Last week we talked about the pros and cons of eating soy including it’s role in breast cancer and it’s affect on the, errr, manly arts.

As always, show notes are below.

July 19, 2011 | Tonight on Summer Tomato Live we’re discussing soy. Some say it prevents cancer, others think it promotes it, and some claim it’s evil for causing man boobs. We’ll get to the bottom of these issues and more today during the show.

Join us at 6:00pm PST to learn about how soy affects your health and what to do about it.

To watch live and join the discussion click the red “Join event” button, login with Twitter or your Vokle account, and enter the password when prompted.

I encourage you to call in with video questions, particularly if your question is nuanced and may involve a back and forth discussion. Please use headphones to call in however, or the feedback from the show is unbearable.

See you soon!

Show notes:

Relevant links:

Probiotics and Fermented Foods – Episode 6

Seaweed, salt and iodine – Office Hours (it’s in there I swear)

Cholesterol Explained

Chinese food safety issues

Healthy Vegetarian and Vegan Diets

Miso

Soy sauce

Someone asked during the show how this advice applies to soy sauce. Turns out there are 2 different methods of brewing soy sauce. The traditional way is fermented and has the same attributes as fermented soy products mentioned in the episode. The other method creates the sauces by hydrolyzing soy, which creates a number of unwanted byproducts including MSG and potentially some carcinogenic chemicals. The Wikipedia article on soy sauce is very informative.

Breast cancer

Meta-analysis of soy intake and breast cancer risk

Soy isoflavones consumption and risk of breast cancer incidence or recurrence: a meta-analysis of prospective studies

Epidemiology of soy exposures and breast cancer risk

Soyfood intake in the prevention of breast cancer risk in women: a meta-analysis of observational epidemiological studies

Prostate cancer

Soy consumption and prostate cancer risk in men: a revisit of a meta-analysis

What about demasculizing men?

One of the biggest fears men have about eating soy is the possibility of phytoestrogens demasculizing men, creating sexual dysfunction, infertility and the dreaded man boobs.

Indeed, there have been several studies in rodents suggesting that soy can interfere with reproductive pathways and fertility. However, human and monkey studies show that most men have no need to fear soy.

Acute exposure of adult male rats to dietary phytoestrogens reduces fecundity and alters epididymal steroid hormone receptor expression.

Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis

Soybean isoflavone exposure does not have feminizing effects on men: a critical examination of the clinical evidence

Dietary soy protein containing isoflavonoids does not adversely affect the reproductive tract of male cynomolgus macaques (Macaca fascicularis)

Hypogonadism and erectile dysfunction associated with soy product consumption

Osteoporosis

Soy isoflavone intake inhibits bone resorption and stimulates bone formation in menopausal women: meta-analysis of randomized controlled trials

Effect of long-term intervention of soy isoflavones on bone mineral density in women: a meta-analysis of randomized controlled trials

Heart disease

Soy protein effects on serum lipoproteins: a quality assessment and meta-analysis of randomized, controlled studies

Non-soy legume consumption lowers cholesterol levels: a meta-analysis of randomized controlled trials

Relation between soy-associated isoflavones and LDL and HDL cholesterol concentrations in humans: a meta-analysis

The effect of soy protein with or without isoflavones relative to milk protein on plasma lipids in hypercholesterolemic postmenopausal women.

Association of dietary intake of soy, beans, and isoflavones with risk of cerebral and myocardial infarctions in Japanese populations: the Japan Public Health Center-based (JPHC) study cohort I.

Notably, this was not convincing enough for the American Heart Association

A Statement for Healthcare Professionals From the Nutrition Committee of the AHA

Thyroid issues

If you have moderate hypothyroid issues, it may be prudent to restrict your soy intake to low levels.

The effect of soy phytoestrogen supplementation on thyroid status and cardiovascular risk markers in patients with subclinical hypothyroidism: a randomized, double-blind, crossover study

Effects of soy protein and soybean isoflavones on thyroid function in healthy adults and hypothyroid patients: a review of the relevant literature.

Impact of flavonoids on thyroid function

Memory/cognitive effects of soy

High Tofu Intake Is Associated with Worse Memory in Elderly Indonesian Men and Women

Borobudur revisited: soy consumption may be associated with better recall in younger, but not in older, rural Indonesian elderly.