Anyone who is not very adept at the version or lives in predominantly cloudy cities can suffer a little more with low vitamin D. It is not difficult to obtain it, but it takes a little attention to food and habits.
A few minutes in the sun, without sunscreen, and a diversified diet are enough to keep the rates regular in most cases.
- 1 What is vitamin D?
- 2 What is it for
- 3 Vitamin or hormone?
- 4 Types
- 5 The benefits
- 6 Recommended daily intake
- 7 Where to find
- 8 Food source of vitamin D
- 9 Supplementation
- 10 Vitamin D deficiency
- 11 What causes vitamin D deficiency?
- 12 Excess of vitamin D
- 13 Exams
- 14 How to increase vitamin D levels?
Vitamin D is mainly attributed to the functions of structuring and maintaining bone tissue and balancing the levels of calcium and phosphorus in the body (homeostasis). In addition, studies show the involvement of vitamin D with other vital processes, such as cell reproduction, hormone secretion and the performance of the immune system.
The substance has a very different behavior from other vitamins , which are found in abundance in food, since the synthesis of vitamin D comes mainly from the exposure of the skin to the sun, which generates a photosynthetic reaction, resulting in its biologically active form.
There are three sources of vitamin D: diet, sun exposure and supplementation.
Among them, sunbathing represents between 80 and 90% of vitamin intake, with the remainder generally occurring through food, except in cases where vitamin supplements are ingested.
Ideally, food supplements should only be used in cases of deficiency and expressly indicated by a doctor.
Even in the 1990s, vitamin D was only attributed to the strengthening and structuring of bones. However, recently there was a great interest from researchers regarding the contribution of the substance to the organism and it was found that it acts directly or indirectly in various tissues of the body.
The major function of vitamin D is to improve the absorption of calcium and phosphorus that occurs in the intestines and bones. When interacting with bone tissue, the substance regulates the release and promotes the reabsorption of nutrients, which helps in the structuring and strengthening of bones, maintaining the balance of blood plasma.
In addition, other organs and cells respond to the action of vitamin D, such as the brain, heart, stomach and lungs.
Studies suggest that there is a relationship between vitamin deficiency and diseases such as tuberculosis , diabetes , autism , arthritis , respiratory diseases and degenerative diseases, for example.
In the bones
Vitamin D behaves as a bone structural component. It is synthesized by osteoblasts and osteoclasts (cells that manufacture and repair bone tissue). In the absence of the vitamin, there may be a higher incidence of breaks and fractures, in addition to bone malformation.
During childhood and adolescence, vitamin D promotes good development and strengthening of this tissue.
In the heart
Vitamin D3 acts in the regulation of cardiac functions and blood pressure, which occurs by controlling the growth of smooth muscle tissue cells, the degree of myocardial contraction and the inhibition of an enzyme called renin (responsible, among other things, for relieving the pressure and strain of the heart).
Recent studies by the Health Professionals Followup Study (HPFS) indicate that vitamin D deficiency raises the risk of cardiovascular disease . In addition, maintaining adequate levels of the substance can considerably reduce the risk of high blood pressure, which can lead to heart failure or heart attack.
In the brain
Some studies indicate that certain brain regions can use the vitamin to produce proteins . Thus, neurological diseases, such as Alzheimer’s, autism and depression , may be associated with vitamin insufficiency.
In addition, the vitamin is associated with the regulation of the production of several cells, helping correct brain function.
In the immune system
The autoimmune diseases are caused by hyperactivity of the defense system of the body, which begins to attack its own cells.
Vitamin D can act on immunity in two ways: through the prevention of some diseases and also as a support for the treatment of others.
Vitamins are substances that the body is unable to produce and, therefore, are obtained through food. Unlike A, B and C, which come from external sources, vitamin D is largely produced in the skin as a response to sun exposure.
At the beginning of the 20th century, researchers and scientists were investigating an outbreak of rickets, which mainly affected England. In the midst of the studies developed, there was a previously unknown substance: vitamin D.
The substance was so named because, at first, it behaved the same as the 3 elements previously discovered and isolated (vitamins A, B and C), which are not produced by the body and must come from external sources.
In 1916, researchers at the University of Wisconsin understood the relationship between decreased sun exposure and cases of rickets. They also found that countries with low solar incidence did not have high rates of the disease as they generally had a diet based on wild fish and cod liver oil, which are some of the few foods rich in vitamin D.
At the time, the outbreak of the disease was controlled with vitamin supplementation.
