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Comment by jfim | Hacker News Reader

How would banning tuna fishing make it impossible for the world's poor to have a balanced diet? Is it because it would also ban subsistence fishing?

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I would guess it's because tuna is a very cheap source of lots of protein: 100g of tuna is 29g protein for a fraction of a buck (canned). I'm pretty sure that's the cheapest source of protein available (in $/g). eggs are not as cheap, and they don't keep anywhere as long as a stack of canned tuna.

In places I've lived recently, canned tuna isn't the cheapest source, though it's cheap-ish. Canned chicken is cheaper in most of the USA. Even fresh or frozen meats can be cheaper, e.g. chicken in the USA, or pork in Denmark. As well as lower-end sausages and other processed meats. Plus, nearly all vegetable sources of protein, like beans or lentils, are cheaper than those.

I would also not suggest canned tuna as a staple protein, because of its high mercury levels. It's okay to eat occasionally, but eating ~10 cans/week as your main source of protein isn't a good idea. The safe consumption quantity for a typical adult is in the range of 2-3 cans per week of chunk-light, or 1 can/week of albacore.

Here in the UK, if you don't mind buying in larger cans, salmon gives you practically the same protein for your money. Example from the most popular supermarket chain:

Tuna -- 26.4g protein for 0.55GBP (48g/GBP): http://www.tesco.com/groceries/product/details/?id=283723541

Salmon -- 84.8g for 1.80GBP (47g/GBP): http://www.tesco.com/groceries/product/details/?id=258098027

And the salmon is from Alaska, where the fishery is well managed and sustainable.

Not that I want to tell you what to do or not to do in your own kitchen but please be very careful with canned fish from larger cans, use the whole can at once or transfer the contents to another container that you can properly close.

That tuna says it was "fished by pole and line" though, which

a) is really surprising - someone above said that made tuna much more expensive, which is also what I'd intuitively expect;

b) seems to put it ethically around the same level as the salmon.

I think lentils, chickpeas, soy and co. are the cheapest protein. In general in Italy canned tuna (granted it's solid and in olive oil) is never cheaper than 10 euro/kg, and can be as expensive as 35 euro/kg. That's more expensive than fresh chicken, pork and many cuts of beef.

Some really good threads on fermented foods have come up recently (1,2,3). In relation to these healthy, cost-effective protein sources, this legume, soy, afaict, needs fermentation before ingestion (0). See # What Soy Products are Good For You?

0: http://articles.mercola.com/sites/articles/archive/2010/09/1... 1: https://news.ycombinator.com/item?id=9699993 2: https://news.ycombinator.com/item?id=10603067 3: https://news.ycombinator.com/item?id=10524582

Hemp seed has 36g of protein per 100g and is a lot cheaper and environmentally more sustainable to produce, contains omega acids in the perfect ratio for humans (but dose not have the same bio-availability), dose not have high levels of mercury (that's more of a problem with farmed fish not wild).

This seems like one optimal protein source, since we could also squeeze out its oil and use it for diesel fuel. Then, Spirulina, can act as another protein source which can also provide bio-available essential fatty acids.

How do farmed tuna have more mercury than wild harvested? They're both swimming in the same ocean eating the same pilchards.

I'm presuming it's because farmed tuna are fed a diet low in mercury vs. wild tuna eating things that have concentrated mercury over time?

You have it backwards. The farmed has been found to have higher mercury content.

What about beans?

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