Chapter 8 – Vitamins
8.4 The Water-Soluble Nine: Vitamins You Need All the Time
Vitamin C: Ascorbic Acid
Like vitamin E (discussed in the previous section), vitamin C acts as an antioxidant, helping protect cells from damage caused by free radicals. It also helps regenerate vitamin E, allowing it to continue its protective role.
Vitamin C also plays an important role in iron absorption. It enhances the absorption of nonheme iron (the form found in plant foods) by converting it to a form that is easier for the body to absorb. This is why pairing foods like beans or spinach with vitamin C–rich foods can improve iron status.
One of vitamin C’s most important functions is in the production of collagen, the protein that provides strength and structure to the skin, blood vessels, gums, and other connective tissues. Figure 8.17 illustrates vitamin C’s role in collagen formation.
When vitamin C intake is too low, the body cannot produce strong, stable collagen. As a result, collagen fibers become weak, leading to fragile tissues and impaired wound healing. Because collagen is essential for maintaining tissue integrity, inadequate vitamin C can slow healing and contribute to symptoms such as bleeding gums and poor recovery from injuries.
Scurvy (Vitamin C Deficiency)
Scurvy is a disease caused by a lack of vitamin C. Because vitamin C is essential for collagen production, deficiency weakens connective tissues throughout the body. One of the most noticeable signs is bleeding gums, which occur when fragile blood vessels and gum tissue break down. Other symptoms include poor wound healing, joint pain, fatigue, and increased risk of infections.
Although rare today, scurvy can still develop in individuals with very limited diets lacking fruits and vegetables. [1]
Vitamin C and Chronic Disease
Vitamin C has been widely studied for its potential to reduce the risk of chronic diseases, particularly those affecting the heart and blood vessels. Research suggests that the most significant benefits come from vitamin C obtained through foods, not supplements. [2]
Cardiovascular Disease
The role of vitamin C in preventing disease has been studied for many years. Overall, people who consume more vitamin C–rich foods, particularly fruits and vegetables, tend to have a lower risk of heart disease and stroke. Studies show that higher vitamin C levels in the blood—which usually reflect higher fruit and vegetable intake—are linked to a reduced risk of cardiovascular disease. In one large study, people with the highest vitamin C levels had a much lower risk of having a stroke.
It is important to note that these benefits come from vitamin C in foods, not from taking vitamin C supplements.
Cancer
Some research suggests that consuming foods rich in vitamin C may reduce the risk of certain cancers, including those of the mouth, throat, stomach, colon, and lungs. However, not all studies show the same results. When a lower cancer risk is observed, it is associated with eating fruits and vegetables, rather than taking vitamin C supplements. This is likely because fruits and vegetables contain many protective compounds, not just vitamin C.
Immunity and the Common Cold
Vitamin C plays a role in the immune system, which is why many people take it to prevent or treat colds. However, research shows that vitamin C does not prevent colds for most people. Taking vitamin C regularly may slightly reduce the duration of a cold or alleviate symptoms, but consuming large doses does not provide additional benefits. Eating vitamin C-rich foods is still the best approach.
Gout
Gout is a painful condition caused by high levels of uric acid in the blood. Some evidence suggests that a higher intake of vitamin C may help lower the risk of developing gout, although further research is needed. Eating a diet rich in fruits and vegetables provides vitamin C along with many other health-protective nutrients. Whole foods—not supplements—are linked to the greatest health benefits.
Too Much Vitamin C
Taking large amounts of vitamin C—usually from supplements—can cause side effects. The most common problems are stomach cramps, nausea, and diarrhea. To help prevent these effects, the Upper Intake Level (UL) for adults is set at 2,000 milligrams per day, which is much higher than the recommended daily amount.
At extremely high doses, especially when taken with iron, vitamin C may actually increase oxidative stress rather than reduce it. This is one reason health experts recommend getting antioxidants mainly from foods, rather than high-dose supplements. Some studies also suggest that large doses of vitamin C supplements may increase the risk of kidney stones, particularly in people who already have a higher risk for developing them.
How Much Vitamin C Do We Need?
The Recommended Dietary Allowance (RDA) for vitamin C varies by age and sex. Young children ages 1–3 need 15 mg per day, while adult women need 75 mg per day and adult men need 90 mg per day. These recommended amounts are designed to prevent scurvy and to support normal immune function and overall health.
