Why I Quit Soy After Having A Large Fibroid

Yep, I gave soy the boot.

Phytoestrogens are heavily debated when it comes to hormone health. So I thought I’d write a post on the “why” I gave soy up after sporting a relatively large fibroid.

First, what is a phytoestrogen? Simply put, it is a plant-derived compound that acts as an estrogen in our body. Some experts point to phytoestrogens being a good thing, because they displace our more virulent estradiol, which can cause problems when it get too high, or isn’t detoxed properly. Other experts believe strong phytoestrogens, like soy, actually increase our levels of estrogen and therefore can exacerbate estrogen-dependent issues like fibroids.

I’m not 100% in one camp or the other. I think both sides have made good points, and have the studies to back them up. Nonetheless, I landed on soy being worth taking out of my diet.

So let’s break down why of all the phytoestrogens, I decided to remove soy to support a fibroid-free uterus.

Impact on your thyroid

What does your thyroid have to do with your hormones? Well, a lot. Thyroid hormones, particularly the active T3, play a role in ovarian function. Lowered thyroid function can throw off our estrogen, progesterone, and testosterone levels. So we want to keep our thyroid functioning well in order to decrease the likelihood of estrogen dominance, which is an underlying cause of fibroids.

There are many studies that show conflicting information when it comes to phytoestrogens’ – soy in particular – affect on the thyroid. But if you already suffer from hypothyroidism (which many women do) AND you have a fibroid(s) or have previously had one, it seems like exercising caution is probably the best approach. Here are a few studies that show a link between soy and hypothyroidism:


Photo by Sydney Sims on Unsplash

Speaking of thyroid, most of us are low on iodine

Soy’s impact seems to be of greater significance when we are iodine-deficient. Unfortunately, many of us are. In the study, Goitrogenic and estrogenic activity of soy isoflavones, the author’s note that, “Iodine deficiency greatly increases soy antithyroid effects, whereas iodine supplementation is protective.” (Pssst – iodine deficiency also often plays a role in fibroids and ovarian cysts).

Soy is in everything, and THAT’S a big part of the problem

We often point to other cultures who have traditionally used a food to their benefit. This is certainly true when it comes to soy, and the fact that it has long been a staple in some Asian cultures. The problem is, we are trying to compare apples to oranges. As a 2016 French study noted:

“Recently, it was reported that, with the industrialization of soybean process, phytoestrogen exposure dramatically increased in both humans and cattle, whereas traditional Asian soy-food-processing empirically removed isoflavones. Phytoestrogen exposure has also become more widespread with the progressive internationalization of soybean use in human and cattle food.”

Just as important to understand is that the GMO soy of today is very different than the soy eaten traditionally (where it was often combined with iodine-rich foods such as seaweed). This overview study also found that “phytoestrogens should be considered as modern endocrine disruptors and studied as such.”

There’s actual studies that tell us soy increases fibroid activity

Here are just a few:

Soy-Based Infant Formula Feeding and Ultrasound-Detected Uterine Fibroids among Young African-American Women. “Our observation that women fed soy formula as infants have larger fibroids than unexposed women provides further support for persistent effects of early life phytoestrogen exposure on the uterus.”

Frequent milk and soybean consumption are high risks for uterine leiomyoma: A prospective cohort study. “Milk or soybean consumption and frequent oral contraceptive use are associated with a high risk of uterine leiomyoma (aka fibroids – note from me), and proper education on the prevention of uterine leiomyoma is highly recommended in clinical practice.”

Adverse effects of phytoestrogens on reproductive health: a report of three cases. “Abnormal uterine bleeding with endometrial pathology in three women was found to be related to a high intake of soy products. All three women improved after withdrawal of soy from their diet.”

It’s up to each woman to decide if she wants to remove soy from her diet or not. It’s well worth also paying attention to how your body reacts, and things like hypothyroid symptoms (cold hands and feet, hair loss, brain fog, brittle nails and dry skin are some of them) usually begin to present themselves rather quickly.

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