Wednesday, May 7, 2014
Wisdom Wednesday: Krebs’s Citric Acid Cycle (CAC)
The most common chief complaint heard in a physician’s office is fatigue. It is much more prevalent that pain, the second most common complaint. Why do so many of us lack energy? There are many possible answers, but often fatigue is caused by poor energy production in the body.
There are four macronutrients, the foods we use to generate energy. They are protein, fat, carbohydrate (sugar) and alcohol. Yes, alcohol is now officially listed as a separate food group. Regardless of which food group you ingest, it is converted to glucose if it is to be burned as fuel to create energy. That chemical process that creates all the energy in every cell of the body is called the Krebs’s Citric Acid Cycle (CAC).
Fat can be stored for later use or converted to glucose. Protein is used initially for growth and repair of tissue. However, any excess protein is either converted to fat and stored or converted to glucose. Protein is not stored in the body. Alcohol is really a carbohydrate but is also converted to glucose just like fat and protein.
Glucose is a six carbon ring. Initially, it is broken in half to create two molecules of pyruvic acid. This yields three molecules of adenosine triphosphate (ATP), the energy molecule used by every cell in the body. However, it requires two molecules of ATP to facilitate the process, so the net is only one molecule of ATP. This process is called glycolysis or anaerobic metabolism, because it does not require oxygen to run the chemistry.
When you are at rest, most of your metabolism is anaerobic in nature. You break the glucose in half and create a little energy. However, as you begin to exercise, your heart rate increases, providing more oxygen to the tissues. Now your body takes those two molecules of pyruvic acid and strips all the hydrogen molecules off. It attaches them to B vitamins (and a few other chemicals) then sends the B vitamins into electron transport.
Electron transport (catalyzed by Co Q 10) then nets 27 molecules of ATP. This is termed aerobic metabolism because it requires the presence of oxygen. If you do the math, aerobic metabolism is 27 times as efficient as anaerobic metabolism.
This chemistry is most efficient when your heart rate is in your aerobic zone, approximately 70 to 80% of your Vmax (maximum heart rate). Your Vmax is 220 minus your age. So my Vmax is 158 and my aerobic zone is 110 to 130bpm.
The best part is that regular aerobic exercise facilitates more CAC/aerobic metabolism even when you are resting. That is, you actually burn more calories and create more energy when you are sleeping if you exercise on a daily basis.
After evaluating the nervous system, inflammation, and the immune system, I challenge the citric acid cycle to look for metabolic errors. A deficiency of one of the B vitamins is most common, but a lack of magnesium, manganese, lipoic acid, iron, Co Q 10, copper, or phosphorus can impair CAC function, resulting in low energy.
These patients find exercise very difficult or impossible and not effective for weight loss. Often subclinical hypothyroidism is an issue. Once corrected, exercise becomes an efficient mechanism for stimulating CAC. Energy levels rise and excess weight begins to drop.
THE BOTTOM LINE:
Calculate your own Vmax and aerobic zone. Invest in a heart rate monitor, about $75 from a sporting good store, and use it to stay in your zone during exercise. Orange Theory gyms use this protocol for all their workouts. Have a thyroid stimulating hormone (TSH) blood test. The medical range is quite wide, about 0.4 to 4.4, depending on the lab. However, you want to be in the range of 1-2 to reflect healthy thyroid function. If you find exercise is difficult at best, or ineffective for weight loss and energy production, consider having your Krebs’s Citric Acid Cycle checked.