Agro Solvent : Education - Soyabean

Health Benefit
Women's Health Issues

In many countries, people are living longer than ever before. However, a longer life span may also increase your chances of developing the chronic diseases that can accompany aging.

Prevention is the key to improved health throughout your life. Diet is an essential element in any program of disease prevention. As scientists work to identify which foods and substances in foods may benefit health and prevent disease, an increasing amount of research attention is focusing on soy protein.

Soy Protein and Cardiovascular Disease

Considerable evidence supports a role for soy protein in reducing the risk of cardiovascular disease, the number one killer of adults.

Cardiovascular Disease (CVD) remains the number one killer of both men and women. Enormous amount of people have at least one type of CVD. CVD refers to various diseases affecting your heart and arteries --including heart disease, stroke, and high blood pressure, among others.

The Role of Atherosclerosis

Many people think of heart attacks and strokes as sudden events, but in fact, they are the result of a disease process-- atherosclerosis --that has been going on for years. Atherosclerosis is a gradual buildup of plaque in your arteries. This buildup causes arteries to become narrower, which affects blood flow.

A continual blood flow is vital because blood delivers the oxygen and nutrients each cell in your body needs to survive. As plaque grows, it causes a partial or total blockage of blood flow to the area of your body supplied by that artery.

If an artery becomes totally blocked, the cells that it normally supplies with oxygen and nutrients are damaged and can even die. In many cases, complete blockage of a narrowed artery is the result of bleeding into the plaque or is caused by a blood clot that either forms at the site or travels from another part of the body.

The most common type of heart attack occurs when the blocked artery is in your heart--a coronary artery. A heart attack can also be caused by a temporary contraction or spasm in the artery wall that causes it to narrow. Strokes occur when the blocked artery is in the head or neck. Strokes can also be caused by bleeding from an artery in the brain.

Causes & Risk Factors

Many researchers believe that damage to the artery lining, which normally is smooth, is the first step in atherosclerosis. Various substances in your blood are then attracted to this injury site where they are deposited on the surface of and inside the artery wall to form plaque. As plaque grows, the wall thickens and the artery's inner diameter becomes smaller.

How does this damage occur? The initial damage to artery walls is commonly caused by:

higher than normal levels of two fats-- low-density lipoprotein-cholesterol (LDL-cholesterol) and triglycerides--in your blood
high blood pressure
tobacco smoke
other yet to be defined events

Risk Factors for Heart Disease

Increasing age	About 80% of people dying from heart disease are age 65 or older.
Male sex	AMen are at higher risk and typically have their heart attacks at a younger age than women. The death rate from heart disease increases for women after they reach menopause.
Heredity	Heart disease often runs in families.
Race	Compared with whites, African Americans, Mexican Americans, American Indians, native Hawaiians, and some Asian Americans are at increased risk of developing heart disease.
Risk factors that can be changed
Smoking	Smoking is a major risk factor, causing an estimated 20% of CVD deaths.
High LDL-cholesterol	An elevated blood LDL-cholesterol level is a major risk factor.
High blood pressure	High blood pressure, which is a major risk factor, can't be cured but it can be controlled.
Physical inactivity	Being physically inactive is a major risk factor for heart disease.
Obesity and overweight	Having excess body fat, especially in the waist area, increases your risk of heart disease.
Diabetes	Diabetes (diabetes mellitus) is a treatable risk factor for heart disease.

Other factors known to contribute to the risk of developing heart disease include:

response to stress
hormonal factors
use of birth control pills
excessive use of alcohol

A Word about Lipoproteins

Remember the old saying that oil and water don't mix? Cholesterol and blood work under a similar premise. Since cholesterol is a fatty substance, it can't travel around by itself in your blood, which is primarily water. Therefore, cholesterol combines with protein to form a molecule, called a lipoprotein, which can be carried in your blood. Two types of lipoproteins most people are familiar with are low-density lipoprotein-cholesterol (LDL-cholesterol) and high-density lipoprotein-cholesterol (HDL-cholesterol).

An elevated blood level of LDL-cholesterol, or "bad cholesterol," increases your risk of heart disease because these particles contribute to the growth of plaque. But all LDL-cholesterol isn't alike. LDL-cholesterol that has been changed in a chemical reaction called oxidation is more likely to increase atherosclerosis. This discovery has led to greater interest in antioxidants, substances that help reduce oxidation.

HDL-cholesterol is often called "good cholesterol." Since this lipoprotein removes cholesterol from plaque, it is considered an "anti-risk" factor. A higher blood level of HDL-cholesterol helps lower your risk of heart disease.

Soy Protein and Bone Health

Good bone health throughout life helps prevent osteoporosis - a major cause of disability in later years. Research suggests that consuming soy protein may help protect bones from becoming weak and brittle as you age, especially for post-menopausal women as this increases their risk of r osteoporosis.

