Dear Mark: Peanut Edition

Dear_Mark_Inline_PhotoFor today’s edition of Dear Mark, I’m answering a bunch of questions from last week’s post about peanuts. You guys had quite the reaction to it, and today I’m digging into some of your questions and comments. Does roasting create carcinogens in the fat? Should (and can) you sprout peanuts? Are peanuts used to soak up toxins from the soil? How do I know if my peanut butter comes from Valencia peanuts?

And many more.

Todd asked:

I thought the process of roasting peanuts caused the oil in them to become carcinogenic thus the reason to eat all nuts raw?

On the one hand, peanut proteins become potentially more allergenic when roasted. If you’re allergic to peanuts, don’t eat them.

On the other hand, roasting reduces levels of a confirmed carcinogen—aflatoxin—sometimes found in peanuts.

What makes an oil carcinogenic is usually the degree of oxidative damage it’s sustained. Most oxidative damage comes from heat exposure. Luckily, the fat of the peanut is fairly resistant to heat damage. An ounce of peanuts has 14.1 grams of fat, 7.4 of which are monounsaturated, 2.8 of which are polyunsaturated, and 2 of which are saturated.

Monounsaturated fat (MUFA) and saturated fat (SFA) are highly resistant to heat degradation. MUFA is a bit more susceptible to heat than SFA, but the roasting process doesn’t push peanuts high enough for it to matter. The main fat to worry about is the omega-6 polyunsaturated fat—the linoleic acid.

Of course, linoleic acid bound up in a peanut is different than linoleic acid in isolated seed oils. Whole peanuts contain vitamin E and various polyphenols (discussed in the original post), which protect the fragile linoleic acid from oxidation. It can’t protect it completely, but it does inhibit the oxidation. 

Other research on roasted nuts, many of them higher in omega-6 than peanuts, find they have beneficial effects on oxidative stress and oxidative damage to lipids. Peanuts in this respect are likely fine.

Dave wondered:

If you purchase raw peanuts should you or can they be sprouted?

You certainly can. This method for sprouting, drying, roasting, and then grinding peanuts down into sprouted peanut butter is a good one.

Sprouting tends to reduce phytic acid, increase nutrient bioavailability, and even create novel micronutrients—so it’s worth doing if you have the time and inclination. Certainly doesn’t hurt.

Monika asked:

Can you confirm the truth to this? Apparently peanut crops are used to prepare fields for organic agriculture as they absorb toxins readily. So be sure to eat ORGANIC peanuts only.

I’ve heard that too but haven’t seen strong evidence, just uncited assertions. Has anyone else heard this? I’d love to see evidence.

Let’s table that for the time being and talk about pesticides, for which there is data.

The most prevalent pesticide (found in 25% of samples) found on conventional peanuts is piperonyl butoxide, a pyrethroid synergist used to enhance the toxicity of other pesticides. By itself, piperonyl butoxide is less dangerous than some other pesticides. Prenatal exposure to airborne piperonyl butoxide, however, is associated with slightly lower neurodevelopment at 36 months. But that’s airborne piperonyl butoxide; orally ingested piperonyl butoxide presumably follows a different metabolic pathway.

Levels of other, more harmful pesticides show up far less frequently.

Organic is probably better (as is often the case), just to be on the safe side, but I don’t see strong evidence that conventional peanuts are loaded with pesticides.

Eric asked:

Do you know which brands of peanut butter use Valenica peanuts?

Every time I run across a peanut butter using Valencia peanuts, that fact is proudly advertised on the label. If it’s not called “Valencia Peanut Butter,” the ingredients will list “valencia peanuts.”

Zaira asked:

Hi, I have a severe form of arthritis which I treat with high doses of vitamin D. I seem to be sensitive to gluten as it causes the arthritis to flare. I normally avoid peanut but I really like it! Would the agglutinin in peanut have a similar effect to the gluten in wheat, barley, rye and oats for the ones of us with auto-immune diseases?

I’d definitely be careful. Dietary lectins tend to show immunoreactivity to connective tissues in autoimmune arthritis. One older study even specifically fingered peanut agglutinin as showing reactivity in the synovial fluid of rheumatoid arthritis patients.

Let’s put it this way: You’re not missing out on anything important by avoiding peanuts. If you really love peanut butter, you can certainly try. Just make sure to note any worsening of symptoms.

Madeleine asked:

Thanks for the comprehensive analysis Mark! Wondering how peanuts compare to other nuts, like macadamias, almonds, etc. in the same terms, i.e. lectins, mycotoxins, micronutrients, and other long term benefits/risks.
Also, I always eat all nuts raw to avoid damaged PUFAs; is that over-cautious?
Thanks all!?

For micronutrients and other benefits, check out the Definitive Guide to Nuts I did a couple years back.

As far as mycotoxins, peanuts are worse because they grow in-ground and have that much more time to pick up fungal growth. Tree nuts only begin to develop mycotoxin contamination—if at all—during storage.

Peanut agglutinin appears to be the most problematic lectin among the nut lectins.

Regarding raw nuts, see the first answer on today’s post and my older post on roasted nuts. (Yes, it’s probably unnecessary.)

Linda mentioned:

I’ve never really missed peanuts to be honest, but I do crave peanut butter from time to time. As a Dutchie it’s very much part of my cultural background (we’re second only to the US in peanut butter consumption, IIRC).

I’ve discovered that a spoonfull stirred into Greek yogurt makes a very satisfying breakfast, nice and thick and more filling than the yogurt alone, and it takes care of my cravings!

Ever try it stirred into cottage cheese? Not bad.

Mathieu wondered:

The omega3/6 ratio is not an issue ?

From my reading of the evidence, it seems like two factors are more important than careful tracking of your omega-3:omega-6 ratio:

  • Making sure the omega-6 you do consume isn’t oxidized, damaged, or rancid. Eat whole food sources of omega-6 (nuts, seeds, avocados) and when you do consume oils containing omega-6, choose high-quality oils with endogenous antioxidant compounds that inhibit degradation (avocado, olive, etc).
  • Eating adequate amounts of long-chained omega-3 fats. These are the ones found in marine foods like fish and shellfish, as well as pastured eggs.

The trick, if you’re on a high-fat or keto diet, is to keep the portions of high-O6 foods to a reasonable level. Just because a greater proportion of your calories are coming from fat doesn’t mean you should freely consume all sources of fat. Consuming more fat means you should be more careful of the fatty acid composition of your diet, not less, as the imbalances and effects become magnified at greater concentrations.

A standard low-fat dieter might allot a tablespoon of peanut butter in his or her diet. A standard keto eater (who wants to eat peanut butter) should do the same, even though he’s eating more fat overall and has more “room” for fat, in order to keep omega-6 levels at a reasonable level.

That’s it for today, folks. Thanks for your peanut questions!


About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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