SS 193 – Does Soy Mess With Testosterone?

Episode 193 Show Notes

Grant and Heavey discuss whether soy intake causes man boobs or not. If so, what makes soy a breast booster and why? Should the intake of soy really be a cause of concern at all? If soy is one of your primary diet sources, then listen in.

 

[05:15] Done with the Keto Craze

 

A recent episode on Keto Diet (episode 191) actually garnered criticisms. Grant points out that regardless of what science or facts say, it’s about opinion.

 

Grant mentions an article featuring a study where the Keto Diet impacted insulin resistance in a detrimental way, further saying that nobody should use the diet. There have been some positive things from keto like treating seizures and epilepsy. But the doctor in the article says that the uncritical use of a ketogenic diet without careful monitoring is not advisable (it’s been shown in mice though and they’re only testing the immediate effects of coming off of ketosis). Heavey notes there’s this notion of having modified insulin response when you’re on a very low carbohydrate diet and then coming back adjusting to the carbohydrate.

 

All this being said, Heavey thinks it’s hilarious how much people get emotionally caught up in these things. So they prefer sticking to how they currently approach these kinds of issues.

 

[07:55] Soy Gives Men Breasts!

 

Soy giving men man boobs is a common claim for a reason to avoid soy, says Heavey. But there’s a ton of conflicting information out there on soy. Some people claim it’s one of the healthiest foods available and others claim there’s bad side effects like gynecomastia (characterized by the enlargement of male breast gland).

 

Many of the soy-based claims, unfortunately, are just built on cherry-picking research. Nevertheless, soy contains compounds that have antioxidant properties called, isoflavones. Also referred to as phytoestrogens. they are chemically similar to the estrogen called estradiol. This is where the whole notion of men getting boobs comes from. So it’s a lot like estrogen where they can affect our body in a similar manner.

 

[10:55] What Types of Food Contain Isoflavones?

 

Heavey describes this as a mechanistic claim that doesn’t have a lot of sound research behind it. In Japan and China, the daily average intake of these isoflavones is between 25 and 50 mg. In the U.S., the average is 1 mg per day.

 

The isoflavone content of soy food varies from food to food. Soy flour, raw soybeans and soy nuts have the highest concentration of isoflavones. Soy milk, soy sauce, miso soup, edamame have the lowest level. Soy protein powder has a moderate to high amount, but there are forms available where specific processing has been applied to them, such as alcohol wash, which minimizes isoflavone concentration.

 

[12:40] Seriously, Does Soy Give Men Breasts?

 

Isoflavones are chemically similar to estrogen. They may interfere with testosterone production – decreasing testosterone in men and increasing estrogen. However, a meta analysis of 15 randomized control trials showed that there was no significant effect on testosterone in men when consuming soy foods or protein powders that included between 60 to 240 mg of isoflavones per day.

 

For vegans and vegetarians, for instance, soy is one of their primary protein sources. Other sources of soy in the diet are tofu, tempeh, miso, soy sauce, soy milk, and natto (fermented soy beans). For tofu, the average amount of isoflavones per 100 g is 30 mg. So there’s not too much.

 

[14:55] Should Soy Still Be a Cause for Concern?

 

Another study looking into fertility markers in men supplementing the soy protein found that there was no cause for concern after two months. However, Heavey found a handful of case reports (unlike case studies, case reports only look at one person) where very high levels of isoflavone intake around 360 mg per day for an extended period of 6-12 months led to a series of symptoms like gynecomastia, erectile dysfunction, and reduced libido.

 

Heavey concludes that maybe, at very high levels of intake, there are some negative effects. But for all practical purposes, if you’re eating just a normal amount of soy, then more than likely, you’re totally fine.

 

In these randomized controlled trials, however, there were no significant effects measured. This being said, there are no problems at low levels. But at high levels, we don’t really know.

 

[17:20] Soy Equals Proteins

 

Soy is a valid vegetable protein. It’s a complete protein. It means it has all the essential amino acids in it, which is rare among vegetarian sources of protein. This is therefore valuable for vegetarians.

 

Heavey adds there are studies that compare the effect of soy protein against things like whey, well known to be some of the most powerful anabolic types of protein. They looked at the effect of muscle hypertrophy over a short period among inexperienced lifters. The result shows similar muscle growth.

 

There are reasons why one might want to supplement with soy, especially if they’re avoiding dairy proteins and animal-based protein products.

 

[18:30] Soy and Prostate Cancer

 

Heavey also mentions a meta analysis that consists of 30 observational studies. They reported an association between a reduced risk of developing prostate cancer and a higher soy intake. Although it’s just observational, there’s some connection. They’ve done some follow ups on randomized control trials and they’ve seen some promising results as well.

 

[19:10] Soy and Women’s Health

 

Heavey found research related to postmenopausal women with lower levels of estrogen. One meta analysis looked at postmenopausal women supplementing with soy and found no significant difference on sex hormones. However, they’ve seen an elevation in estradiol, but it wasn’t just as significant.

 

He also found that soy supplementation seems to reduce the incidence of hot flushes, This is something perimenopausal women should care about. Particularly, an increase in intake or supplementation of soy decreased hot flushes on average by one incident per day.

 

[20:55] Is Soy a Yay or a Nay?

 

Grant’s take on this is that soy intake is neither a villain or a hero. Heavey adds there is a net positive in making sure that you have sufficient levels of protein in your diet and if you need to get some of that through soy then that should be fine.

 

Meanwhile, there are some claims that soy can affect thyroid health negatively. In test tube experiments, they found that isoflavones inhibit the fundamental processes and the synthesis of the thyroid hormone. But they haven’t really found any real, measurable effect in humans.

 

[23:05] The Best Way to Drink Scotch

 

There’s a common myth about drinking scotch going around out there that you should only drink it neat. Grant believes the way you should be drinking scotch whiskey is the way you’d like drinking scotch whiskey. He actually put ice in a glass and poured scotch into it and he enjoyed it. Ice overly waters it down a bit and it changes the flavor because it’s colder so he wouldn’t want to drink an expensive scotch this way. Nonetheless, you can add ice when drinking Black Label or other less expensive single malts like Glenlivet.

 

So if you want it with ice, that’s okay! It’s how you enjoy it. The ice is there to make it more refreshing. You’d still get some of the essence of it, but it does reduce the impact of the flavors. That being said, you don’t want to waste your nice stuff. Just because it’s scotch doesn’t mean you can’t put ice on it.

Links:

SS 191: Do Keto and Crossfit Mix?