Humans need higher levels of water-soluble vitamins that easily pass through the body

Humans need vitamins, but research is mixed on taking supplements

When an organism needs an organic molecule to survive, but cannot synthesize enough of it itself, that molecule is called a vitamin. Typically, we consume vitamins through food, but many resort to supplements—a common and mostly unregulated practice.

Vitamins are micronutrients human bodies need but don't naturally produce

Each vitamin is found in specific portions of a normal human diet and supports normal human functioning in distinct ways. Vitamin A is found in red meat, carrots, and potatoes and supports vision and skin health, while Vitamin D (common in fish and mushrooms) helps absorb calcium. See sources and uses of each vitamin with this chart.

Yes, you can take too many vitamins and they can make you sick

Too much of vitamins A, D, E, and K (which are fat-soluble) can build up in the body and cause serious health problems, including liver damage, kidney stones, and blood clotting irregularities. Excess iron and calcium can also make it harder for the body to absorb other needed nutrients.

What do vitamins actually do?

Vitamins are molecular tools the body needs to carry out regular cellular processes, such as wound healing. This 45-minute video dives into the science behind vitamins and their role in the body. There are 13 essential vitamins that must be...

Most adults don't need a daily vitamin, and it won't extend your life

A 20-year study by the National Cancer Institute involving almost 400,000 people found that daily multivitamins did not help people live longer. In some cases, these vitamins also increased the risk of death. Although some subpopulations—such as those with documented vitamin deficiencies and pregnant individuals—should take vitamins, daily multivitamins should not be taken uniformly by adults. Instead, patients should discuss vitamins with their clinicians and consider baseline vitamin testing before starting vitamin regimens.

Gummy vitamins have candy-level sugar—and that sweetness is linked to overdoses

A typical gummy vitamin contains about the same amount of sugar in a single serving as one Sour Patch candy. It's linked to the increase in pediatric overdoses for products including multivitamins and melatonin. Gummy formulations also degrade quickly, so they often include much higher levels of the product in each serving than the label advertises—boosting overdose risks due to this unchecked variability. (Some users may experience a paywall.)

Vitamin B1 is linked to gut motility—helping fight constipation—in 2026 research

A study published in early 2026 found a link between vitamin B1 and the successful movement of food through your GI tract, known as gut motility. The work incorporated genetic and survey data about poop frequency to identify genes associated with gut motility and then separately linked poop frequency data with how much vitamin B1 people ingested, theorizing that the vitamin supports the production of acetylcholine, a neurotransmitter that stimulates GI system contractions.

The dietary market is worth more than $60B

Listen to this question and answer session with the US Food and Drug Administration about dietary supplements—vitamins, minerals, probiotics and similar products people may buy in liquid, pill, or powder form. They are categorized legally as a category of food and can be legally brought to market without the FDA even knowing about it, though consumers can tell FDA about issues with the products and FDA can take action to remove dangerous or unlawful items after they're available.

A look at the concentrations of water in the human body and various organs

When we're born, about three-quarters of our bodies are composed of water, dropping to an average of 55-60% for the average adult. The lungs are over 80% water, the kidneys and spleen about 80%, and the heart and brain are approximately three-quarters composed of water—about the same moisture as a banana.

The strange endurance of consuming blood for health

Blood's importance to humanity is best summarized this way: without it, we die. This importance naturally begets assumptions about its medicinal properties, many of which appear accessible through drinking or eating the fluid connective tissue. This article details the history of blood drinking, from ancient Roman gladiators to modern-day sanguinarians.

Why water is the universal solvent, despite not being good at dissolving many substances

Because oxygen attracts electrons much more strongly than hydrogen does in H₂O, the molecule is polar, with a negative charge at the oxygen atom and positive charges at the hydrogen atoms. These charged regions can attract and pull apart charged portions of other polar molecules, such as washable inks, but are unable to dissolve nonpolar materials, such as glass and asphalt.

Remember: Not all fats are bad for you

Contrary to past dietary advice promoting low-fat diets, newer research shows that certain types of fats are both necessary and healthy. It all comes down to the type of fat you eat. Focus on getting "good" unsaturated fats from sources like nuts,...

Transpiration drives water movement through a plant’s vascular system

Water evaporates from the leaves, creating tension that pulls more water upward from the roots through the xylem—the equivalent of plant blood vessels. This process is supported by water molecules sticking to each other (cohesion) and xylem walls (adhesion).

