The Role of Hemoglobin in Oxygen transport
Power in our blood: the role of hemoglobin in oxygen transport
By Sarah Willis PhD
We know that our blood is important for transporting oxygen throughout our body, and it has something to do with hemoglobin. Hmm, let us delve into this for a few minutes to figure out why. Hemoglobin is the oxygen carrying protein in red blood cells which transports oxygen from the lungs to the body via the bloodstream. We remember and know that we need oxygen to live, the more oxygen our cells and tissues have available, the better they can function (i.e., improve efficiency in metabolism). The cells of our bodies need energy to perform work and maintain the biological order for survival.
Remember that our mitochondria (powerhouse of cell) make ATP for different energy metabolisms. The systems are ATP-PCr, phosphagen system, use of creatine phosphate to make ATP; anaerobic glycolysis, ATP production without the use/presence of oxygen; aerobic/oxidative phosphorylation requiring oxygen to pass electrons through protein complexes generating ATP. The goal is to get more oxygen to the cells (different story of how the cells utilize it related to the systems described above), as the more oxygen there is available – the more efficient we can produce energy and work/function/survive.
One section of our body’s oxygen transport system is the oxygen-carrying capacity of our blood. This is important as it brings oxygen in our blood to the tissues of our body. The oxygen-carrying capacity is reliant on our circulation and vascular system as our heart pumps blood through our vessels. Yes, the lungs are part of this as well since we get oxygen from there but let us focus on transportation in the blood.
It is not that simple though, as with many things in physiology, the oxygen-carrying capacity also depends on the environment in our blood. The oxygen hemoglobin dissociation curve is a principle that allows us to understand more about the environment inside our vessels and indicates conditions about the ability or affinity of hemoglobin and oxygen to bind. Factors that affect this are pH, PCO2, temperature, 2,3 DPG (diphosphoglycerate), % fetal Hb. For example, when there is a shift to the right on this curve (see image below), it is called a Bohr effect – meaning that there is a lower affinity for oxygen to bind secondary to an increase in PCO2, decrease blood pH – more acidic (think production of lactate), increased temperature…which ultimately enhances the unloading of oxygen to tissues in order to meet O2 demand. This is a condition found during exercise, since when we exercise – especially at higher and higher intensities, when we demand a great amount of ATP for energy. Thus, we lower the affinity for oxygen to bind with hemoglobin, and oxygen is unloaded from the capillaries to go into the tissue/cells and mitochondria for cellular respiration and energy metabolism. On the other side, a higher affinity for oxygen to bind with hemoglobin is found (the opposite) when oxygen needs to hold onto hemoglobin as a kind of protection. Situations where this higher affinity for them binding is when there is decreased temperature, more basic – alkalinity of pH in blood, lower PCO2 - respiratory distress such as hyperventilation due to pain or anxiety, hypoxia – not enough oxygen in blood/tissues, pulmonary concerns, severe anemia, etc.
So, we understand that Hb mass is important, but how do we improve that as well as our ability to facilitate conditions where hemoglobin and oxygen are bound together to transport further into our muscles and tissues for efficient function and performance?
Foods that contain iron and folate are vital for the ability of increasing Hb mass. With iron, we need a protein called transferrin to bind with iron and transport iron throughout the body. Iron’s role is to help us make red blood cells (which contain hemoglobin). Foods high in iron are: fish, meat, eggs, soy products, broccoli, green leafy vegetables such as spinach, cauliflower, green peas/beans, nuts, seeds, peanut butter; with fruits: apricots, apples, grapes, bananas, pomegranates, watermelons; and drinks = apple juice, beet juice, cocoa, green smoothies, orange juice, beef broth, apricot nectar, etc.
Folate (a.k.a., B9) is important in forming new blood cells and DNA, along with breaking down/creating/utilizing new proteins/preventing birth defects. Folate is found in lesser amounts in many foods we eat, such as dark green leafy vegetables - spinach, romaine lettuce, asparagus, brussels sprouts, broccoli), as well as in beans, peanuts, sunflower seeds, fresh fruit/juice, whole grain, liver, etc. A general recommendation for adults is to consume ~ 400 mcg of folate or folic acid per day.
Of course, training adaptations also improve our oxygen carrying capacity. Specifically, to note that heat training has been shown to be effective in increasing Hb mass without decrements to performance (a 5-week study by Ronnestad et al. (2022) was performed in male XC skiers. Furthermore, a more obvious adaptation would be during altitude training, where spending at least 21 days at altitude to boost the ‘strength in our blood’ via Hb mass. Research has also demonstrated that respiratory training such as breath holds and hypoventilation to be beneficial for increasing Hb mass (Lapointe et al., 2020).
Think about it; by adjusting our nutritional lifestyle, we can improve our body’s oxygen carrying capacity and improve our availability of oxygen. No wonder ‘healthy’ food is important. It helps us prevent cardiovascular diseases, among others, and improves our ability to function/work/perform more efficiently since we have more oxygen available. In conclusion, a combination of both nutritional and exercise will improve our ability to transport oxygen and thus improve our efficiency in energy metabolism which in turn increases our performance capacities. I don’t know about you, but I am going to implement more foods listed above in my nutrition plan and feel my body adapt to new heights. Let’s do this!
