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Soy, or not?

These days, I am often asked if soy products are truly good. Have they been too much transformed? Do they really improve the symptoms of menopause? Will men develop breasts if they eat tofu? Let’s shed light on all of this…

Soy and breast cancer

It has been observed that soy products (or should we say, the isoflavones they contain) may reduce the risks of breast cancer, and the risks of recurrence. What seems to be confusing the issue is the fact that the majority of the people on our planet rarely consume as much soy as Japanese women, who seem to have the lower risk of breast cancer. However, it is believed that if we would eat as much soy from our early age, the risks of breast cancer in Westerners would be greatly reduced. However, the benefits of soy seem to be questioned when breast cancer is diagnosed. During your period of cancer treatment, abstain from consuming too much soy, as the opposite effect could be observed (proliferation of cancerous cells).

The effect of soy on hormones

These famous isoflavones are in fact phytoestrogens, i.e., an active chemical substance from a plant that is said to have effects similar to those of estrogen, a feminine hormone. Because symptoms associated with menopause are caused by a drop in hormones, soy products are said to help alleviate these symptoms (especially hot flushes). Please note that the effects are more pronounced in pre-menopausal women than in women already going through menopause. For men, no links were established between the consumption of isoflavones and the overall testosterone level. They were even associated with a reduction in prostate cancer in men who consume soy products.

Soy and cardiovascular health

Soy and soy products are also associated with a better cardiovascular health. The fact that soy proteins often replace proteins from animal sources (which provide saturated fats, therefore increasing “bad” cholesterol) explains this phenomenon in part. In addition, soy products are rich in polyunsaturated fats (good fats), which help lower “bad” cholesterol.

Quantity of isoflavones

To reap the various benefits of isoflavones, it is recommended that you consume 20 to 80 mg per day, or the equivalent of 80 to 160 g of soy products. To get an idea of the quantities, consult this chart:





Quantity of isoflavones (mg)

Soy flour

50 g

65 to 99 mg

Cooked soy beans

125 ml

47 mg


100 g

43 mg


100 g

22 to 30 mg

Soy beverage

250 ml

20 mg


25 g

10 mg

Soy protein concentrate (water extraction)

50 g

51 mg

Soy protein concentrate (alcohol extraction)

50 g

6 mg

Favour these less transformed foods, rather than soy-based desserts (which are somewhat sweetened) or “meatless” products than are quite salty and more transformed. And you, what are your favourite soy-based recipes?

By Caroline Proulx


Messina, M., & Messina, V. (2010). The role of soy in vegetarian diets. Nutrients, 2(8), doi: 10.3390/nu2080855

Tanaka. M. Et al. Prostate Cancer and Prostatic Diseases (2009) 12, 247–252; doi:10.1038/pcan.2009.10

Extenso. (2012, Novembre 27). Soya et ménopause. Retrieved from http://www.extenso.org/article/soya-et-menopause/

Extenso. (2012, novembre 27). Le soya peut prévenir le cancer du sein? Retrieved from: http://www.extenso.org/article/le-soya-peut-prevenir-le-cancer-du-sein/

Passeportsanté. (2010, Mai). Protéines et isoflavones de soya. Retrieved from http://www.passeportsante.net/fr/Solutions/PlantesSupplements/Fiche.aspx?doc=isoflavones_ps#P41_919

Caroline Proulx

Holder of a bachelor’s degree in nutrition from McGill University, and member of the Ordre Professionnel des Diététistes du Québec, Caroline has been working as a nutritionist for Nautilus Plus since January 2013. A seasoned marathon runner with a passion for cooking, she also animates conferences and motivation groups about nutrition! “As I have not always been a keen athlete, I am very proud of having completed a marathon, and also of preparing the next ones! For me, nutrition is not only the key to optimal performance, but also a medicine in itself. Therefore, my objective is to encourage people to change their habits if they need to and motivate them to never give up, but first and foremost, make them realize that eating healthy is a pleasure that we are lucky to enjoy three times a day!”

Soy, or not?is a post from I'm taking charge. I'm taking charge is a blog that aims to help people in their journey to fitness through articles on training, nutrition, motivation, exercise and healthy recipes.
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