How do Okinawan citizens outlive the rest of the world when their diet consists of a large amount of fish?

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I know fish has its laundry list of benefits, but surely consuming a large amount can have detrimental effects due to mercury, microplastics and PCBs, yet it doesn’t seem to affect blue zones like Okinawa where their citizens outlive most other nations (with a large amount of centenarians) and consume large amounts of fish.

Why is this?

In: 5

The Japanese in general have a very long life expectancy, largely because of extremely low obesity rates. In the US, for example, heart disease is the #1 cause of death and stroke is #5. Fish might contain some harmful chemicals, but it’s also a pretty lean source of protein. What’s important here is not just that they *are* eating fish, but that they *aren’t* eating a lot of high-fat land meats like beef.

That said: nutrition is really complicated. We can be pretty confident that obesity is bad for you, but exactly why obesity occurs is an active area of research (yes, calories-in/calories-out, but there’s lots of variables that influence both).

I used to live in Japan. A few things granny in Japan did, that granny in US cannot do:

Sit on the floor while watching TV & entertaining guests

Walk to the grocery store, taking a rolling tote with her

Drinking green tea every day (until the caffeine became too much)

Eating very small portions (extremely small portions of fish too, by the way)

No red meat, semi-vegetarian diet
LOADS of veggies

Rarely eats bread. Eats rice daily.

Soaking in a hot bath up to her neck most nights

Meditating

Mercury is a bigger problem for larger fishes like sharks, swordfish. Fish commonly eaten in Japan like Mackerel, Cod or Saury should be very low risk. Salmon and Tuna are slightly higher but those are not eaten as often. For those fishes, eating 150 grams a day or so shouldn’t have any long term effects of mercury poisoning.

Fishes are usually much lower in saturated fats compared to pork or beef so the risk of heart disease at an early age is lower.

With the good and bad of eating fish, we don’t fully understand the effects of some thihgs. Mercury we do have a pretty good understanding, eating too much deep sea fish will cause issues. But mercury only causes real problems in high food chain hunting fish. The higher up the food chain a fish is, the more mercury becomes a concern, because mercury accumulates in the flesh of fish and each time a fish is eaten by a larger fish, mercury accumulates. But Not all ocean fish have significant mercury problem, some can be eaten just fine with less concern about mercury intake.

Maybe they naturally have longer telomeres in their DNA?

[Japanese people are notorious for lying about the “alive” status of their relatives to cash in on their pension.](https://www.bbc.co.uk/news/world-asia-pacific-10809128#:~:text=Tokyo%27s%20%27oldest%20man%27%20had%20been%20dead%20for%2030,uncovered%20mummified%20skeletal%20remains%20lying%20in%20his%20bed.)

On multiple occasions, people have gone to congratulate the new oldest person in the world only to find they had died decades earlier.

This skews the stats a bit.

They also tend to be more active.

The average adult in Japan walks almost twice as much every day as the average American.

“The average American walks 3,000 to 4,000 steps a day, or roughly 1.5 to 2 miles.”

https://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/10000-steps/art-20317391

“A National Health and Nutrition Survey revealed that Japanese men walk 6,846 steps a day, while Japanese women walk 5,867 steps each day.”

https://medium.com/beingwell/skip-the-gym-and-get-longevity-the-japanese-way-7575087a7e48

Personally, I average about 10,000-15,000 steps a day. 30,000-40,000 if I go for a long walk.

Over 90% of the population lives in urban areas. It is easy to walk to most of the places you need to go, or take a train. Car use is pretty low. Many people will also use bicycles.

I can easily walk to several different supermarkets in just 15 minutes to do my grocery shopping, visit hundreds of shops, bars and restaurants, watch a movie, go swimming, visit parks etc. Jump on a train for a bit and it opens up thousands more options.

To get to work I have a 10 minutes walk to the train station then a 20 minute walk the other end to get to my workplace. That’s an hour of walking each day just to get to work. On weekends I’ll often go for one, two, or three hour walks around town. Occasionally, I’ll walk home from work. It takes about 5 or 6 hours.

Americans, on the other hand, seem to think that anything over 30 minutes is a long walk – https://www.independent.co.uk/life-style/health-and-families/walking-us-uk-30-minutes-debate-b1905113.html

In addition to this the healthcare system is much cheaper and accessible than the US and there is a focus on preventative healthcare. Stopping issues before they arise. Companies have annual health checks. Local towns will also check people’s health at various stages in life. There is a general attitude that promotes concern over health and looking after yourself.

Other answers have covered the dietary question, but one thing contributing to lifespan in places where there is a concentration of significantly longer-than-average lifespans is a low-stress, slow-paced, repetitive lifestyle.

In many so-called blue zones, the average person’s life really doesn’t look too much different at age 90 than it did at age 20 or 40 or 70. Having a relatively small gap between the social safety net and the social ceiling sets the stage for a long life, and de-risks a person’s life considerably. That said, it’s often not the life trajectory many people would want.