We are now studying carbohydrates and iron in school. I have at the moment decided not to write about carbohydrates here because most of what I've learned about it the last days has been chemistry - how they look like in molecules, which might not be very interesting for you to read. So here are a few facts about iron instead:
Iron deficiency (lack of iron) is one the most common deficit in the world. They say about 15 % has it.
There are different types of iron and you can measure it in different ways through blood tests. People with a lack of iron are often very tired and studies (for example, a study by Dr. Ann B Bruners 1996) shows that it will also give bad memory and makes it harder to concentrate. People who are in risk are mainly pregnant women (especially the last trimester), teenager and women who are menstruating or if you loose blood in another way.
When I was a child, they took a blood test and tested my hemoglobin. They saw there that I had enough iron but then my dads friend (the nutritionist who is having a lecture on monday, open for everyone) told my dad that we should check the serum ferritin which shows more the bodys storage of iron. The doctors didn't understand why and didn't think that was important but they did it anyways and that test showed that pretty much all my storage of iron was empy and I was extremly close to be put in on the hospital for sever iron deficiency. So that's a tip for you, always ask you doctor to test both.
Men on the other hand tends to absorb too much iron and this can also be very dangerous. There are even hypothesis about that this can be a big reason why men don't live as long as women do. Finish studies has also shown that the risk for thrombosis (blodpropp) in the heart increases for every mg of iron men absorbs.
People with high iron storages also have a higher risk for other diseases like atherosclerosis (åderförkalkning) and cancer. High iron stores are actually on nr 2 (smoking is first) on the list of factors of things that increases the risk for cardio vascular diseases (hjärt-kärlsjukdomar) for men. To put it in a perspective - high cholesterol is nr 17.
It is hard to absorb iron though and we only absorb about 10 % of the iron we eat and in general, the body adjust the absorbtion pretty good.
Sources: Näringslära (Magnus Nylander) and Vitaminrevolutionen (Knut T.Flytlie)