Lack of sunshine nutrient may shorten your life

It is both healthy and life-extending to get plenty of summer sun, which is our main source of vitamin D. Just make sure not to get a sunburn. According to a large population study from University of South Australia, too little vitamin D in the blood is linked to early death, especially because of an increased risk of cardiovascular disease, cancer, and respiratory diseases. This is very relevant because, apart from the lack of sunshine during winter, things like sun awareness campaigns, indoor living, being overweight, and having dark skin can contribute to the widespread lack of vitamin D. The official recommendations for vitamin D intake are also comparatively conservative. Therefore, people should strive to optimize their levels of the nutrient, as vitamin D is involved in regulating countless gene activities and other functions in the body.

Studies have revealed that lack of vitamin D is linked to increased mortality. With regard to severe deficiency, however, more research is needed. In the recent study, scientists used data from the UK Biobank, which stores health information from people in England, Scotland, and Wales that were recruited in the period 2006-2010.
A total of 307,601 participants aged 37-73 years were included. The researchers used blood samples to determine the participants’ levels of 25-hydroxyvitamin D, and they also gathered genetic data.
Up until June 2020, the scientists analyzed all-cause mortality, where cardiovascular disease, cancer, and respiratory diseases were the most common causes.
During a follow-up period of 14 years, there were 18,700 deaths. It turned out there was a direct link between low vitamin D levels in the blood (under 50 nmol/L) and early death. The lower the vitamin D level, the higher the risk. All-cause mortality was increased by 25 percent in people whose levels of vitamin D in the blood were 25 nmol/L, compared to those with 50 nmol/L
There were certain limitations, however, because the study did not include people with dark skin color who are less able to synthesize vitamin D from sun exposure than people with light skin. Nonetheless, the scientists conclude that there is a direct link between lack of vitamin D in the blood and the risk of early death. The study is published in Annals of Internal Medicine.

Blood levels of vitamin D are essential for health and lifespan

The current recommendations for vitamin D intake and the recommended threshold values are based on bone health exclusively and do not take vitamin D’s many other functions into account. Also, the form of vitamin D that we produce from sunlight or get from supplements is inactive and must first be converted (by the liver) into the active form called 25(OH)D, which is the type of vitamin that is measured in the blood. When the body’s cells need vitamin D for various functions, 25(OH)D is converted (by the kidneys and various other tissues) into the biologically form of vitamin D called 1,25(OH)D, which controls a number of different genes and a number of other body functions that are important for immune defense, inflammatory response, pulmonary function, brain and nervous system, blood sugar, circulation, and cancer prevention.
Around half the world’s population has too little vitamin D in the blood, which increases their risk of cardiovascular disease, hypertension, cancer, type 2 diabetes, Alzheimer’s disease, respiratory diseases, and early death, according to previously published research.
Vitamin D research also appears to be somewhat misleading because studies typically look at vitamin D intake rather than focusing on how much of the nutrient actually present as 25(OH)D in the blood. In many causes, people who supplement take far too little of the vitamin or use it for too short a period. As a result, their blood content of vitamin D never reaches the optimal level.
The study authors stress that blood levels of 25(OH)D should ideally be above 75 nmol/L in order to offer reliable protection against cardiovascular disease, cancer, and early death.
In Denmark, the official vitamin D recommendations suggest that vulnerable groups get around 5-20 micrograms of the nutrient daily. This is unable to guarantee optimal blood levels of vitamin D. According to the review article in Nutrients, most people who take around 50-100 micrograms of vitamin D daily are able to reach blood levels of 75-100 nmol/L. The European Food Safety Authority (EFSA) states that it is safe to take up to 100 micrograms of vitamin D daily. This amount is less that what a lightly-dressed person with light skin can synthesize from sun exposure on a sunny day during the summer.

Vitamin D from sun and supplements and optimizing blood levels of the nutrient

• Most people with light skin are able to synthesize enough vitamin D from sunlight during the summer. In the winter period, however, the sun is not strong enough
• The quality of a supplement and the dosage are determining for its effect
• Vitamin D dissolved in oil in capsules provides the best bioavailability
• People’s need for vitamin D varies. Supplements are available in doses between 20 and 100 micrograms
• In order to be protected against cardiovascular disease, hypertension, cancer, type 2 diabetes, Alzheimer’s disease, respiratory diseases, and early death, blood levels of vitamin D should be higher than 75 nmol/L

References:

Joshua P. Southerland et al. Vitamin D Deficiency Increases Mortality Risk in the UK Biobank. Annals of Internal Medicine. 2022

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

Debra Sullivan. What are the health benefits of vitamin D? MedicalNewsToday 2019