Vitamin D is also known as the sunshine vitamin. The history of vitamin D is associated with rickets. In the late 17th century, Dutch physicians noticed the prevalence of rickets, a condition characterized by bent and deformed bones and enlarged joints in the hands and feet. In severe cases, patients with rickets had difficulty breathing. In the mid-19th century, many countries in Europe were in the midst of the Industrial Revolution, during which factory buildings were widespread and an abundance of coal was burned in public places as well as in houses for cooking and heating. Severe air pollution often blocked ultraviolet light from the sun’s rays. In addition, many Europeans worked in sweatshops devoid of sunlight. Rickets became an epidemic.
From the 19th to 20th centuries, there were several major breakthroughs in research on rickets. These included the discovery that city dwellers were more likely to be afflicted by the disease compared to people who lived in the countryside, that the lack of sun exposure caused it, and that fish liver oil could cure it. In 1922, Elmer McCollum confirmed that the lipid-soluble substance in fish liver oil that cured rickets was not vitamin A but an unknown substance he named vitamin D. In 1936, Adolf Windaus confirmed that the chemical structure of vitamin D was calciferoL
Upon sun exposure, human skin produces vitamin D. Strictly speaking, the body produces vitamin D; therefore, vitamin D is not an essential nutrient. Nevertheless, vitamin D produced by the skin is not sufficient for the needs of most people. Intake from foods or supplementation is necessary to ensure optimal health. There are many good quality vitamin D supplements are available in the market to fill up this nutritional gap. Here are some of the best vitamin D supplements in the UK.
Vitamin D produced by the skin or from foods is activated in the liver to produce 25-hydroxyvitamin an Also known as “25(OH)D,” 25- hydroxyvitamin D is the major circulating form of vitamin D in the bloodstream, and it is commonly used to assess the blood level of vitamin D. It, in turn, is further activated which is involved in hundreds of gene expressions and numerous physiological functions.
What Are the Major Functions of Vitamin D?
- Calcium homeostasis. Concentrations of calcium are closely regulated in the body, and calcium homeostasis is related to normal physiological functions in the nervous system, bones, muscles, and many other organs. To maintain good health, it is of foremost importance to carefully control calcium concentration in the body. Vitamin D enhances the deposition of calcium in the bones, while parathyroid hormones release calcium from the bones. The interplay between vitamin D and parathyroid hormones controls calcium concentration in the body.
- Phosphorus homeostasis. Similarly, concentrations of phosphorus ions influence many normal physiological functions in muscles, bones, and other organs in the body. When phosphorus levels are low in the blood, vitamin D instructs the intestines to increase absorption of phosphorus ions, and when the phosphorus ion levels are too high, parathyroid hormones instruct the kidneys to excrete excessive phosphorus ions in the urine.
- Cell proliferation and differentiation. Proliferation is a self-replication process by which a cell multiplies and produces more cells, and differentiation is like assigning given cell-specific tasks to perform. When proliferation is dominant, differentiation will be slow, and vice versa. Uncontrollable proliferation can lead to cancer. Vitamin D promotes cell differentiation and prevents cell proliferation to curtail the risk of tumour formation.
- Immune system. Many immune cells—including monocytes, macrophages, and T cells—have their own vitamin D activation processes through which the active form of vitamin D influences the gene expression of immune cells. Vitamin D enhances innate immunity (general immune defence) and inhibits autoimmunity (misdirected immune responses). Vitamin D deficiency increases susceptibility to autoimmune disorders. Read more here.
- Insulin secretion. The active form of vitamin D enters pancreatic cells, regulates gene expression in pancreatic cells, and stimulates the secretion of insulin from pancreatic cells.
What Are the Symptoms of Vitamin D Deficiency?
Vitamin D deficiency causes rickets in children (103) and osteomalacia in adults.
- Rickets. Vitamin D promotes the mineralization of calcium phosphate in the bones, increasing bone density and strength. The bones of children with vitamin D deficiency may grow in length but lack mineralization of calcium phosphate, resulting in soft and porous bones. Such bones cannot support the weight of the body and become bent and deformed This is known as rickets.
