Oxygen, carbon dioxide and the krebs cycle: A metabolic typing perspective - Letters to the Editor - Letter to the Editor

Townsend Letter for Doctors and Patients,  Feb-March, 2002  

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Editor:

As we all know, oxygen plays a central role in the oxidation process, the intracellular creation of energy in the form of ATP. Oxygen is alkaline-forming in the blood, while carbon dioxide -- which is produced as a by-product of the oxidation process -- is acid-forming. The ratio between them is intimately connected with maintaining the optimal blood pH of 7.46, which is the primary goal of the nutritional protocols of Metabolic Typing. At this pH level, all of the systems of the body are encouraged to function harmoniously. If there is an excess of oxygen (or deficit of [CO.sub.2]) the blood will be overly alkalinized. Conversely, if there is an excess of carbon dioxide (or deficit of oxygen) the blood will be overly acidified.

This observation is used during the Metabolic Typing testing protocol to help determine an individual's Metabolic Type. After taking a series of baseline readings, we administer a modified glucose challenge drink (containing significantly less glucose than the medical glucose tolerance test, as well as some added potassium). This drink is acid forming to the two Oxidative types (Fast and Slow Oxidizers), thereby increasing their blood levels of [CO.sub.2] and decreasing their levels of oxygen. This has the effect of increasing the respiration rate, as the body tries to compensate by breathing in more oxygen, while decreasing the ability to hold the breath, due to a deficit of oxygen. Individuals who demonstrate these traits during the testing procedure (determined by comparing the baseline readings with readings taken at a specified time after ingesting the modified glucose challenge drink) will generally, therefore, be one of the two Oxidative types.

Conversely, the glucose challenge drink is alkalinizing to the Autonomic types (Sympathetics and Para-sympathetics), thereby increasing blood levels of oxygen and decreasing levels of [CO.sub.2]. (This phenomenon illustrates one of the key observations of Metabolic Typing, that the same nutrients produce opposite pH effects at the level of the blood in the Oxidative and the Autonomic Metabolic Types). Accordingly, their respiration rate will tend to drop, due to the presence of more than adequate amounts of oxygen, while their ability to hold their breath will increase. These traits would therefore suggest that an individual demonstrating such a shift is one of the two Autonomic types.

The Krebs Cycle Revisited

Inside each of the cells of our body (except mature red blood cells) are several microscopic, oval-shaped organelles known as mitochondria. The mitochondria (or mitochondrion, in the singular) are often referred to as the body's energy furnaces, because it is here that the nutrients extracted from our foods are converted into energy. This happens through a complex set of interactions known as the Krebs cycle (named after its discoverer, Sir Hans Krebs), in association with the electron transport chain, which completes the work started by the Krebs cycle.

Essentially the Krebs cycle (also known as the citric acid cycle) involves a series of enzymatic reactions that transform proteins (in the form of their constituent amino acids), fats (as their constituent fatty acids) and carbohydrates (as glucose) into intermediate substances. These intermediates are then passed into the electron transport chain where they undergo a further series of reactions - receiving and donating electrons down the chain - to produce energy in the form of ATP (adenosine triphosphate), [CO.sub.2] and water. The presence of sufficient oxygen within the cells is essential to the success of this entire procedure, as the term oxidation itself indicates. The primary substrates, or raw materials, for the Krebs cycle are glucose (extracted from carbohydrate foods) and fatty acids. Most of the glucose forms oxaloacetate in the Krebs cycle, while the remaining glucose combines with the fatty acids and amino acids to form acetyl coenzyme acetate (acetyl CoA). These substances are then further sp un around the Krebs cycle with the help of additional amino acids, vitamins, enzymes and organic acids. In a dizzying whirl of back-and-forth biochemical transmutations, acetyl CoA reacts with oxaloacetate to produce citrate (citric acid), which then reconverts back into oxaloacetate until the coenzyme intermediates are shuttled out the bottom of the Krebs cycle into the electron transport chain to complete the production of ATP.

If oxygen is delivered to the cells, this entire enterprise will be compromised. Insufficient oxygen delivery can be due to any of the following: (a) insufficient a lack of oxygen in the blood, if the blood is in an overly acidic state; (b) an excess of oxygen in the blood in, the case of an overly alkaline venous blood pH; this is accompanied by a concomitant lack of [CO.sub.2], which, among its many other functions, acts as a catalyst to release oxygen from the hemoglobin, freeing it up so that it can be absorbed into the tissue cells; or (c) to an insufficiency of the enzyme 2,3-DPG, which is also required to release the oxygen molecule from the red blood cell. Alternately, an imbalance of raw materials fed into the Krebs cycle will result in less than optimal energy production, as both the oxaloacetate and acetyl CoA "sides" of the Krebs cycle need to balance each other out for its full energy potential to be realized.