Clinical Review

Treating hot flushes without hormone replacement therapy

OBG Manag. 2002 May;14(5):70-81

References

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An increasing number of studies suggest that soy and soy isoflavones—in the form of soy flour, soy protein, and dietary supplements—may play an important role in the treatment of hot flushes (Table 1). In general, the average amount of isoflavones consumed in a typical Asian diet is approximately 50 mg. (One gram of soy protein contains approximately 1 mg of isoflavones.) As shown in the table below, all of the methods of taking soy decrease the number and/or severity of hot flushes.

All of the soy studies also confirm the existence of a placebo effect on the treatment of hot flushes. Even so, the soy group typically reports a 15% to 20% greater reduction in symptoms than does the placebo group. This difference between the soy and control groups has led skeptics to believe that the differences may be statistically significant but clinically insignificant. I believe that thinking is wrong. Women who have hot flushes tend to have lower sleep efficiencies and longer REM latencies than women who do not experience this vasomotor symptom.¹⁴ By lowering the frequency of hot flushes by 40% or more, patients who take soy will have 40% or more greater sleep efficiencies. That may improve their quality of life sufficiently to make HRT unnecessary.

Soy has been safely consumed by hundreds of millions of people without complications, with the possible exception of soy allergies (Table 2, 3, and 4). The literature suggests it is safe and effective in dosages of either 40 g of soy protein or 50 mg of soy isoflavones per day. Soy does not stimulate the uterine lining and may be protective of the endometrium if taken with estrogen. The incidence of breast cancer is one-fourth as high in Asia as it is in the United States; many studies have shown soy to be protective of breast tissue. However, soy may stimulate breast tissue in women with a history of breast cancer.

TABLE 1

The role of soy in the treatment of hot flushes

STUDY	NO. PATIENTS	DESIGN	↓FLUSHES SOY (%)	↓FLUSHES CONTROL (%)
Murkies 1995	58	45 g soy flour	40	25
Brzezinski 1997	73/72	Mostly soy 1/4 diet, some flaxseed	54	35
Albertazzi 1998	51/53	60 g soy protein	45	30
Scambia 2000	20/19	50 mg/d isoflavones	45	25
Upmalis 2000	177	50 mg/d isoflavones	30	20
SOURCE: Seibel MM. The Soy Solution for Menopause: An Alternative to Estrogen. New York, NY: Fireside Press; 2002.

TABLE 2

Adverse effects

SOY
Bloating, flatulence
BLACK COHOSH
Abdominal pain, nausea, headaches, dizziness, trembling limbs
DONG QUAI
Photodermatitis, rash
EVENING PRIMROSE OIL
Nausea, softening of stools, headaches, seizures
RED CLOVER
Blood thinning
HRT
Depression, headaches or migraines, breast tenderness, hair loss, nausea or vomiting, vaginal bleeding, jaundice, candidiasis, weight gain, loss of libido, blood clots, increased risk of gall bladder disease and uterine and breast cancer

TABLE 3

Drug interactions

SOY
Thyroid hormones
BLACK COHOSH
Iron therapy medications
DONG QUAI
Treatment with anticoagulants such as warfarin
EVENING PRIMROSE OIL
Anticonvulsants and tricyclic antidepressants
RED CLOVER
Anticoagulants such as warfarin, heparin, clopidogrel, pentoxifylline, or aspirin
HRT
Antibiotics

TABLE 4

Contraindications

SOY
Patients with hypothyroidism. (Soy may bind thyroid medication, thus lowering absorption, but if taken at other times or in supplement form, it should not have an effect on thyroid function.)
BLACK COHOSH
Patients with iron deficiencies
DONG QUAI
Patients with coagulopathies or very heavy menstruation and acute viral infections such as colds or influenza
EVENING PRIMROSE OIL
Patients with temporal lobe epilepsy or schizophrenia
RED CLOVER
Patients with coagulopathies
HRT
Women who have had breast or uterine cancer, unusual vaginal bleeding, or severe liver disease

Black cohosh

A member of the buttercup family, black cohosh has a long history in folk medicine, especially among Native Americans who boiled the root in water and drank the resulting beverage to treat dysmenorrhea, labor pain, upset stomach, and arthritis. In Germany, extracts of black cohosh have been used since the 1940s.

Many substances have been identified in the rhizome, but it is uncertain what the majority of them do or, in fact, which are active ingredients.¹⁵ The effectiveness of black cohosh is based on the total amount of triterpenoid glycosides, typically standardized to 2.5%.¹⁶

Several studies, most of them in the German literature, have shown that black cohosh yields a significant improvement in hot flushes, with reductions of up to 80% reported.^17-19 The usual dosage is 40 drops of the extract twice daily for 6 to 8 weeks, or one to two 20-mg tablets twice daily with liquid (not to be chewed or sucked).

Side effects are uncommon, but occasional stomach pains and intestinal discomfort, dizziness, nausea, severe headaches, stiffness, and trembling limbs have been noted. Germany’s Commission E, which is similar to the U.S. Food and Drug Administration (FDA), recommends that black cohosh not be used for more than 6 months since no studies have been conducted for longer periods of time. Although most data on the safety of black cohosh with regard to breast tissue are reassuring, use caution when administering it to a patient with a history of breast cancer, as black cohosh is a weak estrogen (Table 2, 3, and 4).