Article Criticism (Brain Vitamin D Forms)

The Curious Case of Vitamin D and Brain Health: A Study Worth Revisiting

Recently, the German journal FITBOOK ran an article discussing a study that examined the relationship between Vitamin D levels in brain tissue and cognitive function. The FITBOOK piece itself was riddled with oversimplifications and exaggerations (which I’ve dissected elsewhere), but now it’s time to look critically at the study that sparked the excitement.

At first glance, the study appears to offer intriguing insights into Vitamin D’s potential role in brain health. Upon closer inspection, however, it falls short in several ways. Here’s a breakdown of the study’s key limitations and why its findings need to be taken with a hefty pinch of salt.

Assessments

Article Criticism (FITBOOK Journal)

Response to an Article in German Journal FITBOOK

I commented earlier on another article in FITBOOK concerning the Amazing effect of vitamin D supplementation on metabolism. Now, we need to talk about another article in FITBOOK. The article entitled: “Effect of vitamin D on brain function” discusses a study on Brain Vitamin D Forms, Cognitive Decline and Neuropathology in Community-dwelling Older Adults. The article by Friederike Ostermeyer discusses a recent study examining the relationship between Vitamin D levels in the brain and cognitive function. While Vitamin D is undoubtedly important for overall health, her article exaggerates the findings of the study and misrepresents key points, leaving readers with more hype than substance.

Vitamins

Vitamin D Supplementation

Vitamin D, often called the “sunshine hormone,” plays a vital role in overall health. Many people in the Western world are deficient in it, but before deciding to supplement, it’s essential to test your blood levels (Calcifediol). This can help you understand whether supplementation is necessary and how much you need to reach optimal levels.

Key considerations include your current blood levels, lifestyle, UVB exposure, skin tone, BMI, and health conditions. Vitamin D3 (Cholecalciferol) is the preferred supplement form, as it is more effective than Vitamin D2. Individuals with higher BMIs or certain health conditions may require higher doses or specialized forms like Calcifediol or Calcitriol.

Assessments

Article Criticism (FITBOOK Journal)

Response to an Article in German Journal FITBOOK

The article entitled: “Amazing effect of vitamin D supplementation on metabolism” discusses a recent study that according to the author of the FITBOOK article suggests supplementing 3320 IU of Vitamin D per day. Let’s clarify first that the study entitled: “Modifiers of the Effects of Vitamin D Supplementation on Cardiometabolic Risk Factors: A Systematic Review and Meta-Analysis” has been published in the journal of Engineering and is a meta-analysis, not a new research study.

Vitamins

Vitamin D Unit Converter

Vitamin D (Cholecalciferol) used to be measured in micrograms (mcg). At one point, international units were introduced (IU). Today, either or both IU and mcg are found on supplement labels. Sometimes, it is beneficial to know the amount in IU and the amount in mcg. Especially when you want to use the correct ratio of several vitamins simultaneously. An important example in this context would be the combination of vitamin D and vitamin K. While Cholecalciferol ensures that there is enough calcium in the blood, vitamin K is involved in bringing calcium to the correct location (bones). Calcification of soft tissues such as cartilage and arteries is definitely something no one wants. Therefore, both vitamins should be used together. How much of each is a discussion for another time. However, once you decide and settle on a ratio between vitamins D and K, you can use the below converter to ensure that you use the correct amounts.

Vitamins

Vitamin D Regulation

Calcitriol, the active form of vitamin D, is a powerful hormone that needs tight regulation in the body. It acts like a “key” that fits into specific “locks” (receptors) to manage important functions like calcium and phosphate balance. Too much or too little can cause harm, so the body carefully controls how much is made.
The body converts stored vitamin D (Calcifediol) into Calcitriol in the kidneys, but if Calcitriol levels get too high, enzymes slow down its production and break it down. Calcium and phosphate levels in the blood also help regulate this process.
Low calcium triggers the production of more Calcitriol, while high calcium or phosphate slows it down. Additionally, low phosphate increases Calcitriol, while high phosphate decreases it. These processes work together to maintain balance, ensuring proper calcium and phosphate levels in the blood.
If vitamin D stores are low, the body can’t produce enough Calcitriol, which can lead to health problems.

Vitamins

Calcifediol

[Vitamin D](vitamin-d), also called calcifediol (the short-term storage form), is made in the liver from another form of vitamin D. It usually binds to a protein in the blood, which helps it stay in the body for weeks. If there's not enough of this protein, vitamin D can be broken down and removed from the body through the kidneys. When the body needs more of the active form of vitamin D (/vitamins/vitamin-d/calcitriol), especially for things like low calcium or immune system support, stored vitamin D is quickly converted. [Vitamin D](vitamin-d) levels in the blood can indicate if someone has a deficiency or not. If levels are too low (see table below), the body may struggle to make enough active vitamin D, leading to various diseases.

For more technical details, read on.

The name Calcifediol (aka vitamin D) refers to a hormone that is produced via hydroxylation of Cholecalciferol in the human liver. Calcifediol is typically bound to the D-binding protein (DBP) but can be unbound if there is not enough DBP. If unbound, it is typically degraded and excreted via the kidneys. When bound to DBP, Calcifediol is relatively stable and can circulate in the human blood for weeks. Unless it is converted to Calcitriol and used by downstream processes. If demand for Calcitriol is high, e.g., low calcium or challenges to the immune system, ‘stored’ Calcifediol is converted to Calcitriol quicker.

Vitamins

Vitamin D Solubility

Vitamin D, in fact a hormone, is said to be soluble in fat. Therefore, it has been cautioned, that too large an intake or production of D3 or more precisely Cholecalciferol can be dangerous since it could be stored in fat. Solubility is not that easy, especially when considering biological systems. First of, anything is soluble in anything to a varying degree. When saying D3 is fat soluble, we also need to consider that there are three different molecules that we mean when we say D3 (see vitamin D for a disambiguation).