Dear Mark,

Can you give me more explanation about nuts and seeds? I eat a ton of them and am always confused about which ones are actually nuts and which are seeds and which are legumes. Does it make any difference if you eat them whole, roasted, raw or as nut butter?

Thanks to reader Charlotte for these questions in response to last week’s “Get Primal” post. The classification question does get tricky.

Nuts themselves are actually a kind of fruit, specifically “dried fruit.” But not everything we consider nuts are really nuts. Some are actually seeds, often within fruits or even legumes. A hazelnut is, indeed, a nut. An acorn is also a variety of “true” nut, as are pecans, walnuts and chestnuts. But an almond, for example, is a seed inside a fleshy fruit’s (a.k.a. drupe’s) pit. A pistachio is a seed within a fleshy fruit. Pine nuts are seeds. Cashews are seeds. Peanuts are the seeds of a legume. Technically speaking, all nuts are fruits, and a “true” nut is indehiscent (they don’t – by themselves – open to spread seeds), hard-shelled and generally one-seeded.

But let’s look at all this from a practical perspective: what’s good to eat? “Nuts” in the broad culinary classification contain protein. Big plus. They tend to be high in certain B-vitamins, vitamin E, and many minerals. Another plus. Low carb. Yet another plus. But not all “nuts” are created equal. Some, like peanuts, have high levels of omega-6. As we’ve said a lot lately, we moderns seem to get way more than enough of omega-6 in our diets. Walnuts, for example, offer a nice dose of omega-3. Almonds are a great source of phytochemicals, contain calcium, and are even lower in carbs than most.

And then there’s the issue of aflatoxins, dangerous metabolites produced by certain mold varieties. Aflatoxins are common in what we usually refer to as “tree” and “ground” nuts, including almonds, walnuts and pecans as well as peanuts and cashews. The toxin has been shown to have carcinogenic, mutagenic and immunosuppressive properties. While certain farming practices can reduce the problem, the aflatoxin related molds are considered at least somewhat inevitable. Peanuts are often said to have the highest concentration of aflatoxins, and they are among the most heavily (pesticide) sprayed food grown.

In terms of roasted versus raw, I’d recommend raw to avoid the oxidation that happens during heating. However, there are increasing challenges to the sale of truly raw (untreated) nuts. The Cornucopia Institute offers a great deal of information on the recent raw almond controversy, but all California grown almonds now have either chemical or high heat treatments. The change came after raw almonds were believed to be connected with two salmonella cases, although farming practices vary considerably and may have contributed to the problem. Regarding nut butter versus nuts themselves, it’s your choice. However, be sure to select nut butter (I recommend almond butter) without added ingredients, especially added sugars. And, again, I’d favor raw and organic over conventional and roasted.

Thanks for the questions, everyone!

steffenz, Marcio Cabral de Moura, sproutgrrl Flickr Photos (CC)

Further Reading:

Dear Mark: Beans/Legumes

Smart Fuel: Walnut Oil

Modern Forager: Ten Staples of a Well-Stocked Kitchen

Subscribe to Mark’s Daily Apple feeds

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