vitamin D toxicity - JASE Medical

Interesting Facts About Vitamin A

When we think of food sources of vitamin A and what it does for the body we think of carrots and better vision. While this is true, there are some interesting and often overlooked facts about vitamin A.

What is vitamin A?

Vitamin A is a fat-soluble vitamin that is stored in the liver for up to 4 years. It is a subclass of retinoic acids, a family of lipid soluble compounds that includes retinols, beta carotenes and other carotenoids.

  • The active form of vitamin A is called preformed retinol It is found in fish, organ meats, dairy products, egg yolks and some fortified foods.
  • Provitamin A carotenoids are precursors to vitamin A. Foods containing carotenoids are converted through an enzymatic process into vitamin A. Carotenoids are a class of  compounds yellow, orange, or red fat-soluble pigments, including carotene, which give color to plant parts such as ripe tomatoes and autumn leaves: There are more than 600 known carotenoids. Carotenoids are found in fruits, vegetables and some fish, such as in the pink color of salmon. It is also found in supplement form. One such carotenoid is beta-carotene.
  • Beta-carotene converts to vitamin A and is an antioxidant. Antioxidants are manmade or natural substances that protect cells from damage caused by substances called free radicals. It is converted to retinol in the wall of the small intestine.

Function of vitamin A

Vitamin A plays many important roles in health. 

Preformed vitamin A – retinol is important for vision, especially night vision, anti inflammatory, enhances immune system function, important for developing fetal endothelial cell proliferation, produces pigments in retina, maintains healthy teeth, skeletal and soft tissue. In food form can be protective against some forms of cancer. 

Vitamin A deficiency- 

Vitamin A deficiency is considered to be rare except in premature infants, malnourished areas of the world, gastrointestinal disorders such as celiac, pancreatic insufficiency, bile duct disorder and those who cannot convert beta carotene to active vitamin A due to a BCMO1 gene variation– which results in a poor conversion from beta carotene to vitamin A. (It is estimated that approximately 45 percent of the population may have this conversion defect.

Symptoms of vitamin A deficiency:

Vitamin A toxicity

Most toxicity isa result of supplementation and not food sources. 

Symptoms of vitamin A toxicity:

  • drowsiness
  • irritability
  • abdominal pain
  • nausea
  • vomiting
  • increased pressure on the brain

Supplementation 

Seek advice of a qualified health professional before supplementing vitamin A or beta- carotene. Vitamin A is stored in the liver for up to four years so there is little chance of being deficient unless you have a pre existing condition that impairs vitamin A absorption or genetic impairment.  

In addition, a large scale study called the ATBC study— over 29,000 smokers who supplemented with beta carotene (the precursor to vitamin A) was stopped abruptly because of the high incidence of lung cancer that developed during the study.  The researchers concluded that all smokers should not use beta carotene supplements due to this increased risk of lung cancer. 

Measles management in children

Excerpt from Infectious Diseases in Clinical Practice:

“In November 2019, the National Foundation for Infectious Diseases convened a summit that included multidisciplinary subject matter experts from across the United States to discuss the use of vitamin A in US measles management. The resulting Summit recommendations include that all children in the United States presenting with measles should receive an age-appropriate dose of vitamin A as part of a comprehensive measles management protocol. Multiple studies in populations in which vitamin A deficiency is prevalent have shown that this simple, quick means of improving vitamin A status can dramatically reduce the risk of serious complications and death from measles, with minimal detectable incidence of adverse effects.”

- Brooke Lounsbury, RN

Medical Content Writer

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Vitamin D

Vitamin D is a steroid hormone, and sometimes called “activated vitamin D” or “calcitriol.” Steroid hormones are derived from cholesterol and are lipid-soluble molecules. Examples of steroid hormones include the sex hormones (androgens, estrogens, and progesterone) produced by male and female gonads and hormones of the adrenal glands (aldosterone, cortisol, and androgens). It is a fat-soluble vitamin that helps the body absorb and retain calcium and phosphorus. Both are necessary for building bone. Vitamin D also plays a role in bolstering the immune system to fight off viruses and bacteria. In addition, research suggests that vitamin D could play a role in downregulating autoimmune disease. In addition a randomized 5 year clinic trial of high vitamin D supplementation reduced the incidence of advanced cancer without a diagnosis of cancer at the beginning of the study. Much interest and research is ongoing in this promising field of study.

