> ## Content Index > Fetch the complete content index at: https://the-healing-plate.ghost.io/llms.txt > Use this file to discover other available public pages before exploring further. # Miso Soup Is Salty. The Blood Pressure Studies Say Something Odd - URL: https://the-healing-plate.ghost.io/miso-soup-is-salty-the-blood-pressure-studies-say-something-odd/ - Published: 2026-10-29T16:00:00.000Z - Updated: 2026-10-30T14:50:08.000Z - Description: A real kombu and shiitake broth, the miso stirred in off the boil, and what the science says about the salt, the seaweed and the "live" cultures. - Author: The Healing Plate A real kombu and shiitake broth, the miso stirred in off the boil, and what the science says about the salt, the seaweed and the "live" cultures. You've been told two things about miso soup. It's good for your gut. And it's loaded with salt. Only one is plainly true. It's the salt. But the salt story has an odd twist. The gut story has a hole. And the seaweed carries a warning that rarely makes the label... The broth has a famous past. In 1907, Kikunae Ikeda, a chemist at Tokyo Imperial University, got hooked on the taste of kombu. That's the thick dried kelp behind dashi, the clear stock under miso soup. The broth had a taste that wasn't sweet, sour, salty or bitter. By 1908 he had pulled the cause out of the kelp. It was glutamate. He named its taste umami. So your broth is where a fifth taste was found. Here's the pot... ### Kombu And Shiitake Miso Soup, Serves 4 30 min soaking, 20 min at the stove - 1 liter (1,000 ml) cold water - 5 g dried kombu (half what most recipes use, on purpose) - 4 dried shiitake caps, about 15 g - 60 g miso, about 4 level tablespoons - 150 g firm tofu, cut in 1 cm cubes - 2 scallions, sliced thin ### Method 1. Put the water, kombu and shiitake in a pot. Soak for 30 min, or overnight in the fridge. 2. Heat over medium-low. When tiny bubbles form at the edge, about 10 min in, lift out the kombu. Don't boil it. 3. Lift out the shiitake, cut off the stems, slice the caps thin and drop them back in. 4. Simmer 5 min so the mushrooms cook through. Add the tofu for 2 min more. 5. Turn off the heat and wait about a minute, until the bubbling stops and the pot sits just under the boil. 6. Put the miso in a ladle, dip it in the broth and whisk it smooth with a fork. Stir it through. Never boil it again, or the miso goes flat. 7. Top with the scallions and serve. ### The Fish Version After the kombu comes out, bring the pot to a boil and turn it off. Add 10 g katsuobushi, dried bonito flakes, steep 2 min and strain. Then carry on from step 3\. It's deeper and smokier, and no longer vegan. ## The Salt, Straight Off A Label Miso is cooked soybeans mixed with salt and koji, a mold grown on rice. Then it ferments for months. The salt keeps it safe. Hikari's organic white miso lists 540 mg of sodium in 12 grams. That's from its US Department of Agriculture filing. This pot uses 60 grams. That's about 2,700 mg, or about 675 mg a bowl. The US label daily value is 2,300 mg. So one bowl is close to 30 percent of your day. ## The Blood Pressure Puzzle Here's the odd part. In Japan, miso soup is a top source of salt. You'd expect heavy eaters to have higher blood pressure. In 2017, Koji Ito's team at Kyushu Hospital in Kitakyushu studied 527 adults aged 50 to 81\. How often they ate miso soup had no link to blood pressure. Frequent eaters also had slower heart rates. **THE FINDING:** In a 2017 Kyushu Hospital study of 527 Japanese adults aged 50 to 81, how often people ate miso soup was not linked to their blood pressure, and frequent eaters had lower heart rates. It was a one-time snapshot, not a trial, so it shows a pattern and not a cause. There's one small trial. In 2019, a Japanese team gave 40 adults miso or a plain soy food for 8 weeks. All had high-normal or mildly high blood pressure. Daytime readings didn't change. Night readings fell in the miso group, even with 3.8 g of salt a day against 0.2 g in the other group. Here's the catch. Staff from Marukome, the miso's maker, were authors. And it used two special miso blends, not the tub in your fridge. Rat studies point the same way. Still, I found no trial of ordinary miso soup against the same salt in people for years. Nobody has tested it. On a low-salt plan from your doctor? The label wins. ### Sponsored Scientists Tested Human Brains for Plastic. Every Single One Came Back Positive A study published in Nature Medicine looked for tiny plastic particles inside human brain tissue. They found them in every sample they tested. The brain held far more plastic than the liver or kidneys, about 10 times more. Brains from 2024 contained roughly 50% more than brains from just eight years earlier. And in people diagnosed with dementia, levels were up to 10 times higher. 