Osteoporosis is a chronic disease characterized by low bone mass and density. It leads to weak, fragile bones and a greatly increased risk of bone fractures. Both women and men can develop osteoporosis, but it is five times more common in women. This is due to the fact that women achieve a lower peak bone mass than men and that women loose bone at an accelerated rate for the first few years following menopause.
There's more than one type of osteoporosis.

Postmenopausal osteoporosis
Postmenopausal osteoporosis occurs in women when their estrogen levels drop, around the time of menopause. Symptoms of bone loss typically develop between the ages of 51 and 75, but can occur earlier or later. Women can lose up to 20% of their bone mass in the 5-7 years following menopause.
Senile osteoporosis
"Senile" osteoporosis simply means the condition is due to aging. Researchers believe that this condition is caused by age-related changes in calcium intake and an imbalance between bone resorption and formation. It is twice as common in women as men again due to the difference in peak bone mass and usually affects people over age 70.
Secondary osteoporosis
Secondary osteoporosis occurs as a side effect of medical condition, such as a thyroid disorder, or from using certain drugs, including corticosteroids, barbiturates, anticonvulsants, and excessive amounts of thyroid hormone. In addition, excessive alcohol use and cigarette smoking results in increased bone loss.
Idiopathic juvenile osteoporosis
Idiopathic juvenile osteoporosis is a rare condition that sometimes occurs in children and young adults. These individuals have normal hormone and mineral levels, and there is no obvious reason for them to develop weak bones.

Osteoporosis as a Public Health Threat

Osteoporosis represents a growing public health treat to millions of people. In the United States alone, 10 million people have osteoporosis and 18 million have low bone mass, which increases their risk of developing this disease. Women account for more than 80% of the people with osteoporosis or at risk of developing it.

Osteoporosis takes a great toll in pain, suffering, and disability, in addition to the actual monitory costs involved. It is responsible for more than 1.5 million bone fractures each year, including:

300,000 hip fractures
700,000 fractures to the vertebrae in the spine
250,000 wrist fractures
more than 300,000 fractures at other sites

Don't underestimate the seriousness of a fracture. About 24% of the people over age 50 who fracture a hip die within one year. In addition, one-fourth of the people who were ambulatory before fracturing a hip need long-term care afterward.

Risk Factors for Osteoporosis

There are a number of recognized risk factors for osteoporosis. Some of them you have control over-others you don't. You'll notice some overlap with the previous list of factors that affect bone density.

Major Risk Factors for Osteoporosis

You can't change your...	Who it affects...
Gender	Women are at higher risk as they reach a lower peak bone mass compared to men
Age	Everyone's risk increases with aging because bones become weaker and less dense.
Body size	Women with a thin and/or small body build are at greater risk.
Ethnic heritage	Caucasian and Asian women are at highest risk, although African American and Latino women are also at risk.
Family history	People with parents prone to fractures seem to have lower bone mass and higher fracture risk.
You have control over...
Sex hormones	Risk is greater in women at menopause as the production of estrogen by their body is greatly reduced or in the absence of menstrual periods during adolescence and adulthood; and in men with low testosterone levels.
Eating disorders	Anorexia nervosa and bulimia increase risk.
Diet	A diet low in calcium and vitamin D increases risk.
Activity level	People who are not physically active or who are bedridden for any length of time are at greater risk. It's best to perform both weight-bearing and strength training exercise.
Medications	Use of certain medications, such as glucocorticoids or some anticonvulsants, increase risk.
Cigarette smoking	Cigarette smokers are at greater risk.
Alcohol use	Excessive use of alcohol increases risk.

Sou Protein and Cancer

Although heart disease kills more people, many individuals are more afraid of breast cancer and prostate cancer. Epidemiological (population) studies suggest that soy protein may have a role in reducing the risk of certain cancers.

As the second most common cause of death, cancer is expected to cause more than 550,000 deaths in the year 2000.

Cancer Basics

The term cancer actually refers to more than 100 diseases. What they all have in common is the uncontrolled growth and spread of cells that have become abnormal.

Cells dividing to produce more cells is basic to your body's continued health. However, when new cells that your body doesn't need are produced, they can form a mass of tissue called a tumor. Some tumors are benign, meaning that they aren't cancerous.

Malignant tumors are cancerous. They can invade and damage tissues and organs located near the primary tumor. Cells can also break off from the original tumor and travel to other parts of the body, where they form new tumors -- a process called metastasis.

How Does Cancer Develop?

The initiation phase of cancer consists of damage to the genetic material, called DNA (deoxyribonucleic acid), found in cells. Initiation typically is caused by a carcinogen --anything that can damage cells in a way to make them cancerous.

Carcinogens activate special genes, known as oncogenes, present in the cells. Oncogenes normally control cell growth and multiplication. When activated by a carcinogen, however, oncogenes initiate and continue the conversion of normal cells into cancer cells.

Another genetic change that can lead to cancer is the suppression or loss of tumor-suppressor genes, which normally produce proteins to inhibit cell division.

Potentially cancerous cells are being formed in the body at anytime under certain circumstances. Why doesn't everyone develop cancer, then? For one thing, the immune system destroys many abnormal cells before they have a chance to multiply.