However, currently, the different behavior of vitamin D is recognized, which is the only one in the category that needs to undergo an activation process in the body.
Thus, the substance is, in fact, classified as a fat-soluble pre-hormone (capable of being solubilized in fats), as it is synthesized from the skin.
Vitamin D is subdivided into vitamin D2, called ergocalciferol , and vitamin D3 or cholecalciferol . Both can be obtained through food, however only D3 is synthesized from sun exposure.
Chemically, the structure of types D2 and D3 is quite similar, being differentiated by side chains on carbon 17. D2 has an additional double bond and an incorporated methyl group. In practice, D2 is of vegetable origin and D3 is of animal origin.
Sufficient levels of vitamin D have demonstrated the ability to reduce the development of neoplasms ( cancer ) of the breast, colon and prostate, for example. Other important benefits related to the proper dosage of vitamin D are:
The proper dosage of vitamin D helps in bone strengthening due to the correct absorption of calcium and phosphorus. In addition to aiding in better physical balance and avoiding fractures, teeth and bones suffer less wear due to age.
Benefited brain functions
Some research has linked a significant improvement in memory, reasoning and mood when the vitamin level is stabilized.
Tables of anxiety and depression can respond more quickly to treatment when vitamin D supplementation is associated.
Type 2 diabetes resistance
Recent studies confirm the hypothesis that the lack of vitamin D increases the risks of type 2 diabetes, since vitamin deficiency causes changes in insulin secretion and favors glucose intolerance, factors that lead to the development of this type II diabetes condition.
Researchers observed that hypertensive patients exposed weekly to ultraviolet radiation can reduce blood pressure, minimizing the impacts of the pathology on the body.
Weight loss aid
Vitamin insufficiency is related to slower metabolism, according to some studies. In addition, vitamin D sufficiency can bring more satiety, minimizing caloric intake and helping to maintain adequate weight.
It is observed that in obese individuals, the lack of vitamin D can be one of the factors that promotes the accumulation of fat. In this case, hypovitaminosis is not the cause of obesity , but a condition that makes weight loss difficult. That is, supplementation with the hormone may favor weight loss.
Acts on the immune system
The substance helps to reduce the production of inflammatory substances, which results in the reduction of inflammation markers in the body.
Operates in fertility and pregnancy
Studies suggest the relationship between ideal rates of vitamin D and fertility in women, better inducing ovulation and giving better conditions to those who wish to become pregnant.
The reduction of inflammation caused by vitamin D makes the body adapt well to the placenta and minimize the risk of miscarriage in the first trimester of pregnancy.
Throughout pregnancy, the correct synthesis of the vitamin reduces the risk of developing pre-eclampsia (hypertension during pregnancy).
In addition, the risk of malformation, respiratory problems, autoimmune diseases and autism in the baby is reduced.
Studies suggest that the level of vitamin D sufficiency is above 30mcg / mL, as it would be at this point that the best calcium absorption occurs. However, these values are extremely difficult to achieve and maintain, especially in regions with less sunlight.
The Institute of Medicine (National Academy of Medicine of the United States) published a table indicating the levels of daily vitamin D intake for different age groups – remembering that 1mcg is equivalent to 40 IU (International Unit).
- 0 – 12 months: 400 IU;
- 1 – 8 years: 400 IU;
- 9 – 18 years: 600 IU;
- 19 – 70 years: 600 IU;
- 70 years or more: 800 IU;
- Pregnant women 14 – 18 years old: 600 IU;
- Pregnant women over 18 years old: 600 IU;
- Lactating women between 14 and 18 years old: 600 IU;
- Lactating women over 18 years old: 600 IU.
Fonte: Institute of Medicine. Report Release: dietary reference intakes for calcium and vitamin D. 2010.
* After the first 28 days of life (infants), the recommended daily intake is 400 IU / day for 0-6 months of age; and 400 IU / day for 6-12 months of age, under medical supervision.
Recently, the Brazilian Society of Clinical Pathology / Laboratory Medicine (SBPC / ML) published a note in which vitamin D levels above 20mcg are acceptable and do not require replacement.
However, the elderly, pregnant women, patients with osteomalacia, rickets, osteoporosis , autoimmune diseases and inflammatory diseases comprise the risk group, and it is recommended to keep the levels between 30mcg and 60mcg.
For the American Society of Endocrinology, vitamin D intake can be established with more flexible values, through an estimate. The official indication is that from 1 year of age, the daily intake is 600-1000 IU (15-25mcg), and for adults and the elderly, 1500-2000 IU (37.5mcg-50mcg).
