Red clover (Trifolium pratense) is native to Europe, central Asia, and northern Africa and grows wild in North America. Most people know it because they've hunted for four-leaf clovers. It's the one with the small reddish flower, which is the part used in herbal remedies.
The English and German colonists in America brought over knowledge of red clover from Europe and often drank red clover tea. It was one of the most common ingredients in tonics in the 19th century. They used it for respiratory problems, believing it loosens phlegm and calms bronchitis and cough. They also used it externally for eczema, acne, and wound healing. Some herbal remedies called it a blood purifier and a cancer fighter, which may prove to be the case. Strikingly, it wasn't particularly used for "female complaints."
The blossoms contain a number of active ingredients: isoflavones (formononetin, genistein, daidzein, and biochanin A) and a volatile oil that contains methyl salicylate (an anti-aphrodisiac in butterflies and in humans increases blood flow, especially when rubbed on the skin), coumarin derivatives (blood thinners), and cyanogenic glycosides.
PHYTOESTROGENS
Isoflavones, like red clover's, are a kind of phytoestrogen. Their chemical structure resembles the synthetic estrogens diethylstilbesterol and hexistrol, so they probably act as keys to open estrogen receptors, but it's not at all straightforward. The strength of a phytoestrogen is 4,000 to 4,000,000 times lower than estradiol, and it's not clear what it does do in a receptor once it lands there. So they're not really a substitute yet for HRT. Red clover is at the top of the heap of isoflavones though. One study tested 150 herbs and found that red clover was in the top six both for estrogen receptors and for progesterone receptors.
Though herbal medicine didn't use red clover for female problems, farmers noticed that, when they used red clover as pasturage for their sheep, the ewes were infertile because there were so many changes to their vulva, cervix, and uterus. In fact, Cornell University calls it a "sheep poison." If a snorfledoodled male sheep eats red clover hay, it can actually start producing some milk! Cattle have different kinds of intestines so process the red clover differently. Still, even cows who eat too much can develop cystic ovaries.
But what happens to red clover in human intestines? And what effect does eating just a little bit have, as opposed to eating a bale?
MENOPAUSE SYMPTOMS
Even with the sheep evidence that they can cause changes, there is no definite human evidence that phytoestrogens fight menopausal symptoms any better than a placebo. (Remember, there's a large placebo effect in the hormone jungle, so if you believe in it, it may do you some good..) In fact, the Australian manufacturer of Promensil, a pill that extracts the four isoflavones from red clover, was just found guilty in Australia and New Zealand of misrepresenting the scientific evidence and claiming that Promensil does control menopausal symptoms.
However, if you still have ovaries, and your problem is high estrogen, it's possible that red clover might help. Isoflavones seem to increase sex hormone binding globulin even though they don't bind with it, so they might help tie up excess free estrogen. And, there is a possibility that isoflavones might help osteoporosis of the spine, though not of other bones
CARDIOVASCULAR DISEASE
There may still be reasons to consider using red clover, especially if you aren't getting the benefits of estrogen. For instance, a study of 17 women in a double blind controlled trial looked at the health of their arteries (the elasticity of the large arteries goes down as hormone levels drop). They found that red clover isoflavones helped, perhaps by acting on the smooth muscle cells. Another study tinkered with isolated rabbit coronary artery rings in the lab and thought that genistein and biochanin A caused them to relax.
One of the benefits of estrogen is that it inhibits the oxidation of LDL, the bad cholesterol, preventing it from clogging up arteries. One test tube study thought that daidzein and genistein also inhibited LDL oxidation. However, other studies have not found an effect, so the jury is still out. Another benefit of estradiol and progesterone is that they stop the growth of cardiac fibroblasts, which are linked to hypertension and heart attacks. In the test tube, biochanin A and daidzein also inhibit fibroblasts. Estrogen is the only way to lower Lp(a), which is a risk factor for coronary heart disease. It doesn't respond to diet, exercise, or drugs, so researchers are hopeful that the isoflavones might work too.
Isoflavones aside, coumarin and methyl salicylate are "blood thinners," so they too would help keep the arteries clear.
CANCER
Here's where the situation gets murkier, in part because almost all the data comes from test tubes, where they can use isolated and extremely high levels of the isoflavones, levels that you could never reach in your body. It seems as though low levels of the isoflavones, including the genistein and biochanin A found in red clover, caused one kind of breast cancer cell to grow, while at super high levels, the same isoflavones caused the same breast cancer cells to stop growing.
In real life, however, these isoflavones would never show up all by themselves. Studies where these chemicals were used in combination with other estrogens tell a different story. Low levels of genistein and estradiol (your body's estrogen) together seemed to stop breast cancer cells from growing. In another study, when the isoflavones were added to environmental estrogens (from plastics and fertilizers, etc.), they stopped cancer cell growth. A mixture of all the isoflavones worked the best. That result fit with a study of bladder cancer cells in the test tube, which showed that all the isoflavones worked together to stop cell growth. These isoflavones may also fight pancreatic cancer in women (but not in men), stomach cancer, and colon cancer.
The picture may be confusing because isoflavones may increase growth in estrogen-receptor cancer cells and decrease growth in progesterone receptor cells. Or it may be that the isoflavones are effective against cancer because they are antioxidants and not because they imitate hormones. Or, on the down side, it may be that isoflavones can cause DNA strands to break, aside from what they are doing in the receptors.
It's still early in the research. As an article in the Journal of Clinical Endocrinology and Metabolism concluded, "At this time, it would be premature to recommend specific amounts of dietary phytoestrogens to prevent specific chronic diseases."
THYROID
However, there is one chronic disease that is almost certainly made worse by high levels of isoflavones. Many isoflavones inhibit the chemical that launches thyroid hormone synthesis, but the worst seems to be biochanin-A, which is in red clover (on the other hand, biochanin-A inhibits some types of thyroid cancer cells). Dr. Larrian Gillespie believes that 40 mg. of concentrated isoflavones a day are enough to produce hypothyroid symptoms. So, if you already have hypothyroid, taking concentrated, isolated isoflavones from red clover (as in Promensil) is probably not a good idea.
WARNINGS
Don't take red clover when pregnant because the effects are unknown. WebMD Pharmacy says that fermented red clover should be strictly avoided.
INTERACTIONS
Whole red clover extract containing coumarin and methyl salicylate might increase the strength of Coumadin.
ALLERGIES
People with allergies to fescue grass, ragweed, and timothy grass pollens might be allergic to red clover, which is related, and should try it with caution.
DOSE (according to WebMD Pharmacy)
It seems as though phytoestrogens can concentrate in the body and reach unpredictable levels, so moderation is advised until they figure out more about it. Whole red clover is probably best to use since it will have more of the antioxidant action, probably more of the cardiovascular benefit, and less of the thyroid effect.
Tea--pour 1 c of boiling water over 2 to 3 teaspoons full of dried red clover flowers, cover, and steep 10 to 15 min. drink 3 cups per day
Capsules--2 to 4 grams of whole red clover 3 times per day
Tincture--2 to 4 milliliters 3 times per day
This content was written by staff of HysterSisters.com by non-medical professionals based on discussions, resources and input from other patients for the purpose of patient-to-patient support.
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