Wakame, Wakame!

Seaweeds contribute to longevity by lowering high blood pressure. Because seaweed consumption has been associated with better blood pressure regulation in both children and adults, scientists wanted to test it. They found that blood pressure dropped significantly if one ate 6 grams of dried wakame (as in seaweed salad) for one month; 4 grams was not enough. What is so nice about such whole-food plant-based interventions: Sometimes positive side effects occur. In this study, one participant who had suffered from gastritis experienced healing of the inflammation; in another, the chronic headaches stopped. Seaweed salad may also strengthen immune function. More on that in the chapter “Maintaining the Immune System.”

The healthiest iodine source

One advantage of cow’s milk compared with plant milk is its iodine, a mineral that is indispensable for thyroid function. With cow’s milk, in the USA you cover about a quarter to half of the daily iodine requirement; however, ironically, the milk itself contains only little iodine. The iodine residues in dairy products mainly come from the iodine in the disinfectants against teat infections with which cow udders are treated.

For a comparison of the healthiest iodine sources, see see.nf/iodine. In short, I recommend the dark green sea vegetables. You can reach the recommended daily amount of iodine with about two sheets of the sushi seaweed nori. I always nibble nori as a snack. A teaspoon of mild seaweeds such as dulse or arame, or a tablespoon of seaweed salad, also covers the daily iodine requirement. You can sprinkle dulse—pretty purple flakes—over almost anything, and arame is among my favorite ingredients when cooking soup. Because iodine is stored in the thyroid for a long time, it can be consumed without concern only now and then; that is, you do not have to take it daily. For further safe iodine sources, read my chapter on dietary supplements at the end of How Not to Die.

Ergothioneine: the “longevity vitamin”

Another food that contributes to successful aging in Okinawa is mushrooms. Fruit flies whose food contained one percent oyster mushrooms had a small but significant survival advantage, perhaps because oyster mushrooms are among the most concentrated sources of ergothioneine.

To describe nutrients that are not indispensable but may be necessary for long-term health, the famous emeritus biochemistry professor Bruce Ames coined the term “longevity vitamin” and identified ergothioneine as a likely candidate. In the blood of thousands of subjects, the levels of more than 100 substances were measured, and among them, ergothioneine was most often associated with the lowest rates of disease and death. It was assumed that it acts as a potent antioxidant in and around the mitochondria. Watch the video see.nf/ergo to learn what this vitamin can do and how to get it best.

In short: Mushrooms and tempeh—a soy product fermented with fungi—are the only foods that contain very high amounts of ergothioneine. Porcini are at the top with more than three times as much ergothioneine as oyster mushrooms and shiitake, and those in turn contain three times as much as cremini or portobello cultivated mushrooms. Ergothioneine may be the reason mushroom consumption is associated with a lower risk of all-cause mortality.

Interestingly, ergothioneine levels in the brain seem to decline in those over 60, and this reduction is associated both with a decrease in cognitive ability and with frailty, but seems to have nothing to do with lower mushroom consumption. Perhaps the function of the ergothioneine transporter at the blood–brain barrier declines with age, which would mean that mushroom consumption becomes even more important the older we get.

Mushrooms—a warning

Morels, shiitake, and mushrooms of the genus Agaricus, such as button mushrooms, should be cooked before consumption. Oyster mushrooms can be eaten raw without concern. For the why and for other warnings, see see.nf/caveats.

The “immortality mushroom”

Can mushrooms be used medically? Mushroom-based products make up a substantial portion of the 50 billion US-dollar dietary supplement market. An editor of the journal Fungal Biology wrote: “The attainable profits in this industry are a strong incentive for companies to test the gullibility of their customers, and by now unproven claims define the business of medicinal mushrooms.” He pointed to the quackery of patented “medicines” with names like “Dr. Bonker’s Celebrated Egyptian Oil,” which really exists.

It would not, however, be surprising if mushrooms had any effects. After all, very many drugs have been developed from fungi, not least penicillin, as well as the cholesterol-lowering statin lovastatin and the potent immunosuppressant ciclosporin. Do you still not believe that a modest little mushroom can have pharmacological effects? Do not forget that mushrooms also produce some of our strongest poisons. Some look the part, too, like the fly agaric with its white spots, which achieved great fame through the Super Mario Brothers; others look much more innocent, for example the death cap. A single teaspoon of it is enough for “a slow, agonizing death.”

I discuss the immune-strengthening effect of mushrooms in the chapter “Maintaining the Immune System.” One of the most popular so-called medicinal mushrooms is called reishi in Japan (in China lingzhi), and it is revered as the “immortality mushroom.” It is a white-rot fungus that grows on dead wood. Because it is tough like cork and tastes bitter, it is not really edible, but in some Asian countries people brew a drink from it for a long life. Has the mushroom earned this reverence? Well, it works in tiny worms; it significantly extends the life span of C. elegans, and a related mushroom species delays aging when injected into the bellies of mice. Unfortunately, almost all clinical reishi experiments with human subjects under various conditions over the past few decades have been unsuccessful. It looks most promising for fighting cancer. For details, see see.nf/reishi.

Of course, for a reishi dietary supplement to be able to work, it presumably first has to contain reishi at all. Thanks to the Dietary Supplement Health and Education Act of 1994, in the USA manufacturers—and not the FDA—are themselves responsible for the safety and the unadulterated nature of their products. You can probably already guess how well that works: None of 19 tested reishi dietary supplements contained reishi.

Garlic for arterial health

So far I have told you about sweet potatoes, soy, seaweed, and mushrooms. What about the foods that give traditional Okinawan cooking its zing—garlic, ginger, and turmeric?

In ancient Greece, the art of medicine was divided into three areas: healing through diet, healing through medicine, and healing through surgery. Garlic, Hippocrates wrote, belonged among the medicinal foods—however, it was used against a nonexistent disease called “wandering womb,” so that was where ancient wisdom reached its limits.