Many Brazilian authors and health professionals admit sufficiency levels above 30mcg / mL. Below this value, vitamin deficiency is considered and supplementation can be evaluated, but it is not always necessary. Despite increasing the risk of various diseases, such as cancer and chronic inflammation, the low level is usually well tolerated and has no symptoms.
However, when levels are below 12mcg / mL, deficiency is considered and replacement or supplementation is indicated.
Vitamin D2 is more present in mushrooms, which are fungi, reaching concentrations of up to 100mcg (400 IU) in 100g. Foods like shiitake and shimeji have considerable values of the substance.
The richest sources of vitamin D3 are fish liver oils (such as cod and tuna), sardines, mammalian liver, eggs and dairy products, especially milk.
In both humans and animals, D3 comes from sun exposure , being produced in the dermis and epidermis. From the incidence of UVB rays, a photolytic reaction occurs (from light) and, after a series of transformations, vitamin D3 is activated.
Therefore, sunbathing leads to vitamin production by the body, being the most common source of obtaining the hormone.
On average, for a healthy adult, it is recommended to consume at least 15mcg of vitamin D per day. Among those that provide better amounts per serving are:
- Cod liver oil : 13g per serving; 34mcg; 1360UI;
- Cooked salmon : 100g per serving; 12.5mcg; 500UI;
- Oysters : 100g per serving; 8mcg; 320UI;
- Canned sardines : 100g per serving; 7.5mcg; 300UI;
- Fortified milk : 100g per serving; 2.45mcg; 244UI;
- Fish in general : 100g per serving; 2.2mcg; 88UI;
- Boiled egg : 100g per serving; 1.3mcg; 52UI;
- Ox liver : 100g per serving; 1.12mcg; 44.8UI;
- Yogurt : 240g per serving; 0.1mcg; 4UI.
In general, increasing exposure to the sun and strengthening your diet tends to significantly improve vitamin D rates. However, in cases where the changes do not have the expected effect, it is possible to resort to vitamin supplements.
The options offered are capsules, drops or injectable. Usually, the latter is recommended only when oral absorption is difficult or in critical cases, when vitamin levels need to be raised quickly.
Supplements can be based on the active principle of:
- Colecalciferol (D3);
- Ergocalciferol (D2).
The main difference between the options is the extraction of the vitamin, since D2 is obtained through fungi and can be used by vegetarians and vegans.
Patients with hypersensitivity to the active substance cholecalciferol, to ergocalciferol or to the other components of the formula should not use the supplement, as well as in cases of renal changes or hypercalcemia.
NEVER self-medicate or stop using a medication without first consulting a doctor. Only he will be able to tell which medication, dosage and duration of treatment is the most suitable for his specific case. The information contained in this website is only intended to inform, not in any way intended to replace the guidance of a specialist or serve as a recommendation for any type of treatment. Always follow the instructions on the package insert and, if symptoms persist, seek medical or pharmaceutical advice.
Some medications can interfere with the absorption of the supplement, among them:
- Corticosteroids ;
- Weight loss medications, such as Orlistat and Colestyramine ;
- Medicines for epileptic seizures, such as Phenobarbital and Phenytoin ;
- Aluminum hydroxide- based heartburn medications ,
- Medicines to control cardiac disorders, such as Verapamil , Diltiazem and Hydrochlorothiazide ;
- Medicines that act on gastrointestinal functions, such as Cimetidine .
It is always essential to inform the doctor about the continuous or punctual use of any medication before carrying out exams, changing or starting drug treatments, as well as consuming dietary or vitamin supplements.
Overdosing can occur due to the interaction of medications or the excess of vitamin dosage. In such cases, there may be weakness, fatigue , headaches, vomiting and intestinal changes.
Doctors and researchers have shown considerable interest in studies on the action of vitamin D. There are no conclusive results on all interdependencies of the pre-hormone and other diseases. However, several pathologies and conditions can be directly or indirectly associated with vitamin levels.
Symptoms and conditions
Studies point to a series of diseases and disorders in the body related to vitamin D deficiency. In general, research has identified the prevalence of hypovitaminosis D that can lead to or worsen pathological conditions.
There is also evidence that these diseases are prevented or improved in treatment when combined with vitamin supplementation.
Recent studies show the correlation between lack of vitamin D and vulnerability to depression. Patients with a history of psychological illness showed even more risk of relapse.
The UT Southwestern Medical Center (Texas medical school), in the USA, followed about 12 thousand patients between 2006 and 2010, and found that there was a higher incidence of depression in those who had lower levels of vitamin D.
