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 assessment is a good example of this phenomenon. It appears to happen frequently for vitamins and dietary supplements. Unfortunately, the same issue affects general food as well. Is meat bad for you or not? In the end, a balanced diet with all the necessary nutrients seems most reasonable, rather than chasing specific superfoods. 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.

2024 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.

Vitamin D

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.

2024 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.

Vitamin D

Calcifediol

[Vitamin D](https://www.allmer.de/blog/vitamins/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](https://www.allmer.de/blog/vitamins/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.

Vitamin D

Vitamin D, technically a hormone, is made in the skin when UVB rays convert a cholesterol compound into D3 (Cholecalciferol, or Calciol). Many people don’t make enough due to lack of sun exposure, so we rely on food (like fatty fish) or supplements. Plants provide D2 (Ergocalciferol), but D3 works better in our bodies.

D3 has three key forms:

Calciol: Stored in fat for long-term use; this is the form we produce or ingest.
Calcifediol: Formed in the liver for short-term storage, circulating in blood and commonly tested to check D3 levels.
Calcitriol: The active form, made in the kidneys, with a short lifespan but crucial for biological effects.

We’ll be using the terms Calciol → Calcifediol → Calcitriol throughout future discussions.