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TEAS
Seaweed and soy: companion foods in asian cuisine and their effects on thyroid function in american women.
Teas J, Braverman LE, Kurzer MS, Pino S, Hurley TG, Hebert JR.
J Med Food. 2007 Spring;10(1):90-100.
[abstract only]
"Seaweeds and soy are two commonly eaten foods in Asia. Both have been reported to affect thyroid function, seaweed because of its iodine content and soy because of its goitrogenic effect. Twenty-five healthy postmenopausal women (mean age 58 years) completed a double-blinded randomized crossover study. Ten capsules (5 g/day) of placebo or seaweed (Alaria esculenta), providing 475 mug of iodine/day, were consumed daily for 7 weeks. A powdered soy protein isolate (Solae Co., St. Louis, MO), providing 2 mg of isoflavones/kg of body weight, was given daily during the last week of each treatment arm. On average, this provided 141.3 mg of isoflavones/day and 67.5 g of protein/day. Blood samples and 48-hour urine samples were collected before and after each intervention period, and urinary I/C (mug of iodine/g of creatinine) and serum thyroxine, free thyroxine index, total triiodothyronine, and thyroid stimulating hormone (TSH) were measured. Seaweed ingestion increased I/C concentrations (P < .0001) and serum TSH (P < .0001) (1.69 +/- 0.22 vs. 2.19 +/- 0.22 muU/mL, mean +/- SE). Soy supplementation did not affect thyroid end points. Seven weeks of 5 g/day seaweed supplementation was associated with a small but statistically significant increase in TSH. Soy protein isolate supplementation was not associated with changes in serum thyroid hormone concentrations."
Variability of iodine content in common commercially available edible seaweeds.
Teas J, Pino S, Critchley A, Braverman LE.
Thyroid. 2004 Oct;14(10):836-41.
“Dietary seaweeds, common in Asia and in Asian restaurants, have become established as part of popular international cuisine. To understand the possibility for iodine-induced thyroid dysfunction better, we collected samples of the most common dietary seaweeds available from commercial sources in the United States, as well as harvester-provided samples from Canada, Tasmania, and Namibia. Altogether, 12 different species of seaweeds were analyzed for iodine content, and found to range from 16 microg/g (+/-2) in nori (Porphyra tenera) to over 8165 +/- 373 microg/g in one sample of processed kelp granules (a salt substitute) made from Laminaria digitata. We explored variation in preharvest conditions in a small study of two Namibian kelps (Laminaria pallida and Ecklonia maxima), and found that iodine content was lowest in sun-bleached blades (514 +/- 42 microg/g), and highest amount in freshly cut juvenile blades (6571 +/- 715 microg/g). Iodine is water-soluble in cooking and may vaporize in humid storage conditions, making average iodine content of prepared foods difficult to estimate. It is possible some Asian seaweed dishes may exceed the tolerable upper iodine intake level of 1100 microg/d.”
Algae -- a poor man's HAART?
Teas J, Hebert JR, Fitton JH, Zimba PV.
Med Hypotheses. 2004;62(4):507-10. Review.
[abstract only]
"Drawing inferences from epidemiologic studies of HIV/AIDS and in vivo and in vitro HIV inhibition by algae, we propose algal consumption as one unifying characteristic of countries with anomalously low rates. HIV/AIDS incidence and prevalence in Eastern Asia ( approximately 1/10000 adults in Japan and Korea), compared to Africa ( approximately 1/10 adults), strongly suggest that differences in IV drug use and sexual behavior are insufficient to explain the 1000-fold variation. Even in Africa, AIDS/HIV rates vary. Chad has consistently reported low rates of HIV/AIDS (2-4/100). Possibly not coincidentally, most people in Japan and Korea eat seaweed daily and the Kanemba, one of the major tribal groups in Chad, eat a blue green alga (Spirulina) daily. Average daily algae consumption in Asia and Africa ranges between 1 and 2 tablespoons (3-13 g). Regular consumption of dietary algae might help prevent HIV infection and suppress viral load among those infected."
Dietary seaweed (Laminaria) and mammary carcinogenesis in rats.
Teas J, Harbison ML, Gelman RS.
Cancer Res. 1984 Jul;44(7):2758-61.
[abstract only]
"To test the potential in vivo antitumor effect of dietary seaweed, we induced mammary tumors in female Sprague-Dawley rats with the carcinogen 7,12-dimethylbenz(a)anthracene. Twenty-one-day-old rats (n = 108) were divided into two groups. Controls were fed a standard semipurified diet, and experimental rats received the control diet with 5% Laminaria, a brown seaweed, replacing 5% alphacel . At 55 days of age, each rat received 5 mg 7,12-dimethylbenz(a)anthracene intragastrically. Rats were palpated for mammary tumors and weighed weekly for 26 weeks. Complete autopsies were then done on all rats. The seaweed diet did not alter weight gain or weights of body organs at autopsy. Experimental rats had a significant delay in the time to tumor (p = 0.007); median time until tumor was 19 weeks in experimental rats and 11 weeks in control animals. Among mammary adenocarcinoma tumor-bearing animals, experimental rats had fewer adenocarcinomas/individual (p less than 0.05). There was also an overall 13% reduction in the number of experimental rats with histologically confirmed adenocarcinomas (76% among the control rats compared to 63% among the experimental rats). Components of Laminaria which might account for the observed difference in mammary tumor growth are varied and include the sulfated polysaccharide fucoidan . Rats in the top row of cages had a significant (p = 0.01) delay in time to tumor compared to rats in the lower four rows. In each row, the seaweed-fed rats had a longer time to tumor than did the control rats."
The dietary intake of Laminaria, a brown seaweed, and breast cancer prevention.
Teas J
Nutr Cancer. 1983;4(3):217-22. Review.
[abstract only]
"Based on epidemiological and biological data, Laminaria, a brown kelp seaweed, is proposed as an important factor contributing to the relatively low breast cancer rates reported in Japan. Several possible mechanisms for the influence of Laminaria on breast cancer are proposed: Laminaria is a source of nondigestible fiber, thereby increasing fecal bulk and decreasing bowel transit time; it changes the posthepatic metabolism of sterols; it contains an antibiotic substance that may influence fecal ecology; it contains 1-3 beta glucan, which alters enzymatic activity of fecal flora; and it stimulates the host-mediated immune response. It is suggested that Laminaria may play a role in preventing either the initiation of breast cancer or its promotion by endogenous physiological factors."
The consumption of seaweed as a protective factor in the etiology of breast cancer.
Teas, J
Med Hypotheses. 1981 May;7(5):601-13.
"A review of the biological properties of seaweed is presented and the role of seaweed as a breast cancer anticarcinogen is suggested. Proposed mechanisms of action are: reduction of plasma cholesterol, binding of biliary steroids, inhibition of carcinogenic fecal flora, binding of pollutants, stimulation of the immune system, and the protective effects of beta-sitosterols. In an experiment using sarcoma-180 in mice, seaweed extract appeared to have an antitumor effect. Thus it is suggested that breast cancer may be prevented and that this dietary habit among the Japanese could be an important factor in understanding the lower breast cancer rates reported in Japan."