This is a continuation of our “Hormone Free” Foods post that introduced dietary estrogen and phytoestrogens. Today we will focus on how dietary phytoestrogens in soy can positively impact women’s health. So the next time you think of grabbing that cheese burger, why not opt for a tempeh “BLT” instead!
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Phytoestrogens: Part 2 of 3
Before we get started, if you haven’t already, head to our first post on this topic! “Hormone Free” Foods will give you an introduction into Estrogens and Phytoestrogens. In addition to how they function differently and the importance of fiber in reducing excess estrogen.
What age should you start incorporating soy?
Since soy during early stages of life, such as infancy, is hotly debated and in need of more research, we will start with ages 13-15. This doesn’t mean that occasional soy food should be avoided for those girls younger than 13. More specifically, it means that there is a scientific consensus starting with the age group of 13-15, demonstrating that daily intake of soy should be encouraged and is beneficial.
Puberty and Soy
Starting soy consumption early is important for young girls. Not only does it help to reduce the incidence of soy allergies later on in life, but it also can provide protective effects.
Evidence suggests that soy does not exert adverse hormonal effects in children or affect pubertal development. On the other hand, there is intriguing evidence indicating that when soy is consumed during childhood and/or adolescence, risk of developing breast cancer is markedly reduced.
NIH Study, Health Impact of Childhood and Adolescent Soy Consumption
Dietary estrogen from meat, dairy and eggs have different effects than from soy. Soy contains phytoestrogens that actually have protective effects at all life-stages.
Introducing soy foods during adolescence provides a great source of phytoestrogens. They bind to the “B” receptors (Beta-estrogen receptors) and can reduce the excess growth associated with rising estrogen levels. As a result, high intake of soy in childhood is also associated with reduced risk of premenopausal breast cancer by 43% (NIH Study).
So what is high intake for soy?
This study was done in a Chinese population as a part of the Shanghai Women’s Health Study, because soy consumption is a large part of their culture. However, the soy consumption was still lower than 4.87 grams protein/day for the “Low intake” group. Although, high intake is 12.82 or more grams of protein from soy/day. This can be easily reached by introducing one serving of soy foods a day to your normal diet. The tables below show the phytoestrogen content and protein content for common soy foods.
Harvard Health: Soy isoflavone content
Soy and Breast Cancer
Whole soy foods are a great source of phytoestrogens. For example, edamame, tofu, tempeh, and soy milk are all great sources of phytoestrogens. Try to avoid soy isolated supplements as due to the extra processing, they don’t contain the same amount of phytoestrogens.
Soy products contain what are called isoflavones, which can have anti-carcinogenic and anti-estrogenic properties. Isoflavones have been shown to lower both risk of getting breast cancer and risk of recurrence. This also applies to women with BRCA1 and BRCA2 mutations.
Soy intake was only associated with 27% breast cancer risk reduction in people with normal BRCA genes, but a 73% risk reduction in carriers of BRCA gene mutations. So, a healthy diet may be particularly important in those at high genetic risk. Meat consumption, for example, was linked to twice as much risk in those with BRCA mutations—97% increased risk, instead of just 41% increased risk of breast cancer in those with normal BRCA genes.
Dr. Michael Greger (BRCA Breast Cancer Genes and Soy)
Soy actually Reduces cancer risk, rather than increases cancer risk!
Tamoxifen and Soy
Tamoxifen is one of the main treatments prescribed for ER+ breast cancer (PubChem). ER+ means that the cancer is sensitive to the presence of estrogen and receptor “A” (Alpha-estrogen receptor) causes further cancer progression. What tamoxifen does is it binds to receptor “A” without triggering the “on” switch to signal growth. This prevents your estrogen or dietary estrogen from binding to this site, just as you can only have one key in a lock at a time.
Interestingly, soy actually binds to receptor “B” instead of receptor “A”. This means that eating soy products while on tamoxifen will not make the treatment less effective. As a result, soy can help to improve outcomes for breast cancer survivors by reducing the recurrence and mortality rates (NIH Study).
Menopause and Soy
Would you like to reduce hot-flashes and fatigue? During menopause a women’s estrogen production drops overtime and there are a wide array of symptoms that occur due to this change. Phytoestrogens also have the potential to act as estrogens under these conditions.
A study done on breast cancer survivors who were experiencing menopause, showed that higher soy intake reduced menopause symptoms by 49% and fatigue by 57%. This study was based on the consumption of 24g/day of soy (about 1 serving) versus no soy at all (NIH study). For those who can’t undergo estrogen therapy (ET) due to an estrogen dependent cancer (ER+), soy is a great alternative to safely reduce menopause symptoms.
Women and Soy
Introducing one serving of soy a day into your lifestyle can have many beneficial effects on women’s health. It is no longer a food to be feared, but instead one that will help your body to balance the effects of estrogen naturally. This can help women of any age. From young girls setting them up on a path to reduce their lifetime breast cancer risk, to making menopause more of a graceful transition. Incorporate soy into your daily lifestyle, and check back in later for our next post on Men and Soy, Part 3 of 3.
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Resources:
- Nutritionfacts.org:
- NIH Studies:
- Health Impact of Childhood and Adolescent Soy Consumption
- Adolescent and adult soy food intake and breast cancer risk: results from the Shanghai Women’s Health Study
- Soy Food Intake and Breast Cancer Survival
- Dietary intake of soy and cruciferous vegetables and treatment-related symptoms in Chinese American and non-Hispanic White breast cancer survivors
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