Respiratory Quotient for Proteins

The ratio of carbon dioxide production to oxygen use, known as the “Respiratory Quotient,” can be used to estimate fat and carbohydrate utilisation.

When carbohydrates are broken down with oxygen, one molecule of carbon dioxide is a carbon dioxide emission to oxygen consumption, and the respiratory quotient for carbohydrates is 1.0.

For every 100 molecules of oxygen consumed, 70 carbon dioxide molecules are generated when fat is metabolised in the body’s cells. As a result, the respiratory quotient for fat metabolism averages 0.70. Because a portion of the oxygen metabolised with these foods is required to mix with the extra hydrogen atoms contained in their molecules, less carbon dioxide is generated about the oxygen utilised, and the respiratory quotients for fats and proteins are lower than those for carbohydrates.

Respiratory Quotient for Proteins

Let’s look at how the respiratory quotient can be used to estimate the body’s relative consumption of various nutrients. Remember from Chapter 40 that the respiratory exchange ratio is the emission of carbon dioxide by the lungs divided by the intake of oxygen over the same period. The respiratory exchange ratio is exactly equal to the average respiratory quotient of metabolic processes throughout the body for 1 hour or longer. Because the respiratory quotients for both fat and protein metabolism are significantly less than 1.0, a person with a respiratory quotient of 1.0. Finally, if we omit the generally minor quantity of protein metabolism, respiratory quotients of 0.70 to 1.0 approximate carbohydrate to fat metabolism ratios. To be more precise, one can measure nitrogen excretion to indicate protein use, as explained in the next section. The usage of the three foodstuffs can then be calculated using the proper mathematical procedure.

The following are some of the most noteworthy discoveries from respiratory quotient studies:

1. Almost all of the food digested immediately after a mixed meal containing carbs, protein, and fat is carbohydrates, therefore the respiratory quotient approaches 1.0 at that time.

2. The body has used up most of its readily available carbs by 8 to 10 hours after a meal, and the respiratory quotient approaches that of fat metabolism, which is around 0.70.

3. Because insulin is necessary for carbohydrate utilisation in untreated diabetes mellitus, the body’s cells can only use a small amount of carbohydrate under any circumstances. As a result, when diabetes is severe, the respiratory quotient stays close to 0.70, which is the quotient for fat metabolism.

Proteins

CO₂ released / O₂ consumed   =RQ

No single RQ can be attributed to the oxidation of protein in the diet due to the Intricacy of the multiple ways in which different amino acids might be oxidised; nonetheless, 0.8 is a commonly used estimate.

 RQ is an indirect but quick method to find if a growth medium is absent in a substance. The feeding pump is turned on/off based on the concentration of dissolved oxygen in the fermentation medium, and the DO-stat works on the principle of the respiratory quotient. The OUR or CER analysis can also be utilised as a control parameter to prevent the accumulation of by-products.

Respiratory quotients of some substances

• In severe forms of chronic obstructive pulmonary disease, the respiratory quotient can be useful. There are also the following applications:

• It’s used to see if you’re overfeeding or underfeeding.

• This test is used to determine how well the liver is working.

• Used to predict excess weight in diabetic patients who are not insulin-dependent.

• When a patient has liver cirrhosis and a non-protein respiratory quotient, this test is used to diagnose their condition.

CONCLUSION

The respiratory quotient (RQ) is the amount of carbon that is emitted for every unit of oxygen ingested. Carbon Dioxide Production to Oxygen Utilization Ratio Can Be Used to Calculate Fat and Carbohydrate Consumption.