Seaweed and Cancer

The anticarcinogenic properties of brown seaweeds (kelps, wracks and others) are well known in some cultures but not yet understood. Traditional Chinese medicine includes the brown alga Laminaria in the treatment of cancer and it has also been recommended in ancient Ayurvedic texts. There is even a mention in the Ebers Papyrus of the ancient Egyptians having used seaweed to treat breast cancer.

The first use of seaweed to treat cancer in Western medicine was in the 1960s, when something called Algasol T331 was used in Italy. According to a paper presented in 1966 by Claudio & Standardo, 68% of 162 patients made a good recovery following intramuscular injections. The good recovery seems to have been improved well-being following chemotherapy, including increasing appetite and hair regrowth. Unfortunately, no further research was done.  

In the 1980s, work was done on VivaNatural, a health-food supplement based on a folk remedy for cancer in rural area of Japan. It was studied in a series of animal models. Again, it appeared to be effective, showing more antitumor effect than several conventional cancer chemotherapeutic agents, and again research interest seemed to end.  In other laboratories, brown seaweed extracts have shown inhibition of cancer cells grown in cell culture, inhibition of cancer growth in animals who have been given chemical carcinogens and in animals who have had tumors transplanted into them. Four studies have used powdered seaweed incorporated into rat food, and found that the seaweed-supplemented diet was associated with a delay in time to tumor development and fewer tumors per tumor bearing animal. Other work has focused on particular constituents of kelp, such as fucoidan, a sulphated polysaccharide found only in brown seaweeds and some bacteria. Another line of research has focused on alginic acid. Several studies have also found that kelp extracts appeared to show some activity against HIV in cell culture.

Kombu (Saccharina japonica and other species of the genera Saccharina and Laminaria) and Wakame (Undaria pinnatifida) contain something that is said to cause cancer cells to self-destruct. It has been recently discovered in Japan that this substance is fucoidan, a complex polysaccharide, one of many polysaccharides found in kelps and other seaweeds. In research in Japan, fucoidan administered to cancer cells in a laboratory dish were virtually wiped out within 72 hours. The process by which these cells withered away was self-induced, in that the DNA within each of the cancer cells was broken down by digestive enzymes contained in the cells themselves. This process is known by the technical term apoptosis.

Although fucoidan is found in other seaweeds and plants, kombu and wakame are said to be particularly rich sources. It is interesting to note that Okinawa has the lowest cancer mortality rate in Japan where the people eat their kombu mostly uncooked; by contrast, other parts of Japan where it is used mostly in cooking. However, in general, breast cancer rates are lower in Japan than in western countries, and this may be due to seaweed consumption.

Another caution is that kelp contains high amounts of iodine, and although safely eaten in amounts of about 0.25 ounces/day in Japan by millions of people, in fishing villages where intake can reach up to the equivilent of four ounces per day, iodine-induced goiter can be a problem. Dried kelp expands to about 10 times its size and weight once it has been soaked in water.

A study of the effects of Bladderwrack (Fucus vesiculosus) by a scientist at the University of California at Berkeley (Skibola 2004) suggest that dietary Bladderwrack may prolong the length of the menstrual cycle and exert anti-estrogenic effects in pre-menopausal women. Further, these studies also suggest that seaweed may be another important dietary component - apart from soy - that is responsible for the reduced risk of estrogen-related cancers observed in Japanese populations. However, as concluded by the author, these studies need to be repeated in well-controlled clinical trials to confirm these preliminary findings.

References

Fujihara, M. et al. 1984. Purification and chemical and physical characterization of an antitumor polysaccharide from the brown seaweed Sargassum fulvellum. Carbohydrate Research 125:97-106.

Funayama, S. et al. 1981. Hypotensive principle of Laminaria and allied seaweeds. J. Medicinal Plant Research 41:29-33.

Furusawa, E. et al. 1985. Anticancer activity of a natural product, viva-natural, extracted from Undaria pinnantifida on intraperitoneally implanted Lewis lung carcinoma. Oncology 42:364-369.

Ohigashi, H., Y. Sakai, K. Yamaguchi, I. Umezaki & K. Koshimizu. 1992. Possible anti-tumor promoting properties of marine algae and in vivo activity of Wakame seaweed extract. Biosci. Biotechnol. Biochem. 56:994-995.

Okai, Y., K. Higashi-Okai & S. -I. Nakamura. 1993. Identification of heterogenous antimutagenic activities in the extract of edible brown seaweeds, Laminaria japonica (Makonbu) and Undaria pinnatifida (Wakame) by the umu gene expression system in Salmonella typhimurium (TA1535/pSK1002). Mut. Res. 303:63-70.

Teas, J. 1981. The consumption of seaweed as a protective factor in the etiology of breast cancer. Medical Hypotheses 7:601-613.

Teas, J. 1983. The dietary intake of Laminaria, a brown seaweed, and breast cancer prevention. Nutr. Cancer 4:217-222.

Yamamoto, I. et al. 1984. Antitumor activity of edible marine algae: effect of crude Fucoidan fractions prepared from edible brown seaweeds against L-1210 leukemia. Hydrobiologia 116/117:145-148.