Seaweed salad is put to the test for hypertension.
Wakame Seaweed Salad May Lower Blood Pressure
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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
I used to think of seaweed as just a beneficial whole food source of minerals—like iodine, for which it is the most concentrated dietary source. And, indeed, just a half-teaspoon of mild seaweeds, like arame or dulse, or two sheets of nori a day, should net you all the iodine you need for the day.
But, “the intake of seaweeds is advised” not only as a whole food source of iodine, but also, evidently, “for the prevention of lifestyle-related chronic diseases.” Based on what?
Well, you’ll see this kind of reasoning: the Japanese live long, and they eat seaweed. And so, they speculate that seaweed might have something to do with it, based on suggestive reports. But, when you see lists, like this, of all the supposed biological activities some food has, you want to know is this based on clinical data (meaning on actual people) or so-called preclinical data (based on test tubes and lab animals)? When a study like this is published, talking about the “Effects of seaweed-reconstructed pork diets” on rats, what do you do with that information? Seaweed is one of the ingredients they’re trying to use to improve the “image” of meat products. So, they try to add grape seeds, or flax seeds, or walnuts, or purple rice or, whatever this is. I had to look it up: thong-weed. How’s that for an image booster?
You can look at epidemiological studies (meaning looking at populations). And, indeed, Japanese preschoolers who eat seaweed tend to have lower blood pressures, suggesting seaweed might have beneficial effects—which would make sense, given all the minerals and fiber. But, you can’t prove cause and effect with that kind of study. Maybe it was the other components of the diet that went along with the seaweed-eating.
It’s even harder to do these kinds of studies on adults: so many people are on high blood pressure medications. University of Tokyo researchers took an innovative approach by comparing the diets of people on low-dose, versus high-dose, versus multiple blood pressure medications. And, although they all had artificially normalized blood pressure, those that ate the most fruit and sea vegetables tended to be the ones on the lower doses—supporting a dietary role for seaweed. But, why not just put it to the test?
A double-blind crossover trial found that seaweed fiber lowered blood pressure, apparently by pulling sodium out of the system. I know they couldn’t use real seaweed, because then you couldn’t fool people with a placebo; but, why not just, like, put whole powdered seaweed in pills? This was finally attempted, ten years later.
Compared to doing nothing, they got beautiful drops in blood pressure. But, if you look deeper into the study, they desalinized the seaweed—meaning they took out two-thirds of the sodium naturally found in it. So, that still doesn’t tell us if eating seaweed salad is actually going to help with blood pressure. What we need is a randomized controlled trial with just plain, straight seaweed. But, no one had ever done that study—until this study out of Ecuador.
Six grams of wakame, natural sodium and all, led to a significant drop in blood pressure, especially in those who started out high. Side effects were all minor, and what one might expect increasing fiber intake. And, the nice thing about whole food, plant-based interventions is you sometimes get good side effects as well, such as the resolution of gastritis—stomach inflammation that they’d been having—as well as the disappearance of chronic headaches.
Please consider volunteering to help out on the site.
- Schultz Moreira AR, García-Fernández RA, Bocanegra A, Méndez MT, Bastida S, Benedí J, Sánchez-Reus MI, Sánchez-Muniz FJ. Effects of seaweed-restructured pork diets enriched or not with cholesterol on rat cholesterolaemia and liver damage. Food Chem Toxicol. 2013 Jun;56:223-30.
- Miyake Y, Tanaka K, Okubo H, Sasaki S, Arakawa M. Seaweed consumption and prevalence of depressive symptoms during pregnancy in Japan: Baseline data from the Kyushu Okinawa Maternal and Child Health Study. BMC Pregnancy Childbirth. 2014 Sep 3;14:301.
- Negishi H, Mori M, Mori H, Yamori Y. Supplementation of elderly Japanese men and women with fucoidan from seaweed increases immune responses to seasonal influenza vaccination. J Nutr. 2013 Nov;143(11):1794-8.
- Ono A, Shibaoka M, Yano J, Asai Y, Fujita T. Eating habits and intensity of medication in elderly hypertensive outpatients. Hypertens Res. 2000 May;23(3):195-200.
