List Of Vitamins: Functions, Sources, Daily Intake

Vitamins are extremely important nutrients that our bodies need to carry out normal functions on a daily basis.

They are found in the food we eat and each of the 13 vitamins play critical and unique roles in keeping us healthy.

Lower than necessary intake of any vitamin may cause subtle symptoms and extreme insufficiency or absence of a particular vitamin may cause a specific deficiency syndrome.
List Of Vitamins

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Vitamins are split up into 2 categories: Fat-Soluble and Water-Soluble.

Fat Soluble Vitamins

Fat-Soluble Vitamins (Vitamins A, D, E, K) are stored in the body for much longer. They need help from fat molecules to properly be absorbed from the digestive tract into the body.

Because of the long storage time for fat-soluble vitamins caution should be taken not to consume too much through supplementation. Because there may be associated toxicity in with extremely high doses of fat-soluble vitamins.

Vitamin A

Found in animal products but also found in plants as a pre-cursor called carotenoids, which act as a natural antioxidant in the body.

Carotenoids absorption varies from 5-50% making the actual amount of vitamin A being completely dependent on digestion and fat in the diet.

Once Vitamin A is active in the body it functions in vision (as retinal), normal cell differentiation, gene regulation (as retinoic acid), growth and development, immunity, and reproduction. Vitamin A also influences normal tooth formation, and helps your eyes see at night.

Daily recommended intake of vitamin A varies with the individual. And is whatever is needed to have adequate blood levels and liver stores, usually adjusted by body size.

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Preformed vitamin A exists only in animal products such as fish oil, especially cod and halibut liver oils.

Provitamin A carotenoids are found mostly in dark leafy green vegetables (kale and spinach), yellow-orange vegetables (carrots, sweet potatoes) and fruit (peaches, cantaloupe, apricot).

Vitamin A deficiency can come either as a result of inadequate intake or malabsorption. Although rare in the US, deficiency of Vitamin A may cause impaired vision, night blindness, decreased reproductive function, and lowered immunity.

Doses of vitamin A more than 100 times the required amount (greater than 200 mg) may overcome the livers ability to store the vitamin and lead to liver disease.

Signs of vitamin A toxicity include changes to skin, dry lips, dry nasal passages, peeling of skin, hair loss, an fragile nails.

Vitamin D

This vitamin, also known as the sunshine vitamin, is made from UV rays and cholesterol in the skin.

Some professionals do not refer to vitamin D as a vitamin at all, they call it a hormone. It’s actions as a hormone help to regulate the way genes talk to each other and causes different genes to be turned on or off.

Another function of vitamin D is making sure of calcium and phosphorous levels are balanced in the body by influencing absorption and gene expression.

Vitamin D has also shown evidence to be protective against bone disease, cancer, multiple sclerosis, and type I diabetes.

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Vitamin D Intake: 5 mcg/day for children and young adults,10 mcg/day for adults age 51 and older, 15 mcg/day for adults 71 and older.

These adequate intake levels are assuming the normal adult gets sufficient vitamin D from sun exposure. And vitamin D3 supplementation is often recommended for those who are constantly shielded from sunlight.

Aside from sunlight, dietary vitamin D3 exists in animal products naturally. Especially in fish and liver oils. It is also present in egg yolk, dairy products, and liver.

Vitamin D deficiency is one of the most common vitamins with inadequate intake in the world. It will cause rickets in children and osteomalacia (soft bones) in adults. The minimum blood levels is recommended to be no less than 30 nanograms/ml.

Toxic level of vitamin D is 25 mcg for infants and 50 mcg for adults. Vitamin D toxicity may cause hardening of soft tissues, headache, nausea, and growth retardation in infants.

Vitamin E

This vitamin is an extremely important antioxidant. It protects the body from damaging free radicals, which come from the metabolism or environment.

The antioxidant ability of Vitamin E is attributed to it’s ability to neutralize free radicals and render them harmless.

Vitamin E is known to be importing in protecting the body against aging, arthritis, cancer, cardiovascular disease, cataracts, diabetes, infection, and Alzheimer’s disease.

It is especially abundant in cereals, nuts, seeds, plant oils, asparagus, and margarines.

Vitamin E deficiency may take 5-10 years to develop and will cause neurological problems and absorption issues.

Vitamin E is one of the least toxic vitamins and humans can tolerate at least 100 times the nutritional requirement.

Vitamin K

Vitamin K plays a critical role in blood clotting, bone formation, and enzyme regulation in the brain.

Vitamin K recommended intake levels are 2.5 mcg/day for infants, 60-75 mcg/day for adolescents, and 90-120 mcg/day for adults.

It is most abundantly found in green leafy vegetables like broccoli, cabbage, kale, and spinach. It is also found to a lesser extent in dairy, meat, eggs, fruits, and cereals.

Vitamin K Deficiency is rare but may cause hemorrhage, anemia, and prolonged blood clotting time.

Causes of deficiency include impaired fat absorption and antibiotic use causing destruction of “good” gut bacteria. Vitamin K is made by good bacteria in the gut.

Vitamin K Toxicity: NONE.

Water Soluble Vitamins

Water Soluble Vitamins (B Vitamins & Vitamin C) are rapidly excreted and replaced in the body and need to be in constant supply from the diet.

These vitamins often serve as cofactors for different biochemical processes like the cell’s ability to make energy.

Vitamin C

Vitamin C, also known as ascorbic acid, is an incredible vitamin that serves as a powerful antioxidant. It also helps with the creation of collagen (found in muscle, skin, tendons, etc..), helps with formation of adrenaline, and improves iron absorption.

Due to it’s immune activity, vitamin C promotes resistance to infection and high doses of the vitamin even reduce the severity of the common cold.

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Vitamin C is found in plants and animal tissues, its best sources include sweet peppers, orange juice, broccoli, brussels sprouts, strawberries, and grapefruit.

The recommended intake of vitamin C is normally 15-120 mg per day. Cigarette smoking lowers the amount of vitamin C in the blood so it is recommended that smokers increase their intake to at least 100 mg per day.

Vitamin C deficiency is rare, but may result in scurvy after 45-80 days of vitamin C deprivation. Symptoms of scurvy include wound healing, edema, hemorrhage, weak bones, and weak connective tissue.

Adverse effects of high doses of vitamin C are mostly digestive disturbances like diarrhea. Some studies have noted that high doses of vitamin C may increase the risk of stomach cancer in individuals with an H. Pylori infection.

See Also: Easy Ways To Start Eating More Fruits And Vegetables

B1 (Thiamin)

Main function is energy/carbohydrate metabolism and nervous system function. Sources include yeast, liver, and grains. However cooking may destroy some of the thiamin that is available for the body to use.

Alcohol consumption inhibits the absorption of thiamin, and although rare in the US, deficiency symptoms would include anorexia, weight loss, cardiac, neurological signs.

B2 (Riboflavin)

Main function is metabolism of carbohydrates, proteins, and fats. Riboflavin also works as an antioxidant to protect the body from free radicals. It also plays an essential role in iron metabolism and preventing anemia.

Supplementation of riboflavin has also been shown to help improve cataracts. Due to B2’s inability to be stored in the body, it must be in continuous supply from the diet.

Sources of vitamin B2 (riboflavin) include green leafy vegetables, meat, and dairy products. Unlike thiamin, riboflavin is not destroyed from cooking but adding baking soda may cause some of the food’s riboflavin to be lost.

Deficiency of riboflavin is rare but can be a risk factor for cancer. Symptoms of a deficiency include tearing/burning/itching of the eyes, loss of vision, and soreness/burning of the lips and mouth.

Riboflavin is not known to be toxic even in high doses.

B3 (Niacin)

Main function is energy production and metabolism. Niacin may also play a vital role in DNA repair and gene stability which can influence cancer risk.

Niacin is abundantly found in many foods including lean meats, poultry, fish, peanuts, and yeast.

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Deficiency of B3 is rare but can cause weakness, anorexia, indigestion, skin eruptions as well as nervous system problems like confusion and neuritis.

Very high doses of niacin (1-2 grams, 3x/day) can have side effects due to histamine release such as flushing of the face. High doses can be especially harmful to those with a asthma or peptic ulcer disease.

Vitamin B5 (pantothenate, pantothenic acid)

Plays an important role in energy production and metabolism. It is found widely distributed in foods and can be abundantly found in meats, mushrooms, avocados, broccoli, and egg yolks.

Although deficiency is extremely rare, vitamin B5 deficiency would impair the body’s ability to make fats and produce energy. There are no toxic effects noted for large doses of vitamin B5.

Vitamin B6 (pyridoxine)

Vitamin B6 is an important vitamin for the metabolism of proteins. It is also needed for the formation of adrenaline (epinephrine) and other neurotransmitters, and used to modulate hormonal messages.

Vitamin B6 is found widely distributed in foods especially meats, grains, vegetables, and nuts. Deficiency of vitamin B6 may cause weakness, sleeplessness, nerve pain, and impaired immunity.

Many of the vitamin B6 deficiency symptoms can also be seen with toxicity from extremely high doses.

Vitamin B7 (Biotin)

Biotin is a vitamin that is famous for it’s ability to metabolize proteins and use them in growth and repair of the hair and nails.

In addition to protein metabolism, biotin also helps in the creation of fatty acids and amino acids (building blocks of proteins).  It is an extremely important link in the energy metabolism chain that includes folate, vitamin B5, and B12.

Biotin is another vitamin that is widely distributed into foods especially peanuts, almonds, soy, eggs, yogurt, and sweet potatoes.

Biotin deficiency is extremely rare but has been seen in nursing infants whose mothers’ milk contains low amounts. Biotin has no known toxic effects.

Vitamin B9 (Folate)

Folate has extremely important functions in synthesis and repair of DNA. It is also an important part of the methylation cycle, which controls a many functions in the body.

Folate is also extremely important for the formation of oxygen carrying red blood cells and the immune system’s white blood cells.

Low levels of folate have been shown to be associated with certain tumors in the body’s tissue. Only about half of the folate in food is actually absorbed and a vitamin B12 deficiency can lead to even less folate being used.

Recommended intake of folate varies from 65-600 mcg depending on age and gender. Good sources of vitamin B9 include liver, mushrooms, green leafy vegetables, lean beef, and whole wheat bread.

Storage, cooking, and high temperature processing can cause about 50-90% of folate to be lost in foods.

A deficiency in folate can impair creation of DNA and RNA, impair cell division, and cause a certain kind of large cell anemia (macrocytic).

Signs of deficiency include weakness, depression, and nervous system deficits. Folate is also extremely important in pregnant women, as folate supplementation can reduce the risk of serious birth defects by half.

For this reason, it is recommended that women supplement with an extra 400 mcg of folate before and during pregnancy.

Vitamin B12 (Cobalamin)

Vitamin B12 is an extremely important vitamin for the entire body’s metabolism. Especially the digestive tract, bone marrow, and nervous system.

Sources of Vitamin B12 include liver, kidney, milk, eggs, fish, cheese, and muscle meats while plant foods can only get the vitamin through fermentation.

The lack of abundant plant sources of Vitamin B12 may cause problems for anyone consuming a vegan diet if they do not supplement with the vitamin.

Usually, vitamin B12 is stored in the liver for 5-7 years, so vegans usually do not have symptoms of deficiency until years later.

Vitamin B12 also requires many factors to be properly absorbed. So even if someone is eating enough B12 in their diet they could still develop a deficiency if absorption is off.

Deficiency of B12 impairs the growth and division of cells and organs. B12 deficiency may also cause megaloblastic anemia and can potentially lead to a secondary folate deficiency.

Signs of deficiency may include nervous system abnormalities like numbness, tingling, and burning of the feet. Vitamin B12 has no toxicity.

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