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[Mark Messina]

Thank you for your interest in soy. I look forward to answering your questions, so please check-in periodically for updates.

[Margaret Ludick]

Thank you for your interest in soy. I look forward to answering your questions, so please check-in periodically for updates.
Dr Messina, I am busy setting up a small tofu factory in Cape Town and by chance found the website for the Soy Food Association in SA.   I was sorry to learn that you had to postpone your visit to South Africa - as I was looking forward to the Soy Conference.    I have many questions and a lot to learn.    Hopefully you'll be able to come soon.

Look forward to meeting you.

Regards
Margaret Ludick

[Jose Araya]

Hi Dr., I made this question to Marilyn Nash and she refered me to you. Here I copy-paste the question and the answer. Also I want to know if the soy I am consuming is fermented or not, and which one of those is the bad or the good one. I can say the powder is really fine and that doesnt tastes to much like soy.

Good evening.
I have heard that soy protein lowers testosterone levels in men and could cause infertility. I wonder if that is true, because I am training with weights and I drink soy protein smoothies 82% protein to increase muscle mass. Please make this doubt clear for me. I've heard versions of either side (friends and internet), I do not know what's real ...

Thank you in advance.
Jose Manuel Araya Monge

Dear Jose,

The popular press is full of articles about soy, some saying it's great and some saying it's awful. Some of the articles are based on a particular study that has just been done, some are based on personal experience, some are written by journalists who don't understand the science, some are written by medical doctors, etc. It can be extremely difficult to sort through all of this to make a decision about what is right for you personally.

Remember that soy is a very commonly eaten food in Asia. Many Asians consume soy on a daily basis throughout the course of their lifetime. Long-term dietary patterns are much more likely to have an impact on health than short-term consumption will have, and results of short-term studies often only suggest apparent risk and not real problems. If eating soy were dangerous, we would see large numbers of Asians developing health problems because of it. In fact, Asians have lower rates of chronic disease than westerners do. Whether or not soy is responsible for this lower rate of disease, the low rates indicate that soy is clearly not causing those diseases. Right now there are stories that soy will harm fertility, yet the population in Asia has grown at a tremendous rate.

That said, your situation is more of an extreme consumption of protein, both in quantity and in purified forms. Often high levels of specific components extracted from foods do not have the same effect as eating a normal amount of the foods. I would suggest you visit xxxxxx and pose your concerns to Dr. Mark Messina within this forum. He will hopefully be able to address this issue for you in a balanced way.

Sincerely,
Marilyn Nash

[Mark Messina]

Dear Jose:
Thank you for question.  As you correctly indicate, there are often reports, mostly on the internet but also in other types of media, indicating soy lowers testosterone levels in men and because of this, and perhaps other reasons, soy may not be a good choice for those individuals wanting to increase muscle mass.  In response to your question, first let me say that Ms. Nash makes several important points.

Somewhat coincidentally, because questions do arise about the effects of soy on testosterone, I, along with several colleagues, recently conducted a meta-analysis to address this issue.  A meta-analysis is a statistical process by which data from several studies is combined for the purpose of integrating the findings.  By conducting this type of analysis, it is possible to get a better feel for the totality of evidence than relying on the results from one or two studies. 

The meta-analysis has been completed although it is not yet published.  However, because the results were presented at a recently-held scientific meeting, I can mention here that overall, the studies show there is no effect of either soy protein or isoflavones (plant estrogens in soy) on either total or free (biologically available) testosterone levels in men.
In regard to the other part of your question, note that soy protein is a high-quality protein similar in quality to animal proteins.  Importantly, there are also studies showing that soy protein, when part of overall protein intake, leads to similar gains in muscle mass in response to resistance exercise as other high-quality proteins.  When trying to gain muscle mass, intriguing evidence indicates that it is best to consume protein within two hours of exercising.  Some evidence suggests whey protein may be the ideal protein to consume during this post-exercise period but more research is needed to substantiate this point.

Finally, it is important to recognize that nutritionists recommend getting nutrients from a variety of different sources.  Therefore, protein should come from a variety of different foods, and certainly, the evidence indicates soyfoods are good choices.

[Lory Hayon]

Dear Dr. Messina,
I am a registered dietitian, specializing in PCOS. I am having trouble deciphering the research re; how much soy products, if any to recommend to my PCOS patients. Many patients have hyperlipidemia so they could benefit from the soy, but they also are trying to conceive, so I do not want the isoflavones to interfere with their ovulation cycle? What are your thoughts?