Another way the body gets rid of old or damaged cells is called apoptosis. Each cell has a life span programmed into its DNA and divides a specified number of times before it naturally dies. This programmed cell death regulates the number of cells in tissues and eliminates many potentially dangerous cells in the body, including cancer cells.

ancer may occur when some abnormal cells escape these safeguards. In the second phase of cancer, called promotion, abnormal cells are stimulated to grow and multiply to establish cancer.

Who Is at Risk of Cancer?

Virtually everyone-men, women, and children- is at some risk of developing cancer. Cancer risk increases with age. Almost 80% of all cancers are diagnosed in people aged 55 and older.
A small percent of cancers are hereditary, that is, the malfunction of the oncogene is inherited. However, the vast majority of cancers result from damage done by carcinogens. Here are some major risk factors for cancer.

Risk Factors

Risk Factor	Cancer
Exposure to tobacco smoke and/or smokeless tobacco	Smoking accounts for 85% of lung cancer deaths.
Diet	High-fat diet may be linked to cancers of the breast, colon, uterus, and prostate.
Overweight and obecity	Serious overweight appears to be linked to increased risk of cancers of the prostate, pancreas, uterus, colon, ovary, and breast (in older women).
Exposure to ultraviolet radiation	Ultraviolet radiation from sunlight, sunlamps, and tanning booths can cause skin cancer.
Alcohol use	Drinking large amounts of alcohol may increase the risk of cancer of the mouth, throat, esophagus, and larynx (especially in a cigarette smoker), the liver, and, possibly, the breast.
Radiation	Exposure to large doses of radiation from medical X-rays may increase cancer risk.
Chemicals and other substances in the workplace	Exposure to certain metals, dust, chemicals, or pesticides can increase cancer risk. Known carcinogens include asbestos, nickel, cadmium, uranium, radon, vinyl chloride, benzene, and benzidene.
Hormone replacement therapy	Estrogen alone increases the risk of uterine cancer; adding progesterone reduces this risk. High doses or long-term use of estrogen both appear to increase breast cancer risk.
Diethylstilbestrol (DES)	Some daughters of women given DES during pregnancy have an increased risk of developing abnormal cells in the vagina and cervix.
Family History	A few cancers, including cancers of the breast, ovary, and colon and melanoma, tend to run in families.
Viruses	A few cancers, including cancers of the breast, ovary, and colon and melanoma, tend to run in families.

Additional Health Benefits of Soy Protein

Other potential health benefits of soy protein are currently under investigation. These areas of research include soy protein and diabetes, weight management, and kidney disease. In addition, studies of the antioxidant activities of the bioactive molecules occurring naturally in soy protein cut across several disease states.

Much of the research investigating the potential benefits of soy protein and its components in chronic disease has focused on cardiovascular disease (CVD), certain cancers, and bone health. However, these are not the only areas of interest currently being studied.

Diabetes

Diabetes mellitus is a chronic disease in which the body doesn't properly manufacture or use the hormone insulin . Insulin helps transport glucose from your blood into your cells, where it is used as the body's primary fuel.

Glycemic Index

The type of carbohydrate (sugars and starches ) you eat affects glucose levels. The ability of a carbohydrate-containing food to raise glucose levels is reflected in its glycemic index (GI). Soybeans have a very low GI, meaning they have little effect on glucose levels. In one study, overweight diabetic people who consumed a low-GI diet improved their glucose control, compared with people who ate a high-GI diet.

Cardiovascular Disease

People with diabetes are 2-4 times more likely than those without diabetes to have and to die from heart disease and to have a stroke. Extensive research has identified several ways that consuming soy protein with its naturally occurring isoflavones may help reduce the risk of CVD. The U.S. Food and Drug Administration (FDA) has authorized a Health Claim stating that consuming soy protein as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease.

Kidney Disease

Your kidneys have several vital functions, including filtering waste materials from your blood. High glucose levels associated with diabetes are a major cause of a kidney disease called diabetic nephropathy. High levels of fat in your blood can also damage your kidneys.

People with kidney disease typically are prescribed low-protein diets to reduce the work of their kidneys. However, very low-protein diets are both difficult to follow and may have some negative side effects, such as loss of muscle strength and increased body fat.

However, animal and plant proteins differ in their effect on your kidneys. Consuming soy protein is associated with kidney changes comparable to those resulting from a low-protein diet. This raises the possibility that people with kidney disease may be able to liberalize their protein intake by using soy protein. (Do not change any diet prescribed for kidney failure unless directed by your doctor and registered dietitian).

Research has also shown that consuming soy protein instead of animal protein decreases levels of harmful fats in your blood. In addition to reducing your risk for heart disease, lower blood fat levels may also have a beneficial effect on kidney health.

Weight Management

Overweight and obesity are the number one nutritional problems in the United States. A reduced tendency to burn fat for energy is a major risk factor for weight gain. Increased insulin production promotes fat storage in your body, whereas production of the hormone glucagon enhances your body's use of fat for energy. How might soy play a role? Soybeans have a low GI, meaning that they cause a very small increase in glucose, which limits insulin production. And, compared to animal protein, isolated soy protein has been shown to provoke a greater release of glucagon.

