- 2 Types of vitamins
- 5 Toxicity
- 5.1 Toxicity details
- Vitamin B
There are 14 vitamins that the body requires on a regular basis. While some can be synthesized (such as vitamin D from sunlight), for proper physical and mental health function, most have to be consumed through diet or supplementation.
Vitamins are compounds that are necessary for a wide range of biological functions. They play a role in nearly everything the body does. Each vitamin is responsible for a specific set of functions, and deficiency in a particular type can lead to disease.
Types of vitamins
Here is a list of some of the most common vitamins you should get from your diet our through supplementation.
The belief that carrots are good for your eyesight stems from the fact that they're high in vitamin A, and that A vitamins are necessary for proper retina functioning. But vitamin A is also needed by the immune system and for cell growth. A deficiency can cause skin problems, loss of color vision, nyctalopia (night blindness), and even general blindness (keratomalacia).
While the other vitamins are very straightforward, vitamin B gets a little complicated. It's made up of a range of numbered subcategories (B1, B2, etc.), each of which is actually a distinct vitamin with unique functions. This happened because the entire complex of B vitamins was once thought to be a singular entity. It was later discovered that each component was chemically distinct. It eventaully became standard practice to refer to every component as a number.
To further confuse things, these vitamin B subcategories are sometimes referred to as a different letter, for example, "B7" is sometimes called "vitamin H" and "B9" is also known as "vitamin M."
Products that contain "B-complex" typically have several separate B vitamins, which are preferable when looking for general supplementation. They are typically marketed towards their energy production characteristics.
Below, each B vitamin is listed in more detail:
|Type of B Vitamin||Description|
|Vitamin B1 (Thiamine/Thiamin)|| Vitamin B1 is vital in a number of critical ways. Its primary use is metabolic — it's needed to convert carbohydrates to energy. But it also plays a role in supporting the brain, nervous system, heart and muscle tissues.|
Since it's so widely needed by the body, deficiency can cause a variety of problems. Neurological complications are some of the most typical issues associated with a B1 deficiency, including general confusion, depression, and, in minor cases, irritability.
In severe cases, symptoms can progress to a cardiovascular and nervous system disease called beriberi.
|Vitamin B2 (Riboflavin)||Vitamin B2 is needed for a wide range of functions in both the cells and for proper digestion. Deficiency causes a condition called ariboflavinosis — common symptoms are sore throat, severe chapped lips, swollen or purple tongue, and skin conditions. Prolonged deficiency can cause liver damage.|
|Vitamin B3 (Niacin)||Niacin regulates cholesterol and fat levels and supports the cardiovascular system. Deficiency can cause general fatigue, headaches, nausea, and skin lesions. Prolonged deficiency causes pellagra, a disease with a wide array of nasty symptoms that can eventually lead to death.|
|Vitamin B5 (Pantothenic Acid)||Vitamin B5 is needed to metabolize food. The body doesn't need much of it, however, so cases are rare. Deficiency can cause general fatigue, poor mood, muscle cramps, increased insulin sensitivity, gastrointestinal disorders, and tingling skin (paresthesia).|
|Vitamin B6||Vitamin B6 is widely needed throughout the body for metabolizing amino acids and glucose, for histamine synthesis, and, primarily, for the creation of hemoglobin. Deficiency most commonly leads to an outbreak of dermatitis or rashes, inflammation and/or soreness of the tongue, cracks at the corners of the mouth, bloodshot eyes, confusion, and spells of dizziness.|
|Vitamin B7 (Biotin or Vitamin H)||Vitamin B7 is primarily used in the synthesis of fatty acids and the branched-chain amino acids (BCAAs). Deficiency is exceptionally rare — it's only been seen in diets unusually high in raw egg whites, as they contain a protein that binds with B7 and makes it unavailable (it denatures and ceases to do this when the egg whites are cooked). Symptoms of deficiency are hair loss, dermatitis on the face and around the genitals, bloodshot eyes, depression, fatigue, and hallucinations.|
|Vitamin B9 (Folic Acid or Vitamin M)||Vitamin B9 is another vitamin widely used throughout the body, but it's primarily needed to form and repair DNA and cells. Deficiency can cause a sore or swollen tongue, diarrhea, anemia, depression, and confusion. A folic acid deficiency during pregnancy can also cause neural defects in the fetus. In developing countries, B9 deficiency has been associated with increased rates of malaria in children under age 5.|
|Vitamin B12||Vitamin B12 regulates the nervous system, aids in brain and cell function, and is key in the formation of blood. Initial symptoms of deficiency are neurological — loss of memory, general fatigue, depression, even mania or psychosis, in some cases. Sustained deficiency can cause serious and irreparable damage to the brain and central nervous system.|
|Bp (Choline)||Bp is much more commonly referred to as choline, though it's part of B-complex. It's used to maintain cells, aid in neural transmission, and for digestive system support. Deficiency can cause fat to accumulate around the liver and eventual kidney death if sustained for a long period.|
Vitamin C is used throughout the body. It's needed to synthesize collagen, carnitine, tyrosine, and neurotransmitters. It's also the most common antioxidant in a regular diet, is a major fuel source for immune system cells, and is an antihistamine. The most colorful and well-known disease caused by a C deficiency is scurvy, though cases are rare these days thanks to the vitamin's ubiquity in diet.
