NMU 261 – Soy Isoflavones Linked to Reduced Risk of Cancer Incidence by 10%

Nutrition/Natural Medicine Update No 261 (October 19, 2022)

with Dr. James Meschino

Topic: Soy Isoflavones Linked to Reduced Risk of Cancer Incidence by 10%

Source: Frontiers of Nutrition Journal (2022)

An important paper was published in the journal, Frontiers of Nutrition in March 2022, which compiled the data from eighty-one prospective studies looking at the impact of soy intake on overall cancer risk. As the researchers concluded, “a higher intake of soy was significantly associated with a 10% reduced risk of cancer incidence”. More specifically the ingestion of soy isoflavones, not soy protein, was associated with reduced cancer risk, such that every 10 mg per day intake of soy isoflavones translated into a 4% reduction in cancer risk. This means that an intake of 25 mg of soy isoflavones daily, on average, which is easy to achieve, may reduce your risk of cancer by approximately 10%. Similar protective effects were seen for specific cancers, with the evidence being especially strong for the prevention of lung and prostate cancers. A number of studies over the years have shown that soy intake helps to reduce the risk of cardiovascular disease, but the evidence for cancer prevention appears to be strong enough that the researchers stated in their conclusion that these findings support recommendations to include soy as part of a healthy dietary pattern for the prevention of cancer.

The research paper highlighted details of some of the eighty-one studies reviewed in this meta-analysis whereby some of the studies have shown a significant reduction in the incidence of certain cancers in the presence of higher intakes of soy including, reduced risk of:

• Bladder cancer
• Colorectal cancer in postmenopausal women
• Stomach, prostate, and lung cancer

Keep in mind that all the studies following breast cancer survivors, to date, have shown that women consuming at least 23 mg of soy isoflavones per day, on average, show a significant reduction in breast cancer recurrence and relapse, and mortality, compared to women who avoid consuming soy products or consume very small amounts. In the paper the researchers explained some of the ways that soy isoflavones are shown to help prevent cancer, citing increased antioxidant protection, anti-inflammatory properties, modulating genes that control cell division and programmed cell death (apoptosis), and inhibiting tumor cells from forming new blood vessels to nourish themselves (anti-angiogenesis). But they make that point these studies also suggest that some undesirable lifestyle practices can counter the cancer-protective effects of soy, making soy isoflavone intake less protective against cancer, as appears to be the case in patients who are obese, physically inactive, in those who smoke, and individuals consuming high amounts of alcohol.  However, as part of a healthy lifestyle program the addition of 25-75 mg of soy isoflavones per day, on average, appears to be one additional strategy that can help to significantly reduce the risk of cardiovascular disease and overall cancer risk.

Of course, if you are allergic to soy foods, then soy products of all types are off your list. But for everyone else, I think this is important information to consider.  I have included a list of soy foods and the number of soy isoflavones they contain in the text below, along with a link to the March 2022 research paper I am citing here.  I hope this is helpful.

Soy Foods and Amount of Isoflavones: Source: J Nutrients 2018 Soy foods and soy bioactive substances. https://www.researchgate.net/publication/322292620_Soy_Soy_Foods_and_Their_Role_in_Vegetarian_Diets

Reference:

Fan Y et al. Intake of Soy, Soy Isoflavones and Soy Protein and Risk of Cancer Incidence and Mortality Front. Nutr., 04 March 2022
https://www.frontiersin.org/articles/10.3389/fnut.2022.847421/full

Eat Smart, Live Well, Look Great,

Dr. Meschino