Because smoking increases free radicals in the body, smokers need an extra 35 milligrams of vitamin C per day compared to non-smokers. Although quitting smoking is the best recommendation, choosing vitamin C–rich foods—such as oranges, strawberries, bell peppers, broccoli, and tomatoes—can help those who continue to smoke meet this higher need naturally.
What are the best Sources of Vitamin C?
Citrus fruits are excellent sources of vitamin C, and so are many vegetables. In fact, British sailors in the past were often referred to as “limeys” as they carried sacks of limes onto ships to prevent scurvy. Vitamin C is not found in significant amounts in animal-based foods.
Because vitamin C is water-soluble, it leaches away from foods considerably during cooking, freezing, thawing, and canning. Up to 50 percent of vitamin C can be boiled away. Therefore, to maximize vitamin C intake from foods, you should eat fruits and vegetables raw or lightly steamed. For the vitamin C content of various foods, see Figure 8.19.
B-Complex Vitamins
The B-complex vitamins are a group of eight water-soluble vitamins that work together to help the body convert food into energy, support the nervous system, and promote the production of healthy red blood cells. Although they are grouped together as a “complex,” each B vitamin has a unique structure and specific role in metabolism and overall health.
The story of the B vitamins began in the late 1800s and early 1900s, when scientists were searching for the cause of beriberi, a disease characterized by weakness, nerve damage, and heart problems. Beriberi was especially common in populations that relied on polished white rice, which had its outer layers removed during processing. Researchers observed that people who consumed unprocessed (whole) rice did not develop the disease.
At the time, scientists did not yet know the exact nutrient responsible, but they proposed that a missing substance in refined foods prevented beriberi. They called this unknown compound the “anti-beriberi factor,” later referred to as vitamin B. As research advanced, scientists discovered that this was not a single vitamin, but a group of B-complex vitamins, each with unique roles in the body.
Casimir Funk and the Discovery of Vitamins
In 1912, Casimir Funk, a Polish biochemist, helped move this research forward by isolating a substance from rice bran that could help prevent beriberi. He proposed that certain diseases were caused by deficiencies of essential nutrients and introduced the term “vitamine” (meaning “vital amine”). Although not all vitamins are amines, the term was later shortened to vitamin.
Funk’s work was a major step in nutrition science, helping establish the idea that specific nutrients are required in the diet to prevent disease and maintain health. The photo in Figure 8.17 shows a patient studied by Casimir Funk in 1912 who was suffering from beriberi. Notice the patient's weak legs and difficulty walking. [3]
The first B vitamin identified was thiamin (vitamin B₁), which is essential for energy metabolism and nerve function. Over time, additional B vitamins were discovered, including riboflavin (B₂), niacin (B₃), vitamin B₆, folate, vitamin B₁₂, and others. Together, these nutrients became known as the B-complex vitamins.
Today, the B-complex vitamins are recognized as essential for energy production, brain function, DNA synthesis, and red blood cell formation. Because they are water-soluble and not stored in large amounts in the body, they must be consumed regularly through the diet, making a varied and balanced diet especially important.
Thiamin (B₁). Riboflavin (B₂), Niacin (B₃), Pantothenic Acid (B5), and Biotin (B7)
Thiamin, Riboflavin, and Niacin
Thiamin (vitamin B₁) plays a key role in energy metabolism, especially in the breakdown of carbohydrates, and is essential for normal nerve and muscle function. One of the richest natural sources of thiamin is pork, which contains levels much higher than those in most other meats. Highly fortified breakfast cereals, such as Total®, are also excellent sources of thiamin and provide a reliable way to meet daily needs. Even cereals packed with added sugars typically contain 20% of the Daily Value for most B vitamins.
Riboflavin (vitamin B₂) is involved in energy production and helps maintain healthy skin and eyes. Riboflavin has a distinctive bright yellow-green (fluorescent) color when exposed to ultraviolet light. Because riboflavin is destroyed by light, foods that contain it—especially milk—are packaged in opaque containers to protect the vitamin from degradation. Fortified breakfast cereals and pork also contribute to the diet's riboflavin intake.
Niacin (Vitamin B₃) plays a key role in energy metabolism, DNA repair, and nervous system function. Niacin also supports healthy skin and proper digestion. In addition to dietary sources such as pork, poultry, fish, peanuts, and fortified cereals, the body can synthesize niacin from the amino acid tryptophan, provided overall protein intake is adequate.
Niacin deficiency leads to pellagra, a condition classically described by the “four Ds”: dermatitis, diarrhea, dementia, and, if untreated, death. The dermatitis associated with pellagra is characterized by rough, darkened, scaly skin that typically appears on sun-exposed areas. Pellagra was historically common in populations whose diets relied heavily on corn-based staples lacking adequate niacin or tryptophan.
