"Wakame Seaweed Salad May Lower Blood Pressure"
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; 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 is 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 flaxseeds, 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 pre-schoolers 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 other components of the diet
that went along with the seaweed eating.
It's even harder to do these kinds of studies on adults,
since 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 put whole powdered seaweed in pills?
Which was apparently finally attempted 10 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 about 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 listings as well,
such as the resolution of gastritis—stomach inflammation
that they'd been having—as well as the disappearance of chronic headaches.