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In 1990, Japan's National Cancer Center began to track 21,852 women aged 40 to 59\. Seiichiro Yamamoto's team reported on them in 2003\. Women eating the most soy compounds had about half the breast cancer risk of those eating the least. More miso soup showed the same link. That's observational. Only 179 of the women got breast cancer. Big miso eaters may also differ in many ways. It's a lead, not proof. ## The Gut Claim, Checked Unpasteurized miso holds live microbes. But a living food isn't a probiotic. In 2021, a panel led by Maria Marco at the University of California, Davis set the bar. To earn the word probiotic, a fermented food's microbes must be named, alive when you eat them and shown to help. Miso hasn't cleared that bar. I found no human study showing its microbes survive your stomach and do you good. A hot bowl may kill many of them first. Nobody seems to have measured that either... In 2021, Hannah Wastyk and Justin Sonnenburg at Stanford had 18 adults eat fermented foods daily for 10 weeks. Think yogurt, kefir and kimchi. Their gut microbes grew more varied. And 19 markers of inflammation fell. That was a mix of foods, not miso. ## The Seaweed Needs A Light Hand Kombu is rich in iodine, which your thyroid needs. The National Institutes of Health sets the adult need at 150 micrograms a day. Its safe upper limit is 1,100. In 2004, Jane Teas at the University of South Carolina tested 12 kinds of seaweed. Iodine ran from 16 micrograms per gram in nori to over 8,000 in one kelp product. In 2015, Ryoko Katagiri's team at the University of Tokyo tracked 390 Japanese adults. The middle intake was 632 micrograms a day for men and 462 for women. Kelp and kelp stock made up nearly 90 percent of it. Too much can backfire. In December 2009, Bonsoy, a soy milk made with kombu, was pulled from Australian shelves. Sydney doctors linked it to thyroid trouble in adults and newborns. One sample held 25,000 micrograms per liter. That's why this pot uses 5 grams and pulls the kombu before the boil. Nobody has measured how much iodine that leaves in your bowl. ## The Shiitake, Without The Hype Dried shiitake add more savory depth. They also bring copper. Federal food data puts four dried caps, about 15 grams, at 86 percent of the copper you need in a day. You'll see shiitake sold as an immune cure. It isn't one. The human studies are small. They measured blood markers, not fewer colds. One real caution. Raw or undercooked shiitake can cause an itchy rash like whip marks. A 2016 review from Rutgers blames lentinan, a fiber that heat breaks down. Five min at a simmer fixes it. ## Three Things Worth Knowing 01 #### Read The Sodium Per Gram Labels list different serving sizes, so compare tubs by sodium per gram. Then level off your spoons. A heaped spoon adds salt fast. 02 #### Unpasteurized Is A Bonus, Not A Cure If you want the live cultures, look for "unpasteurized" on a chilled tub. Just know nobody has shown those microbes do anything for you. 03 #### Don't Eat The Kombu Strip It holds far more iodine than the broth. Toss it, or reuse it once for a weaker second stock. ### Here's What I'd Do This Week - **Soak the kombu and shiitake the night before.** The soup then takes 20 min. - **Do the bowl math on your own tub.** Then times the sodium per gram by 15 grams a bowl. - **Keep it to one bowl a day.** The salt and the iodine both add up. - **Ask first if you have thyroid or blood pressure trouble.** Bring the label to your doctor. Ikeda tasted something in kelp broth and wouldn't let it go. He was right about the taste. The other claims deserve that stubborn look. Salt is real. The blood pressure puzzle is real but thin. And the gut promise is untested. Make the pot this week. Stir the miso in off the boil. Read the label before you reach for a second bowl. **Stay well,** The Healing Plate You're receiving this because you subscribed at [Unsubscribe](%%{unsubscribe%5Furl}%%) · [Preferences](%%{manage%5Faccount%5Furl}%%) · [Forward to a friend](mailto:?subject=Miso%20Soup%20Is%20Salty.%20The%20Blood%20Pressure%20Studies%20Say%20Something%20Odd.&body=Something%20worth%20reading%20from%20The%20Healing%20Plate%3A%20https%3A//the-healing-plate.ghost.io/) For educational purposes only. Not medical advice. Not a substitute for professional care. Always consult your healthcare provider before making changes to your diet or supplements.