Antioxidant Function of Soy

Oxidation is a chemical reaction that damages cells and tissues in the body, contributing to the process underlying most heart disease and stroke. Oxidation also plays a role in the cell damage that initiates cancer. Laboratory research has shown that genistein, the major isoflavone in soy, is a potent antioxidant, meaning that it limits or prevents oxidation.

Looking to the Future

Researchers continue to investigate the many potential health benefits of consuming soy protein. Keep watching for news about soy protein and your health.

Although cardiovascular disease (CVD) is a leading cause of death among women around the world, many of them fear breast cancer the most and believe it to be their number one health concern. Bone health is also a major health concern for women who have reached menopause. Additionally, one of the primary reasons perimenopausal and early postmenopausal women seek medical attention is for relief of many of the symptoms associated with menopause, including hot flushes.

As more women turn 50, they are looking for non-pharmacologic answers to their health concerns. Learn how soy provides benefits to help prevent or manage chronic disease.

Soy Protein and Menopause

Research has shown that Asian women who consume large amounts of soy have fewer menopausal symptoms and less osteoporosis and cardiovascular disease than women in the West.

Menopause Basics

More than one third of the women in the United States, about 36 million, have been through menopause. With a life expectancy of about 81 years, a 50-year-old woman can expect to live more than one third of her life after menopause. Scientific research is just beginning to address some of the unanswered questions about these years and about the poorly understood biology of menopause.

Menopause is the point in a woman's life when menstruation stops permanently, signifying the end of her ability to have children. Known as the "change of life," menopause is the last stage of a gradual biological process in which the ovaries reduce their production of female sex hormones--a process which begins about 3 to 5 years before the final menstrual period. This transitional phase is called the climacteric, or perimenopause. Menopause is considered complete when a woman has been without periods for 1 year. On average, this occurs at about age 50. But like the beginning of menstruation in adolescence, timing varies from person to person.

Health Risks Posed at Menopause

Estrogen has a number of benefits that can be lost when levels drop too low. For much of their adult lives, women have a lower risk of heart disease than men the same age. However, once a woman reaches menopause and her estrogen levels fall, her prevalence of CVD rises to equal and finally surpass that of men.

The risk of osteoporosis in women rises as estrogen levels decrease, both during perimenopause and following menopause. Without estrogen's protective effects, the rate of bone loss is increased; it is highest during the first five to seven years after menopause.

Menopausal Symptoms

Some women experience few, if any, symptoms at menopause. However, the majority of Western women experience some noticeable symptoms as their estrogen levels decrease. Physical symptoms can include hot flashes, night sweats, and insomnia; changes in vaginal tissues and a decrease in the ability to control urination; headaches; aching and painful joints; and sore breasts. Psychological effects associated with menopause include sudden mood changes, irritability, problems with concentration and memory, anxiety, a feeling of being unable to cope, and even depression.

Hot flashes are sudden feelings of intense heat, which usually last from thirty seconds to five minutes. They often start in the neck and spread upward to the face and scalp and down to the upper chest. A woman having a hot flash may have a flushed face and sweat profusely. Some women even experience a strong and/or rapid heartbeat and feel dizzy during a hot flash. Hot flashes that occur at night are called night sweats. It is not unusual for a menopausal woman to wake several times during the night with her night clothes and the bed sheets soaking wet. These disturbances contribute greatly to the insomnia that may become a problem at menopause.

Without estrogen, the tissues lining the vagina become thinner and more fragile, and there is a lessening of lubrication. The most common result of this change is discomfort and pain during intercourse. The tissue lining the urinary tack undergoes similar changes, leading to a decrease in the muscle tone that controls the release of urine from the bladder. This inability to control loss is called urinary incontinence. Some women have stress incontinence, which is a sudden leaking of urine when they cough, sneeze, or exercise. Urge incontinence occurs when a trigger, such as laughter or a sudden movement, produces a feeling of needing to urinate, followed by a leaking of urine.

For some women, menopause is a time of emotional upheaval, with sudden mood swings, irritability, and depression. Declining estrogen levels may have a direct effect on mood and other feelings. And, of course, insomnia and lack of restful sleep can be major contributors to moodiness, irritability, and the other psychological side effects sometimes associated with menopause.

Soy Protein and Menopausal Symptoms

A survey of 8,000 women conducted in Scotland indicated that 57 percent of the women responding had experienced one or more of the menopausal symptoms mentioned above. This percent is actually lower than the estimates of 70 to 85 percent usually given for North American women.

The interesting fact is that Asian women had a much lower incidence of menopausal symptoms. For example, studies estimated that less than 25 percent of Japanese women and 18 percent of Chinese women complained of hot flashes. These observations led researchers to investigate the possible effects on menopausal symptoms of dietary factors in Asian cuisines, including soyfood consumption.

