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We know vitamin D as that crucial fat-soluble vitamin that is essential for our bone health and calcium homeostasis. This role of vitamin D is vital, and when vitamin D deficiencies grew in incidence, weak bones came out as a significant consequence.
And that is why we know this vitamin in this context. But there is more to it as a holistically essential nutrient than we have heard. The most exciting thing about vitamin D is that it is synthesized by the skin from cholesterol when the compound gets sunlight exposure.
This article compiles all about the recommended dietary allowance of vitamin D, its benefits, risks, side effects, and contraindications.
Health Benefits of Vitamin D Supplementation
A vitamin D supplement of a dosage of 600 IU/day will take care of the health of your whole body in general. But mainly speaking, taking vitamin D supplement regularly has the following benefits:
Vitamin D promotes Bone Health
This is the most popularly documented health benefit of vitamin D. Vitamin D in combination with adequate calcium has shown a significant increase in the bone mineral density in individuals of all ages.
Vitamin D supplementation of around 600 IU/day increases the absorption of calcium and phosphorus minerals in the intestine. This way, it provides optimum blood levels of both for healthy mineralization of the bones. Without vitamin D, all your calcium supplements and sources will go in vain because the calcium will pass unabsorbed through the gut.
The importance of Vitamin D in bone health and strength can be seen in the fact that vitamin D deficiency results in rickets in children and osteomalacia in adults. Also, patients with a condition that characterizes weak or soft bones benefit from vitamin D and calcium supplementation, such as osteoporosis.
In patients with impaired vitamin D supplementation and consequent conditions such as osteoporosis and rickets, supplementation with vitamin D and calcium has shown an improvement in the bone mass density in only five weeks.
In old age, vitamin D supplementation of around 800 IU/day can reduce the risk of fractures and falls by increasing bone strength.
A review and meta-analysis of 12 randomized controlled trials involving individuals of age more than 65 years looked at the effects of vitamin D supplementation on the risk of fractures. The research concluded a 20 percent reduced risk of hip and non-spine fractures in individuals supplemented with almost 500-800 IU/day.
Vitamin D Strengthens the Muscle
In the systematic review and meta-analysis of various recent studies, researchers have found a strong connection between lean muscle mass and active vitamin D levels in the blood.
People with less body fat composition and more lean body mass tend to have adequate vitamin D levels. This suggests that vitamin D enhances muscle mass and strength in the body.
25-hydroxy vitamin D concentrations have been linked to physical activity and muscle strength as the average concentrations have been seen to prevent falls in the elderly. The risk of falls and fractures is equally connected to bone and muscle strength and mass.
Due to the same effect, adequate vitamin D supplementation has also shown benefits in managing multiple sclerosis. People with MS who had higher vitamin D levels showed lesser disease symptoms and less severe disability.
Vitamin D Lowers the Risk for Viral Diseases
Randomized controlled trials and their results and reviews have shown that vitamin D deficiency increases the risk of developing viral infections. Vitamin D deficient individuals also have an increased risk of recurrence of some viral infections.
Vitamin D can directly inhibit the viral replication and multiplication in the infected system of the body. Besides, it has strong immunomodulatory and anti-inflammatory benefits against viral diseases and infection. These are the reasons why people who get slightly more than adequate vitamin D from supplements or food sources have a lower risk of developing HIV, Hepatitis, or COVID-19.
People at risk of influenza or COVID-19 are recommended high doses of vitamin D, around 10,000 UI/day for a few weeks, to rapidly increase the 25 hydroxyvitamin D concentrations.
Vitamin D deficiency has also been shown to exacerbate acute respiratory distress syndrome, and supplementation improves the prognosis of the same. This observation also indicates the contributory role of vitamin D in managing, treating, and preventing viral infections and diseases, especially in the respiratory system.
Vitamin D Supplements Help Fight against Autoimmune Diseases
Investigators from Brigham and Women’s Hospital conducted a study called Vitamin D and omega-3 trial (VITAL). It was a randomized controlled study with almost 25000 old age men and women from the USA.
