phytic acid

Rancid Fats
02/09/2010 - 20:11

 

This post by Holly Hickman takes issue with the idea that phytic acid in nuts is bad news. I posted very recently about this issue and came to the opposite conclusion. Perhaps it is because my site is oriented towards people eating paleo to help autoimmune conditions. Holly is right that every plant food contains some sort of "don't eat me" chemical. You can be sensitive to many of these...or none of them. There are plenty of people who gobble down Planter's Mixed Nuts without a problem, but I'm not one of them. I can eat a few fresh nuts, but something like almond-flour crackers would make me sick for days. If your gut has problems, it's worth it to examine your intake of plant foods and figure out which ones are making your problems worse. 

It's also worth remembering that nuts were seasonal and eaten in small amounts by paleolithic people. When we buy shell nuts we forget how tough they are to crack! Shelled nuts might also be a bad idea because the fats in nuts can go rancid easily. Rancid fats might sound gross, but actually some rancid fats do not have a detectable taste or smell. 

That's bad news, because according to Oxidized Fat in the Diet by Jeffrey S. Cohn is a review article summarizing several research studies, 

Consumption of lower levels of oxidized fat on repeated occasions may pose a more chronic threat to health, however, particularly because low-level oxidation of meat, milk, poultry and cereal products during storage and processing is virtually unavoidable [4]. More extreme oxidation of fat can also occur when oils are used for cooking.

He mentions that the natural oxidation of cholesterol produces at least 30 different compounds that are biologically active and are particularly prevalent in the milk and egg powders used in processed foods. Compounds such of these are shown in experiments to absorb quite easily into the intestinal wall. In animal studies, oxidized fat led to higher incidence of atherosclerosis. In studies of healthy adults, the consumption of these fats led to impaired arterial function. These effects were not seen following low-fat meals or meals of less oxidized fats.

Comparative Nutritional Value of Diets Containing Rancid Fat, Neutral Fat, and No Fat by Dorothy Whipple is an old one and describes the diet of lab animals. Lab rats fed slightly rancid fats slowly developed horrible symptoms like swelling, hair loss, and neurological degeneration...and eventually died prematurely. Animals fed no fats developed the typical dry-skin symptoms and lived somewhat longer. Animals fed fresh fats were the healthiest and lived the longest. The researcher concluded that in terms of her experimental animals, it was better to feed no fat than oxidized fat, though neither was optimal.

Nuts are probably not the worst source of rancid fats. If you are eating paleo, you are avoiding most of the worst sources like cereals, milk powders, egg powders, and other trash. But I still think it's worth seeking out the best freshest nuts if you are going to eat them. This nut-growing website notes that "Levels of vitamin E are reduced by around 30% after three months of refrigerated storage."....most walnuts aren't even refrigerated. The best chefs contract with growers and buy fresh nuts which they freeze. 

I'm definitely thinking of contacting a NY farmer and doing a nut CSA here. Right now there isn't one, which is too bad.

Comment?: 3
Phytic Acid: taking off the paleo blinders
02/02/2010 - 11:46

Nuts are delicious...they aren't a grain, they are full of fat, low-carb, they are "paleo" what is there not to love? 

Apparently, lots. I addressed their imbalance of fats in a previous post and how they probably aren't paleo, but today an article on Cheeseslave about dental health got me interested in more:

In the interview, Rami told me that peanuts are as bad as soybeans when it comes to phytic acid content. He said that nuts are extremely high in phytic acid. He said that he thinks peanut butter that has not been soaked and sprouted is a “garbage food”. Rami told me that seeds are the absolute worst. Even worse than soy or peanuts. Sesame seeds have double or triple the phytic acid that soy has.

Let's look at the data:

How can paleo dieters bash grains and legumes for antinutrients when they are eating just as many in the form of nuts and seeds? It makes me wonder... which is really a better choice: a "paleo" pancake made from almond butter or a traditionally fermented idli? The idli probably has less phytic acid, that's for sure.

