What About the Sodium in Miso?

According to the second World Cancer Research Fund/American Institute for Cancer Research expert report, “[s]alt is a probable cause of stomach cancer,” one of the world’s leading cancer killers. If the report’s estimate of an 8 percent increase in risk for every extra gram of salt a day is correct, then in a country like the United Kingdom, nearly 1,700 cases of stomach cancer happen every year just because of excess salt intake, as you can see at 0:27 in my video Is Miso Healthy?, and, in a country like the United States, it would be thousands more annually.

The risk of stomach cancer associated with salt intake appears on par with smoking or heavy alcohol use, but may only be half as bad as opium use or increased total meat consumption, as you can see at 0:43 in my video. These findings were based on a study of more than a half million people, which may explain why those eating meatless diets appear to have nearly two-thirds lower risk.

We know dietary salt intake is directly associated with the risk of stomach cancer, and the higher the intake, the higher the risk. A meta-analysis went one step further and looked at specific salt-rich foods: pickled foods, salted fish, processed meat, and miso soup. Habitual consumption of pickled foods, salted fish, and processed meat were each associated with about a 25 percent greater risk of stomach cancer. The pickled foods may explain why Korea, where the pickled cabbage dish kimchi is a staple, appears to have the highest stomach cancer rates in the world, as you can see at 1:39 in my video. But researchers found there was no significant association with the consumption of miso soup. This may be because the carcinogenic effects of the salt in miso soup are counteracted by the anti-carcinogenic effects of the soy, effectively canceling out the risk. And, if we made garlicky soup with some scallions thrown in, our cancer risk may drop even lower, as you can see at 2:06 in my video.

Cancer isn’t the primary reason people are told to avoid salt, though. What about miso soup and high blood pressure? Similar to the relationship between miso and cancer, the salt in miso pushes up our blood pressures, but miso’s soy protein may be relaxing them down. If we compare the effects of soy milk to cow’s milk, for example, and, to make it even more fair, compare soy milk to skim cow’s milk to avoid the saturated butter fat, soy milk can much more dramatically improve blood pressure among women with hypertension, as you can see at 2:43 in my video. But would the effect be dramatic enough to counter all the salt in miso? Japanese researchers decided to put it to the test.

For four years, they followed men and women in their 60s, who, at the start of the study, had normal blood pressure, to see who was more likely to be diagnosed with hypertension in that time: those who had two or more bowls of miso soup a day or those who had one or less. Two bowls a day may add a half teaspoon of salt to one’s daily diet, yet those who had two or more bowls of miso soup every day appeared to have five times lower risk of becoming hypertensive. So, maybe the anti-hypertensive effects of the soy in the miso exceed the hypertensive effects of the salt.

Indeed, miso paste, a whole soy food, can be used as a “green light” source of saltiness when cooking. That’s why I used it in my pesto recipe in How Not to Die and in my How Not to Die Cookbook. It can help you in Shaking the Salt Habit.

Not convinced that salt is bad for you? Check out these videos:

Not convinced that soy is good for you? See:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Healthier Salt Substitutes

As I discuss in my video Shaking the Salt Habit, the two most prominent dietary risks for death and disability in the world are not eating enough fruit and eating too much salt. Eating too little fruit kills nearly five million people every year, and eating too much salt kills four million.

There are three things we can do to lower our salt intake. First, don’t add salt at the table. One third of us add salt to our food before even tasting it! Second, stop adding salt while you’re cooking. At first, the food may taste bland, but within two to four weeks, “as the sensitivity of the salt taste receptors in the mouth become more sensitive to the taste of salt in the usual concentrations”—believe it or not—you may actually prefer the taste of food with less salt. Some of the flavorings you can use in the meanwhile instead of salt include “pepper, onion, garlic, tomato, sweet pepper, basil, parsley, thyme, celery, lime, chilli, nettle, rosemary, smoke flavoring, curry, coriander and lemon.” Even if you did add salt while cooking, though, it’s probably better than eating out, where even at non-fast food restaurants, they tend to pile it on. And, finally, avoid processed foods that have salt added.

In most countries, only about half of sodium intake comes from processed foods, so there’s more personal responsibility. In the United States, however, even if we completely stopped adding salt in the kitchen and dining room, it would only bring down salt intake a small fraction. This has led public health commentators to note how challenging it is for everyone to reduce their salt intake, since so much of our sodium intake is out of our control. But is it? We don’t have to buy all those processed foods. We can choose not to turn over our family’s health to food corporations that may not have our best interests at heart.