Soy Protein Benefits in Menopause

Many women in Western countries experience similar symptoms at menopause, such as hot flashes, trouble sleeping, lack of energy, and headaches, among others.

Research has shown that Asian women who consume large amounts of plant estrogens, especially the isoflavones in soy, have fewer menopausal symptoms and less osteoporosis and cardiovascular disease that women in the West. This has led to increased interest in evaluating soy as a possible alternative for ERT or HRT in women who are either not willing or not able to take these hormone therapies. There are a growing number of studies investigating the potential effects of soy protein on symptoms and other changes that are associated with menopause. Here is a review of the potential benefits soy protein may have to offer.

Soy Protein and Hot Flashes

Of the physical symptoms commonly associated with menopause, hot flashes are perhaps the easiest to measure. Although the hot flush (or hot flash) is the most common symptom of menopause, there is a wide variation in its frequency among women in different parts of the world. In Europe and the United States, 70-80 percent of menopausal women experience hot flushes, in Malaysia 57 percent, in China 18 percent, and in Singapore 14 percent. One of the most striking dietary differences among women in these areas is their intake of dietary soy protein and its phytoestrogens.

In one study by Murkies and associates, postmenopausal women who were regularly experiencing hot flashes were given either soy flour or wheat flour over a three-month period. Although both groups had a decrease in the number of hot flashes they experienced and in their menopausal symptom score, the soy produced a more rapid response.

A recent study by Albertazzi and colleagues in which soy protein with naturally occurring isoflavones was compared with a placebo (casein) in postmenopausal women showed a stronger result. In this study, the researchers found that soy protein was significantly superior to the placebo in reducing the mean number of hot flashes experienced daily. The women taking soy protein had a 26-percent reduction in the mean number of hot flashes by the third week, increasing to a 33-percent reduction by the fourth week, and a 45-percent reduction by the end of the twelfth week.

Soy Protein and Bone Health

Since the prevalence of osteoporosis isn't the same across cultures, researchers are looking to other cultures for clues to possible ways of reducing this disease. Surveys of women in Japan, for example, have raised questions about factors affecting bone health. Although Japanese women consume less calcium than most women in Western countries and are unlikely to use Estrogen Replacement Therapy (ERT) or Hormone replacement Therapy (HRT), they have a lower prevalence of fractures. Some intriguing research in postmenopausal women compared the effects on bone of consuming isolated soy protein with naturally occurring isoflavones or animal protein in the form of casein and nonfat dry milk. In this short-term study the women receiving isolated soy protein increased bone mineral density in the lumbar portion of their spine.

Some researchers believe that part of the answer to this puzzle may lie with the high intake of soyfoods in the traditional Japanese diet. They first looked at the effects of soy protein itself on calcium metabolism. More recently, research has focused on the potential effects of the isoflavones found in soy.

Soy Protein & Calcium Scientists have extended the scope of the research showing that the amount of calcium excreted increases as protein intake goes up. They discovered that not all types of protein have the same effect-protein from animal sources causes much greater calcium loss than vegetable protein. This has been confirmed in a study of 755 Japanese men and women. Researchers found that consuming animal protein was associated with an increase in calcium excretion. However, they found no significant relationship between calcium excretion and the consumption of plant protein.

These findings become more meaningful when they are translated into the effect on bone fractures. As part of the large Nurses' Health Study, researchers looked at usual dietary intake and fracture rates in 85,900 women. First, they compared women averaging less than 68 grams of protein per day with those consuming more than 95 grams. The woman eating more protein had an increased risk of fracturing their forearm. Next, the researchers evaluated the type of protein being consumed. The increased risk of forearm fracture was seen in women consuming animal protein. Consumption of vegetable protein, however, was not associated with an increased risk.

The Isoflavone Story Another area of intense study is the potential effect of soy isoflavones on bone health. Isoflavones are a type of phytochemical, or "plant chemical." The isoflavones found in soy and thus soy protein are genistein, daidzein, and glycitein.

Soy Protein and Cardiovascular Disease

For much of their adult lives, women have a lower risk of heart disease than men the same age. However, once a woman reaches menopause and her estrogen levels fall, her prevalence of CVD rises to equal and finally surpass that of men.

A considerable amount of the research investigating soy protein and its naturally occurring isoflavones has focused on cardiovascular disease (CVD). CVD, which includes heart attack, stroke, and high blood pressure, is the number one killer of American women.

Although CVD represents a major cause of death in many nations, statistics are not uniform in all areas of the world. For example, a look at the most recent worldwide statistics for CVD show that the death rate (number of deaths per 100,000 population) in the United States is 201 for women, but in Japan, the death rate is 99 for women. There are a number of factors that may contribute to such a significant difference. Diet is certainly one of them. In comparing Eastern and Western diets, researchers have turned to the study of soy.

There are two primary ways that soy may protect against the damage done by LDL-cholesterol. Soy isoflavones not only help reduce LDL-cholesterol levels, they also act as antioxidants.

