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Toilet paper

Toilet paper (sometimes called toilet tissue, toilet roll, or bathroom tissue ) is a tissue paper product primarily used to clean the anus and surrounding region of feces (after defecation), and to clean the external genitalia and perineal area of urine (after urination).

It is commonly supplied as a long strip of perforated paper wrapped around a paperboard core for storage in a dispenser near a toilet. The bundle, or roll of toilet paper, is known as a toilet roll, or loo roll or bog roll in Britain.

There are other uses for toilet paper, as it is a readily available household product. It can be used like facial tissue for blowing the nose or wiping the eyes. Some people may use the paper to absorb the bloody discharge that comes out of the vagina during menstruation. It can be used to wipe off sweat or absorb it. Toilet paper can be used in cleaning like a less abrasive paper towel. As a prank, toilet papering is a form of temporary vandalism by adolescents and often directed at someone who has to clean up the mess.

Most modern toilet paper in the developed world is designed to decompose in septic tanks, whereas some other bathroom and facial tissues are not. Wet toilet paper rapidly decomposes in the environment. Toilet paper comes in various numbers of plies (layers of thickness), from one- to six-ply, with more back-to-back plies providing greater strength and absorbency. Some people have a preference for whether the orientation of the roll on a dispenser should be over or under.

The use of paper for hygiene has been recorded in China in the 6th century AD, with specifically manufactured toilet paper being mass-produced in the 14th century. Modern commercial toilet paper originated in the 19th century, with a patent for roll-based dispensers being made in 1883.

History
Although paper had been known as a wrapping and padding material in China since the 2nd century BC, a reference to the use of toilet paper dates back as early as c. 589 when the scholar-official Yan Zhitui (531–591) wrote:

"Paper on which there are quotations or commentaries from the Five Classics or the names of sages, I dare not use for toilet purposes."

During the later Tang dynasty (618–907 AD), an Arab traveller to China in the year 851 AD remarked:

"... they [the Chinese] do not wash themselves with water when they have done their necessities; but they only wipe themselves with paper."

During the early 14th century, it was recorded that in what is now Zhejiang alone, ten million packages of 1,000 to 10,000 sheets of toilet paper were manufactured annually. During the Ming dynasty (1368–1644 AD), it was recorded in 1393 that an annual supply of 720,000 sheets of toilet paper (approximately 2 by) were produced for the general use of the imperial court at the capital of Nanjing. From the records of the Imperial Bureau of Supplies of that same year, it was also recorded that for the Hongwu Emperor's imperial family alone, there were 15,000 sheets of special soft-fabric toilet paper made, and each sheet of toilet paper was perfumed.

Elsewhere, wealthy people wiped themselves with wool, lace or hemp, while less wealthy people used their hand when defecating into rivers, or cleaned themselves with various materials such as rags, wood shavings, leaves, grass, hay, stones, sand, moss, water, snow, ferns, plant husks, fruit skins, seashells, or corncobs, depending upon the country and weather conditions or social customs. In Ancient Rome, a sponge on a stick was commonly used, and, after use, placed back in a pail of vinegar. Several talmudic sources indicating ancient Jewish practice refer to the use of small pebbles, often carried in a special bag, and also to the use of dry grass and of the smooth edges of broken pottery jugs (e.g., Shabbat 81a, 82a, Yevamot 59b). These are all cited in the classic Biblical and Talmudic Medicine by the German physician Julius Preuss (Eng. trans. Sanhedrin Press, 1978).

The 16th-century French satirical writer François Rabelais, in Chapter XIII of Book 1 of his novel sequence Gargantua and Pantagruel, has his character Gargantua investigate a great number of ways of cleansing oneself after defecating. Gargantua dismisses the use of paper as ineffective, rhyming that: "Who his foul tail with paper wipes, Shall at his ballocks leave some chips." (Sir Thomas Urquhart's 1653 English translation). He concludes that "the neck of a goose, that is well downed" provides an optimum cleansing medium.

The rise of publishing by the eighteenth century led to the use of newspapers and cheap editions of popular books for cleansing. Lord Chesterfield, in a letter to his son in 1747, told of a man who purchased

"a common edition of Horace, of which he tore off gradually a couple of pages, carried them with him to that necessary place, read them first, and then sent them down as a sacrifice to Cloacina; thus was so much time fairly gained..."

In many parts of the world, especially where toilet paper or the necessary plumbing for disposal may be unavailable or unaffordable, toilet paper is not used. Also, in many parts of the world people consider using water a much cleaner and more sanitary practice than using paper. Cleansing is then performed with other methods or materials, such as water, for example using a bidet, a lota, rags, sand, leaves (including seaweed), corn cobs, animal furs, sticks or hands; afterwards, hands are washed with water and possibly soap.

On 18 July 2024 the sale of ruble-note artwork on toilet paper was banned by a Moscow judge.

As a commodity
Joseph Gayetty is widely credited with being the inventor of modern commercially available toilet paper in the United States. Gayetty's paper, first introduced in 1857, was available as late as the 1920s. Gayetty's Medicated Paper was sold in packages of flat sheets, watermarked with the inventor's name. Original advertisements for the product used the tagline "The greatest necessity of the age! Gayetty's medicated paper for the water-closet".

Seth Wheeler of Albany, New York, obtained the earliest United States patents for toilet paper and dispensers, the types of which eventually were in common use in that country, in 1883. Toilet paper dispensed from rolls was popularized when the Scott Paper Company began marketing it in 1890.

The manufacturing of this product had a long period of refinement, considering that as late as the 1930s, a selling point of the Northern Tissue company was that their toilet paper was "splinter free". The widespread adoption of the flush toilet increased the use of toilet paper, as heavier paper was more prone to clogging the trap that prevents sewer gases from escaping through the toilet.

