Precision Nutrition Week 3

Chapter three: Super Science-y. Rather than take us all back to physiology class, I’m going to go off on a tangent. It all started with two little side notes about the effect on vitamins on metabolism… And ended up pretty science-y anyway. Talking about chemical reactions can do that!

First, a quick recap: Metabolism is the total of all chemical reactions in your body, including both the processes that break down and those that build up. These processes are fuelled by the food we eat. For this post, any metabolic processes discussed will be catabolic or break down processes.

Vitamins (and minerals) do not themselves provide energy, but without them, metabolic processes could not be completed.  The Vitamin B complex contains eight separate vitamins; each molecule is in the same family but chemically different from one another and includes:

  • Vitamin B1 (thiamine)
  • Vitamin B2 (riboflavin)
  • Vitamin B3 (niacin)
  • Vitamin B5 (pantothenic acid)
  • Vitamin B6
  • Vitamin B7 (biotin)
  • Vitamin B9 (folic acid)
  • Vitamin B12

If they don’t provide energy, what DO they do?

If vitamins can’t supply energy, what good are they?  Well, most vitamins (B complex and others) have essential roles in our metabolism and other physical processes. The B complex gives us more than enough to look at in one post: each of the eight B complex vitamins are involved in the aerobic and anaerobic metabolic processes that refill our energy supplies.

After the food we eat is broken down into its sub-units (glucose from carbohydrates, amino acids from proteins, fatty acids from fats), it is metabolised further within our aerobic or anaerobic pathways, or both. The B vitamins are involved in these processes as coenzymes, or small molecules that help the processes take place, and as the foundations of other molecules needed in the process. Without adequate amounts of all B vitamins, all energy renewal in our bodies would grind to a complete halt!


Vitamins B2, B3, B5, and B6 are all involved in glucose metabolism in the anaerobic or aerobic pathways – respectively, glycolysis and the Krebs cycle, which is the first half of aerobic metabolism. These vitamins help move molecules from place to place and pick up by-products like the hydrogen ions that cause muscle fatigue. B5 is also a necessary component of the molecule acetyl Co-A, which is the starting point for aerobic metabolism.

I’m separating out the second half of aerobic metabolism, called the electron transport chain, because every  B vitamin is involved in this process, working as supporting coenzymes or being used to help create the other molecules necessary to complete the energy renewal process.


B3, B5, and B6 are the major players in protein metabolism. We don’t often think of proteins as a source of potential energy, but after undergoing some molecular changes, amino acids can be converted to glucose for use in anaerobic or aerobic metabolism, or to acetyl Co-A or other molecules needed for use in the Krebs cycle. Once the molecular change takes place, the B vitamins kick in and perform the same functions seen with carbohydrate metabolism.


As we all know, fat is our big time energy storage facility. When broken down, fatty acids provide far more energy replenishment than either carbohydrate or proteins. Once again, B vitamins play a major role in our cells’ ability to get the energy out: Fatty acids are broken down into acetyl Co-A to be used in aerobic metabolism. The breakdown of fatty acids requires B2, B3, B5, B7, and lastly B12. Once we get to the electron transport chain, all the other B vitamins pitch in as well.

Stocking up

B vitamins are found in a wide range of foods, including animal protein sources, whole grains, and fruit and veggies (sounds like every diet recommendation in the world). A lot of foods today are also fortified with added vitamins – check the side of the cereal box and refer to the full list of B complex vitamins above. How many do you recognise?  Though there is some argument about whether these added vitamins are as beneficial as those that occur naturally, they can’t hurt.

To get the most “B” from your diet, bear in mind that B vitamins are easily destroyed by sunlight, heat, and exposure to oxygen. You can minimize exposure by keeping your fruit and veg wrapped up tight or in an airtight container, and out of the sun. B vitamins are also water soluble, which is a double whammy: they can leach out of foods when washed or cooked in water, and they can leach out of us, too. Excess B vitamins will be filtered out by the kidneys and excreted, so it’s important to keep replenishing them, either through diet or supplementation. Just one more example of how the right diet helps you achieve your training goals – no matter what they are.


1. Berardi, J and Andrews, R. 2010. The Essentials of Sport and Exercise Nutrition. Precision Nutrition, Inc.
2. Doug Kalman MS, RD, FACN. Vitamins: Too much of a good thing? Viewed 12 June, 2011. <;
3. Christa can Tellingen, MD. 2001. Biochemistry from a phenomenologial point of view. Viewed 12 June, 2010. <;