Direct Cholesterol-Lowering Effect Studies in animals and in humans have investigated the cholesterol-lowering ability of soy protein. Significant research has been done to investigate soy protein's effects on LDL-cholesterol and triglyceride levels in your blood. The 1995 New England Journal of Medicine meta-analysis mentioned earlier combined the results of 38 clinical studies evaluating the effect of consuming soy protein on LDL-cholesterol, triglyceride, and HDL-cholesterol levels.

This groundbreaking research showed that consuming an average of 47 grams of soy protein daily: decreased total cholesterol by 9.3% decreased LDL-cholesterol by 12.9% decreased triglycerides by 10.5% increased HDL-cholesterol by 2.4%.

The reductions in total cholesterol, LDL-cholesterol, and triglycerides were statistically significant; the increase in HDL-cholesterol was not large enough to be of statistical significance. In the summer of 1995, Dr. James W. Anderson and his associates published a landmark meta-analysis of the effects of soy protein on lipoprotein levels in the blood. (A meta-analysis uses statistical methods to combine the results of a number of smaller studies.) The meta-analysis, which appeared in The New England Journal of Medicine, analyzed the combined data from thirty-eight clinical studies, which together included 730 research volunteers.

It showed that replacing animal protein with soy protein resulted in a 9.3-percent decrease in total cholesterol, a 12.9-percent decrease in LDL-cholesterol, and a 10.5-percent decrease in triglyceride, which is another blood fat associated with CVD. All of these decreases were statistically significant. The individuals who originally had the highest blood-cholesterol levels experienced the greatest degree of cholesterol lowering.

The meta-analysis had two major effects. First, it raised public awareness of soy protein's potential health benefits in CVD. Second, it spurred what has become a steadily increasing interest in investigating soy and soy protein among members of the research and medical communities. The next logical question was: what component or components in soy lowers cholesterol?

All of these studies help show that soy protein with naturally occurring isoflavones lowers blood cholesterol levels, that soy protein without isoflavones does not lower blood cholesterol, and that isoflavones without soy protein also do not lower blood cholesterol.

Soy Protein and Bone Health

Good bone health throughout life helps prevent osteoporosis - a major cause of disability in later years. Research suggests that consuming soy protein may help protect bones from becoming weak and brittle as you age.

Osteoporosis Basic

Osteoporosis is a chronic disease characterized by low bone mass and density. It leads to weak, fragile bones and a greatly increased risk of bone fractures . Both women and men can develop osteoporosis, but it is five times more common in women. This is due to the fact that women achieve a lower peak bone mass than men and that women loose bone at an accelerated rate for the first few years following menopause.

There's more than one type of osteoporosis.

Postmenopausal osteoporosis.
Postmenopausal osteoporosis occurs in women when their estrogen levels drop, around the time of menopause. Symptoms of bone loss typically develop between the ages of 51 and 75, but can occur earlier or later. Women can lose up to 20% of their bone mass in the 5-7 years following menopause.
Senile osteoporosis.
"Senile" osteoporosis simply means the condition is due to aging. Researchers believe that this condition is caused by age-related changes in calcium intake and an imbalance between bone resorption and formation. It is twice as common in women as men again due to the difference in peak bone mass and usually affects people over age 70.
Secondary osteoporosis.
Secondary osteoporosis occurs as a side effect of medical condition, such as a thyroid disorder, or from using certain drugs, including corticosteroids, barbiturates, anticonvulsants, and excessive amounts of thyroid hormone. In addition, excessive alcohol use and cigarette smoking results in increased bone loss.
Idiopathic juvenile osteoporosis.
Idiopathic juvenile osteoporosis is a rare condition that sometimes occurs in children and young adults. These individuals have normal hormone and mineral levels, and there is no obvious reason for them to develop weak bones.

Osteoporosis as a Public Health Threat

Osteoporosis takes a great toll in pain, suffering, and disability, in addition to the actual monitory costs involved. It is responsible for more than 1.5 million bone fractures each year, including:

300,000 hip fractures
700,000 fractures to the vertebrae in the spine
250,000 wrist fractures
more than 300,000 fractures at other sites

Symptoms of osteoporosis often don't appear until your bones become so weak that they either collapse or break. The first symptoms of collapsed vertebrae may be severe back pain, a loss of height, or deformities, such as the "dowager's hump" seen in some older women. A bone weakened by osteoporosis may break when you have a fall or even a minor bump.
Don't underestimate the seriousness of a fracture. About 24% of the people over age 50 who fracture a hip die within one year. In addition, one-fourth of the people who were ambulatory before fracturing a hip need long-term care afterward.

