Vitamin

A vitamin (from Latin vita "life" + ammonia_) is a nutrient that animals need in small amounts to prevent a specific `deficiency disease`_; there is no chemical definition of a vitamin. [1]

Most animals obtain vitamins through diet. Different types of animals need different sets of vitamins. Humans require 13 vitamins: A, C, D, E, K, and eight B vitamins (B1, B2, B3, B5, B6, B7, B9, and B12). (Other substances once thought to be vitamins were given numbers in the B-vitamin numbering scheme, but were subsequently discovered to be inessential for life.)

Vitamin Chemical Deficiency diseases Food sources
A Retinoid_ Xerophthalmia  
B1 Thiamine_ Beriberi_ ?
B2 Riboflavin_ Stomatitis_ Bread
B3 Niacin_ Pellagra_ ?
B5 Pantothenic acid Acne, paresthesia_  
B6 Pyridoxine Acne, pink eye  
B7 Biotin_ Neurological issues in infants  
B9 `Folic acid`_ Anemia_  
B12 Colbalamins Anemia_  
C L-ascorbic acid Scurvy Lemons
D Calciferol_ Rickets Cod liver oil
E Tocopherol, Tocotrienol    
K Phylloquinone, Menaquinone Nerve damage  

Most of the vitamins were discovered around the same time in the early 20th century, together with the concept of deficiency diseases. Before their discovery, people thought diseases were caused only by germs_. [1]

Contents

1   Classification

Vitamins can be classified by whether they are fat-soluble or water-soluble.

2   Kinds

2.1   Vitamin B

Vitamin B refers to a class of water-soluble vitamins.

2.2   Vitamin C

Vitamin C is ..

[2]

It is not easy to find fresh foods that lack vitamin C. Plants and animals tend to be full of it, since the molecule is used in all kinds of biochemical synthesis as an electron donor. But the same reactive qualities that make the vitamin useful also make it easy to destroy. Vitamin C quickly breaks down in the presence of light, heat and air. For this reason it is absent from most preserved foods that have been cooked or dried. Its destruction is also rapidly catalyzed by copper ions, which may be one reason sailors, with their big copper cooking vats, were particularly susceptible.

Because our bodies can't synthesize the vitamin, they have grown very good at conserving it. It takes up to six months for scurvy to develop in healthy people after vitamin C is removed from the diet, and only a tiny daily amount is enough to keep a person healthy.

2.3   Vitamin D

Vitamin D (= calciferol) refers to a group of fat-soluble `hormone steroids`_ that are responsible for increasing absorption of calcium, magnesium_, and phosphate_ in the intestines_. Insufficient amounts of vitamin D can lead to rickets in children and osteomalacia_ in adults. [4] Vitamin D is produced naturally in the skin when exposed to `ultraviolet light`_.

2.3.1   Chemistry

static/images/Cholecalciferol.png

Cholecalicerfol.

In humans, the most important compounds in this groups are vitamin D3 and vitamin D2.

In supplements and fortified foods, vitamin D is available in two forms, D2 (ergocalciferol) and D3 (cholecalciferol) that differ chemically only in their side-chain structure. Vitamin D2 is manufactured by the UV irradiation of ergosterol in yeast, and vitamin D3 is manufactured by the irradiation of 7-dehydrocholesterol from lanolin and the chemical conversion of cholesterol. The two forms have traditionally been regarded as equivalent based on their ability to cure rickets and, indeed, most steps involved in the metabolism and actions of vitamin D2 and vitamin D3 are identical. Firm conclusions about any different effects of these two forms of vitamin D cannot be drawn. [4]

Cholecalicerfol (D3) enters the body by being produced when cholesterols_ in the skin are exposed to `UVB radiation`_ or through ingestion. [5] Ultraviolet (UV) B radiation with a wavelength of 290–320 nanometers penetrates uncovered skin and converts cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes vitamin D3 [4] Season, time of day, length of day, cloud cover, smog, skin melanin content, and sunscreen are among the factors that affect UV radiation exposure and vitamin D synthesis. [4] Complete cloud cover reduces UV energy by 50%; shade (including that produced by severe pollution) reduces it by 60%. [4] UVB radiation does not penetrate glass, so exposure to sunshine indoors through a window does not produce vitamin D. [4]