Vitamin D is found in two main forms:

Vitamin D2 (ergocalciferol) – The main source is from plants. Mushrooms, when exposed to UV light produce D2. Fortified cereals are usually fortified with vitamin D2

 

Vitamin D3 (cholecalciferol) – The main source is from animals- Sources of D3 are egg yolks, cod liver oil, fatty fish-salmon, sardines, herring, tuna, beef liver. In addition, when skin is exposed to sunlight vitamin D3 is produced. The body only produces enough vitamin D3 from sunlight as it needs then stops producing it.

The liver metabolizes vitamin D2 and vitamin D3 and form the active compound known as calcifediol. A study done by the National Institute of Health on post-menopausal vitamin D deficient women showed that vitamin D3 yielded twice more calcifediol than an equal amount of vitamin D2.

Excess Vitamin D3 is stored in the bodies adipose tissue and liver and is converted by the kidneys to the active form of vitamin. Excess vitamin D is almost exclusively from supplement sources.

According the NIH:

The amount of vitamin D you need each day depends on your age. Average daily recommended amounts are listed below in micrograms (mcg) and International Units (IU):

Life Stage Recommended Amount
Birth to 12 months 10 mcg (400 IU)
Children 1–13 years 15 mcg (600 IU)
Teens 14–18 years 15 mcg (600 IU)
Adults 19–70 years 15 mcg (600 IU)
Adults 71 years and older 20 mcg (800 IU)
Pregnant and breastfeeding teens and women

15 mcg (600 IU)

 

The 25-hydroxy vitamin D test (a blood test) is the most accurate way to measure how much vitamin D is in your body.

Factors affecting vitamin D deficiency

  • Older adults skin doesn’t absorb vitamin D as well as younger population. Dark skin also doesn’t absorb vitamin D very well either
  • Some diseases- celiac, Crohn’s disease, ulcerative colitits, limit absorption of fats and vitamin D
  • Obesity and gastric bypass may need more vitamin D

Signs of vitamin D deficiency- up to 42 percent of the US population is deficient

  • Rickets in children
  • Osteomalacia in adults
  • Not sleeping well.
  • Bone pain or achiness.
  • Depression or feelings of sadness.
  • Hair loss.
  • Muscle weakness.
  • Lowered immunity to infections-viral and bacterial

Signs of vitamin D toxicity

Vitamin D toxicity is not common, except when extremely high doses of vitamin D is taken in supplement form for a long time (months).

  • Hypercalcemia
  • Nausea, vomiting
  • Can progress to bone pain and kidney stones

How to Improve Your Vitamin D Status

In addition to adequate sunlight exposure, vitamin D requires other nutrients and minerals to work properly. It is always best to get your nutrition from food sources, however long winters and low sunlight may require supplementation. If supplementing with vitamin D, it is best to take with fat since it is a fat-soluble vitamin.

Vitamin K2(MK-7)- activates osteocalcin, which integrates calcium into the bone. Activates matrix GLA protein (MGP) to bind excess calcium and promote arterial flow and flexibility. Food sources include fermented foods, natto

Magnesium- helps convert vitamin D to active form. Food sources include leafy greens, beans, legumes, almonds, cashews

Zinc– synergistic effect- vitamin D enhances zinc action and homeostasis and zinc enhances vitamin D absorption. Food sources include oysers, red meat, poultry

Boron– increases vitamin D in the blood. Food sources include coffee, milk, apples, dried and cooked beans, and potatoes

Cold water fish– salmon, herring, sardines, tuna

- Brooke Lounsbury, RN

Medical Content Writer

Lifesaving Medications

Everyone should be empowered to care for themselves and their loved ones during the unexpected.

Recent Posts

Keeping you informed and safe.

Join Our Newsletter

Our mission is to help you be more medically prepared. Join our newsletter and follow us on social media for health and safety tips each week!