Vitamins Overview
Vitamins are organic compounds that people need in small quantities. Each has a different role in maintaining health and bodily function.
In fact, each organism has different vitamin requirements. For example, humans need to get vitamin C from their diets, while dogs can produce all the vitamin C that they need.
However, most vitamins need to come from food because the body either does not produce them or produces very little.
Although, for humans, vitamin D is not available in large enough quantities in food. Therefore, the human body synthesizes the vitamin when exposed to sunlight, and this is the best source of vitamin D.
Moreover, different vitamins play different roles in the body, and a person requires a different amount of each vitamin to stay healthy.
What are Vitamins?
Vitamins are organic substances present in minute amounts in natural foodstuffs. Having too little of any particular vitamin may increase the risk of developing certain health issues.
In fact, a vitamin is an organic compound, which means that it contains carbon. It is also an essential nutrient that the body may need to get from food.
Moreover, there are currently 13 recognized vitamins.
Fat-soluble and water-soluble vitamins
Vitamins are either soluble, or dissolvable, in fat or water. Following are both types described below:
Fat-soluble vitamins
Vitamins A, D, E, and K are fat-soluble. Meanwhile, the body stores fat-soluble vitamins in fatty tissue and the liver, and reserves of these vitamins can stay in the body for days and sometimes months.
Moreover, dietary fats help the body absorb fat-soluble vitamins through the intestinal tract.
Water-soluble vitamins
Water-soluble vitamins do not stay in the body for long and cannot be stored. However, they leave the body via the urine. Furthermore, because of this, people need a more regular supply of water-soluble vitamins than fat-soluble ones.
The 13 Essential Vitamins
Below, list of 13 essential vitamins each currently recognized:
Vitamin A
Chemical names: retinol, retinal, and “the four carotenoids,” including beta carotene.
- It is fat-soluble.
- Function: It is essential for eye health.
- Deficiency: This may cause night blindness and keratomalacia, which causes the clear front layer of the eye to grow dry and cloudy.
- Good sources: These include liver, cod liver oil, carrots, broccoli, sweet potatoes, butter, kale, spinach, pumpkins, collard greens, some cheeses, eggs, apricots, cantaloupe melon, and milk.
Vitamin A helps maintain healthy vision. Without vitamin A, a person could experience vision problems and possibly vision loss.
Types
Vitamin A is not a single vitamin but a collection of compounds known as retinoids. Retinoids occur naturally in the human body, and they are present in some dietary sources.
Some foods provide retinols, which the body can use directly as vitamin A. Others provide provitamin A, compounds that the body converts into vitamin A.
Function
Vitamin A supports several functions throughout the body, including:
- Vision
- The immune system
Dietary sources
People can obtain vitamin A through dietary sources.
Although, animal sources provide preformed vitamin A, or retinols. However, this type is ready for the body to use.
In fact, plant sources provide carotenoids, such as beta-carotene, which is a powerful antioxidant. Rather, the body can convert these into vitamin A.
Moreover, for this reason, lists of ingredients often show vitamin A content as “vitamin A RAE.” RAE means “retinol activity equivalents.”
Animal sources of vitamin A include:
- Black-eyed peas
- Carrots
- Beef liver
- Cantaloupe
- Fish liver oil
- Cheese, milk, and other dairy products
- Fortified breakfast cereals
- Sources of beta carotene include:
- Sweet potato
- Kale, spinach, and other green, leafy vegetables
Recommended Intake
Nutritionists measure some vitamins in two ways:
- Micrograms (mcg) RAE
- International units (IU)
Food packages usually show the amounts in IU. A diet that contains 900 mcg RAE of vitamin A, which is the recommended intake for males over 14 years of age, would provide around 3,000–36,000 IU of vitamin A, according to the Office of Dietary Supplements (ODS).
However, anyone who has concerns about their vitamin A intake should seek advice from a health professional, who will help them understand these measures.
Moreover, the recommended intake of vitamin A varies by age and sex.
The 2015–2020 Dietary Guidelines for AmericansTrusted Source recommend consuming the following amounts each day. Amounts are in mcg RAE.
| Age (years) | 1–3 | 4–8 | 9–13 | 14 and over |
| Female | 300 | 400 | 600 | 700 |
| Male | 300 | 400 | 600 | 900 |
Deficiency
Vitamin A deficiency is rare in the United States, but it can affect a person who:
- Follows a plant-based diet
- Has cystic fibrosis
In fact, a long-term deficiency can lead to a loss of night vision and possibly a total loss of vision.
Overdose
Too much vitamin A can be toxic.
It can affect:
- People who take vitamin A supplements
- Those with a high intake of fish liver oil
- Individuals who take medications that contain retinoids, such as acitretin (Soriatane), a treatment for psoriasis
During pregnancy, high levels of vitamin A can harm a growing fetus.
Symptoms of an overdose include:
In severe cases, coma and death can result.
Vitamin A supplements are available for purchase online. However, people should speak to a doctor before taking these or other supplements.
The time a person takes a vitamin can affect its impact.
Vitamin B1
Chemical name: thiamine.
- It is water-soluble.
- Function: It is essential for producing various enzymes that help break down blood sugar.
- Deficiency: This may cause beriberi and Wernicke-Kosakoff syndrome.
- Good sources: These include yeast, pork, cereal grains, sunflower seeds, brown rice, whole grain rye, asparagus, kale, cauliflower, potatoes, oranges, liver, and eggs.
Vitamin B2
Chemical name: riboflavin.
- It is water-soluble.
- Function: It is essential for the growth and development of body cells and helps metabolize food.
- Deficiency: Symptoms include inflammation of the lips and fissures in the mouth.
- Good sources: These include asparagus, bananas, persimmons, okra, chard, cottage cheese, milk, yogurt, meat, eggs, fish, and green beans.
Vitamin B3
Chemical names: niacin, niacinamide.
- It is water-soluble.
- Function: The body needs niacin for the cells to grow and work correctly.
- Deficiency: Low levels result in a health issue called pellagra, which causes diarrhea, skin changes, and intestinal upset.
- Good sources: Examples include chicken, beef, tuna, salmon, milk, eggs, tomatoes, leafy vegetables, broccoli, carrots, nuts and seeds, tofu, and lentils.
Vitamin B5
Chemical name: pantothenic acid.
- It is water-soluble.
- Function: It is necessary for producing energy and hormones.
- Deficiency: Symptoms include paresthesia, or “pins and needles.”
- Good sources: These include meats, whole grains, broccoli, avocados, and yogurt.
Vitamin B6
Chemical names: pyridoxine, pyridoxamine, pyridoxal.
- It is water-soluble.
- Function: It is vital for the formation of red blood cells.
- Deficiency: Low levels may lead to anemia and peripheral neuropathy.
- Good sources: These include chickpeas, beef liver, bananas, squash, and nuts.
Vitamin B7
Chemical name: biotin.
- It is water-soluble.
- Function: It enables the body to metabolize proteins, fats, and carbohydrates. It also contributes to keratin, a structural protein in the skin, hair, and nails.
- Deficiency: Low levels may cause dermatitis or inflammation of the intestines.
- Good sources: These include egg yolk, liver, broccoli, spinach, and cheese.
Vitamin B9
Chemical names: folic acid, folinic acid.
- It is water-soluble.
- Functions: It is essential for making DNA and RNA.
- Deficiency: During pregnancy, this can affect the fetus’s nervous system. Doctors recommend folic acid supplements before and during pregnancy.
- Good sources: These include leafy vegetables, peas, legumes, liver, some fortified grain products, and sunflower seeds. Also, several fruits have moderate amounts.
Vitamin B12
Chemical names: cyanocobalamin, hydroxocobalamin, methylcobalamin.
- It is water-soluble.
- Function: It is essential for a healthy nervous system.
- Deficiency: Low levels may lead to neurological problems and some types of anemia.
- Good sources: Examples include fish, shellfish, meat, poultry, eggs, milk and other dairy products, fortified cereals, fortified soy products, and fortified nutritional yeast.
Doctors may recommend that people with vegan diets take B12 supplements.
Vitamin C
Chemical name: ascorbic acid.
- It is water-soluble.
- Function: It contributes to collagen production, wound healing, and bone formation. It also strengthens blood vessels, supports the immune system, helps the body absorb iron, and acts as an antioxidant.
- Deficiency: This may result in scurvy, which causes bleeding gums, a loss of teeth, and poor tissue growth and wound healing.
- Good sources: These include fruit and vegetables, but cooking destroys vitamin C.
Vitamin D
Chemical names: ergocalciferol, cholecalciferol.
- It is fat-soluble.
- Function: It is necessary for the healthy mineralization of bone.
- Deficiency: This may cause rickets and osteomalacia, or softening of the bones.
- Good sources: Exposure to UVB rays from the sun or other sources causes the body to produce vitamin D. Fatty fish, eggs, beef liver, and mushrooms also contain the vitamin.
People obtain vitamin D:
- As supplements
- Naturally through exposure to sunlight or in the diet
- Through fortified foods
The body obtains the compounds it needs to make vitamin D from food. It also produces vitamin D when ultraviolet (UV) light meets the skin.
Types
Vitamin D is not a single substance but a group of compounds collectively known as calciferol.
The body absorbs calciferol into the bloodstream and then converts it to calcitriol.
Two types occur naturally:
- Vitamin D-3, found in animal fats
- The vitamin D-2, found in plants, such as mushrooms
Function
Vitamin D has two main roles in the body:
- It maintains bone health.
- Vitamin D supports the immune system.
Dietary sources
A person can obtain some vitamin D from the sun, but most people will also need to use other sources, too. The main alternative is food.
Dietary sources include:
- Beef liver
- Eggs
- Fortified dairy products, plant-based milks, and cereals
- Oily fish and fish oils
Recommended intake
Experts measure vitamin D in international units (IU).
Current guidelines recommend that people of all ages intake of 600 IU of vitamin D daily. This is hard to measure, however, as it is not easy for a person to know how much vitamin D they obtain from sunlight.
Deficiency
A vitamin D deficiency can affect:
- Older adults and children who do not spend much time out of doors
- People with darker skin
- Some people with chronic health conditions
- Those who live far from the Equator, where winter days are short
- People with obesity
The main effects of vitamin D deficiency include:
- Osteomalacia, when bones become soft
- Rickets, when a child’s bones do not develop as they should
- Osteoporosis or loss of bone mass
- Increased risk of infection and autoimmunity
Overdose
It is rare for a person to have too much vitamin D, but using supplements could trigger this.
Having too much vitamin D could lead to high levels of calcium in the blood.
This can lead to:
- A buildup of calcium in tissues and blood vessels
- Headaches
- Nausea
- Low appetite and weight loss
- High blood pressure
- Heart or kidney damage
Vitamin D supplements are available for purchase in pharmacies and online. A person should speak to their doctor before using these supplements, however.
Vitamin E
Chemical names: tocopherol, tocotrienol.
- It is fat-soluble.
- Function: Its antioxidant activity helps prevent oxidative stress, an issue that increases the risk of widespread inflammation and various diseases.
- Deficiency: This is rare, but it may cause hemolytic anemia in newborns. This condition destroys blood cells.
- Good sources: These include wheat germ, kiwis, almonds, eggs, nuts, leafy greens, and vegetable oils.
Vitamin E is an antioxidant that can help the body destroy free radicals. Free radicals are unstable atoms that can cause oxidative stress. Oxidative stress can lead to cell damage, and this can result in cancer and other diseases. Vitamin E may help protect the body from a range of health issues.
Types
There are eight forms of vitamin E, but only alpha-tocopherol meets humans’ needs, according to the ODS.
Function
Some reasons why the body needs vitamin E are:
- To boost the immune system
- As an antioxidant
- To dilate blood vessels and help prevent clotting
Dietary sources
Good sources of vitamin E include:
- Almonds, hazelnuts, and peanuts
- Sunflower seeds and oil
- Kiwi fruit and mango
- Spinach and broccoli
- Wheat germ oil
Recommended intake
Current guidelines recommend people consume the following amounts of vitamin E. Experts measure vitamin E intake in milligrams (mg) AT, but packaging currently uses international units (IU).
| Age (years) | 1–3 | 4–8 | 9–13 | 14 and over |
| Female | 6 mg (9IU) | 7 mg (10.4 IU) | 11 mg (16.4 IU) | 15 mg (22.4 IU) |
| Male | 6 mg (9IU) | 7 mg (10.4 IU) | 11 mg (16.4 IU) | 15 mg (22.4 IU) |
The ODS note that, during breastfeeding, a female should consume 19 mg (28.4 IU) each day.
Deficiency
Vitamin E deficiency is rare, but it can affect people with Crohn’s disease or cystic fibrosis. These conditions affect the liver’s ability to absorb vitamin E.
A deficiency can result in:
- A weekend immune system
- Nerve and muscle damage that affects movement and coordination
- Vision problems
As vitamin E is an antioxidant, a long-term deficiency could increase the overall risk of various diseases.
Overdose
Obtaining vitamin E through natural sources is unlikely to lead to an overdose, although supplement use can increase this risk.
People who use blood-thinning medication, such as warfarin (Coumadin) should ask their doctor before taking vitamin E supplements, as these may interfere with blood clotting.
Vitamin E supplements are available for purchase in pharmacies and online.
Vitamin K
Chemical names: phylloquinone, menaquinone.
- It is fat-soluble.
- Function: It is necessary for blood clotting.
- Deficiency: Low levels may cause an unusual susceptibility to bleeding, or bleeding diathesis.
- Good sources: These include natto, leafy greens, pumpkins, figs, and parsley.
Vitamin K helps the body form blood clots. Blood clotting is essential to prevent excessive bleeding.
Types
There are several types of vitamin K.
The two most common groups are:
- Vitamin K-1 (phylloquinone), present in green, leafy vegetables and some other plant sources
- And vitamin K-2 (menaquinones), present in animal sources and fermented foods
There are also synthetic forms and other forms that the body makes.
