Regulating protein for longevity (and more)

You’ve undoubtedly read the flurry of news reports connecting calorie restriction to a longer life span. Now, scientists have started looking at possible reasons why–as well as ways to achieve similar results without starving ourselves silly.

Earlier this week, a British study came out in the journal Nature that examined what happened when researchers varied the ratios of key nutrients–such as vitamins, lipids, and amino acids–in the diets of fruit flies (which, believe it or not, share a lot of relevant DNA with us). While changing the amount of vitamins and lipids had no effect on the flies, tweaking amino acids proportions had a huge impact. Especially critical was an amino acid called methionine, which occurs to differing degrees in the proteins we eat. Specifically, reducing methionine levels in a high-calorie diet seemed to prolong life-span. If the same holds true in the real world, it looks like you might be able to cut down just your intake of high-methionine protein and get the same chance on youth as you would if you dramatically slashed calories.

The study didn’t stop there. One of the biggest hurdles in this whole “eat less, live longer” approach is that while cutting calories prolongs the duration of our reproductive lifespans, it reduces real-time fertility. The research team was able to show that adding methionine to a low-calorie diet seemed to boost fertility while still keeping lifespan high. The scientists believe that this fertility tangent might be just one of many ways methionine can help our bodies work optimally on fewer calories. The possible takeaway? If you’re on a diet that involves cutting calories (even if you’re not trying to get pregnant), you might want to be doubly sure you’re getting enough high-methionine protein.

I’d never heard about methionine before, so in case you’re in my boat, here’s a quick primer: In addition to contributing to this new nutrition puzzle, methionine has been shown to promote liver function, where it’s especially useful in helping the liver process fats. The amino acid also has strong antioxidant properties (it fights toxins and free radicals), and has been tied to promoting brain health and good cardiac/circulatory performance. As for sources, egg whites top the list, with beef, chicken, and fish (including crustaceans) not far behind. Cheeses (especially cottage cheese, which is right up there with some meats), lentils, garlic, and–curiously–seaweed are other good bets.

A lot more research obviously needs to happen before we’re likely to see recommendations for how to work this development into a healthy diet. Personally, I’m taking the study as a tip to be mindful of keeping a balance between protein sources and calories. If I’m eating a whole lot of food, it’s probably a good idea to skip the steak. When I’m consuming fewer calories, though, something like lean red meat might be important to keeping my body at optimal health. In short, for me, this is one more reminder that it’s balance and variety–and not the big sweeping decisions–that make the strongest difference.