Therefore, maintaining vitamin sufficiency can reduce the risks of depression, in addition to assisting in better responses to therapies and medications.
Risks during pregnancy and lactation
As vitamin D improves immunological conditions, deficiency can favor embryonic rejection, causing abortion, which has a greater incidence in the first trimester.
The pre- eclampsia (high blood pressure during pregnancy) and gestational diabetes may be related to vitamin D levels, as there is a substance interacting with the production of renin (which interacts with the cardiac function) and insulin action (which regulates blood glucose).
The risks of infections and poor baby development are reduced. The low vitamin D synthesis of the pregnant woman may favor autism and respiratory problems in the child.
In addition, for those who are still planning to become pregnant, maintaining adequate vitamin levels favors fertility, acting on ovulation.
Muscle fatigue or weakness
There is evidence that low levels of vitamin D can cause tiredness and chronic fatigue. Researches show that the symptoms are more present in those who ingest less vitamin, even if there is no deficiency of the substance.
Vitamin D deficiency in pregnant women may be associated with deviations in the baby’s brain development, leading to autism spectrum syndrome.
Studies show that the majority of those diagnosed with autism have hypovitaminosis D. In 75% of the cases studied, there were improvements in the learning and development of the autistic person by regulating vitamin levels through supplementation and greater sun exposure.
Due to the stimulation of peptide and antimicrobial synthesis, low levels of vitamin D favor infections and inflammations due to low immunity.
In a study published in the Annals of the New York Academy of Sciences ( scientific journal of the New York Academy of Sciences ), it is suggested that the vitamin may still act as an anti-infective agent, reducing the incidence of urinary tract infections, influenza , dengue , hepatitis B and C and diseases in the respiratory tract. It can also reduce the use of antibiotics .
Researchers from the British Medical Journal (UK periodical) evaluated patients of all age groups who were taking vitamin supplementation. The results indicate that there were immunological improvements, decreasing the cases of acute respiratory tract infections.
For those who start treatment with antibiotics, the body’s response is usually faster, avoiding adaptation or resistance to the medication.
Bone weakness and osteoporosis
In the absence of the nutrient, there may be a 30% drop in the absorption of the ingested calcium. This leads to bone weakening and increases the chances of osteoporosis.
In this case, falls or fractures can be aggravated by the lack of vitamin D, since recovery is slower. In addition, hypovitaminosis may be associated with high bone pain rates, especially in the lower back.
This is because the lack of vitamin D causes inadequate mining of substances by the bone. Meaning that there is an imbalance in the absorption and release of calcium by the tissue.
To reestablish the values, the organism increases the bone reabsorption of substances, with the purpose of releasing more calcium into the blood.
With the calcium reduction in the bones, the fracture, crumbling or weakening of bone mass indices are increased.
Type 2 diabetes
Some research shows that vitamin D can affect the insulin response to glucose. The active form of the vitamin acts directly on the insulin action. Vitamin D, by acting on calcium regulation, stimulates the expression of the hormone insulin.
When calcium levels are reduced, they impair the binding of insulin receptors, causing glucose levels to be affected.
Therefore, there is evidence that the greater the vitamin D deficiency, the greater the risk of the patient developing type 2 diabetes.
As vitamin D acts on calcium absorption, all organs and tissues that interact with the mineral are affected.
Although hair loss is a condition caused by numerous deregulations or diseases, there are indications that the lack of vitamin D is related to some of them.
The alopecia areata is an autoimmune disease where there is severe bone weakening and loss of hair, which has low synthesis of nutrients.
In addition, calcium promotes the synthesis of keratin, a substance that impacts the health of hair and nails. Thus, indirectly, adequate levels of vitamin D reduce hair loss, strengthen nails and improve the appearance of tissues.
Studies suggest that vitamin D can act on the immune system and prevent autoimmune diseases, such as multiple sclerosis, type 1 diabetes, rheumatoid arthritis and inflammatory bowel disease.
Although it is not conclusive, there may be a relationship between low levels of vitamin D and type 1 diabetes (insulin dependent). It is also possible that the development of diabetes 1 is prevented with the normalization of vitamin levels.
Although vitamin D supplementation is not a substitute for primary treatment, nor is it a consensus among the medical community, maintaining adequate levels of the nutrient can assist in the control and prevention of autoimmune diseases in general.
Some cases point out that vitamin D deficiency may be associated with the development of cancer. Among the types most related to vitamin deficiency, breast, colorectal, ovarian, prostate and melanoma are quite frequent in studies already carried out.