Biotin and Pantothenic Acid
Biotin (vitamin B7) plays a crucial role in fatty acid synthesis, amino acid metabolism, and glucose production. Eggs are an excellent source of biotin; however, raw egg whites contain a protein called avidin, which binds biotin and reduces its absorption. For this reason, eggs should be fully cooked, as heat inactivates avidin and allows biotin to be absorbed normally. Biotin is commonly included in cosmetics and hair products, although scientific evidence supporting its effects on hair and nails in non-deficient individuals is limited.
Pantothenic acid (vitamin B₅) is required for the formation of coenzyme A (CoA), which is essential for energy metabolism and the synthesis of fatty acids, cholesterol, and hormones. Pantothenic acid is widely distributed in foods, making deficiency rare. Like biotin, pantothenic acid is frequently added to cosmetics and hair-care products, reflecting its role in skin and cellular metabolism. A deficiency in chickens results in crusty lesions, as noted in Figure 8.23.
DID YOU KNOW: Five of the eight B-Complex vitamins function in energy, specifically in energy metabolism. Enriched grain products have additional amounts of thiamin, riboflavin, and niacin added. This table compares major food sources of the five vitamins.
| Food | B-1 Thiamin | B-2 Riboflavin | B-3 Niacin | B-5 Pant, Acid | B-7 Biotin* |
|---|---|---|---|---|---|
| Beef liver, 3 oz | 0.2 mg | 2.9 mg | 14.9 mg | 8.3 mg | 30.8 mcg |
| Total Cereal, 1 c | 1.5 mg | 1.7 mg | 20.0 mg | 9.9 mg | 0 |
| Whole Egg, 1 | 0.1 mg | 0.14 mg | 0.04 mg | 0.06 mg | 10.0 mcg |
| Pork Chop, 3 oz | 0.54 mg | 0.21 mg | 6.5 mg | 3.8 mg | 3.8 mcg |
| Rice, brown, 1 c | 0.36 mg | 1.39 mg | 5.17 mg | 0.77 mg | 0 |
| Rice, white, 1 c | 0.31 mg | 0.03 mg | 3.42 mg | 0.76 mg | 0 |
| White bread, 1 sl | 0.143 mg | 0.07 mg | 1.25 mg | 0.13 mg | 0 |
| Yogurt, plain , 1 c | 0.11 mg | 0.57 mg | 0.30 mg | 1.6 mg | 0.2 mcg |
| Milk, whole 1 c | 0.09 mg | 0.37 mg | 0.20 mg | 1.7 mg | 0.3 mcg |
| Sunflower seed, 1 oz | 0.92 mg | 0.08 mg | 1.19 mg | 2.0 mg | 2.6 mcg |
| Noodles, egg 1 c | 0.46 mg | 0.29 mg | 3.33 mg | 0.43 mg | 0 |
| Orange, 1 med | 0.15 mg | 0.06 mg | 0.6 mg | 0.68 mg | 0 |
| Banana, 1 med | 0.04 mg | 0.09 mg | 0.78 mg | 0.39 mg | 0.2 mcg |
| Sweet potato, 1 small | 0.21 mg | 0.21 mg | 3.0 mg | 1.77 mg | 4.8 mcg |
Vitamin B6: From PMS to Pregnancy
Vitamin B₆ (pyridoxine) is a water-soluble B vitamin that plays a central role in amino acid metabolism, neurotransmitter synthesis, red blood cell formation, and immune function. It is also involved in converting the amino acid tryptophan into niacin and serotonin, linking vitamin B₆ to both energy metabolism and mood regulation.
Vitamin B₆ may help reduce symptoms of premenstrual syndrome (PMS), such as mood changes, irritability, anxiety, and bloating, likely due to its role in neurotransmitter production. However, evidence is mixed, and more research is needed.
Vitamin B₆ is also used to treat nausea and vomiting during pregnancy and is often more effective when combined with doxylamine. The American College of Obstetricians and Gynecologists recommends it as a first-line option for morning sickness. Pregnant women should consult a healthcare provider before taking supplements.
High-dose vitamin B₆ is no longer recommended for PMS because long-term use can cause nerve damage (sensory neuropathy), leading to numbness, tingling, and difficulty walking. Supplements should be used only within safe intake levels. [4]
Food sources of vitamin B₆ include poultry, fish, pork, potatoes, bananas, chickpeas, and fortified cereals, making it relatively easy to meet daily needs through a balanced diet.
