Soy: Beneficial or Harmful?

A common question in my practice revolves around soy. Should you consumed or avoid it, especially for women who have breast cancer risk factors? It is a valid question, and the medical research has begun to debunk the myth that soy is detrimental.
The form of soy is important; soy from food seems to be safe, but soy in high supplement form has shown mixed results.
Why are patients worried? Soy contains phytoestrogens (plant estrogens). The thought is that phytoestrogens have similar effects as estrogen produced by humans or other animals.
However, the story is complex: soy actually may help prevent breast cancer and its recurrence. It may also have other positive health effects.

Breast Cancer Impact
The Shanghai Breast Cancer Survival Study, an over 5,000 patient observational trial that followed patients for a median of 3.9 years, has had resounding effects on the way we think of soy in relation to breast cancer.
The population consisted of women who had already had one occurrence of breast cancer that was in remission. The women who consumed the most soy from food, measured as soy isoflavones or soy proteins, had a 32 percent reduction in a second occurrence of breast cancer and a 29 percent reduction in breast cancer mortality, compared to those who consumed the least.
This inverse relationship was seen in both estrogen receptor-positive and estrogen receptor-negative women. It is more difficult to treat estrogen receptor-negative women; therefore, making these results even more impressive.
A 2008 meta-analysis suggested that soy decreases breast cancer risk on a dose-dependent curve; for every 10 mg of soy isoflavones daily, there was a 16 percent reduction in breast cancer risk.

Soy and soy isoflavones may help improve cognitive function in postmenopausal women. This effect was seen only in women who increased their soy intake before age 65. There may be a “critical window” of therapeutic opportunity in early stages of post-menopause where soy has the greatest impact.
Soy is not the food with the greatest phytoestrogens, flaxseed is. In a randomized control trial, a daily flaxseed bar did no better at reducing vasomotor symptoms in postmenopausal women, such as hot flashes, than a fiber placebo bar. This took the study’s authors by surprise; preliminary studies had suggested the opposite.
Reinforcing these results, another trial failed to show any beneficial effect of soy isoflavones on menopausal symptoms or on preventing bone loss.

Lung Cancer Treatment and Prevention
Soy isoflavones help to boost the effect of radiation on cancer cells by blocking DNA repair in these cells. They also protect surrounding healthy cells with an antioxidant effect. Soybeans contain three powerful components, genistein, daidzein and glycitein, that provide this effect.
Pretreating lung cancer patients, may promote better outcomes.
The risk of lung cancer was also shown to be reduced 23 percent in one meta-analysis of 11 trials. In subset data, when analysis was restricted to the five highest quality studies, there was an even greater reduction: 30 percent.

Soy may have modest effects in reducing cholesterol levels. Interestingly, people who convert a soy enzyme to a substance called equol, an estrogen-like compound, during digestion were considered the only ones to benefit; however, one study showed that equol non-producers also benefited with a reduction in LDL “bad” cholesterol.
The equol producers maintained their HDL “good” cholesterol whereas the non-producers saw a decline.
What does all of this tell us? Soy is most likely beneficial for men and women alike, even in those with a risk of breast cancer. It does not mean we should eat a soy-based diet, but rather have soy in moderation – on a daily basis, perhaps. It is best to eat whole soy, not soy isolates.
Also, soy supplements are not the same as foods that contain soy, so it is best to consume soy in foods.

Is a calorie just a calorie?

Summer weather has arrived, and many are considering the best way to lose their “pandemic weight gain.” In terms of weight loss, a calorie may be a calorie. However, in terms of its effect on body composition, disease modification and prevention, this may not be true.

A low-carb, high-protein and high-fat diet
A study published in the Journal of the American Medical Association (JAMA) showed that a low-carbohydrate, high-protein diet was more effective at burning calories after initial weight loss than other diets.
Twenty-one young, obese and overweight adults were given a 12-week period to lose 10 to 15 percent of their body weight. They were then put on three different diets and assessed over a four-week period with each: a low glycemic index diet, a low-fat diet and a very low-carbohydrate diet.
The diet that seemed to show the most benefit for maintaining weight loss was the very low-carbohydrate diet, which was high in protein and high in fat – an Atkins-type diet.
This diet lowered the resting energy expenditure the least, meaning that the body burned calories more efficiently. Patients expended 300 more calories on this low-carbohydrate diet than on the low-fat diet and 150 more calories than on the low glycemic index diet.
Why did the low-carbohydrate diet show the best results for maintain weight loss and burning more calories? Jules Hirsch, M.D., former emeritus physician in chief at Rockefeller University, responded in the New York Times when the study was published.
His background included 60 years of obesity research, and he believed that the difference seen with the Atkins-type diet was due to water loss. He wrote that, while weight loss is dependent on the traditional formula – the number of calories consumed minus the number of calories burned on a daily basis – diets’ compositions do affect patients’ overall health.

Low-carb, high-protein diet negative effects
Interestingly, another study published in the British Medical Journal the same week as the JAMA study showed a potentially increased risk of cardiovascular disease with a low-carbohydrate, high-protein diet. This was a prospective trial involving 43,396 Swedish women with a 15.7-year duration.
There was a four percent increase in risk for every 10 percent increase in protein or, as the authors point out, for every additional boiled egg consumed. This is a modest, yet harmful, effect.
Low-carb, high-protein diets have also shown an increased risk of kidney stones. There was a doubling of uric acid levels and a significant increase in calcium levels in the kidney over a six-week period. The study was small, 10 participants, and short in duration.
However, it does make you think that low-carb, high-protein diets from animal sources may not be the best option for overall health.

Does protein source matter?
Interestingly, another study showed that a low-carb, high-protein diet may vary in its effects, depending on the protein source. If high protein levels and fat came from animal sources, then there was an increased risk of death from heart disease and cancer, 14 and 28 percent respectively.
However, if the protein and fat came from plant sources, such as nuts and beans, the risks of all-cause mortality and mortality from cardiovascular disease were decreased by 20 and 23 percent, respectively. The study was a meta-analysis of the Nurses’ Health Study, with over 85,000 women, and the Physician’s Health Study, with approximately 45,000 men, both long-term studies.
No one will argue that weight loss is important, especially for those patients who are obese. However, when choosing a diet, it is important to consider also its effectiveness for disease treatment and prevention.
Diets that are considered to be most effective are those that are plant-based and nutrient-rich. Why lose weight for vanity, when you can lose weight and gain health at the same time?

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