This can occur because hypovitaminosis affects cell dysregulation, causing cells to proliferate uncontrollably.
Research shows that, when cancer is diagnosed, vitamin D metabolism may be directly related to the prevention of angiogenesis (when new blood vessels are created, spreading the disease). Therefore, adequate intake of the nutrient can delay the evolution of the disease, even preventing the progression to malignant cancer.
Many studies suggest the relationship between obesity and low levels of vitamin D. When there is a reduction in body fat, the levels of vitamin synthesis tend to improve, even without changes in diet or exposure to the sun. That is, weight loss would bring direct improvements to the synthesis of the pre-hormone.
As the kidney participates in the activation of vitamin D precursors, kidney disease increases the risk of vitamin deficiency. In addition, cystic fibrosis can affect the organ and result in hypovitaminosis.
Conditions that affect the intestine and alter the absorption of vitamins can also affect vitamin D deficiency, including celiac disease, short bowel syndrome and Chron’s disease.
In addition, stones in the gallbladder alter the secretion of bile and reduce the absorption of fat-soluble vitamins. Among the resulting changes is hypovitaminosis D.
Overdosing is an uncommon condition, as the population usually lacks vitamin D levels. However, excessive use of supplements or changes in the body can result in hypervitaminosis.
The recommended intake of supplements and multivitamins is not harmful to health and there are few reported side effects. However, high doses of vitamin D can affect the kidneys and cause adverse effects.
In general, component poisoning occurs at around 150 mcg / mL and can take months to clear from the body. In addition, there are cases relating excess vitamin D to other symptoms, such as:
- Digestive disorders;
- Alteration of the intestinal flow (diarrhea or constipation);
- Loss of bone mass;
- Renal insufficiency;
- Mental confusion.
The detailed examination is done through blood sampling that measures 25-hydroxy-vitamin D, called calcidiol (total vitamin D), and 1,25-dihydroxy-vitamin D, called calcitriol.
25-hydroxy-vitamin D is the inactive precursor to vitamin E and has higher levels in healthy patients. When the value is below 30 mcg / mL, it may be necessary to perform vitamin replacement or supplementation.
The levels of 1,25-dihydroxy-vitamin D refer to the active form of vitamin E, in general, the values are lower than 25-hydroxy-vitamin D. The test is indicated for the assessment of hypercalcemia (excess of calcium in the blood). In cases where the value is lower than expected, kidney disease may be indicated. Already at very high levels, the change may be an indication of lymphomas or sarcoidosis .
There is no determination as to the reference values for vitamin D. Thus, most experts are based on the average result of the population. Values that are generally used are around:
- Overdose : above 100 mcg / mL;
- Sufficiency : equal to or above 30 mcg / mL;
- Insufficiency: between 10 mcg / mL and 30 mcg / mL;
- Deficiency : equal to or below 10 mcg / mL.
Experts point out that sunbathing for about 20 minutes daily is enough to improve vitamin levels.
It is worth remembering that the use of the protector interferes with the absorption of ultraviolet rays, as its function is to perform the sun block and protect the skin. Products with sun protection factors (SPF) 8, reduce the absorption of vitamin D by approximately 90%, SPF 15 reduces about 95%, while SPF 30 can prevent 99% of synthesis.
In addition, geolocation determines the solar incidence and alters the reception of UVB rays. Between November and March, locations with latitudes around 45 degrees north (between the equator and the North Pole) or 40 degrees south (between the equator and the Antarctic Circle) become inefficient for vitamin D absorption .
In general, considering the characteristics of the Brazilian territory, doctors and dermatologists recommend sun exposure with the use of the protector on the face and neck, dispensing it on the arms and legs.
Due to the risks of skin cancer and premature aging, the ideal is also to opt for times of mild sun intensity, such as between 9 and 10 am, keeping the use of sunscreen only on the face.
Vitamin D requirements and the absorption process vary widely. A balanced diet and moderate sun exposure, in general, are sufficient to stabilize vitamin levels.
When there are problems with the absorption of nutrients or diseases that lead to a decrease in vitamins, supplementation may be indicated, always under the recommendation of a health professional.
Most of the population has sub-optimal levels of vitamin D. The condition, in general, poses no health risks. However, when the vitamin absorption values drop a lot, being indicated as deficiency, there may be a compromise in the proper functioning of the organism.
Combining a balanced diet, exposure to the sun and, if indicated by the doctor, vitamin supplements, are measures that assist in well-being and disease prevention.
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