Modern cases of scurvy are generally only seem in individuals who have bulimia or alcoholism. Less severe early signs of deficiency include fatigue, depression, bleeding gums, easy bruising, and joint pain.
For years, vitamin D was thought to play a role in supporting bone health, but the evidence isn't entirely conclusive. The vitamin is defined more by what happens when you're deficient: rickets and osteoporosis.
As with scurvy, however, diet and supplementation have largely eliminated rickets outside of developing countries. Also known as the sunshine vitamin, vitamin D is the only vitamin that isn't essential in diet, as the skin can synthesize it from sun exposure.
Vitamin E works in tandem with vitamin C as one of the most common and potent antioxidants. It's also a critical component in muscle growth, gene expression, and neurological function. Deficiency can cause mobility or coordination problems, muscle weakness or failure, nerve disease, impaired immune function, retinal damage, and the death of red blood cells.
There are actually two types of vitamin K: K1 and K2. Unlike B-complex, they're generally regarded as one entity as the colon can synthesize K2 from K1. Vitamin K is most critical in blood coagulation. Lack of the nutrient can lead to uncontrolled bleeding, osteoporosis, and heart disease.
All of those "for men," "for women," and "silver" vitamin formulations aren't just marketing fluff. The primary determinants for your RDA are age and gender.
The above table, with data provided by the IOM, lists each vitamin with corresponding RDA (recommended daily allowance) and UL (tolerated upper limit) for male and female adults. Always consult with your pediatrician before giving children or infants a vitamin. Also, women who are pregnant or lactacting should discuss their vitamin needs with her health care provider.
|Type of B Vitamin||Males: RDA||Females: RDA||UL|
|Biotin (Vitamin B7)||19 to 70+ years: 30 mcg||19 to 70+ years: 30 mcg||N/A|
|Choline (Bp)||19 to 70+ years: 550 mg||19 to 70+ years: 425 mg||3,500 mg|
|Folic Acid (B9)||19 to 70+ years: 400 mcg||19 to 70+ years: 400 mcg||1,000 mcg|
|Niacin (B3)||19 to 70+ years: 16 mg||19 to 70+ years: 14mg||35 mg|
|Pantothenic Acid (B5)||19 to 70+ years: 5 mg||19 to 70+ years: 5mg||N/A|
|Riboflavin (B2)||19 to 70+ years: 1.3 mg||19 to 70+ years: 1.1mg||N/A|
|Thiamin (B1)||19 to 70+ years: 1.2 mg||19 to 70+ years: 1.1mg||N/A|
|Vitamin A||19 to 70+ years: 900 mcg||19 to 70+ years: 700 mcg||3,000 mcg|
|Vitamin B6|| 19 to 50: 1.3 mg |
50 to 70+ years: 1.7 mg
| 19 to 50: 1.3 mg |
50 to 70+ years: 1.5 mg
|Vitamin B12 (Cobalmin)||19 to 70+ years: 2.4 mcg||19 to 70+ years: 2.4 mcg||N/A|
|Vitamin C||19 to 70+ years: 90 mg||19 to 70+ years: 75 mg||2,000mg|
|Vitamin D||19 to 50: 5 mcg50 to 70 years: 10 mcg70+: 15 mcg||19 to 50: 5 mcg50 to 70 years: 10 mcg70+: 15 mcg||50 mcg|
|Vitamin E||19 to 70+ years: 15 mg||19 to 70+ years: 15 mg||1,000 mg|
|Vitamin K||19 to 70+ years: 120 mcg||19 to 70+ years: 90 mcg||N/A|
Vitamin supplements are available individually, in packs of individual pills for each type of vitamin, or with many or all of the daily vitamins, amalgamated into one pill called a multivitamin.
In recent years, a number of studies suggesting that taking the hard pill form of vitamins may lead to incomplete absorption has created a surge in popularity of alternate forms.[15,16] To promote absorption, consume your vitamins in these forms:
Vitamins that are mixed with a powdered food can also promote absorption.Gelcaps
Most vitamin supplements are formulated synthetically. Unless you're consuming your vitamin from dietary sources (food vs. capsules or powders), it's likely your vitamins were made in a lab. This is not necessarily a bad thing — your synthetic vitamin C pill is the same the C in your orange. One benefit of getting your vitamins from food is that they provide additional micronutrients and plant-based phytonutrients that are not found in synthetic multivitamins.Synthetic vitamins are also sometimes added to beverages in the manufacturing process. Vitaminwater is a popular example. Today, several vitamin beverages, such as Odwalla, are marketed for the purpose of providing a concentration of vitamins from fruits and vegetables.
All vitamins have a potential upper limit (UL), after which they can have toxic effects. Fat-soluble vitamins are the only ones that you really need to be concerned with. Vitamins A, D, E, and K differ from water-soluble vitamins in that they are stored in body fat for later use, and will accumulate to toxic levels over time, especially if you take more than your RDA, or have a health condition that prevents your liver from properly processing nutrients.
Water-soluble vitamins (B-complex and vitamin C) still have toxic thresholds, but to reach them they generally must be taken in massive single doses that would not be encountered in nature (or even in supplementation).
Depending on the type of vitamin you take, toxicity symptoms can range from irritating to dangerous.
Vitamin K toxicity
Of the fat-soluble vitamins, you don't need to worry about vitamin K. There's no recommended UL as there's never been a known case of toxicity due to overdose.
Vitamin A toxicity
Vitamin A's average toxic dose (which should not be confused with the tolerable upper limit) is 120,000 IU (international units) per day, but liver damage has occurred at doses of 15,000 IU per day (toxicity is exacerbated by poor overall diet and alcohol consumption).
Vitamin E toxicity
Vitamin E's upper recommended limit is 1,000mg (1,500 IU) per day for adults. While not as dangerous as A or D, at toxic levels the primary concern is that an overdose can prevent blood from clotting. Other symptoms may include blotchy skin, decreased production of thyroid hormones and increased triglycerides.
Vitamin D and toxicity
The actual limits of toxicity of vitamin D (and resulting symptoms) are still somewhat in dispute among experts, but the IOM has set the toxicity threshold at either 300,000 IU in a 24-hour period, or over 10,000 IU per day for three or more consecutive months. Unfortunately, the symptoms are vague and overlap with many other common maladies, such as nausea, reduced appetite, excessive thirst or urination, gastrointestinal pain or disorders, fatigue, muscle weakness, and confusion. A simple test can determine if vitamin D is the culprit by checking your blood calcium levels — if they're too high, you'll have to cut down your intake for several months and possibly take a prescribed corticosteroid.
Children and pregnancy
Toxicity can occur in children beginning at 1,500 IU/kg of body weight. Potential symptoms are many and varied. The most serious are hair loss, muscle weakness, weakened bones (leading to risk of fractures), weight loss, and anemia. Vitamin A toxicity can also damage the fetus during pregnancy.
