The term 'vitamins' refers to the group of organic substances that are essential for the healthy functioning of the human body. There are 13 universally recognized vitamins. These are classified into fat-soluble and water-soluble vitamins. Each vitamin plays a vital role when it comes to helping us attain optimal health. Vitamin D is a fat-soluble vitamin that is essential for the absorption of calcium and phosphate. Ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) are the two forms of vitamin D that are used by humans. Our body naturally synthesizes cholecalciferol when we are exposed to sunlight, hence vitamin D is also referred to as the 'sunshine vitamin'. On the other hand, ergocalciferol is produced by certain plants, invertebrates, and fungi in response to exposure to the sun. Cholecalciferol is believed to be more potent and less toxic when compared to ergocalciferol. Those of you who choose to take vitamin D supplements need to understand that an overdose can have serious repercussions on their health.
Vitamin D Overdose
Unlike the water-soluble vitamins that are absorbed into the bloodstream, fat-soluble vitamins such as vitamin D are stored by the fatty tissue of the body. When the intake of water-soluble vitamins is more than what the body needs, these are flushed out by way of urine. This minimizes the risk of vitamin toxicity. This doesn't hold true for fat-soluble vitamins. Since these are stored by the body, an overdose could give rise to certain side effects. Since vitamin D is fat-soluble, it must be taken as per the recommended dietary allowance. This will help in preventing vitamin D side effects.
◘ Since vitamin D facilitates the absorption of calcium, and helps to maintain normal levels of calcium and phosphorus in the blood, an overdose is most likely to cause calcification of soft tissues in the body. This puts a person at a greater risk of developing kidney stones.
◘ An overdose could also lead to excessive production of urine. Taking high doses could lead to nocturia, which is a medical condition characterized by the need to get up many times at night to pass urine.
◘ Increased levels of calcium in blood (hypercalcemia) is one of the most common side effects of a vitamin D overdose. Those who suffer from hypercalcemia are likely to experience symptoms such as excessive thirst, nausea, muscle weakness, muscle cramps, pain in the abdomen, confusion, or lethargy.
◘ An overdose could also make a person prone to heart ailments or high blood pressure. Loss of appetite, nausea, vomiting, constipation, bone pain, insomnia, or frequent urination are some of the problems that may occur due to an overdose.
Side effects could also occur due to adverse drug interactions. If you have been asked to take vitamin D supplements, make sure that you inform your doctor about any other drugs that you may be taking.
◘ Vitamin D can increase the absorption rate of aluminum. Since aluminum is often used in antacids, ensure that you don't take antacids and vitamin D at the same time. People who have been diagnosed with kidney disease must be extra cautious if they are taking vitamin supplements and antacids.
◘ Vitamin D may alter the effects of certain drugs. For instance, it may increase the effects of digoxin, which is a drug that is used to treat cardiac arrhythmia or congestive heart failure.
◘ Those who have been diagnosed with kidney stones need to be very careful if they are taking water pills and vitamin D together. If not taken in right amounts, these could cause elevated levels of calcium in the body.
◘ Cimetidine is a drug that could affect the absorption of vitamin D by interfering in the process involving the conversion of vitamin D into its active form.
RDA for Vitamin D
Earlier, the recommended dietary allowance for this vitamin was set at 5 micrograms or 200 IU (international units). However, with the rising cases of vitamin D deficiency, the Institute of Medicine, which is a non-profit NGO that is a part of the United States National Academies, updated the recommended dietary intake in 2010. Here's the revised RDA as per the age groups.
◘ The daily RDA for infants in the age group of 0-12 months has been changed to 400 IU.
◘ The daily tolerable upper intake level (the highest level of daily intake of a nutrient that is not likely to pose a health risk to almost all individuals) for infants in the age group of 0 to 6 months has been set as 1,000 IU, whereas upper intake level for infants in the age group of 6 to 12 months is set at 1,500 IU.
◘ The daily RDA for growing children and adults who are below the age of 70 years is 600 IU.
◘ The daily tolerable upper intake level for children in the age group of 1 to 3 years has been changed to 2,500 IU, whereas the upper level intake for children in the age group of 4 to 8 years has been set at 3,000 IU.
◘ The daily RDA for people older than 70 years has been set at 800 IU, while the tolerable upper intake limit for pregnant women, nursing mothers, children who are older than 9 years, and adults has been set at 4,000 IU.
◘ A single dose which is beyond the tolerable upper limit of 4,000 IU, or intake of high doses for a prolonged time period of time is likely to cause vitamin D side effects.
Researchers believe that factors such as age and physical health must be taken into account while deciding the RDA. As we age, our body's ability to synthesize this vitamin from sunlight declines. Thus, elderly must either take supplements or foods fortified with this vitamin to meet their body's requirements. Including sardines, mackerel, eel, herring, egg yolks, cooked beef, liver, cod liver oil, certain types of mushrooms, or other food items that are rich in this vitamin in the diet may also prove beneficial.
Vitamin D Deficiency
Health problems are most likely to be experienced by those who don't include the dietary sources of this vitamin in their diet. Those who don't get adequate sunlight or don't consume foods rich in this vitamin may experience distressing symptoms on account of a vitamin D deficiency. At times, a deficiency may result from the inability of the digestive tract to absorb this vitamin. Since liver or kidney diseases impact the ability of the body to convert it to an active form, people who suffer from such ailments might exhibit symptoms of this deficiency.
Deficiency of this vitamin can trigger a wide range of health problems. These include:
◘ The deficiency of this vitamin can lead to rickets in children. Rickets is a disease that is typically characterized by bone deformities.
◘ Adults suffering from this deficiency are prone to osteomalacia, which is a condition that is characterized by the weakening of the muscles and bones. It may cause pain in the bones, muscles, and joints.
◘ Obesity, skin pigmentation, or inflammatory bowel disease can also be attributed to this deficiency.
◘ This deficiency can also hamper the production of insulin in the body, thereby making a person susceptible to type 2 diabetes.
◘ As this vitamin also affects the working of our nervous system, a deficiency could trigger psychological problems such as depression or schizophrenia.
◘ It is believed that a vitamin D deficiency could cause Seasonal Affective Disorder (SAD). Also referred to as seasonal depression, SAD is a condition wherein the affected person may feel depressed especially when winter approaches. The symptoms of seasonal depression could be alleviated by taking vitamin D supplements. Light therapy may also be recommended for people who have been diagnosed with SAD.
Excess of anything is bad, which is why people who are taking vitamin D supplements must adhere to the prescribed dosage. It would be best to fulfill your body's requirements by either including food items that are rich in vitamin D to your diet or by getting the much-needed supply of sunshine vitamin by basking in the sun.
Disclaimer: This article is for informative purposes only, and should not be used as a replacement for expert medical advice.