Saturday, November 15, 2014

Paleo Diet - Why Nuts Are Permitted Despite the Phytic Acid

Crack open any book that advocates and explains the Paleo diet, and you will inevitably come across the words "phytic acid."  You will also hear it in proximity with another term - antinutrient.  So, what is phytic acid, and why is it bad?

Phytic acid, scientifically known as inositol hexakisphosphate, or IP6, is a cyclic acid.  It is the main form of storage of phosphorus in plants.  It is, indeed, an antinutrient.  And what is that?  Antinutrients are molecules that interfere with the absorption of nutrients.






The molecular diagram of phytic acid.


How does phytic acid interfere with the body's ability to absorb nutrients?

Its chemical makeup makes it strongly attracted to certain essential elements, most of all calcium, copper, iron, magnesium, and zinc.  When it binds to them in the intestine and reacts, it results in the molecules precipitating out in the intestine.  Once this process happens, the gut cannot absorb them, and they pass through the remainder of the alimentary canal and are excreted with the waste products. 

It is easy to understand why it is found in the hulls of nuts, and seeds as well.  Plants cannot move, so they invented their own defense mechanisms, which is to render them as nutritionally deficient as possible.  There are some animal species that were able to successfully counter this by making copious amounts of phytase in their system, which effectively neutralizes the phytic acid, enabling them to absorb the nutrients.  Humans, however, are not one of those species, therefore, we have to watch our intake of phytic acid.

Grains and legumes are off the Paleo diet for this very reason.  They contain an abundance of phytic acid.  Since the modern food pyramid was developed, mineral deficiencies, as well as obesity and diabetes, have skyrocketed.

So Why Are Nuts Allowed?

This is a valid question to any follower of the Paleo or Primal diet.  Nuts, by weight, in fact do contain more phytic acid than grains or legumes.  So what's so right with nuts, and so wrong with the other two?

One of the main reasons is volume.  When people eat bread, rice, grains, or beans, it tends to be the main or one of the main aspects of the meal.  Nuts tend to be eaten in much, much lower volume.  People do not fill half, or over half their plate with a mound of nuts, as they would with rice, or beans.  Nuts, more often than not, are a snack, eaten between meals.  Even when eaten with meals, they are usually a garnish.  Because they are known to be quite high in calories, they are not usually consumed in large mass.

The second reason is nutrition.  Nuts contain very heart and brain healthy fats, high in Omega-3.  They are also rich in other nutrients, such as Vitamin E and B12.  Brazil nuts contain the highest concentration of selenium, while walnuts are high in manganese. 

If you happen to be a person that eats considerably more nuts than average, one technique to eliminate most of the phytic acid content is to soak them in salty water for approximately one day.  If you eat only a few a day, you don't have to bother with the soaking, provided you are eating a diet that avoids most phytic acid.  In very moderate amounts, phytic acid has benefits.  One example is the inhibition of the crystallization of calcium.  This has the effect of lowering one's risk of kidney stones.  The main problem with phytic acid is that the standard American diet, and probably the standard diets in most parts of the world, contains too large of a quantity.

To reiterate, the best time to have nuts is in between meals, at least a couple hours after.  That way, most of the food from the previous meal will have passed the stomach, and will not be interfered with by the phytic acid from the nuts.   Make fruits, vegetables, and meat the bulk of your diet, and you can snack on a few nuts in between meals without any worry.


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