Mark Messina, PhD, MS, has kindly answered the following questions, which were asked during the webinar:

I have concerns regarding soya consumption by men and effects on testosterone levels.
A meta-analysis published in 2010 that included 32 studies and 36 treatment groups found there were no significant effects of soy protein or isoflavone intake on levels of total testosterone, sex hormone binding globulin, free testosterone or the free androgen index.¹ Studies published subsequent to this analysis are supportive of this conclusion.^2,3

I would like to ask about the impact of soy consumption in infancy and long term fertility.
To definitively answer this question would require a 20-year intervention study that would likely not make it through an internal review board because one would have to randomly assign infants to specific feeding regimens.  Conducting a retrospective study involving adults is also difficult because accurately recalling the particulars of soy infant formula use is obviously not easy.

You may be interested in knowing that in 2009, the US National Toxicology Program (NTP) Center for the Evaluation of Risks to Human Reproduction evaluated the safety of soy infant formula (they also did so in 2006 and although their initial conclusions supported the safety of SIF, no final report was issued^4,5).  The conclusion of the 14-member panel of independent scientists was that there was “minimal concern” (the five levels of concern are negligible concern, minimal concern, some concern, concern and serious concern) about the safety of soy infant formula.⁶  In response to the NTP report, the American Academy of Pediatrics submitted a formal letter to the NTP, which is part of the public record, in which they stated their position that there is negligible concern about the safety of SIF.

Would you say soy foods are safe to recommend to breast cancer patients who have just completed their chemotherapy? I understand isoflavones are safe for post-menopausal women and don’t affect breast tissue.
The prospective epidemiologic data show that post-diagnosis soy intake improves prognosis.  More specifically, a meta-analysis of five prospective studies, two from the United States^7,8 and three from China,^9-11 involving over 11,000 women with breast cancer, found soy consumption after a diagnosis of their disease was associated with statistically significant reductions in breast cancer recurrence (hazard ratio, 0.85; 95% CI: 0.77, 0.93) and mortality (hazard ratio, 0.79; 95% CI: 0.72, 0.87) (table 7).¹²  Importantly, soy consumption was similarly beneficial in Asian and non-Asian women.¹³  Also, in contrast to the results in ovariectomized athymic mice showing genistein (primary soybean isoflavone) negates the inhibitory effect of tamoxifen^14,15 and an aromatase inhibitor¹⁶ on mammary tumor growth, the prospective epidemiologic data suggest that soyfood intake may actually enhance the efficacy of these treatments.^10,13

The positions of the American Cancer Society¹⁷ and the American Institute for Cancer Research¹⁸ are that  soyfoods can be safely consumed by women with breast cancer.  In addition, the World Cancer Research Fund International recently concluded there is a possible link between consuming soyfoods and improved breast cancer prognosis.¹⁹

My concerns are: Soy is usually transgenic, genistein is considered to increase GI permeability due to the size of its molecules and cause indirect allergies…
The US National Academy of Sciences just released a report that addresses these issues. They concluded that these concerns are without foundation.  The report is worth a read and can be downloaded at https://nas-sites.org/ge-crops/.

The ratio of Omega 6 to 3 is high when ideally it should be 3:1. Surely soya intake should be reduced due to high omega 6 intake alone?
Concern about a high omega-6 to omega-3 causing inflammation is based on the premise that dietary linoleic acid (LA) intake increases endogenous arachidonic acid (AA) levels from which a number of pro-inflammatory eicosanoids are produced.  However, this reasoning is not supported by the clinical evidence.^20-23  Extensive research shows that increasing LA intake has little effect on endogenous AA levels.  When analyzing the results of 11 different comparisons in humans, Rett et al.²² found that when LA intake decreased by as much as 90%, there were no significant changes in plasma/serum phospholipid AA content.  Similarly, increases in dietary LA intake, by as much as 550%, were not significantly correlated with changes in plasma/ serum phospholipid AA content.

LA intake probably does not increase AA content because the estimated fractional conversion rate of LA to AA is only 0.3% to 0.6%.²⁴  Furthermore, the evidence does not support the idea that all of the eicosanoids produced from AA are pro-inflammatory.  It is now recognised that there a mix of both pro- and anti-inflammatory eicosanoids is produced from AA.²⁰  This may also explain why extensive clinical research has failed to find pro-inflammatory effects of LA intake.²¹

What is defined as one serving of soy?
I use USDA serving sizes which are 250 ml soymilk, 100 g tofu, 28 g soy nuts.

You mentioned adolescents should have soya products but at what age would you say that children should start to have them considering the oestrogenic effects?
My recommendation for females to consume soy beginning in childhood and/or adolescence was based on epidemiologic studies indicating consumption during this time reduces later risk of developing breast cancer.^25-28  The epidemiologic studies mostly have focused on the teenage years but the results from one very small study suggest consumption beginning in childhood is even more protective than during the teen years.²⁵  One serving per day is associated with a reduction in risk.  No human evidence indicates this amount causes any hormonal disturbances.  In fact, consuming as much as 3-4 servings of soy per day has been shown not to influence the age of onset of menses.²⁹

For patients on a FODMAP diet, they are allowed to have soya milk (not from whole beans) but not whole beans. Why is this when it has prebiotic effects?
Soymilks that are made from isolated soy protein do not contain the oligosaccharides, which is likely why they are allowed. Soy milks made from whole beans will contain some oligosaccharides and for this reason are restricted in the initial phases of the low FODMAP diet . It may simply be that the osmotic effects of soybean oligosaccharides in very sensitive people outweigh the beneficial prebiotic effect.

Where can we find evidence that Alpro is non GMO?
No, Alpro does not use any genetically modified ingredients in its products. They can fully guarantee that their soya beans are free from any genetic manipulation. This would go against the core values of Alpro. Alpro developed a specific monitoring system with the specialized Cert-ID Company. This is a worldwide renowned company that specializes in monitoring any possible genetic modification of crops and gives out GMO-free certificates. Alpro is able to trace back any soya bean from the farm, through the production process, to the shop. Additionally, Alpro have a close relationship with their suppliers and pay a premium price on soya beans that are not genetically modified.

Source: Alpro website, frequently asked questions https://www.alpro.com/uk/faq/detail/does-alpro-use-any-genetically-modified-ingredients 

Since America produces predominantly GMO soy, is this okay to consume? Shouldn’t we be consuming non GMO soy for maximum benefit?
Whether to consume GMO soy is a personal decision.  The evidence indicates GMO soy is nutritionally equivalent to non-GMO soy.  Estimates are that >90% of soybeans produced in the US are genetically modified but most of the soybean produced are used for animal feed.  There are plenty of commercially available soyfoods produced from non-GMO soybeans in the US.

During the question of GMO, you mentioned that most soya beans produced are used for animal feed. It got me thinking about what soy fed livestock produce, milk or meat has an affect on our metabolism? I am aware that most animal studies in relation to soy foods can be misleading because rodents in particular metabolises soy isoflavinoids differently to humans. But is that the same for say cattle? Do you have any thoughts of soy fed meat or milk produce having an effect on human metabolism? I would be interested in hearing your thoughts or hypothesis.
I am not entirely sure I understand your question.  But if the question is “does the meat from cattle fed feed containing isoflavones affect our metabolism differently than meat from cattle not exposed to isoflavones” then I believe the answer is almost certainly “no.”  Any isoflavones to which the cattle are exposed are quickly excreted.  They are not stored in tissues and therefore would not likely affect the composition of the meat.

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