The factors that affect UV radiation exposure and research to date on the amount of sun exposure needed to maintain adequate vitamin D levels make it difficult to provide general guidelines. It has been suggested by some vitamin D researchers, for example, that approximately 5–30 minutes of sun exposure between 10 AM and 3 PM at least twice a week to the face, arms, legs, or back without sunscreen usually lead to sufficient vitamin D synthesis. [4] However, there are no studies to determine whether UVB-induced synthesis of vitamin D can occur without increased risk of skin cancer. [4]

Ergocalciferol (D2) cannot be produced and must be ingested. [5]

Neither form is bioavailable until they undergo two rounds of hydroxylation_. [5] (The first hydroxylation occurs in the liver, the second takes place in the kidneys.) [5] Eventually, both forms are metabolized intro calcitriol_. [5]

Vitamin D obtained from sun exposure, food, and supplements is biologically inert and must undergo two hydroxylations in the body for activation. The first occurs in the liver and converts vitamin D to 25-hydroxyvitamin D [25(OH)D], also known as calcidiol. The second occurs primarily in the kidney and forms the physiologically active 1,25-dihydroxyvitamin D [1,25(OH)2D], also known as calcitriol [4]

Vitamin D promotes calcium absorption in the gut and maintains adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and to prevent hypocalcemic tetany. It is also needed for bone growth and bone remodeling by osteoblasts and osteoclasts [1,2]. Without sufficient vitamin D, bones can become thin, brittle, or misshapen. Vitamin D sufficiency prevents rickets in children and osteomalacia in adults [1]. Together with calcium, vitamin D also helps protect older adults from osteoporosis. [4]

Calcitriol functions as a chemical signal and initiates the creation of proteins which assist in regulating calcium and phosphorus absorption in the small intestine. Furthermore, calcitriol triggers the formation of osteoclasts, which play a primary role in bone remodeling and calcium reabsorption into the bloodstream. [5]

Ergocalciferol is produced industrially by exposing fungus to specific wavelengths of UVB radiation (light). [5]

2.3.2   Consumption

Age determines the amount of vitamin D a person needs daily. The Food and Nutrition Board (FNB) at the Institute of Medicine of The National Academies recommends adults 19-70 years old take 600 International Units (IU) daily. [3]

Almost all milk is fortified with 400 IU of vitamin D per quart. But dairy products are usually not fortified. Some cereals are as well. [3]

The National Health and Nutrition Examination Survey (NHANES), 2005–2006, estimated vitamin D intakes from both food and dietary supplements [4,27]. Average intake levels for males from foods alone ranged from 204 to 288 IU/day depending on life stage group; for females the range was 144 to 276 IU/day. When use of dietary supplements was considered, these mean values were substantially increased (37% of the U.S. population used a dietary supplement containing vitamin D.). [4]

A vitamin D deficiency can occur when usual intake is lower than recommended levels over time, exposure to sunlight is limited, the kidneys cannot convert 25(OH)D to its active form, or absorption of vitamin D from the digestive tract is inadequate. Vitamin D-deficient diets are associated with milk allergy, lactose intolerance, ovo-vegetarianism, and veganism. [4]

Obtaining sufficient vitamin D from natural food sources alone is difficult. For many people, consuming vitamin D-fortified foods and, arguably, being exposed to some sunlight are essential for maintaining a healthy vitamin D status. In some groups, dietary supplements might be required to meet the daily need for vitamin D. [4]

Older adults are at increased risk of developing vitamin D insufficiency in part because, as they age, skin cannot synthesize vitamin D as efficiently, they are likely to spend more time indoors, and they may have inadequate intakes of the vitamin. [4]

Few foods food contain vitamin D. The flesh of fatty fish (such as salmon_, tuna_, and mackerel_) and fish liver oils are among the best source. [4] Fortified foods provide most of the vitamin D in the American diet.

Selected food sources of Vitamin D
Food IUs
Cod liver oil, 1 tablespoon 1360
Salmon, cooked, 3 ounces 447
Tuna fish, canned in water; 3 ounces 154
Orange juice fortified with vitaim D, 1 cup 137
Milk, vitamin D-fortified , 1 cup 115
Liver, beef, cooked, 3 ounces 42
Egg, 1 large 42
Cereal, fortified, 1 cup 40

The major natural source is synthesis of vitamin D3 in the skin from cholesterol through a chemical reaction that is dependent on exposure to the sun. Skin exposed to sunshine indoors through a window will not procued vitamin D. [3] Cloud days and dark-colored skin also reduce the amount of vitamin D produced by the skin. [3]