Folate (B9): Small Vitamin, Big Role in Growth
Folate (vitamin B₉) functions as a coenzyme in DNA and RNA synthesis. Because folate is essential for cell division, tissues with rapidly dividing cells—such as the bone marrow—are most affected by deficiency. When folate intake is inadequate, cells grow but cannot divide properly, leading to macrocytic (megaloblastic) anemia, a condition characterized by fewer but abnormally large red blood cells (Figure 8.23).
Folate is especially critical during early pregnancy for the normal development of the central nervous system. Maternal folate deficiency increases the risk of neural-tube defects, including spina bifida, which occurs when the spinal cord does not fully close and can result in lifelong physical and neurological complications (Figure 8.25). Rates of neural-tube defects declined significantly in the United States and Canada after the mandatory fortification of enriched grain products with folic acid in the late 1990s. Clinical trials also show that taking folate supplements before conception and during pregnancy greatly reduces this risk, leading to a higher RDA for pregnant women.
Dietary Sources of Folate
Folate is the natural form of the vitamin found in foods, while folic acid is the synthetic form used in supplements and fortified products. Because folic acid is more easily absorbed than food-based folate, intake is measured using dietary folate equivalents (DFE) to account for these differences in bioavailability.
Good sources of folate include dark leafy green vegetables, fruits, legumes, and some animal products. In the United States, the Food and Drug Administration requires certain grain products—such as breads, cereals, flours, and cornmeal—to be fortified with folic acid to help increase intake in the population. Figure 8.26 includes food sources of folate and folic acid.
Dietary Reference Intakes of Folate
Adults need about 400 mcg of folate per day, and needs increase to 600 mcg during pregnancy.
Vitamin B₁₂ (Cobalamin): Only in Animal Products
Vitamin B₁₂ (cobalamin) is the only vitamin that contains a metal ion (cobalt) and functions as a coenzyme in several essential metabolic reactions. It is required for fat and protein metabolism, hemoglobin synthesis, and DNA production, and it works closely with folate in cell division. Because of this relationship, vitamin B₁₂ deficiency produces effects similar to folate deficiency, including macrocytic (megaloblastic) anemia. In infants born to vitamin B₁₂–deficient mothers, deficiency is also associated with an increased risk of neural-tube defects.
Absorption of vitamin B₁₂ is complex and requires a healthy stomach, pancreas, and small intestine. Specialized stomach cells produce intrinsic factor, a protein necessary for vitamin B₁₂ absorption in the small intestine. Conditions that reduce intrinsic factor—such as autoimmune disorders, chronic stomach inflammation, or Helicobacter pylori infection—can lead to pernicious anemia, a form of vitamin B₁₂ deficiency anemia. Vitamin B₁₂ malabsorption is most common in older adults, due to age-related changes in digestive function. Treatment may include high-dose oral or sublingual supplements or injections when absorption is severely impaired.
Dietary Sources of B₁₂
Vitamin B₁₂ is found naturally in animal-derived foods, including meat, fish, poultry, eggs, and dairy products. While plant foods do not naturally contain vitamin B₁₂, fortified breakfast cereals are an important source, especially for individuals who consume little or no animal products. For the vitamin B₁₂ content of foods, see Figure 8.27.
RELATIONSHIP BETWEEN Vitamin B12, Folate, and Vitamin B6
Vitamin B₁₂, Vitamin B6, and folate are essential for converting homocysteine into methionine, a process important for normal cell function. When intake of any of these three B vitamins is low, homocysteine levels can build up in the blood.
Elevated homocysteine levels are associated with several health concerns. High levels may damage the inner lining of blood vessels, promote inflammation, and increase the likelihood of blood clot formation. These changes are linked to a greater risk of cardiovascular diseases, including heart disease and stroke. Some research also suggests a possible link between high homocysteine levels and cognitive decline, though this relationship is still under investigation.
Maintaining adequate intake of vitamin B₁₂, folate, and vitamin B₆ helps support normal homocysteine metabolism and may reduce these health risks.
DID YOU KNOW: Energy drinks are packed with B-vitamins and caffeine, but does that make THEM "healthy'?
Energy drinks and vitamin-enhanced waters were widely marketed as products that boost energy, focus, and performance, especially among teens and young adults. These beverages often contain high amounts of B vitamins—including thiamin (B1), riboflavin (B2), niacin (B3), vitamin B6, and vitamin B12—sometimes providing several hundred percent of the daily recommended intake.
