It is believed that the Japanese have a lower breast and prostate cancer incidence due to the consumption of a diet high in seaweed (iodine), fish (omega 3) and soybeans (isoflavones).
Seaweed is a great source of minerals, vitamins, fibre and many other nutrients. An important mineral to mention is iodine, whose deficiency may be a cause of hypothyroidism, prostate cancer and breast cancer with distant metastasis (Rappaport, 2017).
Seaweed is classified according to its colour: red, green and brown. Interestingly, brown seaweed is high in fucoidan, an element with anti-cancer, anti-cancer proliferation and anti-inflammatory properties. The most common brown seaweed is: kelp, wakame, mekabu, kombu.
Kelp is a great source of iodine, reduces inflammation, may reduce blood sugar and lowers oestrogen production, preventing growth and risk of breast cancer. It may protect against cancer in women who take the birth control pill. Wakame also reduces breast cancer risk due to its fucoidan content. Wakame root, mekabu, induces cell death in human hormone receptor negative (ER-/PR-) breast cancer cells.
In addition, many brown types of seaweed contain high levels of melatonin which prevents and treats several cancers such as prostate, breast, gastric and colorectal cancers (Li et al., 2017).
- Thyroid Carcinoma: incidence increases after a prolonged iodine deficiency
- Breast Cancer: incidence of breast cancer may be influenced by the iodine intake.
- Prostate cancer: Iodine supplementation reduces cell proliferation and induces apoptosis in human prostate cancer cells.
It is better to consume seaweed as food rather than fucoidan, kelp or other seaweed supplements.
Some seaweed can worsen high blood pressure due to its sodium content.
Avoid if you have diarrhoea, loose or watery stools.
Some seaweed is high in vitamin K and may interfere with anticoagulants such as heparin or warfarin.
Seaweed may not be appropriate for patients with kidney issues.
Kelp-> Dosage: 3g in tablets or capsule, or one teaspoon of granules per day (Pitchford,2002)
Note: always check with your nutritionist and doctor before taking any supplement.
- Feldt-Rasmussen, U. (2004). Iodine and Cancer. Liebertpub, 11,5. https://doi.org/10.1089/105072501300176435
- Funahashi, H., Imai, T., Mase, T., Sekiya, M., Yokoi, K., Hayashi, H. … Shibata, A. (2001). Seaweed prevents breast cancer? Retrieved from https://pubmed.ncbi.nlm.nih.gov/11376555/
- Li, Y., Li S., Zhou, Y., Meng, X., Zhang, J-J., Xu, D-P. and Li, H-B (2017). Melatonin for the prevention and treatment of cancer. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5503661/
- Mitro, S., Rozek, L., Vatanasapt, P., Suwanrungruang, K., Chitapanarux, I., Srisukho, S. …Meza, R. (2016). Iodine deficiency and thyroid cancer trends in three regions of Thailand, 1990-2009. Retrieved from https://pubmed.ncbi.nlm.nih.gov/27420631/
- Olvera-Caltzontzin, P., Delgado, G., Aceves, C. and Anguiano, B. (2013). Iodine Uptake and Prostate Cancer in the TRAMP Mouse Model. Retrieved from https://molmed.biomedcentral.com/articles/10.2119/molmed.2013.00093
- Pitchford, P. (2002). Healing with Whole Foods. North Atlantic Books: Berkeley, California
- Rappaport, J. (2017). Changes in Dietary Iodine Explains Increasing Incidence of Breast Cancer with Distant Involvement in Young Women. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5327366/