Hummus is a popular dip made primarily from cooked, mashed chickpeas blended with tahini, lemon juice, and garlic. Concerns sometimes arise regarding whether this food contains hormones that could affect the body. Hummus does not contain human or animal estrogen, which are steroid hormones produced within the body. However, because it is made from plant-based ingredients, hummus does contain naturally occurring compounds known as phytoestrogens, which exhibit hormone-like activity.
The Difference Between Estrogen and Phytoestrogens
Estrogen refers to a group of steroid hormones, such as 17β-estradiol, synthesized by the human body, primarily in the ovaries. These hormones travel through the bloodstream and bind to two types of specific cellular targets called estrogen receptors (ER-alpha and ER-beta), initiating a biological response. Estrogen plays a role in functions like bone density, cardiovascular health, and the reproductive system.
Phytoestrogens, conversely, are non-steroidal compounds found naturally in plants, including legumes and seeds. Their chemical structure resembles estradiol, allowing them to interact with human estrogen receptors. Phytoestrogens are significantly weaker than endogenous estrogen, often estimated to be a thousand times less potent. They function as modulators of hormonal signaling rather than replacement hormones.
Phytoestrogens are often classified as selective estrogen receptor modulators (SERMs). They exhibit preferential binding to the ER-beta receptor over the ER-alpha receptor. Since the two receptor types are distributed differently throughout the body, phytoestrogens can exert different effects depending on the tissue. This selective action distinguishes them from the body’s own estrogen, which binds with roughly equal affinity to both ER-alpha and ER-beta.
The Phytoestrogen Content of Hummus Ingredients
The phytoestrogens in hummus come from its two main components: chickpeas and tahini (a paste made from sesame seeds). Chickpeas, a legume, contain phytoestrogens belonging to the isoflavone and coumestan classes. Specific isoflavones found in chickpeas include genistein and biochanin A, though their concentration is modest compared to levels found in soybeans.
Chickpeas contain approximately 0.89 milligrams of genistein and 0.95 milligrams of biochanin A per 100 grams of the dried bean. The primary phytoestrogen source in hummus is tahini, which is rich in lignans. The main lignan compounds in sesame seeds are sesamin and sesamolin.
Sesame seeds contain a high concentration of total lignans, ranging from about 405 to 1178 milligrams per 100 grams in the raw seed. In finished tahini, the total lignan content is still substantial, ranging widely from 11 to 763 milligrams per 100 grams, depending on the seed type and processing method. The overall phytoestrogen profile of hummus is defined by the isoflavones from the chickpeas and the more concentrated lignans contributed by the tahini.
How Dietary Phytoestrogens Affect the Body
Phytoestrogens from hummus must first be processed by the body before they can exert a biological effect. These compounds are poorly absorbed in their original form and rely on the gut microbiota for metabolism. Gut bacteria convert the precursor compounds into metabolites that are more readily absorbed and biologically active.
The isoflavones from chickpeas are transformed by certain gut microbes into metabolites like equol, while tahini lignans are converted into enterolignans, such as enterolactone. These metabolites possess greater bioavailability and interact more effectively with estrogen receptors in human cells. However, the individual capacity to produce these active metabolites, particularly equol, varies significantly among people due to differences in gut flora composition.
The effect of these compounds is context-dependent, reflecting their SERM activity. When endogenous estrogen levels are low (such as during menopause), the weak action of phytoestrogens can provide a mild estrogenic signal by binding to unoccupied receptors. Conversely, in a high-estrogen environment, these compounds compete with the body’s estrogen for receptor sites, exhibiting a net anti-estrogenic or blocking effect. The amount of phytoestrogens consumed in a typical serving of hummus is quite small in the context of the total diet, and the physiological impact is considered mild and modulatory rather than strongly hormonal.