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Anand Kumar

Why is our blood not blue?

Updated: Jul 27



Mammals evolved to use oxygen to remove waste, carbon from our cells. Click here to learn more on oxgen. The courier responsible to deliver oxygen to all the cells in our body is a protein called haemoglobin. Haemoglobin is rich in iron. Iron is the reason why our blood is red and not blue. If we had evolved to use haemocyanin like octopus, our blood would be indeed blue. Now that we know little bit more about the color of our blood, let's dive into why we keep hearing about anemia, particularly women. Anemia is defined as low haemoglobin in our blood.

As always why should we care? When we are anemic (low haemoglobin), lower amount of oxygen is delivered to our cells. So, we have to breathe more and our heart has to pump more number of times so that our cells get enough amount of oxygen. The symptom is typically fatigue from higher breathing and heart rate. Both can be found by regularly monitoring and recording your breathing rate and pulse. However to absolutely confirm anemia, a simple blood test to measure the number of Red Blood Corpuscles (RBCs) would do. RBCs are the transport vehicles for haemoglobin. When haemoglobin is low, typically RBCs would be low as well. If needed, we can obtain the amount of haemoglobin and iron content in our blood. As women lose blood as part of their monthly menstrual cycle, they are more prone to anemia. Women have only 6 month supply of iron stored in their body whereas men have 3 years supply. Ironic isn't?

We can deduce that iron deficiency would cause anemia as we need iron to make haemoglobin. Vitamin B9 (folate) and Vitamin B12 (cobalmin) is also needed for healthy RBCs. When we do fall short of iron, our body can make it up. The iron absorption is not a fixed number. Our body has evolved with such efficiency and we don't give it enough credit. For example, they absorb more iron from our food when we are iron deficit and less iron when we are iron replete. The body conserves iron by reabsorbing the iron released when our old RBCs are broken down, thereby boosting our iron stores. In spite of all the body's magic, we are largely deficient in iron shows how the poor quality of our lifestyle.

It is a no brainer that we need to consume more iron in our diet. Animal food is rich in iron. Not only that, animals contain heme iron, which our body can absorb more (bio-available) than non heme iron, that are found in plant-based foods. Even with heme iron, our body can only absorb up to ~30%. But I have seen women who eat meat suffer from anemia as well. So, obviously there is more than meets the eye. Meat eaters used to eat all parts of the animal including organs. Nowadays, we have become picky and squeamish. We eat muscles alone. Thus, we lose out on our iron intake as organs are the ones rich in iron, especially liver. Liver is also rich in Vitamin B9 and B12.

Vegetarians do not need to fret. As always they must get a variety of vegetables and fruits to make sure they do not fall short in any one vitamin or mineral. So, it's important not to be picky when you are a vegetarian and eat as diverse as possible. Same applies to iron as well. Some iron rich sources are lentils, dark green leaves and black sesame seeds. Moringa(drumstick) leaves come to mind. Cooking with iron vessels increases our iron intake. Dark green leaves are also rich in Vitamin B9 (Folate).

However, the iron found in plant-based sources and milk are of the non-heme type. For non-heme iron, the upper limit of absorption rate is ~20%. As you can see, they are less bioavailable than heme iron whose upper limit of absorption rate is ~30%. So, when we eat iron-rich plant based foods, we must eat foods rich in Vitamin C as it helps to absorb more iron. Also, we must not eat milk products as the calcium in milk as it reduces the absorption of non-heme iron more than heme iron. Even the tannins in tea, coffee and chocolate reduce absorption of non-heme iron. Do consider a iron supplement if you are still anemic.






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