- Osteomalacia. Calcium in bones exists in a homeostatic state—an equilibrium of deposition and removal. Vitamin D deficiency causes removal rather than deposition of calcium in the bones, triggering loss of bone density and, in severe cases, resulting in osteomalacia, or soft bone disease, which is characterized by an aching pain in the lower back, pelvis, hips, legs, and ribs in adults. Osteomalacia can lead to osteoporosis
What Are the Risk Factors for Vitamin D Deficiency?
- Geography. The closer a place is to the equator, the stronger the intensity of ultraviolet light from the sun. Therefore, people who live closer to the equator have a lower risk of vitamin D deficiency compared to those who live farther away from the equator. Indeed, people •m live at the 43rd parallel north and farther are more susceptible to vitamin D deficiency. In those regions, every year from October to April, ultraviolet light from the sun cannot reach the surface of the Earth, so the skin ceases to produce vitamin D, increasing the risk of deficiency.
- Sun protection. Except for beachgoers and those who love outdoor activities, most people try to avoid sun exposure. Sun umbrellas, hats, long sleeves, long pants, and sunscreen are common remedies to shun sun exposure. Excessive avoidance of the sun can cause vitamin D deficiency.
- Infants fed with breast milk The vitamin D content of breast milk is relatively low. Infants who are born to Asian and African families in the northern hemisphere are at especially high risk of vitamin D deficiency A daily dose of 400 ILT is recommended for infants to avoid vitamin D deficiency.
- Obesity. Vitamin D is a lipid-soluble vitamin. Upon absorption in the intestines, vitamin D dissolved in chylomicrons (fat globules) is transported to the liver and other organs in the body. In the bloodstream, vitamin D binds to a vitamin D-binding protein, which is then absorbed by fat tissue. In other words, in obese individuals, vitamin D is mostly stored in fat tissue, while the rest of the body is devoid of vitamin D, causing vitamin D deficiency. Weight loss is the only way to release it from fat tissue and increase vitamin D levels.
- Chronic kidney disease. An enzyme in the kidneys is required for final activation of vitamin D in the body, which creates the active form of vitamin D. Chronic kidney disease hinders the activation of vitamin D in the kidneys, resulting in vitamin D deficiency.
- Enteritis (inflammation of the small intestine). Inflammatory bowel diseases—such as keratin,e colitis, Crohn’s disease, and fat malabsorption—may lower the absorption of vitamin D in the intestines, aggravating the risk of vitamin D deficiency.
Do I Need Sun Exposure?
Vitamin D has a host of health benefits, including maintaining healthy bones and lowering the risk of heart disease, stroke, asthma, inflammation, and autoimmune diseases. Vitamin D also may extend life expectancy.
The amount of sun exposure required to produce an adequate amount of vitamin D depends on the colour of your skin and where you live. For example, to produce 1,000 Ili of vitamin D in Chicago, Caucasians require 15 minutes, Asians and Hispanics 30 minutes, and Africans 2 hours. The best time for sun exposure is on a sunny day when your shadow is shorter than your height, during which time the skin is most efficiently producing vitamin D. People who live in places at or above the 43rd parallel north can only achieve this from May through September, so in the winter, they may have to rely on intake through vitamin D-rich foods or supplements to obtain adequate amounts of vitamin D.
Vitamin D Supplements
- Dosage. The most common dosages of vitamin D supplements are 400-5,000 III, which largely exceed the recommended dietary allowance. Two types of vitamin D supplements are vitamin D2 and vitamin D3. Vitamin D2 comes from plant-based foods and vitamin D3 from animal-based foods. Vitamin D2 and vitamin D3 are similar. although D3 is more potent than D2. Ultraviolet B rays from sunlight trigger the skin to produce vitamin D3, but fish liver oil and deep-sea fish are also excellent sources of vitamin D3. Vitamin D supplements in the marketplace predominantly contain vitamin D3.
