How Much Fish Do Centenarians Eat for Longevity?

People hoping to live to an old age often instinctively add more fish, more salmon and more ‘superfoods’ to their diet. Yet researchers studying the well-known regions with exceptionally high numbers of centenarians reveal a different pattern. Fish is eaten there regularly, but in modest portions and chosen with care, as part of a diet that is largely plant-based.

What regions with many centenarians have in common

The so-called regions with unusually large numbers of very old people are spread across the world: on a Japanese island, a Greek island, in Italy, in a Californian community and in parts of Costa Rica. Their cultures, climates and lifestyles differ greatly, yet the same dietary habits appear time and again.

• Vegetables, pulses and wholegrains form the core of everyday meals
• Animal products play only a minor part
• Fish appears on the menu only a few times each week
• Portions are modest, meals are generally simple and are often shared with family

Older people in these places tend to remain notably active, move every day and preserve their independence for a long time. Researchers do not attribute this to one ‘miracle cure’, but to a combination of factors: a high intake of plant foods, little excess energy intake, hardly any highly processed products and carefully measured fish consumption.

Fish appears in the diets of centenarians like a seasoning: regularly, but sparingly.

Why small oily fish stand out

One feature is particularly striking: people in these regions mainly cook or grill small, oily fish. Rather than eating huge salmon steaks, many choose sardines, small mackerel or similarly ‘unremarkable’ species.

Nutritional powerhouses in a small package

When prepared well, these small fish provide an impressive range of nutrients:

• Omega-3 fatty acids, which may reduce inflammation and help protect the heart and blood vessels
• Vitamin B12, needed for nerves and blood formation
• Iodine and selenium, which support normal thyroid function
• High-quality protein, which helps maintain muscle - especially important in later life

At the same time, small fish accumulate far fewer contaminants over their lifetime than large predatory fish higher up the food chain. This lowers the risk of consuming excessive mercury or other industrial chemicals.

Large fish can act like sponges for contaminants in the body; smaller species are usually much cleaner.

Why eating too much fish can cause problems

Anyone eating generous daily portions of large marine predators such as swordfish consumes not only omega-3 fatty acids, but also higher levels of harmful substances. Health authorities have therefore warned for years against overdoing fish intake, particularly during pregnancy and breastfeeding and for children.

The opposite happens in regions with many very old residents: fish is eaten in moderation, with a preference for species considered relatively low in contaminants. This combination may be key to gaining the benefits while keeping risks low.

What a longevity researcher recommends

A well-known Californian ageing researcher describes an eating pattern that closely matches diets in regions with many older people. His central principle is that plant foods remain the foundation, complemented by a small but regular amount of fish.

For adults, he advises two to three portions of fish each week. He highlights three priorities:

• Eat mostly plant-based foods, including vegetables, pulses, grains and nuts
• Choose fish carefully, particularly smaller oily varieties
• Consider its origin and avoid species high in mercury

In his view, suitable choices include sardines, small mackerel, certain salmon varieties, trout and cod. Seafood with a high B12 content but low contaminant exposure also fits this approach.

What official bodies say about fish and health

European health authorities likewise consider fish a useful component of a heart- and brain-friendly diet, but with clear limits. They recommend at least one serving of oily fish a week, often around 140 grams when cooked.

They emphasise two points in particular:

• Fish oils can improve blood-fat levels and lower the risk of cardiovascular disease.
• At the same time, oily marine species contain more environmental pollutants than many other foods.

This leads to upper limits for certain groups. Pregnant and breastfeeding people, along with children, should avoid heavily contaminated species where possible and limit their overall intake. The central message remains the same: fish is beneficial, but it should be portioned sensibly.

How much fish per week is realistically worthwhile

When the guidance from longevity researchers and public authorities is considered side by side, a fairly clear picture emerges. Their shared ground is remarkably close to what is actually eaten in regions with large numbers of very old people.

Aspect	Recommendation
Frequency	2–3 fish meals per week
Portion size	Approx. 100–150 g cooked fish per portion
Fish types	Small, oily species rich in omega-3
Dietary foundation	Predominantly plant-based foods

Anyone who eats a small portion of oily fish twice a week is surprisingly close to the diet of many centenarians.

More important than the precise number of grams is fish’s role within the overall diet: it is not a daily star attraction, but more of an accompaniment with a clearly defined purpose.

Practical ways to put this into everyday life

Nobody needs to move to a Japanese village to follow this pattern in daily life. A weekly plan could look something like this:

• Tuesday: a vegetable stir-fry with chickpeas and a small serving of fried sardines
• Friday: wholewheat pasta with tomato sauce and a moderate portion of baked salmon
• Sunday: vegetable soup with a piece of trout cooked in the oven or on the grill

On the remaining days, plant-based protein sources take centre stage: beans, lentils, tofu, nuts or seeds. This keeps the fish share low without making it feel like a sacrifice.

Risks that many people underestimate

Fish is often regarded as an entirely healthy food. However, the debate around marine pollution reveals another side. In many sea areas, microplastics, heavy metals and residues from industrial chemicals circulate in the water. Large predatory fish at the top of the food chain build up these substances in their tissue.

Regularly eating very large portions of these species increases long-term exposure to such substances. For vulnerable groups, including unborn babies and young children, this may affect brain and nervous-system development.

Small, short-lived species and fish from strictly controlled aquaculture can reduce this risk. That is another reason these varieties rank highly in dietary advice focused on the long term.

More than fish: what else centenarians do differently

Fish is only one piece of the puzzle. In regions with many very old people, the whole lifestyle also plays a role. Many residents move naturally through everyday activities, such as gardening and walking for journeys, while spending little time sitting for hours. Meals are rarely eaten alone in front of a screen; instead, they are shared with others.

There are also often established routines, such as a late, light evening meal, regular periods of rest and few highly processed foods. Together, these habits place less strain on the metabolism and cardiovascular system; moderate fish consumption provides refinement rather than the main focus.

What this view of fish means for your own diet

Anyone wishing to follow the example of centenarians does not need to copy every tradition. It is more useful to assess everyday habits: how often do you eat fish? Which species do you choose? And how large are the portions?

Even small adjustments can shift the balance: replace a large serving of salmon with a smaller one, try sardines or other small species from time to time, and deliberately choose plant-based protein sources on two days each week. This brings your diet closer to patterns associated with high life expectancy in different parts of the world - without radical restrictions.