What Is Vitamin D?
Vitamin D is counted as a nutrient that can be ingested through diet and a hormone synthesized by the human body. It is one of the fat-soluble vitamins that help absorb and retain calcium and phosphorus in the body. In their adequate doses, these minerals are essential for maintaining bone strength. Additionally, certain scientific studies claim that vitamin D decreases the growth of cancer cells, incidences of developing infections, and lowers inflammation. Many of the body’s organs and tissues have receptors for vitamin D, which suggest important roles beyond bone health, while scientists actively investigate its other possible functions.
Vitamin D is naturally present in some foods. However, few foods are fortified with it to increase its source options. The limited choices make it difficult to obtain optimal vitamin D from foods. So, most people rely on vitamin D supplements to fulfill their needs. These supplements are available as pre-vitamin D or ergocalciferol and vitamin D3 or cholecalciferol. Ergocalciferol and cholecalciferol occur naturally in animals and plants and require ultraviolet-B (UVB) sun rays for their production. Hence, vitamin D is also known as ‘the sunshine vitamin.’ The D2 form is synthesized in plants and fungi; the D3 variant is in animals and humans. Although vitamin D is produced in the human skin, still, many people face its deficiency because of the restricted availability of sunlight in the areas where they reside or due to limited sun exposure because of thick clothing or fewer outdoor activities. Darker skin individuals often possess insufficient vitamin D levels, as melanin in the skin hampers their vitamin D production.
What Is the Need for Vitamin D?
The body requires vitamin D to keep bones, muscles, and teeth healthy. Vitamin D assists intestinal absorption of calcium and aid in the maintenance of optimal calcium and phosphorus blood levels, which are critical for the proper mineralization of bones. Vitamin D may also help carry good immune function and decrease the chances of autoimmune diseases like diabetes, asthma, and rheumatoid arthritis.
What Are the Recommended Dosages of Vitamin D?
The advised dosages of vitamin D are:
RDA: The recommended dietary allowance for vitamin D means the amount of vitamin D needed to sustain proper health of bones and normal metabolism of calcium in healthy individuals with minimum sun exposure. For adults of 19 years and older, RDA for vitamin D is 600 IU (15 mcg) per day for males and females, and for those over 70 years, it is 800 IU (20 mcg) daily.
UL: It means the tolerable upper level of vitamin D intake. That is the maximum daily consumption that causes no deleterious effects on health. For vitamin D, the UL for adults and children of 9 years and above is 4,000 IU (100 mcg).
What Are the Food Sources of Vitamin D?
Certain foods naturally contain a high amount of vitamin D3, like the flesh of fatty fish and liver oils. Smaller quantities are also present in egg yolks, cheese, and beef liver. Mushrooms also possess little vitamin D2; however, the commercially-sold mushrooms contain increased D2 quantity after intentional exposure to ultraviolet light. Some foods and supplements are also loaded with vitamin D, such as dairy products and cereals.
What Are Vitamin D-Fortified Foods?
Fortified foods are food items that are artificially enriched with different micronutrients to prevent deficiency and augment their consumption by people. Manufacturers incorporate nutrients not found naturally in the products, like bread, cereals, milk, etc. Likewise, many food items, such as milk, are fortified with vitamin D. Also, a very small number of foods are a rich source of vitamin D. However, certain fortified foods also include some unhealthy ingredients like sugar or hydrogenated fats, besides vitamin D.
Several yogurts and cereal types contain vitamin D, extra sugar, or saturated fat. Margarine is fortified with vitamin D and may possess partially hydrogenated oils. Labels should be read before choosing fortified foods.
What Is Vitamin D Deficiency?
Vitamin D deficiency occurs in people of all ages. An inadequate diet, insufficient sun exposure, malabsorption, and metabolic diseases cause vitamin D deficiency. People intolerant or allergic to milk, eggs, lactose intolerance, or veganism are highly susceptible to developing the deficiency.
Patients with inflammatory bowel disease, ulcerative colitis, Crohn’s disease, and conditions that interrupt normal fat digestion. As vitamin D is a fat-soluble vitamin, its absorption depends on the intestinal fat absorption of an individual.
Vitamin D blood levels decrease with obesity. Though vitamin D accumulates in fatty tissue deposits in such people, the body becomes incapable of utilizing them completely. So, increased supplementation of vitamin D is needed.
After gastric bypass surgery, in which the upper part of the small intestine is removed, vitamin D absorption gets impaired.
Prolonged vitamin D deficiency leads to the following conditions:
Rickets: It is seen in infants and children, in which soft bones fail to harden, and skeletal deformities occur.
Osteomalacia: This condition occurs in adults, in which bones become weak and softened. However, it is reversible and requires supplementation intake as its treatment.
What Is Vitamin D Toxicity?
High supplement intake can lead to vitamin D toxicity. Neither the food nor increased sun exposure can cause vitamin D toxicity. Vitamin D supplements should not be consumed more than 4,000 IU per day. The manifestations of vitamin D toxicity include:
Anorexia (loss of appetite).
Decreased body weight.
Increased blood calcium levels, causing hardening of blood vessels and tissues and possibly damaging the heart and kidneys.
Sufficient intake of vitamin D is imperative for the body. Therefore, adequate information and consumption of vitamin D-rich foods are needed. Fortified vitamin D foods are new choices. Artificial supplements can fulfill this requirement.