The study showed that individuals who regularly took vitamin D and omega-3 fatty acids had a lower incidence of autoimmune diseases such as rheumatoid arthritis, autoimmune thyroid disease, autoimmune gastritis, and psoriasis.
Vitamin D has been shown to fight and prevent autoimmune mechanisms in the body by suppressing the formation and proliferation of B cells and the resultant antibodies. It also stops the proliferation of T-cells and suppresses the formation of Th-17 (T-helper cells), which cause inflammation.
These steps collectively inhibit the production of inflammatory cytokines such as the interleukins 17 and 21 and increase the production of the anti-inflammatory ones such as the Interleukin-10.
It also inhibits the dendritic cell proliferation and the monocyte production of inflammatory cytokines the way it does with the B- and T-cells.
So, on the whole, serum 25-hydroxyvitamin D tames the inflammation and its causative agents throughout the body. This not only prevents the development of autoimmunity but also helps manage the autoimmune disorders and their disabilities better.
Serum 25 hydroxyvitamin D levels have been observed as quite lower than normal in patients with multiple sclerosis, inflammatory bowel disease, type 1 and type 2 diabetes mellitus, rheumatoid arthritis, and systemic lupus erythematosus (SLE), an autoimmune skin disorder.
Concluding the discussion, the immune cells have the tendency to respond and react to vitamin D in ways that result in the amelioration of immune responses and inflammation.
Vitamin D May Reduce Depression
Low vitamin D levels have been linked to mood disorders, anxiety, and depression. People with vitamin D deficiency have responded to vitamin D supplementations with lowered depression and mood swings.
A number of studies demonstrate poor vitamin D status in people suffering from depression. Also, a systematic review and meta-analysis of a couple of studies have also linked postpartum depression with reduced levels of vitamin D after pregnancy.
Studies conducted by Hoogendijk and his colleagues observed that serum 25 hydroxyvitamin D levels were 14 percent lower in depressed individuals than the non-depressed. But this observation does not confirm if hypovitaminosis is the cause of depression or the consequence of a depressive mental condition.
Many cohort studies have been performed to establish this, but researchers are only getting mixed results. Some biologists suggest with conviction that vitamin D deficiency can deactivate or retard the action of the feel-happy hormone serotonin in the body.
Seasonal depression links more strongly with serum vitamin D levels since it is the concentration of vitamin D that changes and varies with the weather. These observations are enough to get a patient with seasonal depression tested for serum vitamin D levels.
On the whole, Vitamin D is known as the ‘happy hormone’ because it makes all your organs and organs system happy. Its most important role is in controlling and reducing inflammation, which improves the overall health of individuals of all ages and makes them feel happier and healthier.
Vitamin D Deficiency may be linked to Hypertension
Vitamin D levels in the serum have been directly linked to an activation of the blood pressure control systems in the body. These especially result in reduced systolic blood pressures in old age people with compromised blood vessel walls and essential hypertension.
There is unprecedented evidence that says hypertension links to low vitamin D serum levels. this implies that when patients with depression and with a simultaneous vitamin D deficiency are treated with vitamin d supplementation, their depression ameliorates.
But some studies have also gained mixed results on whether vitamin d can help treat high blood pressure or not.
Vitamin D has not been established as a part of hypertensive therapy. And it is not recommended to take vitamin d supplements to treat high blood pressure.
Vitamin D Status may be Linked with a Reduced Risk of Cancer Mortality.
Vitamin D supplementation has been associated with a reduced risk of various types of cancer. Calcium intake and adequate vitamin D were associated with a reduced risk of breast cancer in women of all ages.
A study conducted in 1999 by the Nutrition Examination Survey tested the effect of vitamin D on breast cancer and colorectal cancer risk. It established that women who lived in the regions of the USA with a high solar radiation exposure showed a reduced breast cancer risk due to better vitamin D production and availability.