Softer, two ply toilet roll was introduced in Britain in 1942, by St Andrew Mills in Walthamstow; this became the famous Andrex.

Moist toilet paper, called wet wipes, was first introduced in the United Kingdom by Andrex in the 1990s. It has been promoted as being a better method of cleaning than dry toilet paper after defecation, and may be useful for women during menstruation. It was promoted as a flushable product but it has been implicated in the creation of fatbergs; by 2016 some municipalities had begun education campaigns advising people not to flush used wet wipes.

More than seven billion rolls of toilet paper are sold yearly in the United States where an average of 23.6 rolls per capita per year is used.

In 1973, Johnny Carson joked in his Tonight Show monologue about comments made by Wisconsin congressman Harold V. Froehlich about the possibility of a toilet paper shortage. Subsequently, consumers purchased abnormal amounts, causing an actual shortage in the United States for several months.

Toilet paper has been one of the commodities subject to shortages in Venezuela starting in the 2010s; the government seized one toilet paper factory in an effort to resolve the problem.

During the COVID-19 pandemic, toilet paper shortages were reported in March 2020 in multiple countries due to hoarding and panic buying. At first, few believed the pandemic would be serious. Later, people realized they might need to stock up on certain items in case of a shelter-in-place order, or in case they did not know how long such an order would last; suppliers could not assure that they could keep up with demand. However, manufacturers continued to produce even more than they had before. Demand was higher for the types of toilet paper used at home because so many people were at home who would have used toilet paper away from home. In some countries the bidet was already seen as a solution, and a survey before the pandemic had indicated an increasing number of Americans would be interested. Amid the panic buying during the pandemic, the Australian toilet paper brand Quilton donated a million of toilet paper rolls to vulnerable Australians who were struggling due to the shortages of toilet paper.

In 2022, British toilet paper packaging started displaying bowel cancer symptoms to raise awareness, following campaigning from blogger and journalist Deborah James, who later died from the disease in June 2022. At the time, half of all Britons could not name any of the main symptoms of bowel cancer. Andrex were the first brand to take the lead on the matter, then various supermarkets followed suit.

Description
Toilet paper is available in several types of paper, a variety of patterns, decorations, and textures, and it may be moistened or perfumed, although fragrances sometimes cause problems for users who are allergic to perfumes. The average measures of a modern roll of toilet paper is c. 10 cm (3$15⁄16$ in.) wide, and 12 cm (4$23⁄32$ in.) in diameter, and weighs between 85 g and 196 g. An alternative method of packing the sheets uses interleaved sheets in boxes, or in bulk for use in dispensers. "Hard" single-ply paper has been used as well as soft multi-ply.

Sheet size
The format of individual sheets of toilet paper, which is given by a perforation line, varies nationally. In Germany, Holland, France, Poland, Switzerland, for example, about postcard size is standard (about 100 × 140 mm), so about DIN format (DIN A6 105 × 148 mm). In England, the usual format is already somewhat wider, about 115 × 135 mm. The most extreme landscape format with 115 × 102 mm exists in Thailand. The most extreme portrait format (not counting toilet paper rolls without any perforation) is 100 × 366 mm; a promotional toilet paper from Schmidt Spiele in Germany. Manufactured toilet paper sheet in the United States was sized 4.5 in × 4 in. Since 1999 the size of a sheet has been shrinking; Kimberly-Clark reduced the length of a sheet to 4.1 in. Scott, in 2006, reduced the length of their product to 3.7 in. The width of sheets was later reduced giving a general sheet size of 3.7 in long and 4.1 in wide. Larger sizes remain available.

Sheet ply
The ply of a toilet paper refers to the number of layers per sheet. Rolls are typically available in single-ply, 2-ply, 3-ply, and 4-ply.

Roll length
Phrases like "single roll", "double roll", "triple roll", "jumbo roll", and "mega roll" commonly used in retail advertising refer to the number of sheets per roll (though the actual number of sheets is also usually disclosed on packaging). A longer roll needs to be replaced less often, but the very largest sizes do not fit all toilet paper dispensers, especially in older homes.

Materials
Toilet paper is usually manufactured from pulpwood trees, but is also sometimes made from sugar cane byproducts or bamboo.

Toilet paper products vary greatly in the distinguishing technical factors, such as size, weight, roughness, softness, chemical residues, "finger-breakthrough" resistance, water-absorption, etc. The larger companies have very detailed, scientific market surveys to determine which marketing sectors require or demand which of the many technical qualities. Modern toilet paper may have a light coating of aloe or lotion or wax worked into the paper to reduce roughness.

Quality is usually determined by the number of plies (stacked sheets), coarseness, and durability. Low grade institutional toilet paper is typically of the lowest grade of paper, has only one or two plies, is very coarse and sometimes contains small amounts of embedded unbleached/unpulped paper; it was typically called "hard" toilet paper. A brand disinfected with carbolic acid was manufactured in Sheffield, United Kingdom under the Izal brand name by Newton Chambers until 1981. Mid-grade two ply is somewhat textured to provide some softness and is somewhat stronger. Premium toilet paper may have lotion and wax and has two to four plies of very finely pulped paper. If it is marketed as "luxury", it may be quilted or rippled (embossed), perfumed, colored or patterned, medicated (with anti-bacterial chemicals), or treated with aloe or other perfumes.