Bats are uniquely suited to act as reservoirs of viruses

Some of the deadliest diseases to jump from animals to humans originate in bat species. This rich visualization explores the diversity of bats and the factors that make them efficient vectors for harboring and transmitting disease, from their long lifespans to their migration patterns.

Learn how cholera bacteria sicken humans

Once a person has ingested large amounts of the bacteria, typically through contaminated water, cholera bacteria begin producing and releasing a toxin inside their host. It attacks the mucosal lining of the intestine, making it hard to absorb liquids. This process leads to cholera's characteristic symptoms, like voluminous, watery diarrhea.

Nanoplastics can bypass the blood-brain barrier and may harm the nervous system

Nanoplastics are formed from the breakdown of microplastics and can breach cells. Their large surface area relative to size allows them to carry higher concentrations of forever chemicals than the surrounding environment into sensitive organs.

Adhesion molecules and intercellular junctions allow cells to connect together

While some organic structures are mostly composed of non-cellular components (e.g., collagen and calcium phosphate minerals in bones), tissues and organs composed of connected cells rely on specialized proteins and connections to create watertight seals that protect cells within the interior from environmental molecules.

Why vascular dementia develops

This type of dementia, the second most common form after Alzheimer's, develops due to microscopic bleeds and blood vessel blockages in the brain. The condition isn't curable but medications to help with blood clotting and high blood pressure are part of a suite of interventions designed to minimize damage to the brain.

Cantaloupe’s textured skin boosts the risk of food poisoning

Food safety expert Darin Wetwiler says he prefers to stay clear of this fruit altogether since it’s so hard to keep the textured skin pathogen-free. He advises trying to avoid pre-cut cantaloupe in particular, since consumers won’t know when the fruit was sliced and pathogens on the outside could have been spread to the part we consume during slicing and multiplied.

How does food move through the body?

Food passes through the digestive system via muscle movement known as peristalsis, during which a rippling contraction slowly pushes content through tubular organs, such as the esophagus and intestines. This is similar to what happens when one squeezes a tube of toothpaste, contracting the tube behind the content and forcing the tube in front of the content to expand, allowing the content to move forward.

MS risk is shaped by geography, not just genes

Latitude—and related vitamin D exposure—seems to affect MS risk. People who migrate from a high-risk MS latitude (like northern Europe or the northern US) to a lower-risk latitude (like tropical areas) before age 15 tend to adopt the lower risk of their new country—suggesting there's a critical window for environmental exposure.

Mineral and chemical sunscreens protect differently but both guard against UV damage

UVA rays age the skin, while UVB rays are more directly linked to skin cancer. Mineral sunscreens, with ingredients like zinc oxide, physically block rays, while chemical ones absorb UV and turn it into heat.

Tannins contribute to a wine's composition

Tannins are compounds found in many different types of food, including grape skins. When consumed, they produce a noticeable drying effect in the mouth. Because of the difference in production methods, red wines typically have tannins while white wines do not.

Poison ivy is in the same family as mangoes, cashews, and pistachios—and they all produce oily urushiol in their raw, unprocessed state—but they are typically prepared in ways to avoid causing human discomfort.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

Women typically have more robust immune responses than men

This difference helps women better combat infectious diseases, but this more turbo-charged response may also make women more vulnerable to autoimmune diseases by potentially priming their immune systems to overreact to their own cells and tissues and label them as invaders that must be destroyed. Roughly 80% of American women have autoimmune conditions.

Explaining why salt should be used to season food early in the cooking process

Experiments involving the same dishes, with salt added at the start of cooking versus at the end, have been shown to yield drastically different taste outcomes because salt takes time to diffuse into foods, particularly vegetables, whose cells are surrounded by cellular membranes and walls. Salting at the end will produce a concentrated surface coating, rather than even seasoning.

Tattoos remain visible on your skin thanks to immune cells called macrophages

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

Ebola infects and disables immune cells, triggering a cascade of events that leads to small blood clots throughout the body, weakening blood vessels and interrupting blood flow to key organs.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Telehealth demand for GLP-1s for weight loss is booming as consumers seek easier access.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

Doctors differentiate between a phobia and fear by asking patients whether their fear interferes with their day-to-day activities.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

Venture capital is a form of funding provided to early-stage companies with high growth potential, typically in exchange for an equity (or ownership) stake

The United States is one of only around two dozen countries with a fully federal system of government, in which power is divided between national and state governments.

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

NBA superstar Victor Wembanyama spent the 2025 summer training with monks in central China to enhance his body and mind.