- Types. Vitamin D supplements can be found as tablets, soft gels, and drops. Vitamin D liquid drops are inexpensive and easy to use One drop usually contains 400 IU of vitamin D3. If a daily dose of 2,000 ILT is needed: just use five drops. Vitamin D is tasteless and odourless, so liquid drops can be added directly to meals or beverages.
- Bone density. Vitamin D regulates the metabolism of calcium and phosphorus ions in the body. Supplementation with vitamin D can enhance the bone density of teenage girls and help postmenopausal women avoid bone loss. The suggested daily dose is 800 RJ of vitamin D3.
- Bone fractures. Bone fractures are a major problem for people aged 65 and older. Supplementation with vitamin D can reduce the risk of bone fractures. Studies from Australia have shown that elderly individuals with blood levels of vitamin D in the range of 24-29 ng/ml were the least likely to experience bone fractures: since vitamin D can strengthen bones and muscles. It can also be used by athletes whose blood levels of vitamin D are below 20 ng/ml, which can make them prone to exercise-induced injuries.
- Insulin resistance. Obese individuals whose blood levels of vitamin D are below 20 ng/ml have a 12 times higher risk of insulin resistance compared to individuals of normal weight. Insulin resistance is a major risk factor for cardiovascular diseases, diabetes, and Alzheimer’s disease. Vitamin. D supplementation can reduce the risk of insulin resistance in obese individuals.
- Cardiovascular disease. A high level of C-reactive protein in the blood indicates systemic inflammation in the body, which heightens the risk of cardiovascular diseases. Vitamin D supplementation can lower the levels of C-reactive protein, reducing inflammation and the risk of cardiovascular diseases.
- Asthma. Vitamin D supplementation can alleviate pulmonary inflammation, enhance lung function, and control asthma. Supplementation with vitamin D can enhance the efficacy of inhaled corticosteroids in asthmatic patients. The suggested daily dose is 800 TU.
- Chronic obstructive pulmonary disease. Supplementation with vitamin D can mitigate symptoms of chronic obstructive pulmonary disease. The suggested daily dose is 2,000
- Childhood allergies. Children and teenagers whose blood levels of vitamin D are below 15 ng/ml have an increased risk of developing childhood allergies. When pregnant women take vitamin D supplements at a daily dose of 800 IU during the last three months of pregnancy, it reduces the risk of childhood allergies in their babies.
- Fibromyalgia. Fibromyalgia is a chronic disease characterized by a diffuse or sharp pain in joints and muscles. Studies from Austria have shown that supplementation with vitamin D improved symptoms of fibromyalgia in patients. The suggested daily dose is 1,200 IU of vitamin D.
- Lupus erythematosus. Vitamin D supplementation can improve symptoms in patients with lupus erythematosus. Adding vitamin D to prescribed medications alleviates the frequency of relapses and enhances immune functions in patients with lupus erythematosus.
- Depression. Low blood levels of vitamin D increase the risk of depression in elderly individuals. Supplementation with vitamin D can alleviate depression symptoms in type 2 diabetes patients as well.
- Dementia. Elderly individuals whose blood levels of vitamin D are below 10 ng/ml have a greater risk of dementia and Alzheimer’s disease. Supplementation with vitamin D at a dose of 500 ITJ reduces the risk of Alzheimer’s disease by 77%. Elderly individuals whose blood levels of vitamin D are higher than 20 ng/ml decrease their risk of Parkinson’s disease by 60%.
- Cancers. Low blood levels of vitamin D put you at a higher risk of colorectal cancer, breast cancer, melanoma, bladder cancer, and lung cancer. Supplementation with vitamin D improves symptoms of cancer as well as survival rates. The suggested daily dose is 800 IU of vitamin D3.
- Other diseases. Low blood levels of vitamin D heighten the risk of rheumatoid arthritis, heart disease, hypertension, and coronary artery disease, shortening life expectancy overall.
What Types of Drugs May Interact with Vitamin D?
Anticonvulsant medications, cholesterol-lowering drugs, and chemotherapy can reduce blood levels of vitamin D.