Brown Seaweed as a Breast Cancer Preventive

• Serum estrogen and urinary phytoestrogen concentrations affected by seaweed and soy [ Time Frame: 14 wks ] [ Designated as safety issue: No ]
  6 wk seaweed then 1 wk seaweed plus soy; OR 6 wk placebo then 1 wk soy 3 wk washout period, then crossover to alternate arm
• Serum antioxidant and homocysteine concentrations associated with seaweed and soy [ Time Frame: 14 wks ] [ Designated as safety issue: No ]
  6 wks seaweed followed by 1 wk seaweed plus soy OR 6 wk placebo followed by 1 wk soy 3 wk washout period, then crossover to alternate arm
• Serum IGF-1 and IGFBP3 changes associated with seaweed and soy supplementation [ Time Frame: 14 wk ] [ Designated as safety issue: No ]
  6 wk seaweed then 1 wk seaweed plus soy OR 6 wk placebo then 1 wk soy plus placebo 3 wk washout then crossover to alternate arm

Japanese postmenopausal women in Japan have about one ninth the rate of American postmenopausal women. Rates of breast cancer double even after just ten years among Japanese women who migrate to the US. Diet is thought to be an important factor, and the investigators were interested in whether dietary seaweed, with and without soy supplements, could influence known biomarkers of breast cancer risk in American women.

33 healthy postmenopausal women were randomized to 6 wk seaweed then 1 wk seaweed plus soy or 6 wk placebo then 1 wk placebo plus soy. Blood and urine samples were collected at the end of each treatment period and analyzed for estrogen, homocysteine, antioxidants, insulin-like growth factors and thyroid hormones. Urine was analyzed for phytoestrogens and iodine.

• Breast Cancer
• Thyroid Hormones

• Dietary Supplement: Alaria esculenta, soy protein isolate
  5 g/d Alaria esculenta, given in pills to be taken in the evening for 6 wks Soy protein isolate powder (2 mg/kg body wt)given during the 7th wk with Alaria
  Other Name: Solae Soy Food Ingredient Powder (AB1.2 HG 20CA 29)
• Dietary Supplement: Soy protein isolate, placebo
  Placebo (10 capsules/d of maltodextrin to be taken in the evening for 7 wks) followed by 1 wk placebo capsules plus soy protein isolate powder, to be taken once a day in the evening
  Other Names:

  • Solae Nutritious Food Ingredient Powder (AB1.2 HG 20CA 29)
  • Maltrin M100 maltodextrin (Grain Processing)

• Experimental: Arm 1: seaweed and soy
  5 g/d seaweed for 6 wk, then 5 g/d seaweed plus soy supplement for 1 wk
  Intervention: Dietary Supplement: Alaria esculenta, soy protein isolate
• Experimental: Arm 2 Placebo, soy
  6 wk placebo (10 maltodextrin 5 g/d capsules), followed by 1 wk of placebo capsules and soy powder
  Intervention: Dietary Supplement: Soy protein isolate, placebo

• Teas J, Hurley TG, Hebert JR, Franke AA, Sepkovic DW, Kurzer MS. Dietary seaweed modifies estrogen and phytoestrogen metabolism in healthy postmenopausal women. J Nutr. 2009 May;139(5):939-44. Epub 2009 Mar 25. Erratum in: J Nutr. 2009 Sep;139(9):1779.
• Teas J, Braverman LE, Kurzer MS, Pino S, Hurley TG, Hebert JR. Seaweed and soy: companion foods in Asian cuisine and their effects on thyroid function in American women. J Med Food. 2007 Mar;10(1):90-100.
• Teas J, Pino S, Critchley A, Braverman LE. Variability of iodine content in common commercially available edible seaweeds. Thyroid. 2004 Oct;14(10):836-41.

Inclusion Criteria:

• Postmenopausal (self-reported cessation of menstruation 1 y prior to enrollment)
• If breast cancer survivor, all therapy completed at least 6 months prior to enrollment
• Agreed to eat their normal diet, avoiding seaweeds and phytoestrogen-rich foods,
• Restricting alcoholic intake to #2 drinks (24 g alcohol)/wk -Continuing habitual intake of vitamins, supplements, and medications during the study. -

Exclusion Criteria:

• No allergies to seaweed, soy, shellfish, or iodine
• No current use of tobacco;
• No thyroid dysfunction or treatment within the previous 5 y;
• Negative thyroid peroxidase antibodies as determined by screening;
• No hormone replacement therapy or for breast cancer survivors, no chemotherapy or radiation treatments within the preceding 6 mo
• No history of cancer (other than breast cancer)
• No current gastrointestinal disorders or diabetes; omnivorous eating habits, including meat and dairy products at least twice/wk
• No oral antibiotics, iodine containing medications, or corticosteroids treatment within the previous 3 mo.