Function
Apart from blood clotting, vitamin K may also:
- Enhance bone health
- Lower the risk of heart disease
- Reduce the buildup of calcium in the blood
Dietary sources
Food sources of vitamin K-1 and K-2 include:
- Butter
- Egg yolks
- Kale
- liver
- Parsley
- Spinach
Recommended intake
Experts do not have enough evidence to recommend a specific intake of vitamin K suitable to meet the needs of 97-98% of healthy individuals.
Instead, they recommend an adequate intake (AI), an amount assumed to provide nutritional adequacy, as follows:
| Age (years) | 1–3 | 4–8 | 9–13 | 14–18 | 19 and over |
| Female | 30 | 55 | 60 | 75 | 90 |
| Male | 30 | 55 | 60 | 75 | 120 |
Deficiency
The body is not able to store as much vitamin K as it does vitamin A or D. This means a person needs a regular intake of vitamin K, and there is a higher chance of a deficiency.
A vitamin K deficiency may result in:
- Excess bleeding
- Lower bone density, in the long term
Vitamin K supplements are available for purchase in pharmacies and online.
However, people should speak to a doctor before using them, especially if they use blood thinners or have a condition that affects blood clotting.
Vitamin Supplements
Many people in the United States take multivitamins and other supplements, though these may not be necessary or helpful, according to research.
In fact, a balanced, varied diet that contains plenty of fruits and vegetables should be the primary source of vitamins. Meanwhile, the Department of Health and Human Services provide up-to-date guidelines detailing the best ways to get enough nutrients from the diet.
Moreover, fortified foods and supplements may be appropriate in some cases, however, such as during pregnancy, for people with restricted diets, and for people with specific health issues.
However, anyone taking supplements should be careful not to exceed the maximum dose, as research shows that taking too much of any vitamin can lead to health problems.
Also, some medications can interact with vitamin supplements. Overall, it is important to speak with a healthcare provider before trying any supplement.
Summary
Vitamins are essential nutrients that mainly come from foods. Each performs various roles in the body, and deficiencies of different vitamins can harm health in different ways.
Aim to get vitamins from a balanced, varied diet that contains plenty of fruits and vegetables. If a person is pregnant or has a health issue or a restricted diet, a doctor or nutritionist may recommend supplements.
Biospecimens
Bay Biosciences is a global leader in providing researchers with high quality, clinical grade, fully characterized human tissue samples, bio-specimens, and human bio-fluid collections.
Samples available include cancer (tumor) tissue, cancer serum, cancer plasma, cancer, peripheral blood mononuclear cells (PBMC). and human tissue samples from most other therapeutic areas and diseases.
Bay Biosciences maintains and manages its own bio-repository, the human tissue bank (biobank) consisting of thousands of diseased samples (specimens) and from normal healthy donors available in all formats and types.
In fact, our biobank procures and stores fully consented, de-identified and institutional review boards (IRB) approved human tissue samples and matched controls.
Our human tissue collections, specimens, and bio-fluids come with detailed patient clinical data associated with them.
So this critical patient’s clinical data includes information relating to their past and current disease, treatment history, lifestyle choices, biomarkers, and genetic information.
Additionally, new effective treatments (drug discovery & development) in oncology, and other therapeutic areas and diseases are identified by researchers using patient’s data which is extremely valuable.
Bay Biosciences banks wide variety of human tissue samples and biological samples, including cryogenically preserved at – 80°C.
For example fresh frozen tissue samples, tumor tissue samples, formalin-fixed paraffin-embedded (FFPE), tissue slides, with matching human bio-fluids, whole blood and blood-derived products such as serum, plasma and PBMC.
Bay Biosciences is a global leader in collecting and providing human tissue samples according to the specified requirements and customized, tailor-made collection protocols.
Please contact us anytime to discuss your special research projects and customized human tissue sample requirements.
Types of Biospecimens
Bay Biosciences provides human tissue samples (human specimens) from diseased and normal healthy donors which includes:
- Peripheral whole-blood
- Amniotic fluid
- Bronchoalveolar lavage fluid (BAL)
- Sputum
- Pleural effusion
- Cerebrospinal fluid (CSF)
- Serum (sera)
- Plasma
- Peripheral blood mononuclear cells (PBMC)
- Saliva
- Buffy coat
- Urine
- Stool samples
- Aqueous humor
- Vitreous humor
- Kidney stones (renal calculi)
- Other bodily fluids from most diseases including cancer.
Moreover, we can also procure most human bio-specimens, special collections and requests for human samples that are difficult to find. All our human tissue samples are procured through IRB-approved clinical protocols and procedures.
In addition to the standard processing protocols, Bay Biosciences can also provide human plasma, serum, and PBMC bio-fluid samples using custom processing protocols; you buy donor-specific collections in higher volumes and specified sample aliquots from us.
Bay Biosciences also provides human samples from normal healthy donors; volunteers, for controls and clinical research, contact us Now.
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