Here's a brief overview of the richest natural food sources of each vitamin:
Vitamin A: sweet potato, carrots, kale, squash, romaine lettuce
Vitamin B1: trout, pork, macadamia nuts, sunflower seeds, whole wheat bread
Vitamin B2: almonds, red meat, mackerel, eggs, pork
Vitamin B3: yellowfin tuna, chicken breast, turkey, pork, liver, peanuts
Vitamin B5: shiitake mushrooms, trout, avocados, eggs, pork
Vitamin B6: sunflower seeds, pistachios, tuna, turkey, chicken
Vitamin B7: yeast, liver, kidney, egg yolk, soybeans
Vitamin B9: black eyed peas, lentils, spinach, asparagus, romaine lettuce
Vitamin B12: clams, beef liver, mackerel, crab, silken tofu, bran
BP: shrimp, eggs, scallops, chicken, turkey, collard greens
Vitamin C: chili peppers, guava, bell peppers, leafy greens, broccoli
Vitamin D: salmon, sardines, tuna, milk, eggs, shiitake mushrooms
Vitamin E: sIlken tofu, spinach, almonds, sunflower seeds, avocados
Vitamin K: leafy greens, scallions, Brussels sprouts, broccoli, chili powder
Most foods contain at least one of the essential vitamins in some amount. Many processed foods are also fortified with synthetic vitamins as a way to be more attractive to consumers.
A well-balanced diet is the best way to meet all of your vitamin needs, but supplementation can help when that isn't possible, or when your nutrient needs exceed normal standards due to high-level training.
Because vitamins are defined by the FDA as dietary supplements, the agency's monitoring responsibility is limited to removing illegal substances from the market rather than verifying quality or content. Independent reviews that are accompanied by testing from unbiased labs are generally your most reliable source of information on supplement standards and safety.WarningsVitamins and supplements are drawn from varying sources, and potency and quality may vary. While the science is not entirely conclusive on the subject, synthetic vitamins sometimes haven't fared as well in studies as those from natural sources, in terms of uptake and absorption.[22, 23]Beverages like Vitaminwater are particularly worrisome sources of vitamins. In addition to entirely synthetic vitamin content, the beverages tend to be packed with large amounts of refined sugar and empty carbohydrates that can be detrimental to health.
Where to buy
You can compare the various vitamin supplements on the market here at PricePlow. In addition to our reviews, ingredient lists, and videos, our comparison shopping engine and price-drop notifications can help you to save 30% to 50% off of retail prices.
- Tanumihardjo, S.A.; The American Journal of Clinical Nutrition; Vitamin A: biomarkers of nutrition for development;" 2011
- American Cancer Society; Vitamin B Complex;" January 2013
- PubChem; "Riboflavin;" 2013
- PubChem; "Niacin;" 2013
- PubChem; "Pantothenic Acid;" 2013
- PubChem; "Pyridoxine;" 2013
- PubChem; "Biotin;" 2013
- PubChem; "Folic Acid;" 2013
- PubChem; "Vitamin B12;" 2013
- PubChem; "Choline;" 2013
- PubChem; "Ascorbic Acid;" 2013
- PubChem; "Vitamin D; 2013
- PubChem; "Vitamin E;" 2013
- PubChem; ">Vitamin K;" 2013
- Lichtenstein, AH, et. al; Journal of the American Medical Association; "Essential Nutrients: Food or Supplements. Where should the emphasis be?;" July 2005
- Leonard, SW, et. al; The American Journal of Clinical Nutrition; "Vitamin E bioavailability from fortified breakfast cereal is greater than that from encapsulated supplements;" January 2004
- Rasmussen, SE, et. al; European Journal of Nutrition; "A safe strategy for addition of vitamins and minerals to foods;" 2005
- National Institutes of Health; "Vitamin A Fact Sheet for Health Professionals;" June 2013
- National Institutes of Health; "Vitamin E Fact Sheet for Consumers;" October 2011
- National Institutes of Health; "Vitamin D Fact Sheet for Health Professionals;" June 2011
- Food and Drug Administration; "Dietary Supplements Q&A;" 2013
- Burton, GW, et. al; The American Journal of Clinical Nutrition; "Human plasma and tissue alpha-tocopherol concentrations in response to supplementation with deuterated natural and synthetic vitamin E;" April 1998
- Annals of Internal Medicine; "Daily multivitamin supplements did not reduce risk for major CV events over > 10 years in men;" February 2013