To advance decomposition of the paper in septic tanks or drainage, the paper used has shorter fibres than facial tissue or writing paper. The manufacturer tries to reach an optimal balance between rapid decomposition (which requires shorter fibres) and sturdiness (which requires longer fibres). Compaction of toilet paper in drain lines, such as in a clog, prevents fibre dispersion and largely halts the breakdown process.

A German quip says that the toilet paper of Nazi Germany was so rough and scratchy that it was almost unusable, so many people used old issues of the Völkischer Beobachter instead, because the paper was softer.

Color and design
Colored toilet paper in colors such as pink, lavender, light blue, light green, purple, green, and light yellow (so that one could choose a color of toilet paper that matched or complemented the color of one's bathroom) was commonly sold in the United States from the 1960s. Up until 2004, Scott was one of the last remaining U.S. manufacturers to still produce toilet paper in beige, blue, and pink. However, the company has since cut production of colored paper altogether.

Colored toilet paper remains commonly available in some European countries. Here in solid color toilet paper base, apart from the natural tones between white and gray or beige, pastel shades prevail: pink, apricot, light yellow and light blue. In rare cases, pale purple or pale green can be found. However, rich colors are rarely used, such as black, wine red, neon green, royal blue. Flat printed toilet paper is uncommon. If there is printing, it is often one color. Common print colors are pink and pinkish red, also blue, more rarely purple, orange, brown or green.

Design
Today, in the United States, plain unpatterned colored toilet paper has been mostly replaced by patterned toilet paper, normally white, with embossed decorative patterns or designs in various colors and different sizes depending on the brand. The patterns are in most cases "scatter patterns", that is, a motif is distributed ("scattered") several times (irregularly) over the surface. Stripes and dot patterns are rare. Occasionally, toilet papers have an embossed crocodile, wave, circle or check pattern. Some are additionally printed. Ornaments usually stand on their own as self-contained units. They never go uninterrupted (for example, as a border) from the first to the last sheet.

Motifs
Predominant is everything that is associated "softness" and "fluffiness". There are decorations with bears, cats, rabbits, down feathers, clouds. Another motifs are things associated with "lightness": Clouds, downy feathers, leaves of all kinds, butterflies, flying birds. Another association is anything associated with pleasant fragrance: especially flowers of all kinds. Rare are motifs intended to appear noble, such as the Bourbon lily. Less rare are allusions to water, such as fish, shells and other aquatic creatures.

Toilet papers are also provided with texts (jokes, poems), joke motifs (banknotes) or advertising imprints.

Texture
Toilet paper is offered in different qualities. The cheapest toilet papers have a texture close to crêpe paper. They are often made of recycled material. Expensive toilet papers are made from particularly absorbent, delicate tissue paper. Toilet paper usually has a smooth surface. With several intentions, it is occasionally embossed. On the one hand, the embossing can serve to stabilize the paper. Furthermore, wiping can become more effective. Thirdly, there are design reasons. In Switzerland, in particular, there are often toilet paper with burls. In Germany, the number of plies is considered a quality feature. In the USA, Great Britain and Japan, the quality feature is that the toilet paper is as delicate and fine as possible.

Additives
Some toilet papers are perfumed. Popular scents are chamomile, peach or rose. Other toilet papers are impregnated with antibacterial additives.

Dispensers
A toilet roll holder, also known as a toilet paper dispenser, is an item that holds a roll of toilet paper. There are at least seven types of holders:

 * 1) A horizontal piece of wire mounted on a hinge, hanging from a door or wall.
 * 2) A horizontal axle recessed in the wall.
 * 3) A vertical axle recessed in the wall
 * 4) A horizontal axle mounted on a freestanding frame.
 * 5) A freestanding vertical pole on a base.
 * 6) A wall mounted dispensing unit, usually containing more than one roll. This is used in the commercial/away-from-home marketplace.
 * 7) A wall mounted dispensing unit with tissue interleaved in a "S"-type fold so the user can extract the tissue one sheet at a time.

Some commercial or institutional toilet paper is wrapped around a cylinder to many times the thickness of a standard toilet paper roll.

Orientation
There are two choices of orientation when using a holder with a horizontal axle parallel to the wall: the toilet paper may hang over or under the roll. The choice is largely a matter of personal preference, dictated by habit. In surveys of American consumers and of bath and kitchen specialists, 60–70% of respondents prefer over. This is said to exhibit endianness, which applies not only to eggs, but to toilet paper. Most Americans think it should go over the top, like a waterfall.

Decoration
Toilegami refers to toilet paper origami. Like table napkins, some fancy Japanese hotels fold the first squares of toilet paper on its dispenser to be presented in a fashionable way.

Recreational use
In the United States, toilet paper has been the primary tool in a prank known as "TP-ing" (pronounced "teepeeing"). TP-ing, or "toilet papering", is often favored by adolescents and is the act of throwing rolls of toilet paper over cars, trees, houses and gardens, causing the toilet paper to unfurl and cover the property, creating an inconvenient mess.

Children and cats may unroll an entire roll of toilet paper by spinning it until it completely unravels on the floor, or as a game by children wadding up one end, putting it in the toilet bowl without tearing it and then using the flushing of the toilet to pull new paper into the toilet, with the objective of flushing the entire roll down the toilet section at a time without the toilet paper breaking. Special toilet paper insert holders with an oblong shape were invented to prevent continuous unrolling without tearing to discourage this practice.

Toilet paper pranks include musical toilet paper holders and inserts that are activated by the unrolling of the toilet paper and will loudly play an embarrassing song calling attention to the person defecating.

Other gags include custom toilet paper printed with jokes, stories or politician's images.

Mechanics
Alexander Balankin and coauthors have studied the behavior of toilet paper under tensile stress and during wetting and burning.

Toilet paper has been used in physics education to demonstrate the concepts of torque, moment of inertia, and angular momentum; and the conservation of momentum and energy.

Environmental considerations
One tree produces about 800 rolls (400 lb) of toilet paper and about 83 million rolls are produced per day. Global toilet paper production consumes 27,000 trees daily.

More than seven billion rolls of toilet paper are sold yearly in the United States alone. Americans use an average of 141 rolls per capita a year which is equivalent to 12.7 kg of tissue paper per year. This figure is about 50% more than the average of other Western countries or Japan. The higher use in the United States may be explained by the fact that other countries people use bidets or spray hoses to clean themselves. Millions of trees are harvested in North and South America leaving ecological footprint concerns.

, between 22% and 48% of the toilet paper used in the United States comes from tree farms in the U.S. and South America, with the rest mostly coming from old, second growth forests, and, some from virgin forests.

Alternatives to virgin wood pulp
Toilet paper made from recycled paper avoids the direct environmental impact of cutting down trees, and is commercially available. Recycled newspaper can contain BPA, an endocrine disruptor.

Toilet paper produced from bamboo is commercially available, and is in some ways more environmentally friendly than virgin pulpwood, because bamboo grows faster, taking less land and less water. For North American consumers, the Natural Resources Defense Council recommends recycled tree pulp over bamboo toilet paper, because tree forests promote more biodiversity and bamboo products must be shipped from Asia.

Toilet paper produced from bagasse, a byproduct of sugarcane, is commercially available, and avoids cutting down any plants because sugarcane is already grown for sugar production.

The most environmentally friendly alternatives are to rely solely on soap and water for anal hygiene.

title: Toilet paper


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Niacin

Niacin, also known as nicotinic acid, is an organic compound and a vitamer of   vitamin B3, an essential human nutrient. It is produced by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variety of whole and processed foods, with highest contents in fortified packaged foods, meat, poultry, red fish such as tuna and salmon, lesser amounts in nuts, legumes and seeds. Niacin as a dietary supplement is used to treat pellagra, a disease caused by niacin deficiency. Signs and symptoms of pellagra include skin and mouth lesions, anemia, headaches, and tiredness. Many countries mandate its addition to wheat flour or other food grains, thereby reducing the risk of pellagra.

The amide derivative nicotinamide (niacinamide) is a component of the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP+). Although niacin and nicotinamide are identical in their vitamin activity, nicotinamide does not have the same pharmacological, lipid-modifying effects or side effects as niacin, i.e., when niacin takes on the -amide group, it does not reduce cholesterol nor cause flushing. Nicotinamide is recommended as a treatment for niacin deficiency because it can be administered in remedial amounts without causing the flushing, considered an adverse effect.

Niacin is also a prescription medication. Amounts far in excess of the recommended dietary intake for vitamin functions will lower blood triglycerides and low density lipoprotein cholesterol (LDL-C), and raise blood high density lipoprotein cholesterol (HDL-C, often referred to as "good" cholesterol). There are two forms: immediate-release and sustained-release niacin. Initial prescription amounts are 500 mg/day, increased over time until a therapeutic effect is achieved. Immediate-release doses can be as high as 3,000 mg/day; sustained-release as high as 2,000 mg/day. Despite the proven lipid changes, niacin has not been found useful for decreasing the risk of cardiovascular disease in those already on a statin. A 2010 review had concluded that niacin was effective as a mono-therapy, but a 2017 review incorporating twice as many trials concluded that prescription niacin, while affecting lipid levels, did not reduce all-cause mortality, cardiovascular mortality, myocardial infarctions, nor fatal or non-fatal strokes. Prescription niacin was shown to cause hepatotoxicity and increase risk of type 2 diabetes. Niacin prescriptions in the U.S. had peaked in 2009, at 9.4million, declining to 800thousand by 2020.

Niacin has the formula and belongs to the group of the pyridinecarboxylic acids. As the precursor for nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate, niacin is involved in DNA repair.

Definition
Niacin is both a vitamin, i.e., an essential nutrient, marketed as a dietary supplement, and in the US, a prescription medicine. As a vitamin, it is precursor of the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). These compounds are coenzymes for many dehydrogenases, participating in many hydrogen transfer processes. NAD is important in catabolism of fat, carbohydrate, protein, and alcohol, as well as cell signaling and DNA repair, and NADP mostly in anabolism reactions such as fatty acid and cholesterol synthesis. Vitamin intake recommendations made by several countries are that intakes of 14–18 mg/day are sufficient to meet the needs of healthy adults. Niacin but also nicotinamide (niacinamide) are used for prevention and treatment of pellagra, a disease caused by lack of the vitamin. When niacin is used as a medicine to treat elevated cholesterol and triglycerides, daily doses range from 500 to 3,000 mg/day. High-dose nicotinamide does not have this medicinal effect.

Vitamin deficiency

Severe deficiency of niacin in the diet causes the disease pellagra, characterized by diarrhea, sun-sensitive dermatitis involving hyperpigmentation and thickening of the skin (see image), inflammation of the mouth and tongue, delirium, dementia, and if left untreated, death. Common psychiatric symptoms include irritability, poor concentration, anxiety, fatigue, loss of memory, restlessness, apathy, and depression. The biochemical mechanism(s) for the observed deficiency-caused neurodegeneration are not well understood, but may rest on: A) the requirement for nicotinamide adenine dinucleotide (NAD+) to suppress the creation of neurotoxic tryptophan metabolites, B) inhibition of mitochondrial ATP generation, resulting in cell damage; C), activation of the poly (ADP-ribose) polymerase (PARP) pathway, as PARP is a nuclear enzyme involved in DNA repair, but in the absence of NAD+ can lead to cell death; D) reduced synthesis of neuro-protective brain-derived neurotrophic factor or its receptor tropomyosin receptor kinase B; or E) changes to genome expression directly due to the niacin deficiency.

Niacin deficiency is rarely seen in developed countries, and it is more typically associated with poverty, malnutrition or malnutrition secondary to chronic alcoholism. It also tends to occur in less developed areas where people eat maize (corn) as a staple food, as maize is the only grain low in digestible niacin. A cooking technique called nixtamalization i.e., pretreating with alkali ingredients, increases the bioavailability of niacin during maize meal/flour production. For this reason, people who consume maize as tortillas or hominy are at less risk of niacin deficiency.

For treating deficiency, the World Health Organization (WHO) recommends administering niacinamide i.e., nicotinamide, instead of niacin, to avoid the flushing side effect commonly caused by the latter. Guidelines suggest using 300 mg/day for three to four weeks. Dementia and dermatitis show improvement within a week. Because deficiencies of other B-vitamins may be present, the WHO recommends a multi-vitamin in addition to the niacinamide.

Hartnup disease is a hereditary nutritional disorder resulting in niacin deficiency. It is named after an English family with a genetic disorder that resulted in a failure to absorb the essential amino acid tryptophan, tryptophan being a precursor for niacin synthesis. The symptoms are similar to pellagra, including red, scaly rash and sensitivity to sunlight. Oral niacin or niacinamide is given as a treatment for this condition in doses ranging from 50 to 100 mg twice a day, with a good prognosis if identified and treated early. Niacin synthesis is also deficient in carcinoid syndrome, because of metabolic diversion of its precursor tryptophan to form serotonin.

Measuring vitamin status
Plasma concentrations of niacin and niacin metabolites are not useful markers of niacin status. Urinary excretion of the methylated metabolite N1-methyl-nicotinamide is considered reliable and sensitive. The measurement requires a 24-hour urine collection. For adults, a value of less than 5.8 μmol/day represent deficient niacin status and 5.8 to 17.5 μmol/day represents low. According to the World Health Organization, an alternative mean of expressing urinary N1-methyl-nicotinamide is as mg/g creatinine in a 24-hour urine collection, with deficient defined as <0.5, low 0.5-1.59, acceptable 1.6-4.29, and high >4.3 Niacin deficiency occurs before the signs and symptoms of pellagra appear. Erythrocyte nicotinamide adenine dinucleotide (NAD) concentrations potentially provide another sensitive indicator of niacin depletion, although definitions of deficient, low and adequate have not been established. Lastly, plasma tryptophan decreases on a low niacin diet because tryptophan converts to niacin. However, low tryptophan could also be caused by a diet low in this essential amino acid, so it is not specific to confirming vitamin status.

Dietary recommendations
The U.S. Institute of Medicine (renamed National Academy of Medicine in 2015) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for niacin in 1998, also Tolerable upper intake levels (ULs). In lieu of an RDA, Adequate Intakes (AIs) are identified for populations for which there is not sufficient evidence to identify a dietary intake level that is sufficient to meet the nutrient requirements of most people. (see table).

The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values (DRV), with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. For the EU, AIs and ULs have the same definition as in the US, except that units are milligrams per megajoule (MJ) of energy consumed rather than mg/day. For women (including those pregnant or lactating), men and children the PRI is 1.6 mg per megajoule. As the conversion is 1 MJ = 239 kcal, an adult consuming 2390 kilocalories should be consuming 16 mg niacin. This is comparable to US RDAs (14 mg/day for adult women, 16 mg/day for adult men).

ULs are established by identifying amounts of vitamins and minerals that cause adverse effects, and then selecting as an upper limit amounts that are the "maximum daily intake unlikely to cause adverse health effects." Regulatory agencies from different countries do not always agree. For the US, 30 or 35 mg for teenagers and adults, less for children. The EFSA UL for adults is set at 10 mg/day - about one-third of the US value. For all of the government ULs, the term applies to niacin as a supplement consumed as one dose, and is intended as a limit to avoid the skin flush reaction. This explains why for EFSA, the recommended daily intake can be higher than the UL.

Both the DRI and DRV describe amounts needed as niacin equivalents (NE), calculated as 1 mg NE = 1 mg niacin or 60 mg of the essential amino acid tryptophan. This is because the amino acid is utilized to synthesize the vitamin.

For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). For niacin labeling purposes 100% of the Daily Value is 16 mg. Prior to 27 May 2016 it was 20 mg, revised to bring it into agreement with the RDA. Compliance with the updated labeling regulations was required by 1 January 2020 for manufacturers with US$10 million or more in annual food sales, and by 1 January 2021 for manufacturers with lower volume food sales. A table of the old and new adult daily values is provided at Reference Daily Intake.

Food preparation
Niacin naturally found in food is susceptible to destruction from high heat cooking, especially in the presence of acidic foods and sauces. It is soluble in water, and so may also be lost from foods boiled in water.

Food fortification
Countries fortify foods with nutrients to address known deficiencies. As of 2020, 54 countries required food fortification of wheat flour with niacin or niacinamide; 14 also mandate fortification of maize flour, and 6 mandate fortification of rice. From country to country, niacin fortification ranges from 1.3 to 6.0 mg/100 g.

As a dietary supplement
In the United States, niacin is sold as a non-prescription dietary supplement with a range of 100 to 1000 mg per serving. These products often have a Structure/Function health claim allowed by the US Food & Drug Administration (FDA). An example would be "Supports a healthy blood lipid profile." The American Heart Association strongly advises against the substitution of dietary supplement niacin for prescription niacin because of potentially serious side effects, which means that niacin should only be used under the supervision of a health care professional, and because manufacture of dietary supplement niacin is not as well-regulated by the FDA as prescription niacin. More than 30 mg niacin consumed as a dietary supplement can cause skin flushing. Face, arms and chest skin turns a reddish color because of vasodilation of small subcutaneous blood vessels, accompanied by sensations of heat, tingling and itching. These signs and symptoms are typically transient, lasting minutes to hours; they are considered unpleasant rather than toxic.

As lipid-modifying medication
In the United States, prescription niacin, in immediate-release and slow-release forms, is used to treat primary hyperlipidemia and hypertriglyceridemia. It is used either as a monotherapy or in combination with other lipid-modifying drugs. Dosages start at 500 mg/day and are often gradually increased to as high as 3000 mg/day for immediate release or 2000 mg/day for slow release (also referred to as sustained release) to achieve the targeted lipid changes (lower LDL-C and triglycerides, and higher HDL-C). Prescriptions in the US peaked in 2009, at 9.4million and had declined to 800thousand by 2020.

Systematic reviews found no effect of prescription niacin on all-cause mortality, cardiovascular mortality, myocardial infarctions, nor fatal or non-fatal strokes despite raising HDL cholesterol. Reported side effects include an increased risk of new-onset type 2 diabetes.

Mechanisms
Niacin reduces synthesis of low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), lipoprotein(a) and triglycerides, and increases high-density lipoprotein cholesterol (HDL-C). The lipid-therapeutic effects of niacin are partly mediated through the activation of G protein-coupled receptors, including hydroxycarboxylic acid receptor 2 (HCA2)and hydroxycarboxylic acid receptor 3 (HCA3), which are highly expressed in body fat. HCA2 and HCA3 inhibit cyclic adenosine monophosphate (cAMP) production and thus suppress the release of free fatty acids (FFAs) from body fat, reducing their availability to the liver to synthesize the blood-circulating lipids in question. A decrease in free fatty acids also suppresses liver expression of apolipoprotein C3 and PPARg coactivator-1b, thus increasing VLDL-C turnover and reducing its production. Niacin also directly inhibits the action of diacylglycerol O-acyltransferase 2 (DGAT2) a key enzyme for triglyceride synthesis.

The mechanism behind niacin increasing HDL-C is not totally understood, but seems to occur in various ways. Niacin increases apolipoprotein A1 levels by inhibiting the breakdown of this protein, which is a component of HDL-C. It also inhibits HDL-C hepatic uptake by suppressing production of the cholesterol ester transfer protein (CETP) gene. It stimulates the ABCA1 transporter in monocytes and macrophages and upregulates peroxisome proliferator-activated receptor gamma, resulting in reverse cholesterol transport.

Combined with statins
Extended release niacin was combined with lovastatin (Advicor), and with simvastatin (Simcor), as prescription drug combinations. The combination niacin/lovastatin was approved by the U.S. Food and Drug Administration (FDA) in 2001. The combination niacin/simvastatin was approved by the FDA in 2008. Subsequently, large outcome trials using these niacin and statin therapies were unable to demonstrate incremental benefit of niacin beyond statin therapy alone. The FDA withdrew approval of both drugs in 2016. The reason given: "Based on the collective evidence from several large cardiovascular outcome trials, the Agency has concluded that the totality of the scientific evidence no longer supports the conclusion that a drug-induced reduction in triglyceride levels and/or increase in HDL-cholesterol levels in statin-treated patients results in a reduction in the risk of cardiovascular events." The drug company discontinued the drugs.

Contraindications
Prescription immediate release (Niacor) and extended release (Niaspan) niacin are contraindicated for people with either active or a history of liver disease because both, but especially Niaspan, have been associated with instances of serious, on occasion fatal, liver failure. Both products are contraindicated for people with existing peptic ulcer disease, or other bleeding problems because niacin lowers platelet count and interferes with blood clotting. Both products are also contraindicated for women who are pregnant or expecting to become pregnant because safety during pregnancy has not been evaluated in human trials. These products are contraindicated for women who are lactating because it is known that niacin is excreted into human milk, but the amount and potential for adverse effects in the nursing infant are not known. Women are advised to either not nurse their child or discontinue the drug. High-dose niacin has not been tested or approved for use in children under 16 years.

Adverse effects
The most common adverse effects of medicinal niacin (500–3000 mg) are flushing (e.g., warmth, redness, itching or tingling) of the face, neck and chest, headache, abdominal pain, diarrhea, dyspepsia, nausea, vomiting, rhinitis, pruritus and rash. These can be minimized by initiating therapy at low dosages, increasing dosage gradually, and avoiding administration on an empty stomach.

The acute adverse effects of high-dose niacin therapy (1–3 grams per day) – which is commonly used in the treatment of hyperlipidemias – can further include hypotension, fatigue, glucose intolerance and insulin resistance, heartburn, blurred or impaired vision, and macular edema. With long-term use, the adverse effects of high-dose niacin therapy (750 mg per day) also include liver failure (associated with fatigue, nausea, and loss of appetite), hepatitis, and acute liver failure; these hepatotoxic effects of niacin occur more often when extended-release dosage forms are used. The long-term use of niacin at greater than or equal to 2 grams per day also significantly increases the risk of cerebral hemorrhage, ischemic stroke, gastrointestinal ulceration and bleeding, diabetes, dyspepsia, and diarrhea.