If we do buy processed foods, there are two tricks we can use. First, try to only buy foods with fewer milligrams of sodium listed on the label than there are grams in the serving size. So, if it’s a 100-gram serving size, it should have less than 100 mg of sodium. Or, second, shoot for fewer milligrams of sodium than there are calories. For example, if the sodium is listed as 720 and calories are 260, since 720 is greater than 260, the product has too much sodium.

That’s a trick I learned from Jeff Novick, one of my favorite dieticians of all time. The reason it works is that most people get about 2,200 calories a day. So, if everything you ate had more calories than sodium, you’d at least get under 2,300 milligrams of sodium, which is the upper limit for healthy people under age 50. Of course, the healthiest foods have no labels at all. We should try to buy as much fresh food as possible because it is almost impossible to come up with a diet consisting of unprocessed natural foodstuffs that exceeds the strict American Heart Association guidelines for sodium reduction.

Not eating enough fruit as a leading killer? For more, see my video Inhibiting Platelet Aggregation with Berries.

In my latest sodium series, I lay out the evidence and dive into the manufactured controversy to expose salt industry shenanigans. See:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Raw vs. Cooked Garlic and Onions for Blood Thinning

As we age, our arteries stiffen. In my video Inhibiting Platelet Activation with Garlic and Onions, you can see charts showing measurements of the stiffness of our aorta, the main artery coming off the heart, as we get older and older. “As the aorta stiffens it leads to a range of linked pathphysiological changes,” such as exposing our brain and kidneys to greater pressure fluctuations, which may increase the risk of stroke and impairment of kidney function.

However, those who consume garlic—less than a quarter teaspoon of garlic powder a day—appear to have less stiffness in their aortas. We think this is because garlic seems to improve the function of the inner lining of our arteries, which helps our arteries relax. But the protective mechanisms of garlic against cardiovascular diseases are multiple, and include a combination of anti-clotting, clot-busting, antioxidant, and blood pressure- and cholesterol-lowering effects. The latest review suggests that long-term garlic intake may drop bad cholesterol levels about 10 percent, and the blood-thinning effects are such that the American Society of Anesthesiology recommends garlic intake be stopped a week before elective surgery.

Or, presumably, you could just cook it to death. Unlike the anticlotting components concentrated in the yellow fluid around tomato seeds, which are heat stable, the antiplatelet activity in garlic and onions is lost with cooking. When comparing  platelet inhibition, garlic appears about 13 times more potent than onion, and eating garlic raw appears to be better than cooked. This suggests that “garlic and onion could be more potent inhibitors of blood [clotting] if consumed in raw than in cooked or boiled form.” So, it might be good to cook garlic right before surgery, but what about the rest of the time when we’re trying to suppress platelet over-activity to decrease the risk of heart attacks and stroke? “As garlic and onion are normally consumed in cooked food, their efficacy as preventive herbs in cardiovascular disease may be doubtful.” But, we can put some raw onion on salads and raw garlic in salsa, dressings, dips, or pesto, right?

Or, we can crush or chop it, wait ten minutes, and then cook it. Researchers demonstrated the platelet-inhibiting power of raw garlic. If you cook it for just a few minutes, it does fine; but after cooking for about five minutes, the benefit is abolished. If, however, you pre-crush the garlic and wait, some of the antiplatelet activity is retained a bit longer. That’s because the enzyme that makes the antiplatelet compounds is activated by crushing but destroyed by heat faster than it creates the compounds. So, by crushing first and letting the enzyme work its magic before cooking, one can delay the loss of function.

Even better, though, is that, (as I discussed in my video Second Strategy to Cooking Broccoli with mustard powder), the addition of a little raw garlic juice to cooked garlic can restore the “full complement of antiplatelet activity that was completely lost without the [raw] garlic addition.”

When onions are cooked, the antiplatelet activity is similarly abolished within ten minutes, but then something strange happens. After 20 or 30 minutes of cooking, the effect on platelets is reversed and appears to make matters worse. Significant pro-platelet activation effects are seen, “suggesting that extensively cooked onions may stimulate rather than inhibit” platelets. That was in a test tube, though. Thankfully, when tested in people, even when onions are dropped in boiling water, fried for 10 minutes, and then left to simmer for 30 minutes, platelet activation drops within one to three hours after eating onion soup.

For background on what platelets are, what they do, and why we should care, see Inhibiting Platelet Aggregation with Berries and Inhibiting Platelet Activation with Tomato Seeds.

What else can garlic do? Check out:

What was that about mustard powder boosting the benefits of broccoli? See my Second Strategy to Cooking Broccoli video. Broccoli is also a potent activator of our liver’s detoxifying enzymes. Learn more in my Best Food to Counter the Effects of Air Pollution video.

Wondering whether it’s better to cook vegetables or eat them raw? See Best Cooking Method and for a surprise update, The Best Way to Cook Sweet Potatoes.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: