I have been watching to some videos on Youtube to see if I should be a vegan. One of the thing that popped out during a discussion was the fact that soy contains a lot of oestrogen which could cause undesirable side effects. However, to my great surprise, the speaker answered by claiming that "meat and cow's milk have twice the amount of oestrogen that's found in soy". I searched rapidly on Google and saw many website claiming the same thing. Is that true?

Claim found in this video.

  • Good question. The claim in that video goes against everything I've ever read or heard on the subject, so I'm interested to see if it can be corroborated.
    – Flimzy
    Commented May 18, 2013 at 23:28
  • 2
    Is there a missing distinction here between how much oestogren/oestrogen-like compounds there is in food, and the amount of oestregen our bodies produce in response? The claim seems to be about the former, but you talk about the latter.
    – Oddthinking
    Commented May 19, 2013 at 5:40
  • At first I thought that the oestrogen was never really in food but only a way people talk about it to say make us produce it. I will clarify the question now that I have been enlightened by new knowledge ^^
    – Zonata
    Commented May 20, 2013 at 19:09

2 Answers 2


It seems unlikely.

  • Soy contains isoflavones which are said to mimic oestrogen.
  • Many cattle are given growth promoting hormones - including oestrogen.

If the sources below are to be believed, the daily amount consumed in soya may be thousands of times greater than that consumed in beef.

  • Soy: 30000 ng
  • Beef: 4 ng or 20 ng.

The first two sources are not great and the products, quantities and consumers in them are not comparable. However I think they are at least indicative of the magnitude of the likely quantities.

According to The Guardian

It has been estimated that infants who are fed soya formula exclusively receive an amount of oestrogen equivalent to five birth control pills every day.

One birth control pill contains 30 to 35 micrograms (mcg) of EE (ethinyl estradiol - a synthetic oestrogen).

According to BeefMyths

3-ounce serving of beef from a steer treated with growth promotants contains 1.9 nanograms of estrogen.

3-ounce serving of beef from a steer raised without growth promotants, such as certified organic beef contains 1.3 nanograms of estrogen.

Sources: Food and Drug Administration; Hoffman and Evers; Scanga et al.; FSIS-USDA; Dr. Harlan Ritchie, Michigan State University; NCBA

In Possible health impact of animal oestrogens in food it says

The theoretical maximum daily intake (TMDI) of oestradiol-17β by consumption of cattle meat is calculated to be 4.3 ng. Following the use of oestradiol-containing growth-promoting agents TMDI is increased by a factor of 4.6 to 20 ng.

  • Good answer, although the quote from The Guardian is a bit incomplete, in the sense that it is not telling us whether 30-35 ug EE/die is dangerous.
    – nico
    Commented May 19, 2013 at 8:54

The person who answered forgot to mention that soy contains Phytoestrogens

And beef contains mammalian estrogen.

Two totally different estrogen. Phytoestrogens do not affect estrogen levels. http://www.ncbi.nlm.nih.gov/pubmed/19524224 Mammalian estrogen does.

  • 4
    You make 4 claims here, but only reference one of them.
    – Oddthinking
    Commented May 22, 2016 at 6:14

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