Is Sunflower Estrogenic?

Is Sunflower Estrogenic? 

You might find information online that says sunflower seeds or sunflower oil is unsafe for people with hormone imbalances or with a history of hormone-related cancers because they're "estrogenic." One article says "Sesame and sunflower seeds are among the highest of all estrogenic foods." Let's take a look and find out: is sunflower estrogenic? 

Sunflower seeds are indeed a rich source of phytoestrogens. If you've experienced estrogen dominance or an estrogen-related cancer, your instinct might be to avoid phytoestrogens. "I already have enough estrogen," you might think. "Why add more?" But, it's not that simple. 

Sunflower seeds contain a class of phytoestrogens called lignans, similar to those found in flax seeds. (Source) Dietary consumption of lignans is actually associated with lower breast cancer risk. (Source) The main phytoestrogen in sunflower is called secoisolariciresinol; it has anticancer, anti-diabetic, antioxidant, and neuroprotective effects. (Source)(Source) 

"Dietary lignans (as well as isoflavonoids) impart chemoprotective effects due to their antioxidant, weak oestrogenic/antioestrogenic, anti-aromatase, and anticarcinogenic/ antitumor properties, thereby protecting against the initiation of various sex hormone-induced cancers.” (Source)

Xenoestrogens vs. Phytoestrogens 

Xenoestrogens and phytoestrogens are often confused or lumped together as "estrogens." But they couldn't be more different. 

Xenoestrogens and phytoestrogens (or their metabolites) both indeed have chemical structures similar to that of the body's estrogens. They both can fit in and interact with estrogen receptors on cell surfaces. But this is where they differ.

We have two main estrogen receptors: ERα and ERβ. (Alpha and Beta). In general (and please understand this is a very complicated process that I'm attempting to simplify) alpha receptors stimulate growth of tissue (including tumors.) And beta receptors, in general, will slow cell proliferation. In fact, scientists have found that if you remove estrogen alpha receptors from tumors, the tumor growth will halt and cancerous cells start to die off. 

Generally, xenoestrogens like BPA, interact and stimulate alpha receptors. It has been found that cancerous tissue has an overexpression of alpha receptors and an under-expression of beta receptors. (Source) And that xenoestrogens possibly throw off communication between cells and cause over-expression of alpha receptors and under-expression of beta receptors. Whereas phytoestrogens and other antioxidants, like the flavonoid naringenin help to increase beta receptors. 

On the other hand, BPA inhibited E2-induced ERβ accumulation, while Nar [naringenin] increased ERβ content of colon cancer DLD-1 cells 

In addition to helping create anti-proliferative beta receptors, when the body digests lignans, it converts them to compounds called enterolactone and enterodiol. Enterolactone and enterodiol help support the liver in creating Sex Hormone Binding Globulin. SHBG is responsible for deactivating both testosterone and excess estrogen. Basically, these lignans help the liver flush out and deactivate excess hormones. 

Their importance can be illustrated using as an example the sex hormone binding globulin "SHBG" This binds circulating testosterone in men and the oestrogen in women and thus the availability of sex hormone to target cells is greatly affected by changes in both its concentration and/or binding properties. [Postmenopausal women excreting large amounts of mammalian lignans have higher levels of SHBG than omnivores or breast cancer patients. And other studies have shown that mammalian lignans and isoflavonoids interact with SHBG in a dose-dependent manner with enterolactone for displacing estradiol.  

It has been found that sunflower seed phytoestrogens help increase ER beta receptors, which would regulate cell proliferation and protect against estrogen-mediated cancers. (Source)

What about Sunflower Oil?

Dermal application of sunflower oil is also safe for people with estrogen dominance and hormone-related cancers. (Barring any personal allergies, of course.)  Even if one was trying to avoid phytoestrogens. The content of these phytoestrogens in oil are quite low to non-existent. (Source) And because it’s the digestion of these lignans that provide the protective phytoestrogenic effect, topical application of sunflower oil would have no phytogestrogenic properties. 

Sunflower oil does contain anti-inflammatory phytosterol compounds, however, so you do get those benefits, in addition to the skin-protective/emollient properties on your skin. (Source) These lipids are large molecules and have been found to not absorb through the epidermal layer and remain on the outermost layers of the strateum corneum. (Source) So when you're applying sunflower oil to your skin, you're simply helping it prevent water loss and inflammation.