Role of Vitamin K in Brain Development
What's vitamin K have to do with higher brain functioning? It's all to do with white over grey matter.
Rapid growth in the brain occurs until age two, and by age five the brain is at 90% of its full size. However, the most important changes in the brain — in terms of higher cognitive functioning—occur after this growth, as the brain prunes grey matter and gains white matter. This process is called myelination.(61-62)
How Can Vitamin K Help Make White Matter in the Brain?
Myelin Ramps Up the Brain
Myelination continues from before birth until death. It's crucial to the efficient relay of information via the neuronal pathways. Myelin insulates neurons and increases conductivity for nerve impulses, both of which are essential for high levels of brain functioning. Some experts compare the brain to the internet, where myelination serves to dramatically increase both speed and bandwidth. In other words, myelinated brain neurons are like a T1 internet connection, while unmyelinated neurons transmit signals like dial-up.(62)
Contrary to the popular belief that adults between the ages of 18 and 55 lose vast numbers of neurons, recent evidence demonstrates there is little (if any) neuron loss. The cortical shrinking that was thought to occur was actually a then-unrecognized effect of tissue-fixing agents which created greater shrinkage in the brain cortex tissue samples of younger individuals than that of older adults. This led to the erroneous conclusion that younger people have a relatively greater density of cortical brain neurons.(62)
Ironically it is the lower levels of myelination associated with youth that in all likelihood caused the shrinkage. Less myelin means less fatty tissue, and is more vulnerable to dehydration during tissue fixation in the laboratory setting. Conversely, the greater myelination in older adult brain tissue did not shrink, and actually reflects higher neuronal density than younger brains.(62)
Blood-thinning drugs such as warfarin inhibit vitamin-K dependent proteins to slow coagulation. However, in the process they also deplete some of the enzymes involved in sphingolipids and myelin. Some animal studies have demonstrated vitamin K supplementation can partially reverse this depletion.(22, 24)
Besides maintaining enzyme levels, vitamin K is also believed to regulate the activity of those enzymes involved in sphingolipid metabolism. This is essential for brain growth. Most evidence suggests that vitamin K's regulatory functions in sphingolipid metabolism are actually not related to its classic calcium-binding role. For example, vitamin K also acts as an antioxidant, protecting sphingolipid metabolism and myelin.(22, 24)