Vitamin D – An underestimated but extremely necessary vitamin
Did you know that it took more than 200 years to prove the vital role of fat-soluble vitamin D, part of one of the most important groups of micronutrients for the human body? The first hint of this was the discovery that the consumption of cod liver oil had a highly beneficial effect on the condition rickets.
Tracing the events over time, it is clear that vitamin D was discovered in 1782 and isolated only in the early 1920s, and today, at the beginning of the 21st century, not only its preventive role against rickets-like conditions is already known, but also its particularly beneficial effects on the immune and nervous systems.
On the other hand, its deficiency and low levels in the body lead to the development of more than 50 pathological conditions, including cardiovascular and neoplastic diseases, as well as lowered resistance forces and diabetes.
Deficit №1 in the modern Western world
Vitamin D deficiency has been found to be most prevalent in modern countries outside the equatorial and tropical belt. This is particularly true in countries of North America, Europe, Asia and the southern part of South America. Populations in the northern United States, Scandinavian countries, the United Kingdom, and Russia are most affected.
More serious statistics on vitamin D deficiency have been kept since 1988. The recommended serum vitamin D concentration of 75 nmol/L is used as a criterion. If in 1988 55% of the population suffered from deficiency, the percentage in 2004 was 77% and nowadays it is 79%. Statistics show that nearly 29% of the US population has vitamin D levels below 50nmol/L. Of course, these numbers are relative because the percentages change based on the season.
Despite the role of geography, there are not a few places in the tropical belt whose population suffers from vitamin D deficiency. For example, in one of the southernmost Iranian cities, nearly 50% of the population suffers from low levels of the vitamin. While in Iran cultural characteristics and clothing are influential, there is no similar excuse for residents of Florida, where 38-40% of the population scores levels lower than 50nmol/L.
Certain population groups are at higher risk of deficiency. These are most commonly persons in various medical conditions, pregnant women, and those belonging to races with darker skin.
Although a large proportion of the population is not deficient, it is interesting to note that vitamin D levels are not in the optimal range for maintaining good health.
What is vitamin D?
Vitamin D belongs to the group of fat-soluble vitamins, and it is extremely rare in nature. In the form of an active vitamin, it exists mainly in products of animal origin, among which fish liver oil, liver, animal fats, cow’s butter and egg yolk stand out.
The fat-soluble vitamin exists in several varieties (D1, D2, D3, D4 and D5), but only vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol, which when activated in the body is converted into a potent steroid hormone) are of medicinal value, being similar in structure, properties and action on the body.
They are synthesized from cholesterol, and its main source for humans is the 7-dehydrocholesterol of the skin, from which it is obtained when irradiated with ultraviolet rays.
They are transported into the blood, bound to plasma globulins, deposited in the kidneys and liver, and are involved in the metabolism of phosphorus and calcium. Without vitamin D, parathyroid hormone, which is a major hormone synthesized and secreted by the parathyroid glands, does not exert its full action.
What do we need to know about vitamin D?
The uniqueness of vitamins lies in the fact that they are absolutely necessary in minute quantities for the maintenance of normal activity and health of humans and animals, as well as for their proper development.
Their absence in the diet disturbs the proper course of almost all physiological processes. Vitamin D is no exception in this respect, as there is already sufficient scientific evidence to prove its preventive and curative function.
Proven benefits in humans :
- Lowering the risk of falls and bone fractures in the elderly. A stronger effect is noted when combined with calcium;
- Improving muscle and neural functionality in the elderly;
- Reduced risk of cardiovascular disease or complications of such diseases;
- A direct relationship between vitamin D levels and high blood pressure has been demonstrated. Higher concentrations of the vitamin lead to lower blood pressure;
- Directly affects the regulation of parathyroid hormone secretion. Used as a reference drug;
- Dramatically lower (50%) the risk of colon cancer;
- Reduces occurrences of asmic attacks in young individuals;
- High vitamin D levels in children are associated with greater height growth. No similar effect is noted in older adults;
- Improve insulin secretion in individuals with type II diabetes or individuals at risk. The effect is directly associated with protective properties at the level of the pancreas;
- Improvement in insulin sensitivity resulting from improved insulin secretion from the pancreas;
- Reduction of inflammation in systemic lupus erythematosus (lupus erythematosus);
- Reduction of symptoms in tuberculosis;
- Slight decrease in the pro-inflammatory cytokine tumor necrosis factor alpha with long-term administration;
- Slight lowering of blood triglyceride levels after long-term use;
- Increase in low testosterone by 30% in men after one year of use. Low testosterone may result from vitamin deficiency;
- High serum vitamin D levels improve calcium metabolism and absorption;
- Dramatically lowers the risk of developing multiple sclerosis as well as reducing some of the symptoms of one that has already occurred;
- Vitamin D supplementation has been associated with a reduced risk of breast cancer, pancreatic cancer, prostate cancer, and ovarian cancer;
- Vitamin D deficiency is associated with low mood and depression, and a direct link between vitamin D supplementation and symptom reduction in depression has been found;
- Optimal serum vitamin D levels positively impact seminal fluid quality.
