Researchers at Queen’s University Belfast and the supplements industry are at odds over consumer exposure to oestrogen in sports supplements.
According to new research by the University in the journal Food Chemistry many sports supplements contain high levels of oestrogenic endocrine disruptors that could pose a risk to males under 16 and postmenopausal women. But the European Specialist Sports Nutrition Alliance has called the research "flawed".
Endocrine disruptors (EDs) are compounds that disturb the endocrine system, a collections of glands that direct hormones to a target organ.
Researchers at Queen’s University Belfast assessed 50 sports supplements for 17β-estradiol - the most potent naturally occurring oestrogen - and calculated the risk to health from exposure for different sexes and age groups.
49 out of 50 supplements study contained 17β-estradiol activity and the highest detected was 6,500 ng per kg of body weight a day, far above the acceptable daily intake (ADI).
A health concern?
“Consumers of sport supplements may be exposed to high levels of oestrogenic endocrine disruptors,” concluded the study.
EDs have been linked to a number of negative health effects for women such as fibrocystic disease of the breast, uterine fibroids and pelvic inflammatory disease and even increased risk of some cancers.
In men, ED exposure has been tied to reduction of testosterone secretion, reduced semen quality and quantity as well as testicular cancer.
Dr Mark Tallon, vice-chair of the European Specialist Sports Nutrition Alliance, disputed the University's findings.
“On a quick review, the study appears to be flawed in a number of ways which suggest that the data is not reflective of the oral intake of such ingredients/products," he said.
"The study makes hypothetical conclusions based on cell culture data and also does not represent the average sports nutrition user, and therefore we do not believe that there is any evidence to support the statement that endocrine disrupters such as those contained in soya of other natural ingredients pose health risks.”
Many exceed ADIs
The Joint FAO/WHO Expert Committee on Food Additives has established an ADI for 17β-estradiol of 0-50 ng/kg of body weight per day with levels below 0.3 mg per day - equivalent to 5 micrograms per kg of body weight per day - said to give no-observed-adverse-effect-level.
The university study found that 17β-estradiol equivalent levels were higher in 33 of the supplements it tested than those in the typical human omnivore diet. The ADI was also exceeded for 13 of the products.
From creatine to protein bars
An earlier study by the same researchers found that 80% of 116 sports supplements purchased at retailers in Ireland contained oestrogenic EDs.
The researchers analysed 50 of these supplements for the present paper. The samples included creatine supplements, whey protein, DHEA, as well as power and protein bars.
The researchers used the recommended daily dose on the package to calculate exposure to 17β-estradiol and assumed the average adult body weight was 60 kg.
Risk groups: Boys and postmenopausal women
The predicted antagonistic effect of 17β-estradiol exposure was higher for males between ages 12 and 16 compared to males over 16. The antagonistic effect for females was lower on the whole, except for postmenopausal women.
“These two groups [boys and postmenopausal women] have the lowest natural hormone levels and the consumption of potent estrogen agonists may increase their 17b-estradiol equivalents 20-fold,” said the study.
“It is of further concern that young boys in particular have been highlighted in studies to be amongst the most targeted sub-groups for sports supplements consumption.”
The researchers called on in vivo studies on absorption and metabolism to give a fuller assessment of the daily 17b-estradiol exposure through sports supplements.
Food Chemistry, Vol. 159, pps 157–165
‘Estrogenic endocrine disruptors present in sports supplements. A risk assessment for human health’
Authors:Plotan et al.