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Soy won’t keep hot flashes away: study

If you're a woman taking soy supplements in the hopes of easing menopausal symptoms, findings from a new study suggest you're wasting your money.

The clinical trial – involving 248 women aged 45 to 60 with five years of menopause – found that taking a daily soy supplement did not slow bone loss or ease hot flashes.

Menopause, defined as the cessation of the menstrual cycle for 12 consecutive months, is often accompanied by rapid bone loss and hot flashes, among other symptoms.

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A hot flash is typically a feeling of intense heat with sweating and rapid heartbeat that lasts from two to 30 minutes. Heat is usually felt in the face or chest, but can also occur in the back of the neck and can spread throughout the body. Roughly 85 per cent of women will experience hot flashes and among them, 20 per cent will seek treatment.

While estrogen therapy – with or without progesterone – prevents most of these symptoms, the overall risks of hormone therapy outweigh its benefits. As a result, many women seek alternatives, including foods and supplements.

Hopes have been high that soy might be a safe and effective alternative to estrogen. The fact that women in Asia experience fewer hot flashes and have lower rates of osteoporosis, breast cancer and heart disease has been attributed to their soy-rich diet.

Soy protein contains phytoestrogens called isoflavones, natural compounds that can bind weakly to estrogen receptors in the body. In so doing, soy isoflavones might offer some of estrogen's positive effects such as relief from hot flashes and delayed bone loss. Earlier findings on soy intake and menopausal symptoms have been mixed.

The current study, published in yesterday's Archives of Internal Medicine, assigned 248 postmenopausal women to a daily 200 milligram soy isoflavone supplement or a placebo. The isoflavone dose was equivalent to twice the highest intake through food sources in the typical Asian diet. Women in both groups had sufficient calcium and vitamin D intake.

After two years, there were no differences to changes in bone density in the spine, hip or femoral neck between the groups. Soy isoflavones also had no effect on hot flashes. Women taking soy did not experience fewer hot flashes, whereas those in the placebo group did.

While soy doesn't appear to be the promising supplement for menopause we once thought, other dietary and lifestyle modifications may help ease menopausal symptoms.

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Avoid potential triggers. Many women report that alcoholic beverages, caffeine, hot drinks, spicy foods and stress can affect the frequency and/or severity of hot flashes. Warm air temperatures that increase core body temperature may also bring on a hot flash.

Maintain a healthy weight. Women who have a body mass index (BMI) of 27 or higher are more likely to experience hot flashes more often and more severely. A healthy BMI is between 18.5 and 24.9. Google "BMI calculator" to determine your BMI.

If you are overweight, take action to lose excess weight at a rate of 1-2 pounds per week. Crash dieting for an extended period – consuming 1,200 or fewer calories per day – can cause bone loss.

Regular exercise can also reduce hot flashes as well as help control weight and maintain bone density.

Add ground flaxseed. Preliminary evidence suggests that consuming four tablespoons of ground flaxseed each day can significantly reduce mild hot flashes. Flaxseed contains phytoestrogens called lignans as well as soluble fibre and omega-3 fatty acids.

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Substitute four tablespoons of ground flaxseed for 3 teaspoons of other fat in your diet. Add ground flax to smoothies, yogurt, hot cereal and quick bread batters.

Consider black cohosh. This herbal supplement seems to offer modest relief for some women. The most consistent evidence is for a specific extract called Remifemin; studies using other formulations are less consistent.

If you want to try black cohosh, discuss it first with your health care practitioner. Based on clinical studies, black cohosh appears very safe. However there have been reports of liver damage, possibly caused by product contamination.

Other supplements. There's no evidence that red clover, chasteberry, dong quai or evening primrose oil eases hot flashes. Don't waste your money.


Get enough calcium. Women, aged 19 to 50, need 1,000 milligrams of calcium each day; older women require 1,200 milligrams. Meet calcium needs from diet first, then supplement if required.

One cup of milk, ¾ cup plain yogurt and 1.5 ounces of cheese all contain roughly 300 milligrams (mg) of calcium. Other good sources include fortified soy beverages (300 mg per 1 cup), sardines with bones (3 ounces = 325 mg), canned salmon with bones (3 ounces = 188 mg), cooked Swiss chard (1 cup = 102 mg), cooked broccoli (1 cup = 62 mg) and almonds (1/4 cup = 92 mg).

Take vitamin D. This nutrient enhances calcium absorption from foods and is essential to preventing osteoporosis. Osteoporosis Canada recommends a daily vitamin D3 supplement of 400 to 1,000 IU for healthy adults under age 50. To achieve optimal vitamin D status, 800 to 2,000 IU per day may be required.

Increase vitamin K rich foods. Vitamin K is needed to activate proteins that bind calcium to bone. Higher vitamin K intakes have been linked with slower bone loss and fewer fractures in postmenopausal women.

Good sources include spinach, kale, Swiss chard, collard greens, arugula, cabbage, cauliflower, soybeans, lean meat and cheese.

Limit sodium, caffeine and alcohol. Excess salt, caffeine and alcohol all cause calcium to be excreted from the body. Keep your daily sodium intake under 2,300 milligrams; adults require 1,200 to 1,500 milligrams per day.

Limit caffeine to 400 milligrams per day (1 cup of coffee = 100 to 175 mg; 1 cup of black tea = 45 mg). If you have osteoporosis, aim for no more than 200 milligrams.

For women who drink alcohol, limit your intake to seven drinks per week.

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