Survival of the Sickest Ch 3 Summary

Chapter 3 in Survival of the Sickest  Dr. Moalem explains how folic acid, vitamin D, and cholesterol all work together. He explains that though the sun is necessary it is constantly a problem for our bodies. Many of the things we are constantly exposed to in nature have this dual relationship...helps one on hand and hurts on another.  We  are always evolving in this balancing act.   We need the sun for the vitamin d it supplies us,but at the same time we are receiving the vitamin d the sun is taking away our folic acid. Now to counteract that our bodies create more cholesterol so that losing that folic acid is no longer an issue. The folic acid isn't dependent on the cholesterol; the vitamin D is.  Now our skin color is the way color it is due to the amount of sun you are exposed to year round. Africans have such dark skin due to the amount of sun they experience. The amount of sun won't make a person very dark if they don't have the traits that allow them to make lots of melanin.  For example, African genetics code for lots of melanin whether exposed to lots of sun or not, whereas European genetics codes for less melanin even if exposed to lots of sun.  There skin is darker so that not as much folic acid is taken from there bodies. I also learned that sun tan lotion is sometimes bad for the human body because it keeps the important vitamin D from absorbing the frolic acid. This results in excess cholesterol which is sometimes harmful to human bodies.