figure below shows how raloxifene altered the women’s body composition: it reduced their fat mass, but also increased lean body mass.

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Raloxifene did not boost the women’s muscle strength, but it did improve some memory functions. [Menopause. 2010 Mar;17(2):309-14.]

“The clinical impact of this finding warrants further research”, the researchers conclude.

Raloxifene and body composition and muscle strength in postmenopausal women: a randomized, double-blind, placebo-controlled trial.

Abstract

OBJECTIVE:

To compare the effects of raloxifene and placebo on body composition and muscle strength.

DESIGN:

Randomized, double-blind, placebo-controlled trial involving 198 healthy women aged 70 years or older conducted between July 2003 and January 2008 at the University Medical Centre, Utrecht, The Netherlands.

METHODS:

Participants were randomly assigned to receive raloxifene 60 mg or placebo daily for 12 months. Measurements were taken at baseline, 3, 6, and 12 months, and change from baseline was calculated. Main outcome measures were body composition (bioelectrical impedance analysis), muscle strength, and muscle power (maximum voluntary isometric knee extension strength, explosive leg extensor power, and handgrip strength).

RESULTS:

At 12 months, the body composition of women taking raloxifene was significantly different from that of women taking placebo: fat-free mass (FFM) had increased by a mean of 0.83 (2.4) kg in the raloxifene group versus 0.03 (1.5) kg in the placebo group (P=0.05), and total body water had increased by a mean of 0.6 (1.8) litres in the raloxifene group versus a decrease of 0.06 (1.1) litres in the placebo group (P=0.02). Muscle strength and power were not significantly different.

CONCLUSION:

Raloxifene significantly changed body composition (increased FFM; increased water content) compared with placebo in postmenopausal women.

PMID: 19884264 [PubMed – indexed for MEDLINE]

Source: http://www.ncbi.nlm.nih.gov/pubmed/19884264