Vitamin D is found in supplements (and fortified foods) in two different forms: D2 (ergocalciferol) and D3 (cholecalciferol). Both increase vitamin D in the blood. [3]

Because vitamin D can come from sun, food, and supplements, the best measure of one’s vitamin D status is blood levels of a form known as 25-hydroxyvitamin D. Levels are described in either nanomoles per liter (nmol/L) or nanograms per milliliter (ng/mL), where 1 nmol/L = 0.4 ng/mL. [3]

In general, levels below 30 nmol/L (12 ng/mL) are too low for bone or overall health, and levels above 125 nmol/L (50 ng/mL) are probably too high. Levels of 50 nmol/L or above (20 ng/mL or above) are sufficient for most people. [3]

By these measures, some Americans are vitamin D deficient and almost no one has levels that are too high. In general, young people have higher blood levels of 25-hydroxyvitamin D than older people and males have higher levels than females. [3]

Vitamin D is commonly added as a fortification in manufactured foods, including fruit juices, meal replacement bars, flour products, breakfast cereals, and milk. Natural source include fish liver oils such as cod liver oil, egg yolks, and liver.


Vitamin D may hinder the production of melatonin.

2.4   Vitamin E

Vitamin E refers to tocopherol and tocotrienol.

In humans, Vitamin E deficiency is rare, occurring as a consequence of abnormalities in absorbing dietary fat rather than from a diet low in Vitamin E.

3   History

It has been known since antiquity that fresh foods in general, and lemons and oranges in particular, will cure scurvy. Starting with Vasco de Gama’s crew in 1497, sailors have repeatedly discovered the curative power of citrus fruits, and the cure has just as frequently been forgotten or ignored by subsequent explorers. [2]

Lind tends to get the credit for discovering the citrus cure since he performed something approaching a controlled experiment. But it took an additional forty years of experiments, analysis, and political lobbying for his result to become institutionalized in the Royal Navy. In 1799, all Royal Navy ships on foreign service were ordered to serve lemon juice: [2]

The scheduled allowance for the sailors in the Navy was fixed at I oz.lemon juice with I + oz. sugar, served daily after 2 weeks at sea, the lemon juice being often called ‘lime juice’ and our sailors ‘lime juicers’. The consequences of this new regulation were startling and by the beginning of the nineteenth century scurvy may be said to have vanished from the British navy. In 1780, the admissions of scurvy cases to the Naval Hospital at Haslar were 1457; in the years from 1806 to 1810, they were two.

In 1941, President Franklin Delano Roosevelt summoned hundreds of scientists, doctors, and food manufacturers to Washington, D.C. to discuss a weapon that would help the U.S. win World War II: vitamins. [1]

Three ideas emerged from the National Nutrition Conference for Defense that still exist today. One was the creation of the Recommended Daily Allowances, the first set of guidelines for how much of each nutrient a person ought to consume. The other was the practice of enriching the country's flour supply with vitamins and minerals—particularly, Price said, with thiamin, or vitamin B1. [1]

The third idea wasn't new, and wasn't born from the conference so much as strengthened by it: the notion that vitamins were the key not only to health, but to a state of health-plus, with the ability to boost bodies past sick, past normal, and into something even better. In recent years, researchers have debunked, over and over, the idea that vitamin supplements confer any measurable benefit at all—but still, around half of Americans take them regularly. [1]

Thiamin, B1, was the first vitamin to be chemically isolated in 1926. [1] People suspected [there were] vitamins before then, but they had never separated one entirely from food. [1]

Starting as early as the late 1910s, and early 20s, food marketers started to latch on to this term vitamin. [1]

Vitamins made the leap from something you could get through food to something you could take as a pill in the 30s. [1]

3.1   Etymology

In 1911, this Polish American biochemist, Casimir Funk, coined the term "vitamins" to describe the group of chemical compounds in food that prevented deficiency diseases. [1] It was inspired by combining the Latin word for life, vita, and amine, which is the chemical structure that the scientists thought all the vitamins would be proven to be, which they're not. And so it originally was "vitamine", and then the "e" got chopped off when it became clear that they actually weren't all amines. [1]

3.2   Vitamin D

Rickets was first described in the mid-17th century by British researchers. In the late 19th and early 20th centuries, German physicians noted that consuming 1-3 teaspoons/day of cod liver oil could reverse rickets . [4]

The fortification of milk with vitamin D beginning in the 1930s has made rickets a rare disease in the United States, although it is still reported periodically, particularly among African American infants and children. Prolonged exclusive breastfeeding without the AAP-recommended vitamin D supplementation is a significant cause of rickets, particularly in dark-skinned infants breastfed by mothers who are not vitamin D replete. [4]


[8]

It wasn't until Chick reported her success to Britain’s Medical Research Council in 1922 that the medical world was convinced the sun prevented rickets.