Vitamin D supplementations hence can reduce breast cancer incidence. Evidence is still inconclusive, but some studies have shown that dietary vitamin D can also play a protective role against prostate cancer risk.
The effect of vitamin D on colorectal cancer has also gained quite a popularity. Individuals who had circulating levels of vitamin D higher than the recommended amounts exhibited a 31 percent reduced colorectal cancer risk despite genetic predisposition.
Heart Benefits of Vitamin D
There are two main ways and mechanisms by which enough vitamin D levels in the serum can help protect against heart disease and also slow down its worsening with age.
Firstly, as we have seen above, low vitamin D levels are associated with high blood pressure. High blood pressure can damage the blood vessels and the heart muscle so much that it eventually progresses to a cardiovascular disease complex. The effect of vitamin D here will be to provide protection against blood pressure-induced blood vessel damage.
So, the second important mechanism against heart disease is repairing the hypertension-induced damage and injury to the blood vessels and the heart. Randomized controlled trials have shown that people who maintain optimum serum levels of vitamin D required for bone density are also protected against the risk of heart attacks and strokes.
A study from the Ohio university observed the effects of vitamin D inoculation on the heart disease components. Interestingly, the researchers concluded that the active form of vitamin D, D3, has beneficial effects on the endothelial cells of the blood vessels.
Also, by reducing the production of inflammatory cytokines, vitamin D exerts prominent anti-inflammatory effects. As inflammation is the major culprit in atherosclerosis, blood vessel damage by free radicals and resultant heart disease, vitamin D indirectly benefits the whole cardiovascular picture.
Benefits of Vitamin D against the Metabolic Syndrome
Clinical trials have suggested that higher levels of vitamin D in the blood are associated with a 51 percent decreased risk of developing metabolic syndrome, a 55 percent reduction in the incidence of diabetes, and a 33 percent decreased chance of cardiovascular disease.
Metabolic syndrome is a chronic disease associated with obesity, insulin resistance, and high blood sugar levels. All these symptoms combine and complex to increase the risk of diabetes mellitus and cardiovascular disease.
Metabolic syndrome is also associated with an unhealthy level of triglycerides, LDL-cholesterol, sugar, toxins, and reactive free radicals in the blood. These are the main contributors to the general inflammation in the body, giving rise to atherosclerosis, hypertension, and heart disease.
Metabolic syndrome is a common complication in postmenopausal women. These have reduced levels of estrogens in their body. And if adequate anti-inflammatory dietary changes and lifestyle modifications are not made, and the genetic predisposition is also there, metabolic syndrome will develop and progress easily over the years in postmenopausal women.
Vitamin D, due to its anti-inflammatory benefits, has been effective at various points of this progressive disease. It ameliorates hypertension, diabetes mellitus, heart disease, blood vessel injury, and free radical damage. On top of everything, it has been shown to significantly reduce the risk of metabolic syndrome in the first place.
Vitamin D also plays a Role in the Proper Healing of the Wounds
Vitamin D plays a role in wound healing by protecting against the risk of various infections. In addition to that, we know that vitamin D has receptors on the immune cells too. It can regulate the production of cytokines and growth factors.
It reduces inflammation and speeds up the healing process. Another mechanism is by regulating the keratinocytes, which are the main cells involved in the reconstruction of the injured or broken tissue.
Vitamin D directly interacts with the growth factors and cytokines to build and reconstruct the tissue and hence helps in healing faster.
Which form of Vitamin D is Better: D2 or D3?
When you are buying vitamin D supplements, you may encounter two different forms of vitamin D: D2 and D3. There has been this never-ending debate going on whether vitamin D2 is better for human supplementation or vitamin D3.
Vitamin D2 is the form produced in plants and is also derived from plant sources. It can also be synthetically made using plant compounds such as the ergosterol found in ergot. And that is why it is also called ergocalciferol.
