Take That to Heart

It was found that higher dietary spermidine levels are associated with lower blood pressure and a lower combined risk of heart attack, stroke, and death from vascular disease. Okay, but the top sources of spermidine in the population studied were whole wheat, apples, pears, and salad. How do we know whether spermidine intake wasn’t simply a sign of an overall healthier diet? Only recently have we discovered that the apparent benefit not only seems to be independent of diet quality, but that the effect is unprecedentedly strong.

800 men and women from 40 to over 80 were followed for 20 years. The researchers analyzed 146 different nutrients in their diet, and the substance that most reliably predicted a long life was spermidine. Those who ate the most spermidine not only had a lower risk of dying from cardiovascular disease; spermidine intake was associated with a lower risk for all common causes of death, which is exactly what we would expect from an anti-aging agent. Crucially, this survival advantage persisted even when diet quality was taken into account, so it didn’t appear to occur simply because the participants ate a generally healthier diet.

How big is the effect we’re talking about here? They compared the mortality rate of those in the top third of spermidine intake (more than about 12 mg daily) with those in the bottom third (less than 9 mg daily). The difference in death rates worked out as if those who consumed more spermidine were 5.7 years younger. By eating larger amounts of certain foods, they had practically turned back the clock by nearly six years.

These results were so extraordinary that the researchers wanted to replicate their findings in a completely different cohort before publication. And indeed, they came to the same conclusion. This led some to suggest that spermidine, the older we get, takes on a status similar to a vitamin. When we are younger, we seem to be able to make enough ourselves, but with age we have to make sure to get enough of it through diet to maintain autophagy into old age. So if spermidine is to be considered an anti-aging vitamin, where do we find this “vitamin”?

Sources of Spermidine

In developed countries, average spermidine intake is about 10 milligrams daily. Some countries in Asia and Europe, especially in the Mediterranean region, reach a daily per-capita intake of 13 milligrams and more, whereas the United States is only at 8 milligrams, which is not surprising, since the main source of spermidine is vegetables.

Swedish scientists calculated that a healthy diet would have to contain 25 milligrams of spermidine for women and 30 milligrams for men. If Americans among us need to increase their average daily intake from 8 milligrams, where are we supposed to get another 20 milligrams? Spermidine-rich foods fall into three main categories: “unprocessed plant-based foods” (including mushrooms, although they are technically not plants), certain fermented foods (if you remember, some bacteria can make it too), and a few organ meats.

Which sources are best? You can classify the nutrients in food in different ways. You could rank them by spermidine per calorie to determine which one gives you the most spermidine for your calories. Or you could sort them by spermidine per dollar to see where you get the most for your money. In the medical literature, they are usually ranked by weight, so you can determine in which foods, gram for gram, spermidine is most concentrated. But for practical reasons, that can be misleading. By that criterion, for example, dill stands out for its high spermidine content and, measured purely by weight, ranks just as high as chickpeas, but a serving of chickpeas (about a third of a can) weighs the same as 100 servings of dill (500 sprigs). On paper, garlic contains as much spermidine as potatoes, but you’re more likely to eat a small baked potato than the same weight in garlic, about 77 cloves. Therefore, it is probably most useful to list spermidine sources by serving sizes.

Best sources of spermidine

(unless otherwise indicated, in milligrams per 100-gram serving)

This is a comprehensive list of practically all the foods I could find that average 2 milligrams of spermidine per serving. Note that I neither limited the list based on availability or taste (since that differs from person to person), nor did I leave out unhealthy items. (Just because French fries and certain aged cheeses contain a lot of spermidine doesn’t mean the road to a long life is paved with cheese fries.)

Also note that the list does not necessarily name the leading sources supplying spermidine to the population as a whole. For example, green peas may be the number one source of spermidine in the United States, even though on this list they rank only seventh among the most concentrated sources. Whole wheat bread has about three times more spermidine than white bread, but in fact people may get 14 times more spermidine overall from white bread because it is so popular. A study in Turkey even calculated white bread as the primary dietary source.

As you go through the list of the best spermidine sources, you’ll notice that soy products take four of the top ten spots. Tempeh, which wins gold, is typically sold in 8-ounce packages (about 225 g), and just one of them could completely close the 20-gram spermidine gap. Mushrooms take silver. Interestingly, plain white button mushrooms might have twice as much spermidine as “fancier” mushrooms like enoki or shiitake. (Heating mushrooms doesn’t seem to affect their spermidine content.)

And who’s next? The competition for the most controversial source comes down to pork pancreas and natto, a fermented soy product that smells strongly and pulls slimy strands. Speaking of stink, the durian fruit, which is said to “smell like semen,” contains even more spermidine than mango. If I had been fair, it would have made the list. (For an explanation of why I excluded durian due to extreme bias, you can read about my only-in-retrospect funny run-in with a durian in How Not to Die.)

Although apples and pears contribute substantially to intake in the population overall, they pale in comparison with mangoes, which average ten times the spermidine concentration. In my calculation I used a small mango, but larger mango varieties like Tommy Atkins, Keitt, Kent, or Haden average 336 grams peeled and pitted, which would dethrone tempeh as champion. Two large mangoes could close the daily spermidine gap.

Milk of animal origin has little or no spermidine, but the bacteria in some aged cheeses produce substantial amounts. While American cheese (a type of processed cheese) and mozzarella have none, blue cheese can reach 1.1 milligrams of spermidine per 30 grams, and as you can see, extra-sharp cheddar aged at least a year actually makes the list. Cheese overall, however, comes in at only 0.6 milligrams, and even some aged varieties like Gouda aged six months leave something to be desired. Yogurt also contains no spermidine, suggesting that only some bacterial species produce it. In sauerkraut, for example, there doesn’t seem to be more spermidine than in fresh cabbage.