BfR Annual Report 2015

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BfR | Annual Report 2015 58
Hormonally active substances in foods
Hormonally active substances may occur as natural in-
gredients in various foods. Examples include hormones
in milk or meat as well as phyto-oestrogens. The phyto-
hormones include 8-prenylnaringenin, which is formed
in hops and found in beer, certain polyphenols in wine
and isoflavones in soy. Occasionally, such ingredients are
added in isolated form to dietary supplements.
In 2015, the BfR was also tasked with the assessment
of health risks of hormones and hormonally active sub-
stances in foods. Hormones are produced in animals as
endogenous messenger substances to regulate meta-
bolic processes. Accordingly, they also occur naturally
in meat and milk. Cow's milk contains higher natural
concentrations of oestrogens and progesterone than the
muscle meat of slaughtered animals, fish or eggs. Natu-
ral hormone levels in meat can vary considerably. The
meat of intact (non-castrated) young boars, for example,
has significantly higher concentrations of the female sex
hormone 17β-oestradiol and the male steroid hormone
nandrolone than the meat of castrated animals. Only a
small portion of the hormones ingested with food is ab-
sorbed by the body and further metabolised. Compared
to the endogenous synthesis of hormones in humans,
the anticipated absorbed amount of hormones is con-
sidered to be low. The available data regarding natural
hormone sources in foods like meat and milk currently do
not point to any health risks.
Isoflavones are secondary plant compounds occurring,
for example, in soy or red clover. Due to potential (weak)
oestrogenic effects in the body, they are also called phyto-
oestrogens. Dietary supplements and dietetic foods with
isolated or enriched isoflavones are offered on the Ger-
man market for the alleviation of menopausal ailments.
The European Food Safety Authority (EFSA) has so far
rejected the health claims made for isoflavones. In 2007,
the BfR already concluded that in particular the long-
term intake of high isoflavone amounts is not without
risk for perimenopausal and postmenopausal women.
In 2015, EFSA released a risk assessment of isolated
isoflavones for the aforementioned target groups. There-
upon, the BfR explained the main findings of the scien-
tific opinion of EFSA in a communication intended for
consumers: Based on the evaluated human studies and
the applied preparations, doses and treatment durations
in these studies, there are no indications of adverse ef-
fects of isolated isoflavones on the female mammary
gland, uterus and thyroid in postmenopausal women.
Based on the relevant studies, EFSA proposed guidance
values for an adequate safe use of isoflavone enriched
products (for example: a maximum supplemental intake
of 100 mg per day for a maximal duration of 10 months
for soy isoflavones and soy extracts, and a maximum
supplemental intake of 43.5 mg per day for a maximal
duration of 3 months for red clover). The BfR supports
these guidance values which should not be exceeded
in the case of postmenopausal women and proposes
that the guidance values should be also used for peri-
menopausal women until sufficient data are available for
this consumer group to complete the risk assessment.
The intake of isoflavone-rich preparations is not recom-
mended for women with a history or current diagnosis of
oestrogen-dependent (cancer) disease of the mammary
gland or the uterus. Since it may not be known whether
such diseases are present, it could be necessary to ob-
tain medical advice before using dietary supplements
with isolated isoflavones.
Isolated endogenous steroids are sometimes added to
dietary supplements, such as the anabolic prohormone
dehydroepiandrosterone (DHEA). In the human body,
this substance can be converted into both male sex hor-
mones like testosterone and female sex hormones like
17β-oestradiol. Studies show that an intake of 25 mg
DHEA per day can change endogenous hormone levels,
particularly in postmenopausal women. Moreover, the in-
take of this substance can result in clinically apparent
hormonal effects like acne in certain population groups.
In addition, it is unclear whether DHEA may influence
the growth of hormone-dependent breast or prostate tu-
mours. Therefore, the BfR does not recommend the use
of steroidal hormones – like DHEA with its prohormonal
effect – without medical supervision and a medical in-
dication.
i More information (in German) on isoflavones at:
Isoflavones are secondary plant compounds
and occur, for example, in soy.