- Hata Y, Nakajima K, Uchida J, Hidaka H, Nakano, T. linical Effects of Brown Seaweed, Undaria pinnatifida (wakame), on Blood Pressure in Hypertensive Subjects. Journal of Clinical Biochemistry and Nutrition Vol. 30 (2001) P 43-53.
- Teas J, Baldeón ME, Chiriboga DE, Davis JR, Sarriés AJ, Braverman LE. Could dietary seaweed reverse the metabolic syndrome? Asia Pac J Clin Nutr. 2009;18(2):145-54.
- Wada K, Nakamura K, Tamai Y, Tsuji M, Sahashi Y, Watanabe K, Ohtsuchi S, Yamamoto K, Ando K, Nagata C. Seaweed intake and blood pressure levels in healthy pre-school Japanese children. Nutr J. 2011 Aug 10;10:83.
- Krotkiewski M, Aurell M, Holm G, Grimby G, Szczepanik J. Effects of a sodium-potassium ion-exchanging seaweed preparation in mild hypertension. Am J Hypertens. 1991 Jun;4(6):483-8.
- Combet E, Ma ZF, Cousins F, Thompson B, Lean ME. Low-level seaweed supplementation improves iodine status in iodine-insufficient women. Br J Nutr. 2014 Sep 14;112(5):753-61.
- Tokudome S, Tokudome Y, Goto C, Suzuki S, Moore MA. Seaweed as a beneficial iodine food source. Asian Pac J Cancer Prev. 2004 Jan-Mar;5(1):89.
- Gomez-Gutierrez CM, Guerra-Rivas G, Soria-Mercado IE, Ayala-Sánchez NE. Marine edible algae as disease preventers. Adv Food Nutr Res. 2011;64:29-39.
- Bocanegra A, Bastida S, Benedí J, Ródenas S, Sánchez-Muniz FJ. Characteristics and nutritional and cardiovascular-health properties of seaweeds. J Med Food. 2009 Apr;12(2):236-58.
- González-Torres L, Churruca I, Schultz Moreira AR, Bastida S, Benedí J, Portillo MP, Sánchez-Muniz FJ. Effects of restructured pork containing Himanthalia elongata on adipose tissue lipogenic and lipolytic enzyme expression of normo- and hypercholesterolemic rats. J Nutrigenet Nutrigenomics. 2012;5(3):158-67.
- Adema H, Huwae, PHM. New and supplementary records of marine Isopoda for the Netherlands and the Southern North Sea since 1956, with a note on Peltogaster paguri (Crustacea, Cirripedia).
- Reddy GV, Sen AR, Nair PN, Reddy KS, Reddy KK, Kondaiah N. Effects of grape seed extract on the oxidative and microbial stability of restructured mutton slices. Meat Sci. 2013 Oct;95(2):288-94.
- Sharma H, Sharma BD, Mendiratta SK, Talukder S, Ramasamy G. Efficacy of flaxseed flour as bind enhancing agent on the quality of extended restructured mutton chops. Asian-Australas J Anim Sci. 2014 Feb;27(2):247-55.
- Min B, Chen MH, Green BW. Antioxidant activities of purple rice bran extract and its effect on the quality of low-NaCl, phosphate-free patties made from channel catfish (Ictalurus punctatus) belly flap meat. J Food Sci. 2009 Apr;74(3):C268-77.
- Canales A, Benedí J, Nus M, Librelotto J, Sánchez-Montero JM, Sánchez-Muniz FJ. Effect of walnut-enriched restructured meat in the antioxidant status of overweight/obese senior subjects with at least one extra CHD-risk factor. J Am Coll Nutr. 2007 Jun;26(3):225-32.
Image credit: Silentpilot via Pixabay. Image was modified.
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
I used to think of seaweed as just a beneficial whole food source of minerals—like iodine, for which it is the most concentrated dietary source. And, indeed, just a half-teaspoon of mild seaweeds, like arame or dulse, or two sheets of nori a day, should net you all the iodine you need for the day.
But, “the intake of seaweeds is advised” not only as a whole food source of iodine, but also, evidently, “for the prevention of lifestyle-related chronic diseases.” Based on what?