Sincerely,
Lory Hayon, RD

[Mark Messina]

Thank you for your question.
Little direct information about the effects of soyfoods, soy protein or isoflavones on the health status of PCOS patients is available.  To my knowledge, only one relevant study has been conducted.*  In this particular study, the isoflavone genistein (36 mg/day) did not significantly affect anthropometric features, the hormonal milieu, menstrual cyclicity and glycoinsulinemic metabolism.  However, genistein did favorable affect LDL-cholesterol and the LDL:HDL ratio. 
In general, soyfoods are considered to be quite heart-healthy as they are low in saturated fat and the protein itself modestly reduces LDL-cholesterol.  In addition, there is intriguing evidence indicating that soyfoods lower blood pressure and that isoflavones improve endothelial function.
The effect of the isoflavones on the menstrual cycle is less clear.  There is no clinical evidence indicating that isoflavones prevent ovulation although isoflavone-rich soy products may increase menstrual cycle length by approximately one day.  Parenthetically, longer cycles are associated with reduced risks for breast cancer.  There also appears to be little effect of soy on female reproductive hormones.  Typical soyfood intake in Japan is about one to two servings per day.  One serving is 3-4 ounces of tofu, one cup of soymilk, or one ounce of soynuts for example.

* Romualdi D, Costantini B, Campagna G, Lanzone A, Guido M. Is there a role for soy isoflavones in the therapeutic approach to polycystic ovary syndrome? Results from a pilot study. Fertil Steril 2007.

[ARTURO JERI]

Dear Dr Messina,
 I was working since 2000 with isoflavonas of Red Clover  and Soy.
 My research study  about Isoflavones of Red Clover and its benefits in The Menopausal Symptoms in Peruvian Women was  published in the FEMALE PATIENT in  Vol 27, August 2002 (pag 235-37)
I have been invited by a Peruvian Pharmaceutical Company in Lima, Peru , to talk about SOY ISOFLAVONES AND MENOPAUSE, I was wondering if you are kind enough to send me , if possible , in power point presentation  some information   about this topic
I am currently working in Australia
Address
TEMORA MEDICAL CENTRE
225 Hoskins St
TEMORA
Nwe SOUTH WALES
AUSTRALIA
e mail: ajeri@temoramedical.com.au

[Arturo Jeri]

Dear Dr Messina,
I have 2 questions for you
1. have soy isoflavones  been approved by the FDA to be used at the dose of 50mg/day for the management of vasomotor symptoms?
I have noted that some Latin american Companies are advertising  soy isoflavones in that way.

2.Equol has been demostrated to have better affinity to beta estrogenic receptors  than daidzein or genistein.
I was wondering if any pharmaceutical company is marketing synthetic equol

Regards
Thank you
Dr Arturo Jeri
Temora Medical Centre
Australia

[Mark Messina]

1          Have soy isoflavones been approved by the FDA to be used at the dose of 50mg/day for the management of vasomotor symptoms? I have noted that some Latin American Companies are advertising soy isoflavones in that way.

The FDA has not approved 50 mg/d isoflavones for the management of vasomotor symptoms.  This is not because of a lack of efficacy, however.  It is the case that many reviews of the literature have stated that the data are not sufficiently definitive to conclude isoflavones alleviate hot flashes.  For example, this was the conclusion of a recent analysis by the Cochrane Collaboration.  However, it was also found by the authors that 5 of 9 studies evaluated reported efficacy.  On this basis alone recommendations for women to try isoflavones for the alleviation of hot flashes can be justified.  Furthermore, when the data are sub-analyzed according to intervention product type, supplements that contain genistein as the predominant isoflavone are consistently found to be efficacious whereas those that are low in genistein are not.

2.         Equol has been demonstrated to have better affinity to beta estrogenic receptors  than daidzein or genistein. I was wondering if any pharmaceutical company is marketing synthetic equol

Equol is a bacterially-derived metabolite of the isoflavone daidzein.  Only approximately 30% of Westerners possess the intestinal bacteria capable of producing equol; this may be important because in 2002, it was formally hypothesized that equol-producers are more likely to benefit from isoflavone exposure than non-producers.  Equol has a relative binding affinity (RBA) for estrogen receptor-beta that is higher than daidzein although it is similar to or somewhat lower that the RBA of genistein.  A Japanese pharmaceutical company, which has a patent for a bacterial process for synthesizing equol, is currently evaluating the efficacy of equol in clinical studies.  Other companies, which have patents for the chemical synthesis of equol, are also evaluating the health effects of this isoflavan.