Risk Factors for Osteoporosis

Major Risk Factors for Osteoporosis

You can't change your...	Who it affects...
Gender	Women are at higher risk as they reach a lower peak bone mass compared to men
Age	Everyone's risk increases with aging because bones become weaker and less dense.
Body size	Women with a thin and/or small body build are at greater risk.
Ethnic heritage	Caucasian and Asian women are at highest risk, although African American and Latino women are also at risk.
Family history	People with parents prone to fractures seem to have lower bone mass and higher fracture risk.
You have control over...
Sex hormones	Risk is greater in women at menopause as the production of estrogen by their body is greatly reduced or in the absence of menstrual periods during adolescence and adulthood; and in men with low testosterone levels.
Eating disorders	Anorexia nervosa and bulimia increase risk.
Diet	A diet low in calcium and vitamin D increases risk.
Activity level	People who are not physically active or who are bedridden for any length of time are at greater risk. It's best to perform both weight-bearing and strength training exercise.
Medications	Use of certain medications, such as glucocorticoids or some anticonvulsants, increase risk.
Cigarette smoking	Cigarette smokers are at greater risk.
Alcohol use	Excessive use of alcohol increases risk.

Soy Protein Benefits in Osteoporosis

Scientists have extended the scope of the research showing that the amount of calcium excreted increases as protein intake goes up. They discovered that not all types of protein have the same effect-protein from animal sources causes much greater calcium loss than vegetable protein. This has been confirmed in a study of 755 Japanese men and women. Researchers found that consuming animal protein was associated with an increase in calcium excretion. However, they found no significant relationship between calcium excretion and the consumption of plant protein.

These findings become more meaningful when they are translated into the effect on bone fractures. As part of the large Nurses' Health Study, researchers looked at usual dietary intake and fracture rates in 85,900 women. First, they compared women averaging less than 68 grams of protein per day with those consuming more than 95 grams. The woman eating more protein had an increased risk of fracturing their forearm . Next, the researchers evaluated the type of protein being consumed. The increased risk of forearm fracture was seen in women consuming animal protein. Consumption of vegetable protein, however, was not associated with an increased risk.

The Isoflavone Story

The isoflavones found in soy and thus soy protein are genistein , daidzein , and glycitein .

Isoflavones can be classified as phytoestrogens , which are substances in plants that have chemical structures resembling estrogen. Isoflavones actually have several potential modes of action in the body. Depending on the circumstances, they may either act like a weak estrogen, act as an antiestrogen (blocking some effects of estrogen), or have effects not related to estrogen.

Purified genistein has been shown to slow the activity of cells that break down bone- osteoclasts- in the laboratory and in animals. Other researchers also found that genistein directly inhibited the breakdown of bone tissue in the laboratory.

Some animal research has shown genistein's effects on preventing bone loss to be similar to those of estrogen. Where genistein and estrogen differed is that the isoflavone had the benefit of not affecting the uterus .

Casein and nonfat dry milk. In this short-term study the women receiving isolated soy protein increased bone mineral density in the lumbar portion of their spine.

Soy Protein and Cancer

Although heart disease kills more people, many individuals are more afraid of cancer. Epidemiological (population) studies suggest that soy protein may have a role in reducing the risk of certain cancers.

Cancer Basic

The term cancer actually refers to more than 100 diseases. What they all have in common is the uncontrolled growth and spread of cells that have become abnormal.

Another genetic change that can lead to cancer is the suppression or loss of tumor-suppressor genes, which normally produce proteins to inhibit cell division.

Cancer may occur when some abnormal cells escape these safeguards. In the second phase of cancer, called promotion, abnormal cells are stimulated to grow and multiply to establish cancer.

Cancer in Women

On average, every 6.4 minutes a woman in the US will be diagnosed with a cancer of the reproductive organs... ovarian, uterine, cervical, vulvar, vaginal or tubal. Each year approximately 82,000 women will be told they have one of these diseases. Youth doesn't protect you from this disease -- it strikes women in their teens as well as postmenopausal women over 50.

Breast cancer is occurring in epidemic proportions in the United States. It is the second leading cause of cancer death in American women and will result in an estimated 40,800 deaths in 2000. About one of every nine women will develop breast cancer during her lifetime. African-American women, who are less likely than white women to develop breast cancer, are more likely than white women to die from it.

The cervix, the narrow neck of a woman's uterus, can go through a series of changes that eventually can lead to cancer. Cervical cancer is the third most common form of cancer of the female genital tract and accounts for 19 percent of these cancers. Cervical cancer occurs almost twice as often in younger African-American than in age-matched white women.

Cancer of the uterus accounts for 5 percent of all cancers in women and is the most common gynecological cancer. Most cancers of the uterus occur in the endometrium, the lining of the uterus. Endometrial cancer occurs most often in older women; it is rare before age 40.

Cancer of the ovary is the second most common gynecologic cancer and the fourth leading cause of death from cancer among women. It generally develops after menopause and is seen more often in women who have had no children or who had trouble conceiving.

Cancer of the vulva and vagina are rare and occur most often in older women. Warning signs include a lump or sore on the vulva (external genitals) or in the vagina.

Soy Protein Benefits in Cancer

A large body of epidemiological evidence demonstrates that consumption of soy foods is associated with a lower risk of certain cancers in Asian countries, e.g. China and Japan, and in certain Asian populations residing in Western countries.

Table hereunder lists the death rates from breast cancers in selected Eastern and Western countries.