Well, you’ll see this kind of reasoning: the Japanese live long, and they eat seaweed. And so, they speculate that seaweed might have something to do with it, based on suggestive reports. But, when you see lists, like this, of all the supposed biological activities some food has, you want to know is this based on clinical data (meaning on actual people) or so-called preclinical data (based on test tubes and lab animals)? When a study like this is published, talking about the “Effects of seaweed-reconstructed pork diets” on rats, what do you do with that information? Seaweed is one of the ingredients they’re trying to use to improve the “image” of meat products. So, they try to add grape seeds, or flax seeds, or walnuts, or purple rice or, whatever this is. I had to look it up: thong-weed. How’s that for an image booster?
You can look at epidemiological studies (meaning looking at populations). And, indeed, Japanese preschoolers who eat seaweed tend to have lower blood pressures, suggesting seaweed might have beneficial effects—which would make sense, given all the minerals and fiber. But, you can’t prove cause and effect with that kind of study. Maybe it was the other components of the diet that went along with the seaweed-eating.
It’s even harder to do these kinds of studies on adults: so many people are on high blood pressure medications. University of Tokyo researchers took an innovative approach by comparing the diets of people on low-dose, versus high-dose, versus multiple blood pressure medications. And, although they all had artificially normalized blood pressure, those that ate the most fruit and sea vegetables tended to be the ones on the lower doses—supporting a dietary role for seaweed. But, why not just put it to the test?
A double-blind crossover trial found that seaweed fiber lowered blood pressure, apparently by pulling sodium out of the system. I know they couldn’t use real seaweed, because then you couldn’t fool people with a placebo; but, why not just, like, put whole powdered seaweed in pills? This was finally attempted, ten years later.
Compared to doing nothing, they got beautiful drops in blood pressure. But, if you look deeper into the study, they desalinized the seaweed—meaning they took out two-thirds of the sodium naturally found in it. So, that still doesn’t tell us if eating seaweed salad is actually going to help with blood pressure. What we need is a randomized controlled trial with just plain, straight seaweed. But, no one had ever done that study—until this study out of Ecuador.
Six grams of wakame, natural sodium and all, led to a significant drop in blood pressure, especially in those who started out high. Side effects were all minor, and what one might expect increasing fiber intake. And, the nice thing about whole food, plant-based interventions is you sometimes get good side effects as well, such as the resolution of gastritis—stomach inflammation that they’d been having—as well as the disappearance of chronic headaches.
Please consider volunteering to help out on the site.
- Schultz Moreira AR, García-Fernández RA, Bocanegra A, Méndez MT, Bastida S, Benedí J, Sánchez-Reus MI, Sánchez-Muniz FJ. Effects of seaweed-restructured pork diets enriched or not with cholesterol on rat cholesterolaemia and liver damage. Food Chem Toxicol. 2013 Jun;56:223-30.
- Miyake Y, Tanaka K, Okubo H, Sasaki S, Arakawa M. Seaweed consumption and prevalence of depressive symptoms during pregnancy in Japan: Baseline data from the Kyushu Okinawa Maternal and Child Health Study. BMC Pregnancy Childbirth. 2014 Sep 3;14:301.
- Negishi H, Mori M, Mori H, Yamori Y. Supplementation of elderly Japanese men and women with fucoidan from seaweed increases immune responses to seasonal influenza vaccination. J Nutr. 2013 Nov;143(11):1794-8.
- Ono A, Shibaoka M, Yano J, Asai Y, Fujita T. Eating habits and intensity of medication in elderly hypertensive outpatients. Hypertens Res. 2000 May;23(3):195-200.
- Hata Y, Nakajima K, Uchida J, Hidaka H, Nakano, T. linical Effects of Brown Seaweed, Undaria pinnatifida (wakame), on Blood Pressure in Hypertensive Subjects. Journal of Clinical Biochemistry and Nutrition Vol. 30 (2001) P 43-53.
- Teas J, Baldeón ME, Chiriboga DE, Davis JR, Sarriés AJ, Braverman LE. Could dietary seaweed reverse the metabolic syndrome? Asia Pac J Clin Nutr. 2009;18(2):145-54.