Flushing
Flushing – a short-term dilatation of skin arterioles, causing reddish skin color – usually lasts for about 15 to 30 minutes, although sometimes can persist for weeks. Typically, the face is affected, but the reaction can extend to neck and upper chest. The cause is blood vessel dilation due to elevation in prostaglandin GD2 (PGD2) and serotonin. Flushing was often thought to involve histamine, but histamine has been shown not to be involved in the reaction. Flushing is sometimes accompanied by a prickly or itching sensation, in particular, in areas covered by clothing.

Prevention of flushing requires altering or blocking the prostaglandin-mediated pathway. Aspirin taken half an hour before the niacin prevents flushing, as does ibuprofen. Taking niacin with meals also helps reduce this side effect. Acquired tolerance will also help reduce flushing; after several weeks of a consistent dose, most people no longer experience flushing. Slow- or "sustained"-release forms of niacin have been developed to lessen these side effects.

Liver damage
Niacin in medicinal doses can cause modest elevations in serum transaminase and unconjugated bilirubin, both biomarkers of liver injury. The increases usually resolve even when drug intake is continued. However, less commonly, the sustained release form of the drug can lead to serious hepatotoxicity, with onset in days to weeks. Early symptoms of serious liver damage include nausea, vomiting and abdominal pain, followed by jaundice and pruritus. The mechanism is thought to be a direct toxicity of elevated serum niacin. Lowering dose or switching to the immediate release form can resolve symptoms. In rare instances the injury is severe, and progresses to liver failure.

Diabetes
The high doses of niacin used to treat hyperlipidemia have been shown to elevate fasting blood glucose in people with type 2 diabetes. Long-term niacin therapy was also associated with an increase in the risk of new-onset type 2 diabetes.

Other adverse effects
High doses of niacin can also cause niacin maculopathy, a thickening of the macula and retina, which leads to blurred vision and blindness. This maculopathy is reversible after niacin intake ceases. Niaspan, the slow-release product, has been associated with a reduction in platelet content and a modest increase in prothrombin time.

Pharmacodynamics
Activating HCA2 has effects other than lowering serum cholesterol and triglyceride concentrations: antioxidative, anti-inflammatory, antithrombotic, improved endothelial function and plaque stability, all of which counter development and progression of atherosclerosis.

Niacin inhibits cytochrome P450 enzymes CYP2E1, CYP2D6 and CYP3A4. Niacin produces a rise in serum unconjugated bilirubin in normal individuals and in those with Gilbert's Syndrome. However, in the Gilbert's Syndrome, the rise in bilirubin is higher and clearance is delayed longer than in normal people. One test used to aid in diagnosing Gilbert's Syndrome involves intravenous administration of nicotinic acid (niacin) in a dose of 50 mg over a period of 30 seconds.

Pharmacokinetics
Both niacin and niacinamide are rapidly absorbed from the stomach and small intestine. Absorption is facilitated by sodium-dependent diffusion, and at higher intakes, via passive diffusion. Unlike some other vitamins, the percent absorbed does not decrease with increasing dose, so that even at amounts of 3-4 grams, absorption is nearly complete. With a one gram dose, peak plasma concentrations of 15 to 30 μg/mL are reached within 30 to 60 minutes. Approximately 88% of an oral pharmacologic dose is eliminated by the kidneys as unchanged niacin or nicotinuric acid, its primary metabolite. The plasma elimination half-life of niacin ranges from 20 to 45 minutes.

Niacin and nicotinamide are both converted into the coenzyme NAD. NAD converts to NADP by phosphorylation in the presence of the enzyme NAD+ kinase. High energy requirements (brain) or high turnover rate (gut, skin) organs are usually the most susceptible to their deficiency. In the liver, niacinamide is converted to storage nicotinamide adenine dinucleotide (NAD). As needed, liver NAD is hydrolyzed to niacinamide and niacin for transport to tissues, there reconverted to NAD to serve as an enzyme cofactor. Excess niacin is methylated in the liver to N1-methylnicotinamide (NMN) and excreted in urine as such or as the oxidized metabolites N1-methyl-2-pyridone-5-carboxamide and N1-Methyl-4-pyridone-3-carboxamide (2PY and 4PY). Decreased urinary content of these metabolites is a measure of niacin deficiency.

Biosynthesis
In addition to absorbing niacin from diet, niacin can be synthesized from the essential amino acid tryptophan, a five-step process with the penultimate compound being quinolinic acid (see figure). Some bacteria and plants utilize aspartic acid in a pathway that also goes to quinolinic acid. For humans, the efficiency of conversion is estimated as requiring 60mg of tryptophan to make 1mg of niacin. Riboflavin, vitamin B6 and iron are required for the process. Pellagra is a consequence of a corn-dominant diet because the niacin in corn is poorly bioavailable and corn proteins are low in tryptophan compared to wheat and rice proteins.

Industrial synthesis
Nicotinic acid was first synthesized in 1867 by oxidative degradation of nicotine with potassium chromate and sulfuric acid — this is the origin of the name. Niacin is prepared by hydrolysis of nicotinonitrile, which, as described above, is generated by oxidation of 3-picoline. Oxidation can be effected by air, but ammoxidation is more efficient. In the latter process, nicotinonitrile is produced by ammoxidation of 3-methylpyridine. Nitrile hydratase is then used to catalyze nicotinonitrile to nicotinamide, which can be converted to niacin. Alternatively, ammonia, acetic acid and paraldehyde are used to make 5-ethyl-2-methyl-pyridine, which is then oxidized to niacin. New "greener" catalysts are being tested using manganese-substituted aluminophosphates that use acetyl peroxyborate as non-corrosive oxidant, avoiding producing nitrogen oxides as do traditional ammoxidations.

The demand for commercial production includes for animal feed and for food fortification meant for human consumption. According to Ullmann's Encyclopedia of Industrial Chemistry, worldwide 31,000 tons of nicotinamide were sold in 2014.

Climate impact
The production of niacin creates nitrous oxide as a by-product, which is a potent greenhouse gas. In 2018, it was discovered that a niacin factory in Visp, Switzerland, was responsible for around one percent of the country's greenhouse gas emissions. Eventually, catalytic scrubbing technology that eliminates most of the emissions was installed in 2021.

Chemistry
This colorless, water-soluble solid is a derivative of pyridine, with a carboxyl group (COOH) at the 3-position. Other forms of vitamin B3 include the corresponding amide nicotinamide (niacinamide), where the carboxyl group has been replaced by a carboxamide group.

Preparations
Niacin is incorporated into multi-vitamin and sold as a single-ingredient dietary supplement. The latter can be immediate or slow release.

Nicotinamide (niacinamide) is used to treat niacin deficiency because it does not cause the flushing adverse reaction seen with niacin. Nicotinamide may be toxic to the liver at doses exceeding 3g/day for adults.

Prescription products can be immediate release (Niacor, 500 mg tablets) or extended release (Niaspan, 500 and 1000 mg tablets). Niaspan has a film coating that delays release of the niacin, resulting in an absorption over a period of 8–12 hours. This reduces vasodilation and flushing side effects, but increases the risk of hepatotoxicity compared to the immediate release drug.

Prescription niacin preparations in combination with statin drugs (discontinued) are described above. A combination of niacin and laropiprant had been approved for use in Europe and marketed as Tredaptive. Laropiprant is a prostaglandin D2 binding drug shown to reduce niacin-induced vasodilation and flushing side effects. A clinical trial showed no additional efficacy of Tredaptive in lowering cholesterol when used together with other statin drugs, but did show an increase in other side effects. The study resulted in the withdrawal of Tredaptive from the international market.

One form of dietary supplement sold in the US is inositol hexanicotinate (IHN), also called inositol nicotinate. This is inositol that has been esterified with niacin on all six of inositol's alcohol groups. IHN is usually sold as "flush-free" or "no-flush" niacin in units of 250, 500, or 1000 mg/tablets or capsules. In the US, it is sold as an over-the-counter formulation, and often is marketed and labeled as niacin, thus misleading consumers into thinking they are getting an active form of the medication. While this form of niacin does not cause the flushing associated with the immediate-release products, there is not enough evidence to recommend IHN to treat hyperlipidemia.

History
Niacin as a chemical compound was first described by chemist Hugo Weidel in 1873 in his studies of nicotine, but that predated by many years the concept of food components other than protein, fat and carbohydrates that were essential for life. Vitamin nomenclature was initially alphabetical, with Elmer McCollum calling these fat-soluble A and water-soluble B. Over time, eight chemically distinct, water-soluble B vitamins were isolated and numbered, with niacin as vitamin B3.

Corn (maize) became a staple food in the southeast United States and in parts of Europe. A disease that was characterized by dermatitis of sunlight-exposed skin was described in Spain in 1735 by Gaspar Casal. He attributed the cause to poor diet. In northern Italy it was named "pellagra" from the Lombard language (agra = holly-like or serum-like; pell = skin). In time, the disease was more closely linked specifically to corn. In the US, Joseph Goldberger was assigned to study pellagra by the Surgeon General of the United States. His studies confirmed a corn-based diet as the culprit, but he did not identify the root cause.

Nicotinic acid was extracted from liver by biochemist Conrad Elvehjem in 1937. He later identified the active ingredient, referring to it as "pellagra-preventing factor" and the "anti-blacktongue factor." It was also referred to as "vitamin PP", "vitamin P-P" and "PP-factor", all derived from the term "pellagra-preventive factor". In the late 1930s, studies by Tom Douglas Spies, Marion Blankenhorn, and Clark Cooper confirmed that niacin cured pellagra in humans. The prevalence of the disease was greatly reduced as a result.

Nicotinic acid was initially synthesized by oxidizing nicotine with potassium chromate and sulfuric acid. Hence, in 1942, when flour enrichment with nicotinic acid began, a headline in the popular press said "Tobacco in Your Bread." In response, the Council on Foods and Nutrition of the American Medical Association approved of the Food and Nutrition Board's new names niacin and niacin amide for use primarily by non-scientists. It was thought appropriate to choose a name to dissociate nicotinic acid from nicotine, to avoid the perception that vitamins or niacin-rich food contains nicotine, or that cigarettes contain vitamins. The resulting name niacin was derived from cotinic id + vitam.

Carpenter found in 1951, that niacin in corn is biologically unavailable, and can be released only in very alkaline lime water of pH 11. This explains why a Latin-American culture that used alkali-treated cornmeal to make tortilla was not at risk for niacin deficiency.

In 1955, Altschul and colleagues described large amounts of niacin as having a lipid-lowering property. As such, niacin is the oldest known lipid-lowering drug. Lovastatin, the first 'statin' drug, was first marketed in 1987.

Research
In animal models and in vitro, niacin produces marked anti-inflammatory effects in a variety of tissues – including the brain, gastrointestinal tract, skin, and vascular tissue – through the activation of hydroxycarboxylic acid receptor 2 (HCA2), also known as niacin receptor 1 (NIACR1). Unlike niacin, nicotinamide does not activate NIACR1; however, both niacin and nicotinamide activate the G protein-coupled estrogen receptor (GPER) in vitro.

In 2024, it was reported that metabolites of niacin promote vascular inflammation and contribute to the risk of developing atherosclerosis.

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title: Niacin