The determination of vitamin D levels in a clinical laboratory continues to be the fastest growing laboratory analysis in recent years in terms of frequency of detection, both in the United States and in other developed countries around the world.
This is based on information from the results of many new studies, some of which will be mentioned later in this article.
Vitamin D Deficiency
Today, it is no longer special news that over 50% of the world’s population suffers from vitamin D deficiency.
This is exacerbated by the misconception that vitamin D deficiency is predominant in young children, while the diet and lifestyle of adults provide the body with sufficient amounts of vitamin D.
However, several epidemiological studies in Europe, Northern Europe and Asia and Africa have shown vitamin D deficiency, especially in the elderly.
Unfortunately, more attention has been paid to this problem only recently, although it is possible to determine the level of vitamin D in the blood (this analysis is not paid for by the state, but it is not expensive, especially considering the subsequent costs and health problems of long-term vitamin D deficiency can cause the human body).
Vitamin D Sources
In nature vitamin D as provitamin exists in two forms:
- the plants originate ergocalciferol (vitamin D2) which because of ultraviolet (UV) light synthesizes from ergo sterol
- the origin of animal cholecalciferol which is formed in the skin (including in human skin) from 7-dehydrocholesterol.
So, because of sunlight, plants, mammals and fish can synthesize vitamin D, except for cats whose skin does not contain 7-dehydrocholesterol.
However, for animals and humans to activate vitamin D, two metabolic changes, first of all in the liver, of hydrolysis in position 25 (25(OH)D), and then in the kidneys–1-a-hydrolysis (1.25 di-hydroxy vitamin D), are required in the kidneys, after which active vitamin D can bind to the vitamin D receptors to take part in gene transcription and regulate ion (Ca/P) homeostasis.
88% of vitamin 25(OH)D circulates with vitamin D binding protein and only 0.03% circulates freely, the rest 25(OH)D binds albumins. Elimination half-life is 2–3 weeks, however, it is shortened if it reduces vitamin D binding proteins in size.
The ability to get vitamin D in food is relatively small compared to endogenous synthesis–only 10%, while endogenous–90%. It also explains the possible deficiency of vitamin D for people who suffer from liver or kidney diseases.
VITAMIN D, How to Take It?
We take some vitamin D with food, but its content is small. Vitamin D contains, for example, cod liver oil (250 μg / 100 g), salmon (30 μg / 100 g), tuna (2.9 μg / 100 g), eggs (1.75 μg / 100 g), fresh chicken liver (0.21 μg / 100 g), fresh bovine liver (0.13 μg / 100 g), wheat biscuits (0.44 μg / 100 g).
Vitamin D3 is more active and stable than vitamin D2. Vitamin D is formed in human skin under the influence of ultraviolet (UV) rays. Several factors are important, such as
- the latitude in which we live;
- the season;
- the weather;
- being in direct sunlight;
- and air pollution.
Given the latitudes, the carcinogenic effects of the sun’s UV rays, the inability of the human body to store vitamin D in the body, the use of sunscreens to protect against the harmful effects of UV rays, we can safely say that vitamin D deficiency must be compensated by diet or with food supplements, especially in early spring, autumn and winter.
We remind you that it would be necessary to determine the level of vitamin D in the blood at least once a year.
Why is vitamin D deficiency dangerous?
For a long time we believed it that rachitis caused by vitamin D deficiency in children and osteomalacia because of calcium malabsorption in adults are virtually the only manifestation of vitamin D deficiency.
However, nowadays it has been discovered that vitamin D deficiency can also lead to chronic diseases such as osteoporosis and cancer.
It turned out that many tissues have vitamin D receptors and the ability to synthesize a-hydroxylase and can themselves produce vitamin D.
In many of these tissues, vitamin D induces “cell differentiation” and monitors cell proliferation.