- Wada K, Nakamura K, Tamai Y, Tsuji M, Sahashi Y, Watanabe K, Ohtsuchi S, Yamamoto K, Ando K, Nagata C. Seaweed intake and blood pressure levels in healthy pre-school Japanese children. Nutr J. 2011 Aug 10;10:83.
- Krotkiewski M, Aurell M, Holm G, Grimby G, Szczepanik J. Effects of a sodium-potassium ion-exchanging seaweed preparation in mild hypertension. Am J Hypertens. 1991 Jun;4(6):483-8.
- Combet E, Ma ZF, Cousins F, Thompson B, Lean ME. Low-level seaweed supplementation improves iodine status in iodine-insufficient women. Br J Nutr. 2014 Sep 14;112(5):753-61.
- Tokudome S, Tokudome Y, Goto C, Suzuki S, Moore MA. Seaweed as a beneficial iodine food source. Asian Pac J Cancer Prev. 2004 Jan-Mar;5(1):89.
- Gomez-Gutierrez CM, Guerra-Rivas G, Soria-Mercado IE, Ayala-Sánchez NE. Marine edible algae as disease preventers. Adv Food Nutr Res. 2011;64:29-39.
- Bocanegra A, Bastida S, Benedí J, Ródenas S, Sánchez-Muniz FJ. Characteristics and nutritional and cardiovascular-health properties of seaweeds. J Med Food. 2009 Apr;12(2):236-58.
- González-Torres L, Churruca I, Schultz Moreira AR, Bastida S, Benedí J, Portillo MP, Sánchez-Muniz FJ. Effects of restructured pork containing Himanthalia elongata on adipose tissue lipogenic and lipolytic enzyme expression of normo- and hypercholesterolemic rats. J Nutrigenet Nutrigenomics. 2012;5(3):158-67.
- Adema H, Huwae, PHM. New and supplementary records of marine Isopoda for the Netherlands and the Southern North Sea since 1956, with a note on Peltogaster paguri (Crustacea, Cirripedia).
- Reddy GV, Sen AR, Nair PN, Reddy KS, Reddy KK, Kondaiah N. Effects of grape seed extract on the oxidative and microbial stability of restructured mutton slices. Meat Sci. 2013 Oct;95(2):288-94.
- Sharma H, Sharma BD, Mendiratta SK, Talukder S, Ramasamy G. Efficacy of flaxseed flour as bind enhancing agent on the quality of extended restructured mutton chops. Asian-Australas J Anim Sci. 2014 Feb;27(2):247-55.
- Min B, Chen MH, Green BW. Antioxidant activities of purple rice bran extract and its effect on the quality of low-NaCl, phosphate-free patties made from channel catfish (Ictalurus punctatus) belly flap meat. J Food Sci. 2009 Apr;74(3):C268-77.
- Canales A, Benedí J, Nus M, Librelotto J, Sánchez-Montero JM, Sánchez-Muniz FJ. Effect of walnut-enriched restructured meat in the antioxidant status of overweight/obese senior subjects with at least one extra CHD-risk factor. J Am Coll Nutr. 2007 Jun;26(3):225-32.
Image credit: Silentpilot via Pixabay. Image was modified.
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Title
Wakame Seaweed Salad May Lower Blood Pressure
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
What other foods might help with high blood pressure? See:
- Hibiscus Tea vs. Plant-Based Diets for Hypertension
- Flaxseeds for Hypertension
- Oxygenating Blood with Nitrate-Rich Vegetables
- Benefits of Blueberries for Blood Pressure May Be Blocked by Yogurt
For more on preventing and treating hypertension, one of our leading killers, see:
- How to Prevent High Blood Pressure with Diet
- How to Treat High Blood Pressure with Diet
- High Blood Pressure May Be a Choice
- Sprinkling Doubt: Taking Sodium Skeptics with a Pinch of Salt
- Drugs and the Demise of the Rice Diet
- Kempner Rice Diet: Whipping Us Into Shape
- The Evidence That Salt Raises Blood Pressure
Want more on seaweed and iodine? Check out:
- Too Much Iodine Can Be as Bad as Too Little
- Which Seaweed Is Most Protective Against Breast Cancer?
- Iodine Supplements Before, During, and After Pregnancy
My video Salt of the Earth: Sodium and Plant-Based Diets further addresses the sodium question.
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