Your body needs 13 essential vitamins to function properly, and most people can get all of them through a balanced diet. These vitamins support everything from vision and bone strength to immune defense and energy production. Understanding what each one does, where to find it, and when supplementation actually makes sense can help you fill gaps without overdoing it.
The 13 Essential Vitamins and What They Do
Vitamins fall into two groups based on how your body absorbs and stores them. Four are fat-soluble, meaning they dissolve in fat and get absorbed alongside dietary fat in your small intestine. Your body can store these in fatty tissue and the liver, so you don’t need them every single day, but that storage capacity also means they can build up to harmful levels if you take too much. The remaining nine are water-soluble. Your body doesn’t store most of them efficiently, so you need a steady supply from food.
Fat-Soluble Vitamins
- Vitamin A maintains healthy skin, teeth, bones, and the tissue in the back of your eye that creates vision.
- Vitamin D helps your body absorb calcium for strong teeth and bones, and it plays a role in regulating calcium and phosphorus in your blood. Your skin also produces it from sunlight.
- Vitamin E acts as an antioxidant, helps form red blood cells, and supports your body’s use of vitamin K.
- Vitamin K is essential for normal blood clotting and contributes to bone health.
Because these four require dietary fat for absorption, eating them with a meal that includes some fat (olive oil, nuts, avocado) makes a real difference. Taking a vitamin D supplement on an empty stomach, for example, means less of it reaches your bloodstream.
Water-Soluble Vitamins
- Vitamin C is an antioxidant that promotes healthy gums, helps your body absorb iron, maintains tissue health, and is essential for wound healing.
- B1 (thiamine) helps cells convert carbohydrates into energy and supports heart function and healthy nerve cells.
- B2 (riboflavin) supports body growth and red blood cell production.
- B3 (niacin) helps maintain healthy skin and nerves.
- B5 (pantothenic acid) is essential for metabolizing food and plays a role in producing hormones.
- B6 helps form red blood cells and maintain brain function, and it supports the chemical reactions involved in protein metabolism.
- B7 (biotin) is essential for metabolizing proteins and carbohydrates and for producing hormones.
- B9 (folate) works with B12 to form red blood cells and is needed for DNA production, which controls tissue growth and cell function.
- B12 supports metabolism, red blood cell formation, and the health of both the central and peripheral nervous systems.
Best Food Sources for Each Vitamin
Whole foods generally deliver vitamins in forms your body absorbs more efficiently than supplements, and they come bundled with fiber, minerals, and other compounds that work together. Here’s where to find the key vitamins:
For vitamin A, dairy products like milk, yogurt, and cheese provide the ready-to-use form (retinol). Carrots, kale, and mango supply a precursor your body converts into vitamin A, though the conversion isn’t perfectly efficient. For vitamin C, kale, broccoli, oranges, and kiwi are top sources. Vitamin K is abundant in dark leafy greens, especially kale and spinach.
The B vitamins are spread across different food groups. B12 comes almost exclusively from animal products: milk, yogurt, cheese, meat, fish, and eggs. Folate is richest in spinach, broccoli, oranges, and bananas. B2 is plentiful in dairy. For vitamin D, fatty fish, fortified milk, and egg yolks help, but sunlight exposure remains the most significant source for most people.
Who Needs More (or Less) Than Average
A standard varied diet covers most people’s needs, but certain life stages and dietary patterns create predictable gaps.
Adults over 65 often struggle with vitamin B12 absorption. A condition called atrophic gastritis, which affects 8% to 9% of adults 65 and older compared to 2% of the general population, reduces the stomach’s ability to produce the acid and proteins needed to extract B12 from food. Depending on how deficiency is measured, between 3% and 43% of older adults living independently have low B12 levels. Vitamin D levels also tend to drop with age because skin becomes less efficient at producing it from sunlight and many older adults spend less time outdoors.
Women who could become pregnant should get 400 micrograms of folate daily, according to the CDC. Folate is critical for DNA production and cell growth during the earliest weeks of pregnancy, often before a woman knows she’s pregnant. This is one case where a supplement is widely recommended even for people eating well.
People on plant-based diets face a well-documented B12 gap. One study comparing vegans to omnivores found vegans consumed a median of 0.29 micrograms of B12 per day from food alone, versus 5.22 micrograms for omnivores, with a recommended intake of 3.0 micrograms. Vitamin D intake was similarly low: 0.94 micrograms for vegans compared to 2.53 for omnivores, against a target of 20 micrograms. Interestingly, vegans who supplemented B12 had blood levels comparable to meat-eaters, showing supplementation works. Without supplementation, though, vegans were significantly more likely to have low vitamin D levels. Riboflavin (B2) is another nutrient the German Nutrition Society flags as critical for vegans to watch.
Vitamins That Support Immune Function
Vitamin C plays a direct role in protecting immune cells from damage during the inflammatory response. It helps maintain the structural integrity of cells when your immune system ramps up to fight an infection. Research shows it supports several specific immune functions, including the activity of natural killer cells (your body’s first responders against infected cells) and the proliferation of infection-fighting white blood cells.
Vitamin D also influences immune regulation, which is one reason deficiency has been linked to increased susceptibility to infections, particularly respiratory ones. Getting enough of both vitamins through food and, when needed, supplementation provides a stronger foundation than megadosing during cold season.
When Supplements Make Sense
Supplements are useful for filling specific, identified gaps rather than as blanket insurance. The situations where they provide the clearest benefit include B12 for vegans and older adults, folate for women of reproductive age, vitamin D for people with limited sun exposure or darker skin at higher latitudes, and iron for people with diagnosed deficiency.
If you do take supplements, quality varies more than most people realize. The FDA doesn’t test supplements for accuracy before they hit shelves. Third-party certification programs from USP and NSF verify that a product actually contains what’s listed on the label in the correct amounts, is free of harmful contaminants, and dissolves properly so your body can absorb it. The USP program has been running since 2001, and NSF has offered verification since 2003. Look for their seals on the bottle.
Safety Limits to Keep in Mind
More is not better with vitamins, especially the fat-soluble ones that accumulate in your body. The Institute of Medicine has established upper intake levels, the maximum daily amount unlikely to cause harm, for several vitamins in adults aged 19 to 70:
- Vitamin A (preformed): 3,000 micrograms per day. Excess can cause liver damage, headaches, and bone thinning.
- Vitamin D: 50 micrograms (2,000 IU) per day. Too much can lead to calcium buildup in the blood.
- Vitamin C: 2,000 milligrams per day. Beyond this, digestive upset and kidney stones become more likely.
- Vitamin E: 1,000 milligrams per day from synthetic sources.
- Niacin (B3): 35 milligrams per day from supplements or fortified foods.
- B6: 100 milligrams per day. Chronic excess can cause nerve damage.
- Folate: 1,000 micrograms per day from synthetic sources.
These upper limits apply to total intake from food, water, and supplements combined. It’s nearly impossible to reach toxic levels from food alone. The risk comes from stacking multiple supplements or taking high-dose single-vitamin pills without a specific reason. A standard multivitamin typically stays well within safe ranges, but adding individual supplements on top can push certain vitamins past these thresholds.