Sunday, June 21, 2015

Macronutrients: carbohydrates


There are two major classes of nutrients: macronutrients and micronutrients.

Macronutrients include Carbohydrates, Fats, Proteins and Water. They are called macro because our daily requirements of them is big, in the order of several grams for the first three, up to liters (and so kilograms) in the case of water. With the exception of carbohydrates, which our body can produce through several metabolic processes, the other three are essential and must be supplied regularly through a balanced diet.

Vitamins and Minerals are the so called micronutrients. Micronutrients are required in traces, nevertheless they are fundamental for health. One notable example is vitamin B12 which, although the requirements are in the order of micrograms (millionth parts of a gram per day), its deficiency is pernicious and subtle, especially in growing kids.

Another example is iodine, a mineral. Chronic deficiency of iodine or bad absorption of the same impairs the correct production of thyroid hormones and causes goiter (enlargement of the thyroid gland itself).

In this post I will introduce the carbohydrates. The post doesn’t have the pretention to be complete, there is really too much to say. It is just and introductory post and I will share more on this extremely important and controversial subject in the incoming articles.

Types of carbohydrates

Depending on their complexity, carbohydrates are generally classified as:

  • simple sugars: monosaccharides,  disaccharides (white table sugar, brown sugar, honey, maple syrup, agave nectar, fruits juices, sodas, candies, ...)
  • starch sugars (rice, white bread, pasta, pizza crust, cookies, yellow potatoes, ...)
  • resistant starches (plantain, banana, sweet potatoes, jerusalem artichokes, cold pasta...)
  • soluble fiber (legumes, oats, rye, chia seeds, sweet potatoes, onions, nuts, ...)
  • insoluble fiber (whole grains, lettuce, cabbage, beets greens, the peel of most fruits, ...)
I will discuss more and in detail with regard to the different roles of each.

Carbohydrates, friend of foe?

If you’ve read my previous posts it should be clear that the question is a trap.

The infamous FDA pyramid recommended a consistent intake of carbohydrates in the form of grains. Recent advertisements in Europe recommend that we continuously snack fruits throughout the day. Industrial dog food itself is being filled with carbs “to give your puppy more energy to play”. These have been the official guidelines for the last 50 years and instilled us the dogma that sugars are good, so white.

On the other side anybody familiar with diabetes, either directly or through a relative, knows that chronic excess in the intake of carbohydrates dramatically raises the risk to develop this disease. So it looks like sugar is black. Additionally I just mentioned that carbohydrates (under the form of glycogen) can be produced by our body so why bothering eating them at all? Let’s go low-carb or even better: zero-carb!

This practice, pretty much in vogue amongst paleo adepts, is a huge mistake and, while it is true that in today’s society we eat too much sugar, they are an important macronutrient which belongs to our genetic heritage. Pretty much like its abuse, the chronic low intake may have important health impacts, as I will have the opportunity to explain in future posts.

Roles of carbohydrates in the body

To finish this introductory article on carbohydrates, some words on the roles.
We have been taught to see carbohydrates uniquely as source of energy. Eat some candies to fuel the brain when you feel mentally tired and foggy, eat a bowl of pasta before running a marathon, etc. This is very unfortunate because in reality carbohydrates are more than that.
Roles of carbohydrates in the body include:

  • source of quick energy for the muscles (this stays)
  • required source of energy for some of the activities of the brain
  • regulation of protein and fat metabolism
  • help fight infections and modulate the immune system 
  • lubricate the joins
  • regulation of the growth of tissues, such as bones and skin
  • eating the right sugars and the right time improves insulin sensitivity
  • resistant starches and soluble fiber are required for the health of large intestine
  • insoluble fiber helps slow down the absorption of other nutrients and to eliminate the waste

Well, seems like sugars are worth more than just calories...

The next macronutrient I will introduce are the fats, an even more controversial topic, so… stay tuned!

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