Vitamin D3, on the other hand, is produced in and derived from animals and animal sources. It is also known as the active form of vitamin D in humans because it is the most efficacious and long-lasting form of vitamin D.
A systematic review and meta-analysis of some randomized controlled studies that compared the effects of both revealed that vitamin D3 exerted stronger vitamin D effects and could maintain its levels in the blood for a longer duration. Vitamin D deficient individuals who lack the enzymes and cofactors for the synthesis and activation of vitamin D can only use the active vitamin D3 form. Besides, since it is the active form, its effects are immediate.
Signs and Symptoms of Vitamin D Deficiency
Vitamin D is counted as one of the essential nutrients for the body. Its deficiency can be the result of chronic kidney disease, old age, a darker skin color, or inadequate sunlight exposure.
Vitamin D deficiency presents as a complex combination of various signs and symptoms.
- Vitamin D is one of the strongest risk factors for getting respiratory illnesses and symptoms. The risk of developing colds, bronchitis, and pneumonia is greatly increased when serum 25 hydroxyvitamin D levels remain lower than normal for a long.
- Since vitamin D is the main nutrient involved in the absorption and deposition of calcium, vitamin D deficiency can be a major cause of day-to-day fatigue and tiredness. Calcium and vitamin D insufficiency together contribute to weak neuromuscular functions and bone and muscle homeostasis.
- The deficiency of vitamin D leads to demineralization of bones. This is especially important in females of older age who may encounter osteoporosis and an increase in bone fractures and falls.
- Insufficient vitamin D may cause pain in the weight-bearing bones of the body. People who report back pain or even arthritis have been recorded to have inadequate vitamin d status.
- Individuals who lack adequate levels of vitamin D report slower wound healing, especially after minor or major surgeries such as dental procedures.
- Due to inefficient calcium and phosphorus homeostasis in severe vitamin d deficiency, patients also experience the symptoms of electrolyte imbalance.
- Patients frequently report a sudden weight gain, and the consequent symptoms and events of metabolic syndrome then ensue.
- Minimal sun exposure and hence compromised vitamin d status has also been linked to muscle weakness. The same muscle weakness is the reason why it can also worsen multiple sclerosis.
Who is at Risk for Developing Vitamin D Deficiency?
The Department of Health and Social Care recommends you take 8 to 10 micrograms of Vitamin D in the form of supplements every day for the risk groups.
People who are at the risk of developing vitamin D deficiency include:
- Those who stay indoors most of the time due to the nature of the job or are housebound
- People who do not expose their skin to the skin, such as those who wear full-body covering clothes
- Those who live in care homes or are ill and cannot leave the bed and hence have insufficient sun exposure.
- Clinical trials suggest that people and races with dark skin may also not make enough vitamin D.
- People who suffer from conditions that limit the absorption of fats and lipids. Since vitamin D is a fat-soluble vitamin, it requires fat solvent for adequate absorption in the gut.
- People who have undergone gastric bypass also suffer from vitamin d insufficiency because the surgery takes away the part of the intestine where absorption of vitamin D occurs.
- High body fat levels, such as in obese people, also limit the absorption of fats and lipids. Along occurs the reduced absorption of vitamin D.
- With increasing age, skin becomes less efficient in synthesizing the active compound vitamin D3.
What is a Good Vitamin D Level ng/ml?
25 hydroxyvitamin D test is the most accurate way of detecting active vitamin D status in your blood. Some experts suggest that 20 to 50 ng/ml is optimum for healthy adults. Many experts recommend that 30 to 60 ng/ml is the optimum level for vitamin D benefits. Blood levels lower than 30 ng/ml in adults can be dangerous.
Recommended Dietary Allowance (RDA) for Vitamin D
Recommended dietary allowance or RDA is the daily intake level that is sufficient to meet the needs of almost 98 percent of the population. Recommended dietary allowance for teens up to 13 years of age is 600 IU/day. In fact, 600 IU/day is deemed the recommended intake level for individuals up to 70 years if the weather conditions are optimal. That is, there are at least three months of the year when the sun shines almost every day.