Death Rates Per 100,000 Population For Breast Cancer

Country	Breast Cancer
Western Nations
United States	21.1
United Kingdom	26.5
Germany	22.1
Eastern Nations
Japan	6.8
China	5.0

The existing data from epidemiological studies, along with supportive data from animal studies, strongly support the concept that consumption of soy protein may reduce the risk of certain cancers in humans. Researchers who are studying the possible role of soy protein in cancer prevention have focused primarily on tumors known to be affected by hormones and diet. Research on soy protein and breast cancer prevention is one of the most active research areas today.

Soy Protein and Breast Cancer

Findings from recently completed epidemiological studies conducted in China (Dai et al., 2001; Shu et al., 2001) and an ongoing study in the U.S. (Wu et al., 2001) demonstrated that consumption of soyfoods during adolescence and adulthood results in a reduction in the incidence of breast cancer in women. These results support the existing knowledge from previously published epidemiological investigations that consumption of soy is beneficial in reducing the risk of breast cancer in women.

Results from animal studies support epidemiological findings. Feeding female rats a diet that contained isolated soy protein inhibits experimentally induced mammary tumor development compared with rats fed a casein-based diet (Barnes et al., 1994; Hawrylewicz et al., 1991). Hakkak et al (Hakkak et al., 2000) investigated the effect of long-term feeding animals a diet containing isolated soy protein on mammary tumor development.

They fed rats a soy protein-containing diet or a casein-based diet for two generations before administering a chemical agent known to induce mammary tumor to the third generation. At the end of the study, there was a significant decrease in the number of mammary tumors and a significant increase in the latency period in rats maintained on the soy protein diet compared with those on the casein diet.

Constantinou et al (Constantinou et al., 2001) examined the synergetic effect of isolated soy protein with tamoxifen on chemically induced mammary tumor development in rats. Tamoxifen is a drug approved by the U.S. FDA for breast cancer prevention in humans. They found that dietary supplementation with isolated soy protein or tamoxifen resulted in a 37% or a 29% reduction in the number of tumors developed in mammary glands compared with the controls.

However, they found a 62% reduction in the number of tumors in the group fed a diet containing both soy protein and tamoxifen compared with the controls. Results from this study showed that soy protein is synergetic with tamoxifen and resulted in a greater inhibition on chemically induced mammary tumor development in animals. It suggests that consumption of soy protein is beneficial to women who use tamoxifen for breast cancer prevention.

Yan et al (Yan et al., 2000) investigated whether dietary supplementation with isolated soy protein reduced pulmonary metastasis of malignant cells from mammary tumors in mice. The spread of cancerous cells from a mammary tumor to the lungs and other organs in the body is a major cause of death in breast cancer patients. Mice were fed a casein-based control diet or a diet supplemented with different contents of isolated soy protein before receiving an injection of mammary tumor cells into mammary glands for primary tumor development.

At the end of the study, the number of tumors formed in the lungs were counted as a measurement of the cancer spread because the more malignant cells spread to the lungs and the more tumors could be developed. The researchers found that there was a significant reduction in the number of metastatic tumors formed in the lungs in mice fed the soy protein diets compared with those maintained on the control diet.

These results demonstrated that soy protein reduced the spread of mammary cancer in animals, suggesting that soy protein is a useful nutritional adjutant in reducing metastasis in breast cancer patients.

Many researchers have investigated the role of genistein, a major soy isoflavone, in mammary tumor development in animals. Fritz et al (Fritz et al., 1998) examined the effect of dietary supplementation of genistein on chemically induced mammary tumorigenesis in rats. Female rats were fed a diet containing different levels of genistein from conception to day 21 post-parturition.

All offspring were weaned at the age of 21 days, maintained on a genistein-free diet, and treated with a cancer-causing agent to induce mammary tumors at the age of 50 days. At the end of the study, animals from mothers fed genistein-supplemented diets had fewer mammary tumors compared with those from mothers fed a genistein-free control diet.

Similar inhibitory effect on mammary tumor development has also been observed when genistein was subcutaneously injected into animals (Murrill et al., 1996; Lamartiniere et al., 1995). Results from these studies suggest that genistein is, at least in part, responsible for the cancer-attenuating effect of soy protein products.

The important thing to keep in mind is that soy isoflavones are chemically similar to naturally occurring and synthetic forms of estrogen. They are able to compete with more potent forms of estrogen at the estrogen receptor but have much less estrogenic activity. Research suggests that soy isoflavones are able to mimic some of estrogen's functions, such as helping prevent bone loss, but may not stimulate the unfavorable responses in breast tissue that may increase the risk of cancer.

This reduced risk of breast cancer doesn't appear to be genetic since it disappears as Asian women move to the West. One study found that in Chinese and Japanese women, the incidence of breast cancer was lowest in those living in Asia, intermediate in those born in Asia but living in the United States, and highest in Asian women born in the United States. Even in this last group, the incidence of breast cancer was appreciably lower than in American Caucasian women.