Chronic Diseases Associated With Low Levels of vitamin D
1. Bone/muscle system
- prone to falls and fractures,
- proximal myopathy (muscle/bone pain);
2. Chronic liver disease
- cirrhosis of the liver,
- primary liver cirrhosis of the liver;
3. Chronic kidney disease;
4. Cardiovascular disease
- ischemic heart disease,
- arterial hypertension,
- peripheral arterial disease;
5. Breathing system
- chronic obstructive pulmonary disease,
6. Autoimmune and chronic inflammatory diseases
- diabetes mellitus (type 1 and 2),
- multiple sclerosis,
- Crohn’s disease,
- rheumatoid arthritis;
8. Cognitive functions (difficulties in performing cognitive tests);
9. Peridontose (periodontitis, teeth loss).
Impact of vitamin D deficiency
Vitamin D deficiency is a worldwide problem, and it is especially important among older people. There are several reasons for this:
- The synthesis of cholecalciferol in the skin after exposure to the sun becomes less effective over the years as the dehydrosterol level 7 decreases in the skin;
- The increase in fat mass leads to the release of the highest fats soluble vitamin 25(OH)D, which lowers its bioavailability;
- When the level of vitamin D is low, its 1.25(OH) 2D shape is impaired because of the lack of substrate, which is addition to its age, is associated with a decrease in renal function that affects the conversion of 25(OH) to 25(OH)2D. The active metabolite 1.25(OH)2D acts via the vitamin D receptor (VDR). In aging, it reduces the expression of VDR (leading to vitamin D resistance) in bones, small intestine and muscle tissue.
One of the most important developments is the interaction between vitamin D and PTH, which is also of great clinical significance.
Like vitamin D, PTH is subject to seasonal fluctuations, but contrary to vitamin D, its highest level is observed in winter. The most important causes of secondary hyperparathyroidism with aging include vitamin D deficiency, renal failure, and reduced intake of calcium with food.
- Adversely affects the bone;
- Promotes muscle protein breakdown;
- Promotes blood calcification, which can lead to cardiovascular events.
Reduced renal function due to the elimination of hyperparathyroidism in older people requires more vitamin D to produce higher levels of 25(OH)D in human organisms.
PTH level for older people with a concentration of 25(OH)D is greater than 40 ng/ml is comparable to those of the same PTH in young people with a concentration of 25(OH)D of about 30 ng/ml5.
Diseases with elevated PTH, primary and secondary hyperparathyroidism, are associated with a higher risk of cardiovascular disease and death.
A quite resent ULSAM (Upsala Longitudinal Study of Adult Man) showed that elevated PTH level results in higher cardiovascular mortality.
Relationship of vitamin D deficiency with heart problems is due both to the direct effect of vitamin D on heart cells and the indirect effect on heart disease factors.
Thus, vitamin D can affect myocardial contractility, natriuretic hormone secretion, regulation of inflammatory cytokinins and renin genes.
The limited volume of the article does not allow to look in detail at the impact of vitamin D deficiency on all organs and their systems.
Therefore, the effect of vitamin D deficiency on insulin secretion, and hence diabetes, breast, colorectal and prostate cancer, and cognitive function and overall mortality, remained.
Doctor should prescribe vitamin D at least once a year for elderly and postmenopausal women. In the northern hemisphere, it could be the end of October, when effects of summer solar radiation on vitamin D synthesis are already over.
If vitamin D deficiency (which is highly probable) is detected, we should start immediately vitamin D replacement therapy from 1000 to 2000 DV per day to until April until sunlight returns to UV radiation.
It is otherwise to patients with impaired renal function who need an active vitamin D such as calcitriol appropriate dose, but these cases are the competence of a nephrologist.
The Bottom Line
Vitamin D is unique in some way with its many pleiotropic effects, we have discovered recently.
Vitamin D deficiently is common not only in children but also in the adult population, which is still not sufficiently diagnosed and treated, although its detection is quick, easy and not too expensive through a laboratory analysis.
Replacement therapy for vitamin D deficiency is available at a reasonable price. There are several misconceptions about the prevention of vitamin D deficiency:
- Only vitamin D function is mineral homeostasis;
- 400 DV per day has an adequate amount of vitamin D;
- The dose of vitamin D of more than 2000 DV per day is toxic;
- Sunbathing is definitely harmful.