For individuals aged more than 70 years, recommended daily intake rises to 800 IU/day. For some populations, especially adolescents, RDAs as high as 1500-2000 IU/day have been recommended to maintain the minimum serum 25 hydroxyvitamin D concentrations of 30 ng/ml.
The tolerable upper intake level or UL for vitamin D is the maximum safe daily intake level that does not cause the toxic effects of vitamin D overload. The UL for adults is 4000 IU/day.
Sources of Vitamin D
Three main routes of getting vitamin D are diet, sun exposure, and vitamin d supplementation.
Sun exposure is the most efficient and proficient method of attaining the right vitamin D levels. That’s why serum 25 hydroxyvitamin D concentrations are the lowest at the end of the winters and highest at the end of summers. And so do some diseases that link with serum vitamin D levels, such as various respiratory infections and seasonal depression.
Some aged individuals or those who are diseased may not be able to fulfill their therapeutic requirements of the vitamin from sun exposure alone. Besides, too much sun exposure is also one of the risk factors for skin cancer. To avoid the skin cancer risk, you may like to apply sunscreen, but again, that would limit the adequate absorption of sunlight for the adequate synthesis of vitamin D.
The second major source of vitamin D is diet and food. Major food sources for dietary intake of vitamin D include:
- Cod liver oil
- Tuna fish
- Fatty fish such as Salmon and swordfish
- Dairy and plant milk
- Egg yolk
- Beef liver
- Vitamin D fortified orange juice
You see, major sources of vitamin D are derived from animals. People who are pure vegetarians can use the third source of vitamin D, which is dietary supplements.
What happens if I take too much Vitamin D?
If you take vitamin D supplements more than the required dosage every day and for a long time, your body may build up excess vitamin D, possibly to toxic levels.
The major complication with too much vitamin D is calcium absorption, which leads to increased calcium levels in the blood, called hypercalcemia. Hypercalcemia is dangerous for almost all the systems of the body.
- Firstly, the kidneys work harder to remove the excess calcium. Excess urination leaves you dehydrated and also increases the chance of kidney stone formation.
- Kidney damage and injury finally progress to loss of its vital maintenance roles, such as blood pressure and red blood cell formation.
- Hypercalcemia causes severe digestive system problems such as nausea, vomiting, and constipation.
- More than enough vitamin D concentrations can also progress to bone pain and joint stiffness.
- Hypercalcemia also interferes with heart function since calcium channels are involved in the pacemaker function in the heart.
Are there any Side Effects of Vitamin D Supplements?
Vitamin D dietary supplements have been deemed safe for all age groups. People have not yet reported any side effects with taking oral vitamin D unless taken too much. As discussed above, people who take vitamin D in dosages greater than 4000 UI/day for too long may begin to experience the typical signs and symptoms of vitamin D toxicity.
Who should not take Vitamin D Supplements?
The following groups should avoid or observe discretion when taking vitamin D:
- Patients with sarcoidosis should not take vitamin supplements. Granulomas in sarcoidosis express high levels of alpha-hydroxylase, which produces high concentrations of vitamin D. Hypercalcemia in sarcoidosis is a consequence of these events.
- Patients with high phosphate and calcium levels in the blood should avoid taking vitamin D supplementation. It may worsen hypercalcemia and hyperphosphatemia.
- People who have existent or an increased risk of developing kidney stones. Vitamin D supplements require strict dosage in such patients.
The Bottom Line
This article briefs all about vitamin D supplements, their side effects, contraindications, and the dietary reference intakes as recommended by the National Institutes of Health (NIH).
In addition to maintaining healthy bones, sufficient vitamin D has magically holistic benefits for your body, as proved by many clinical trials. If you belong to any of the contraindications mentioned above, you should consult health professionals before starting vitamin D therapy.