Since phytic acid robs the body of minerals, I think I will avoid it best I can. If I think about it carefully, since I am eating expensive meat...when I eat phytic acid it is robbing me of money!

The paleo diet can blind people by forcing them to argue about the history of food rather than its objective properties. But nuts lose either way. The only evidence of large-scale consumption of nuts comes from mesolithic and neolithic societies. They were between agrarian and foragers, as they still consumed wild foods, but they also engaged in activities that boasted nut production. As I was reminded in a recent permaculture workshop I took (you can view the slideshow from it here), agroforestry is still a form of agriculture.

Comment?: 11
The Seedy Side of Paleo
01/30/2010 - 19:04

 

woman will be happy when I spend all day gathering 1000 tiny seeds to make tahini with instead of clubbing a deer

 While nuts are well-accepted as paleolithic foods, seeds are little more contentious. Technically nuts ARE seeds, but botanics aside, what we think of as nuts are big enough that gathering a decent amount of calories from them in the wild is feasible. The same can't be said for seeds- most are tiny and it can take a long time to harvest enough to make anything out of. I learned this harvesting pigweed seeds. I was hoping to get enough of this amaranth relative to make porridge with, but I ended up with only enough to garnish a piece of fish. 

What about their place in a modern paleo diet? After all, we eat plenty of things that would have been tough to gather. For me, the problem with seeds is that if you eat large amounts of them you will be eating nutrients in ratios and amounts that are not appropriate for us evolutionarily. Furthermore, the polyunsaturated fats in them go rancid easily. While some might find hemp useful, I think it's a bad food, at least in the US because you cannot buy it whole and how long has that hemp powder been sitting on the shelf? Probably long enough to render some of those nice omega-3 fatty acids rotten. Flax is a popular ingredient in "paleo" baked goods, but ground and shoved in the oven, the fats can't be good. 

Furthermore, if you eat lots of seeds with the exception of flax, the ratio of omega-6 fatty acids to omega-3 fatty acids is likely to tip towards the latter, which is probably not a good thing. 

Several sources of information suggest that human beings evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids (EFA) of approximately 1 whereas in Western diets the ratio is 15/1-16.7/1. Western diets are deficient in omega-3 fatty acids, and have excessive amounts of omega-6 fatty acids compared with the diet on which human beings evolved and their genetic patterns were established. Excessive amounts of omega-6 polyunsaturated fatty acids (PUFA) and a very high omega-6/omega-3 ratio, as is found in today's Western diets, promote the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune disease

Furthermore, the conversion of any omega-3 from plants in your diet is hampered. The omega-3 fatty acids present in plants, alpha linolenic acid, is not immediately usable in the body. In order to be used, it must be converted to Docosahexaenoic acid. The enzymes that do this conversion are called Holman's enzymes. Unfortunately, they are also responsible for converting omega-6 fatty acids (mostly linoleic acid) to arachidonic acid. Lots of omega-6 means that there is not enough of Holman's enzymes to do the job. This is discussed in Susan Allport's book The Queen of Fats

Data for the US indicate that Americans consume between 11 and 16 grams of linoleic acid per day during the years 1989 and 91 and about 1 to 2 grams of alpha linolenic acid. At that ratio, only about 15 percent of the alpha linolenic acid is converted to DHA and eicosapentaenoic acid. At lower ratios, the conservation rate is much higher. The best conversion occurs at a ratio of 2.3:1

For paleo dieters who eat seafood, this shouldn't be a huge problem, but if not, it can be an issue. 

Let's also talk about phytic acid, an anti-nutrient present in many seeds, can reduce mineral absorption. There are a couple of other issues, like some estrogenic compounds in flax.

So that's why, in the Paleo Foods section of the site, I classify seeds as Not Paleo, but give the pros and cons. Some tahini sauce on your kale probably isn't as bad as some whole bran bread, but I would recommend keeping their consumption low. Use them as if you had to gather them yourself. 

Comment?: 3
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