Potential benefits in humans :
- There is strong speculation that low vitamin D levels are associated with fat accumulation. Almost all overweight individuals are deficient in the vitamin. It is possible that optimal levels of vitamin D may help to maintain a leaner shape from body fat;
- A direct link has been found between high serum vitamin D levels in the elderly and lower mortality. It is possible that mortality is lowered due to improved general health or reduction in falls;
- Possibly lowering the risk of contracting influenza;
- Controversial results regarding the increase in physical strength after vitamin D use. May increase strength and explosiveness, as well as improve recovery after exercise;
- Potential benefits in lowering symptoms of arthralgia (joint pain);
- May lower the risk of developing type I diabetes;
- Low vitamin D levels are associated with sleep problems, but there is insufficient evidence at this stage that vitamin D supplementation can improve sleep quality;
- Potential benefits in the treatment of atherosclerosis;
- Potential benefits in regulating aromatization, through the use of calcium metabolism;
- Hypothetical protective effect on the lungs in smokers.
What are the recommended doses of vitamin D?
The recommended daily intake of the vitamin for adult men and women ranges between 400 IU and 800 IU, but most studies find this to be an extremely small and ineffective dose.
The recommended safe maximum dose in the U.S. and Canada is 4,000 IU, although clinical trials have found that a daily dose of 10,000 IU is perfectly safe, and an even higher dose can be taken in some disease states.
Based on practice, the following recommended doses can be derived:
- For adult men and women – a minimum effective dose of 2000-3000 IU per day;
- For athletes – 3000-5000 IU daily;
- For patients with osteoporosis and rickets – 5000-10 000 IU;
- For infants and young children – 500-1000 IU daily;
In some cases, high doses of vitamin D can lead to intoxication. A daily intake of more than 20 000 IU is not recommended. However, if you take the vitamin once a week, then the toxic dose exceeds 300,000 IU.
Getting vitamin D from food and the sun
Food sources that contain significant amounts of vitamin D are relatively few. Two categories of foods are major sources:
- Cod liver oil – the concentration depends on the sources of the oil and the method of processing. Note that 1 ml of oil provides 2.54-2.78 mcg of vitamin D;
- Dairy products – milk is considered a major source of vitamin D, with concentrations again dependent on the quality of the milk and processing. For information, 230 ml of pasteurized milk provides 100 IU of vitamin D, which is grossly inadequate.
The main natural source of vitamin D is the sun. UV rays come into contact with the skin and the stored 7-dehydrocholesterol is converted to cholecalciferol (D-3).
In some cases, however, there are factors that reduce the synthesis of vitamin D by sunlight:
- At latitudes further from the equator, vitamin D synthesis is lower because of weak UV rays;
- Weather and season. Clouds and darkness reduce the sun’s rays;
- Combination of latitude and season. At some latitudes in the northern hemisphere, in the October-March period, no vitamin D can be synthesized;
- In areas with a thawed ozone layer;
- In people with dark skin;
- The use of sunscreens that directly negatively affect vitamin D levels.
Supplementation of the body with vitamin D – forms and method of intake
There are two main forms of vitamin D on the market. One is vitamin D-2 (ergocalciferol), which is derived from plants, and the other is D-3 (cholecalciferol), which is derived from animals and fish. It is vitamin D-3 that is found in one of the best quality sources of the vitamin, cod liver oil.
D-3 is thought to be better absorbed and increases serum vitamin D levels in the body more. There is one study that claims that D-2 is just as effective as D-3, but most reputable studies show just the opposite. Therefore, our recommendation is that when choosing vitamin D as a dietary supplement, it should be in the form of vitamin D-3 (cholecalciferol).
Vitamin D is best absorbed with a small amount of fat, and the type of fat does not matter. Some authors recommend combining with fish oil for better absorption. Vitamin D has been found to be better absorbed with 10-20 grams of fat, compared to no fat, fasting intake, or with food containing more than 35 grams of fat.
What does vitamin overdose lead to?
As is well known, vitamin D is formed in the skin under the influence of the sun’s ultraviolet rays, but the good news is that there is no danger of toxicity manifestations with prolonged sun exposure.
