The Basics of the Zone Diet

This month as part of our continuing discussion on what is the right diet for you, I would like to talk about Dr. Barry Sears’ Zone Diet.


Eicosanoids – What they are and why they are important


Every cell produces hormones called eicosanoids.  There are good eicosanoids and there are bad eicosanoids. Bad eicosanoids are involved at a cellular level in all disease. In fact, Dr. Sears defines optimal health as a proper balance of good and bad eicosanoids. This is called being in the “Zone.”


The beneficial effects of taking a daily aspirin, such as decreasing heart attacks and stroke by “thinning” the blood, is due to aspirin’s effect of decreasing a specific eicosanoid which becomes thromboxane A2 (TB2), which causes blood to clot. TB2 is a powerful vasoconstrictor, meaning it causes blood vessels to constrict or narrow. The problem with taking aspirin on a daily basis is that it can have side effects (i.e., gastrointestinal bleeding); this is due to its decreasing the amount of good eicosanoids.


You may have heard of prostaglandins. These are a type of eicosanoid. Good eicosanoids,like prostaglandin E1, have very positive effects. Some of these welcome effects are: inhibition of platelet clumping, reducing autoimmune responses; decrease of histamine; reduced inflammation; lowering of cholesterol, and on and on. Bad eicosanoids have the opposite effects. In fact Dr. Sears shows how every disease has a high ratio of bad to good eicosanoids.


Controlling the ratio of good to bad eicosanoids

What helps control the ratio of good to bad eicosanoids? Your diet. Dr. Sears feels that the food you eat is the most powerful drug you can take because of its effect on the eicosanoids.


If you stay in the “Zone” you will produce more good eicosanoids.


The Zone Diet, as I see it, has three main components: 

1. The ratio of protein to carbohydrate optimally will be .75. In other words, for every four grams of carbohydrate you need 3 grams of protein. The daily amount of protein a person needs is based on an individual’s body type, height, weight, and whether or not they want to lose or maintain their weight. In his book, The Zone, Dr. Sears includes charts to compute the proper amount of protein.

2. The carbohydrate consumed should have a low glycemic index. This means the rate at which carbohydrates enter the blood stream is slow; too fast and you get an exaggerated insulin response.

3. For every gram of protein there should be a gram of fat. However, the type of fat is critical. 


The building blocks of eicosanoids are the type of fats you eat.

The fat, arachidonic acid, is the building block of all bad eicosanoids. Arachidonic acid is found in the saturated fat of organ meats, egg yolks and fatty red meats. The good fats are the monosaturated fats like olive and canola oils. These oils do not affect insulin and are eicosanoid neutral, meaning they do not go on to produce eicosanoids. 


EFA’s are the building blocks of eicosanoids

Within fats are essential fatty acids (EFA), which are the building blocks of eicosanoids. Excess free radicals oxidize the EFA’s and they then cannot go on to produce eicosanoids.(Free radicals are highly reactive molecules that have been proven or suspected of being agents of tissue damage including aging. They are known as oxidants and thus people take anti-oxidants.Mercury, which is found in so-called silver fillings, is a strong oxidant.)


There are eight EFAs. These can be divided into omega 6 and omega 3 fatty acids. Omega 6’s builds both good and bad eicosanoids. Omegas 3’s are relatively neutral in direct eicosanoid production. 


What we need to produce good eicosanoids


The EFA linoleic acid is found in most foods, and the higher the fat content the more linoleic acid. The delta 6 Desaturase enzyme (D6) converts this linoleic acid to gamma linolenic acid (GLA). As we age our ability to produce GLA decreases. At age 65 our production of GLA is 1/3 what it was at age 25. When you are in the “Zone”, the natural activity of D6 increases. A high carbohydrate diet and partially hydrogenated fats which contain trans fatty acids (i.e., margarine) inhibit D6. Stress, disease, and increased insulin also inhibit D6. Again we see the effect of the wrong protein to carbohydrate ratio and high glycemic foods, through their hyper insulin response. Why is all this so important? We must initially have GLA if we are to ultimately produce good eicosanoids. 


GLA goes to DGLA (dihomogammalinolenic acid) almost automatically. Once at DGLA, there are two biochemical paths available. One path leads to good eicosanoids and the other leads to the bad eicosanoids. To go down the bad road, DGLA is converted by the delta 5 Desaturase (D5) enzyme to arachidonic acid, which is the precursor to bad eicosanoids. So we see D5 is key.If we can inhibit this enzyme, the less arachidonic acid, the less bad eicosanoids and thus the less problem with our health, i.e. the less pain, inflammation heart disease, stroke, hypertension, etc.


Why your diet is important in this biochemical equation


What controls D5? It is activated by insulin. This is where the type of diet is so important.Carbohydrates must be kept in proper ratio to protein and the consumption of carbohydrates with a low glycemic index is crucial.


Another key to the puzzle is an EFA called Eicosapentaenoic Acid (EPA), which is an omega 3 fatty acid. EPA is a key inhibitor of D5. The richest source of EPA is salmon. This is why studies show a diet high in fish can reduce the risk of heart disease. (However, many fish are high in mercury and PCB’s. See my newsletter on fish). In a future newsletter I will go further into the beneficial effect of taking a proper fish oil supplement.


In Summary: the carb/protein ratio, wild salmon and fish oil lead to good eicosanoids

In summation: the closer a person maintains a protein to carbohydrate ratio of .75, the more increase in the activity of the D6 enzyme which gives us GLA. From there the trick is to get GLA to convert to good eicosanoids. This is a function of proper diet, eating wild salmon or by taking a fish oil supplement. 


Next month I will discuss The Blood Type Diet.


© 2005, Mark A. Breiner, DDS

The information presented is for educational purposes only. You should consult a qualified dentist or health practitioner for diagnosis and treatment. 

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