B vitamins play a crucial role in energy metabolism, enabling the body to convert carbohydrates, fats, and proteins into usable energy. However, they do not provide energy themselves. For individuals who already meet their B-vitamin needs through food, consuming extra B vitamins from drinks does not increase energy levels or athletic performance. Excess B vitamins are water-soluble and usually excreted in urine.
The “energy boost” from energy drinks primarily comes from caffeine and sugar, not B vitamins. A single 16-oz energy drink may contain 70–240 mg of caffeine (often from multiple sources, including guarana) and more added sugar than recommended for an entire day. High caffeine intake is associated with anxiety, sleep disruption, elevated heart rate and blood pressure, and increased risk-taking behaviors—especially when energy drinks are mixed with alcohol.[5]
Bottom line: While B vitamins are essential nutrients, most people can meet their needs through a balanced diet. Energy drinks and vitamin waters are not a safe or necessary source of energy, particularly for children, teens, and young adults.
Choline
Choline is a water-soluble compound that is not classified as a vitamin because the body can synthesize it. However, this synthesis is limited, so choline is recognized as an essential nutrient that must also be obtained from the diet. Choline is required for the synthesis of the neurotransmitter acetylcholine, the formation of phospholipids in cell membranes, lipid transport, and homocysteine metabolism. Egg yolks are an excellent dietary source of choline, along with meats, fish, and some legumes. Choline deficiency has been associated with impaired brain development in the fetus during pregnancy and, in adults, can lead to fatty liver and muscle damage.
Needs and Dietary Sources of Choline
Adults need between 425 and 550 mg of choline each day. The main dietary sources of choline in the United States consist primarily of animal-based products such as eggs and other protein foods, as noted in Table 8.3.
| Food | Serving | Choline (mg) | Percent Daily Value |
|---|---|---|---|
| Egg | 1 large | 147 | 27 |
| Soybeans | ½ cup | 107 | 19 |
| Chicken breast | 3 oz. | 72 | 13 |
| Mushrooms, shiitake | ½ c. | 58 | 11 |
| Potatoes | 1 large | 57 | 10 |
| Kidney beans | ½ c. | 45 | 8 |
| Peanuts | ¼ c. | 24 | 4 |
| Brown rice | 1 c. | 19 | 3 |
Summary of Water-Soluble Vitamins
The table below shows the food sources, adult RDA, main functions, deficiency conditions, groups at risk, the toxicity, and upper limit (UL) for the four water-soluble vitamins and choline.
| Vitamin | Sources | Recommended Intake for adults | Major Functions | Deficiency diseases and symptoms | Groups at risk of deficiency | Toxicity | UL |
|---|---|---|---|---|---|---|---|
| Vitamin C (ascorbic acid) | Orange juice, grapefruit juice, strawberries, tomato, sweet red pepper | 75-90 mg/day | Antioxidant, collagen synthesis, hormone and neurotransmitter synthesis | Scurvy, bleeding gums, joint pain, poor wound healing, | Smokers, alcoholics, elderly | Kidney stones, GI distress, diarrhea | 2000 mg/day |
| Thiamin (B1) | Pork, enriched and whole grains, fish, legumes | 1.1-1.2 mg/day | Coenzyme: assists in glucose metabolism, RNA, DNA, and ATP synthesis | Beriberi: fatigue, confusion, movement impairment, swelling, heart failure | Alcoholics, older adults, eating disorders | None reported | ND |
| Riboflavin (B2) | Beef liver, enriched breakfast cereals, yogurt, steak, mushrooms, almonds, eggs | 1.1-1.3 mg/day | Coenzyme: assists in glucose, fat and carbohydrate metabolism, electron carrier, other B vitamins are dependent on | Ariboflavinosis: dry scaly skin, mouth inflammation and sores, sore throat, itchy eyes, light sensitivity | None | None reported | ND |
| Niacin (B3) | Meat, poultry, fish, peanuts, enriched grains | 14-16 NE/day | Coenzyme: assists in glucose, fat, and protein metabolism, electron carrier | Pellagra: diarrhea, dermatitis, dementia, death | Alcoholics | Nausea, rash, tingling extremities | 35 mg/day from fortified foods and supplements |
| Pantothenic Acid (B5) | Sunflower seeds, fish, dairy products, widespread in foods | 5 mg/day | Coenzyme: assists in glucose, fat, and protein metabolism, cholesterol and neurotransmitter synthesis | Muscle numbness and pain, fatigue, irritability | Alcoholics | Fatigue, rash | ND |