On the other hand, the physiological action of the fat-soluble vitamin is related to the regulation and metabolism of calcium and phosphorus in the body, i.e., vitamin D ensures the deposition of both calcium and phosphate ions.
An excess would therefore lead to abnormally high levels of these ions in the blood, resulting in a real danger of bone, kidney and soft tissue damage. This means only one thing – the additional intake of the vitamin must necessarily be consulted with a specialist.
The main symptoms of toxicity due to vitamin D overdose are as follows:
- Fatigue and irritability;
- Headache, slurred speech;
- Dehydration with subsequent constipation;
- Decreased appetite and sharp reduction in body weight (anorexia);
- Muscle weakness;
- High blood calcium levels (hypercalcemia).
The question would probably arise how to protect oneself from vitamin overdose? And the answer is undoubtedly simple – by monitoring the blood status of the fat-soluble vitamin. In addition, a blood test would give us confidence that the vitamin D level is within the normal range.
Experts recommend periodic testing (every six months) to protect you from possible toxicity caused by additional supplementation.
Treatment in these cases usually involves rehydration, stopping the intake of any type of supplement including vitamin D, and limiting calcium intake.
Hypersensitivity to the vitamin
In certain cases, some people find themselves hypersensitive to supplemental vitamin D intake. It is usually seen in patients suffering from hyperparathyroidism, sarcoidosis, and certain types of neoplastic diseases. But on the other hand… what is the cause of low levels of the fat-soluble vitamin?
The simplest yet most logical explanation is a deficiency of direct sunlight. Considering the peculiarities of the climate in the latitude we are in, we usually wear more clothes than necessary.
In addition, people who live in large cities suffer from a vitamin deficiency, not only because of the daily morning fog that absorbs UV rays, but also because of multi-storey buildings.
Last but not least, when we decide to go outdoors, we usually choose a high factor sunscreen, which certainly provides us with good prevention against sunburn, skin aging and cancer, but also against vitamin D.
Diseases associated with low levels of vitamin D in the body
Optimal amounts of this vitamin in the body significantly improve the condition and function of the immune, nervous and bone systems, and deficiency is associated with a number of diseases, the most common of which are:
- Acne, various allergic manifestations, asthma, autoimmune diseases;
- Autism, Alzheimer’s disease, Parkinson’s disease, dementia, depression;
- Kidney failure, arthritis;
- Breast, colon and ovarian cancer;
- Chronic fatigue, colds, and various bacterial and viral infections;
- Formation of dental cavities and poorly coordinated teeth, development of paradontosis;
- Gluten intolerance;
- Osteoporosis, osteomalacia, muscle weakness, pain, rheumatoid arthritis, rickets, frequent sports injuries;
- Chronic obstructive pulmonary disease, tuberculosis;
- Diabetes (type 1 and 2), obesity;
What to combine vitamin D with
Vitamine D can be combined with other fat-soluble vitamins, such as vitamin K-2. The two vitamins have similar and complementary properties in terms of cardiovascular function, insulin sensitivity and the motor system.
Vitamins D is combined with calcium because it plays an important role in its metabolism and dramatically improves its absorption.
Combining vitamins D with fish oil is recommended as a quality source of beneficial fats.
For general health and combining various health effects, vitamins D is successfully combined with zinc and magnesium.
Where can we find vitamin D
Vitamins D is a common dietary supplement that can be found in most supplement stores as well as pharmacies.
Vitamins D is sold on its own, with the most common form being D-3. You may find the vitamin in a dosage form, with doses ranging between 400 IU and 5000 IU. Liquid forms are also not uncommon, in which one drop contains between 400 IU and 1000 IU.
Vitamins D is found in every single multivitamin formula, whether sports or daily. Our recommendation is to avoid a product with vitamins D-2. Some of the best known multivitamins with vitamins D-3 include Pure Nutrition Daily Vitamins, Pure Nutrition Power Pak, NOW Foods EVE, NOW Foods ADAM, Animal Pak.
Vitamins D is almost always present in products with calcium or mineral formulas containing calcium.
We know that vitamins are not a building block, much less a source of energy, but our bodies have a constant need for them.
That is why vitamins D, as part of a complex nutrient system, needs other supporting substances to function properly. These are calcium, magnesium, zinc, boron and vitamins A and K2. Without them, the functioning of the fat-soluble vitamin would not be effective.
Undoubtedly, the best way to obtain these nutrients is the consumption of organic plant food – sufficient amounts of fruits and vegetables, whole grains, seeds and nuts and of organic animal products – liver, milk, butter, cheese, cheese, egg yolks, marrow, eyes. The choice is a matter of taste.
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