Blood levels of vitamin D can predict future health problems and early death

Blood levels of vitamin D serve as an early indicator of future health problems such as cardiovascular disease, osteoporosis, and cancer, according to a review article that was presented recently to the European Society of Endocrinology. Lack of vitamin D is rather common and a threat to public health, which is why the scientists suggest measuring levels of total vitamin D and free vitamin D in the blood. By optimizing levels of the nutrient in the blood it is possible to prevent a host of different lifestyle diseases as well as early death. It is not enough just to take any random vitamin D supplement. It must contain the right dose and have good absorption in order to be able to optimize vitamin D levels in the blood.

Nearly all cells in the body are equipped with vitamin D receptors (VDR). They are important for our health because they control many different genes and metabolic processes. However, surprisingly many doctors and health professionals are not entirely familiar with the many functions of vitamin D. For that reason, a majority of people in the world have too little vitamin D in their blood because recommendations are too low. This increases their risk of numerous age-related and chronic illnesses such as cardiovascular disease, cancer, osteoporosis, and type 2 diabetes.

Measuring vitamin D and using supplements to prevent disease and early death

Vitamin D occurs in many different forms or in different metabolites, and this is what a team of scientists from the University Hospitals Leuven in Belgium wanted to take a closer look at. Vitamin D occurs as a prohormone called 25-dihydroxyvitamin D3, which is the form of vitamin D that is measured in blood tests. Afterwards, 25(OH)D (as it is also named) is converted into the active form of vitamin D, which is called 1,25-dihydroxyvitamin D3 and binds to the different vitamin D receptors.
More than 99 percent of the vitamin D in our blood is bound to proteins. Only a small amount of the nutrient is free and able to be converted into biologically active vitamin D. The scientists behind the new study therefore assumed that levels of free vitamin D in the blood were a safer way of predicting future health problems.
They used data from the European Male Ageing Study, a cohort study that gathered information about men aged 40-79 years in the period between 2003 and 2005. The participants’ blood levels of total vitamin D and free vitamin D were compared with their health status after adjusting for confounding factors such as age, BMI, and smoking.
It turned out that low levels of bound vitamin D and free vitamin D were linked to an increased risk of early death. Still, it was only free hydroxyvitamin D3 that was able to predict future health problems. This was not the case with 1,25-dihydroxyvitamin D3.
The new data confirms that lack of vitamin D increases the risk of many different diseases and early death. The scientists point out that the most accurate method is to measure total levels of vitamin D and free hydroxyvitamin D3.

Why blood levels of vitamin D provide best most accurate picture

In another review article that is published in Nutrients, scientists looked at different studies to find out if suboptimal blood levels of vitamin D represent a major factor in some of the leading causes of death such as cardiovascular disease, hypertension, cancer, type 2 diabetes, and COVID-19.
They gathered data from different population studies and randomized, controlled studies (RCT). Although RCTs are normally viewed as the best and strongest scientific evidence when it comes to pharmaceutical drugs, studies of vitamin D have been flawed for the following reasons:

• The studies were based on vitamin D intake (dose) – not blood levels of the nutrient
• The studies have looked at supplementation of people who did not lack vitamin D
• The studies were conducted with too limited vitamin D doses or their duration has been too short
• The studies have been made with other kinds of vitamin D such as vitamin D2

Because these controlled, randomized studies of vitamin D have had been so flawed, the researchers suggest that studies where actual blood levels of vitamin D have been measured are much more accurate and reliable. On behalf of such studies, the scientists conclude that:

• Optimal blood levels of vitamin D should ideally be above 75 nmol/L (30 ng/ml) for prevention of cardiovascular disease
• If the aim is to prevent many other diseases, the optimal levels are around 100-150 nmol/L.

The scientists also say that the official recommendations for vitamin D are far too conservative because they do not take into account whether or not blood levels of vitamin D are optimal. Many people – especially people with dark skin, overweight individuals, and other vulnerable groups – need supplements with higher doses of vitamin D to optimize their vitamin D status in the blood and avoid diseases and early death.

References:

European Society of Endocrinology. "Vitamin D levels in the blood can predict future health risks and early death." ScienceDaily. 9 September 2020. .

William B. Grant et al. A Narrative Review of the Evidence for Variations in Serum 25-Hydroxyvitamin D Concentration Thresholds for Optimal Health. Nutrients 2022