| B6(Pyridoxine) | Meat, poultry, fish, legumes, nuts | 1.3-1.7 mg/day | Coenzyme; assists in amino-acid synthesis, glycogneolysis, neurotransmitter and hemoglobin synthesis | Muscle weakness, dermatitis, mouth sores, fatigue, confusion | Alcoholics | Nerve damage | 100 mg/day |
| Biotin | Egg yolks, fish, pork, nuts and seeds | 30 mcg/day | Coenzyme; assists in glucose, fat, and protein metabolism, amino-acid synthesis | Muscle weakness, dermatitis, fatigue, hair loss | Those consuming raw egg whites | None reported | ND |
| Folate | Leafy green vegetables, enriched grains, orange juice | 400 mcg/day | Coenzyme; amino acid synthesis, RNA, DNA, and red blood cell synthesis | Diarrhea, mouth sores, confusion, anemia, neural-tube defects | Pregnant women, alcoholics | Masks B12 deficiency | 1000 mcg/day from fortified foods and supplements |
| B12(cobalamin) | Meats, poultry, fish | 2.4 mcg/day | Coenzyme; fat and protein catabolism, folate function, red-blood-cell synthesis | Muscle weakness, sore tongue, anemia, nerve damage, neural-tube defects | Vegans, elderly | None reported | ND |
| Choline | Egg yolk, wheat, meat, fish, synthesis in the body | 425-550 mg/day | Synthesis of neurotransmitters and cell membranes, lipid transport | Non-alcoholic fatty liver disease, muscle damage, interfered brain development in fetus | None | Liver damage, excessive sweating, hypotension | 3500 mg/day |
Do B-Vitamin Supplements Provide an Energy Boost?
Although some marketers claim that taking a vitamin containing 1,000 times the daily value of certain B vitamins boosts energy and performance, this is a myth with no scientific backing. The “feeling” of more energy from energy-boosting supplements stems from the high amount of added sugars, caffeine, and other herbal stimulants that accompany the high doses of B vitamins. As discussed, B vitamins are needed to support energy metabolism and growth, but taking in more than required does not supply you with more energy. A great analogy of this phenomenon is the gas in your car. Does it drive faster with a half-tank of gas or a full one? It does not matter; the car drives just as fast as long as it has gas. Similarly, depletion of B vitamins will cause problems in energy metabolism, but having more than is required to run metabolism does not speed it up. Buyers of B-vitamin supplements beware; B vitamins are not stored in the body, and all excess will be flushed down the toilet along with the extra money spent.
B vitamins are naturally present in numerous foods, and many other foods are enriched with them. In the United States, B-vitamin deficiencies are rare; however, in the nineteenth century, some B-vitamin deficiencies plagued many people in North America. Niacin deficiency, also known as pellagra, was prominent in poorer Americans whose main dietary staple was refined cornmeal. Its symptoms were severe and included diarrhea, dermatitis, dementia, and even death. Some of the health consequences of pellagra are the result of niacin being in insufficient supply to support the body’s metabolic functions.
Review Questions
attributions
This section is an adaptation of "Water-Soluble Vitamins" in Human Nutrition: 2020 Edition by University of Hawai‘i at Mānoa Food Science and Human Nutrition Program licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
- Di Nora A, Finocchiaro MC, Pizzo F, et al. Scurvy, a not obsolete disorder: Clinical report in eight young children and literature review. Open Med (Wars). 2025;20(1):20241086. Published 2025 Sep 25. doi:10.1515/med-2024-1086 ↵
- National Institutes of Health, Office of Dietary Supplements. Vitamin C: fact sheet for health professionals. Updated July 31, 2025. Accessed April 26, 2026. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/ ↵
- Funk C. Studies on beri-beri: VII. Chemistry of the vitamine-fraction from yeast and rice-polishings. J Physiol. 1913;46(3):173-179. doi:10.1113/jphysiol.1913.sp001585 ↵
- National Institutes of Health, Office of Dietary Supplements. Vitamin B6: Fact sheet for health professionals. Updated March 26, 2025. Accessed April 26, 2026. https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/ ↵
- National Center for Complementary and Integrative Health (NCCIH). Energy Drinks. Updated July 2018. National Institutes of Health. Accessed January 6, 2026. https://www.nccih.nih.gov/health/energy-drinks ↵
.jpg){kind=link}