What was it in the sunlight that worked the medical magic? A vitamin. The sun “activated” a substance that came to be known as vitamin D. The discovery of vitamins was itself fairly recent. In the 1890s, a doctor working in the Dutch East Indies successfully traced the cause of a nerve disorder called beriberi to the natives’ habit of eating polished rice—a significant indication that foods contained additional constituents aside from protein, fat, and carbohydrates that were necessary for human health. In 1912, when a Polish chemist named Casimir Funk found the ingredient in rice coatings that prevented beriberi, he called it a “vital amine.” We now call it thiamin, one of the B vitamins.

An ad in the February 1930 edition of Ladies’ Home Journal illustrated Hutton’s problem. Grounded in a uniquely American combination of fear and optimism, the ad boasted that by exposing Quaker’s Muffets (shredded whole wheat breakfast biscuits) to the power of the sun, a chemical substance named “Vitamine D” was activated. Other cereals—like National Biscuit’s Shredded Wheat, or Kellogg’s Corn Flakes, or General Foods’s Post Toasties—might offer healthy breakfast options, but only Quaker products contained vitamin D. “Please note this,” the ad went on. “Under the law, no other cereal maker is permitted to employ this process.”

Up until then, millions of mothers had been spooning cod liver oil—which was expensive, tasted bad, and varied in quality and potency—down the gagging throats of their protesting children. Now, Quaker implied, mothers could hold rickets at bay by serving up a tasty bowl of Muffets.

General Foods had known this was coming for years, and feared it. But it had never been able to put sunshine in its cereals thanks to that “under the law” part of the Quaker ad. The process of activating vitamin D in food had been locked up by a patent, and an aggressive cartel had formed to neutralize competitors. In the vitamin D game, Quaker was in and General Foods was out.

In the beginning, fame was the prize in vitamin research, not money. This is why most of the early research on vitamins took place in universities: Scientists were freed from the demands of commerce. Patenting a discovery was taboo. The ethos demanded science for the sake of science, and for the public good.

With the cultures of business and academia circling each other, it didn’t take long for someone to break the taboo. The big leap came in 1922 when Frederick Banting and Charles Best at the University of Toronto announced that they had treated diabetes with a purified cow pancreas extract called insulin. The two scientists quickly patented their process and gave the rights to the university—which then licensed Eli Lilly and Company to produce insulin for the U.S. and Latin American markets in return for a 5 percent royalty on net sales. Lilly would go on to dominate the insulin market for the next 50 years and grow into a pharmaceutical powerhouse, and the university reaped millions.

In 1924 Harry Steenbock published a paper in the Journal of Biological Chemistry detailing an experiment that involved exposing rat food to light from a quartz-mercury vapor lamp. Rats who ate the irradiated food did not get rickets; control rats did. Somehow, and he wasn’t sure exactly how, the light had activated anti-rachitic properties in the food.

With the help of a tough-minded Chicago patent attorney and Wisconsin alum named George Haight, he set up an independent, private, nonprofit business group called the Wisconsin Alumni Research Foundation (WARF). WARF made a secret agreement with Quaker Oats in 1926. Quaker could experiment with what was being branded as the “Steenbock Process” for small yearly royalties. If the company commercialized a product, it would pay WARF an annual fee of up to $60,000 (almost $800,000 in today’s dollars) once sales began.

But Quaker wasn’t the only suitor. M.S. Fine, the research director at Postum (soon to become a division within General Foods), had written to Steenbock about “commercial use…of the patent” shortly after his paper was published. Steenbock and Haight kept Postum in the dark as they cut their initial deal with Quaker Oats, but they quickly realized they’d undershot. Demand for use of the patent was overwhelming. Not only was Postum being persistent but some of the most famous names in American homes—Upjohn, Kraft Cheese, Cream of Wheat, Eli Lilly, Palmolive, Procter & Gamble—were clamoring for rights to the Steenbock Process. John Harvey Kellogg even began a personal correspondence with the professor.

While Steenbock’s motives may have originally been pure, the seeds of a monopolistic cartel were planted early on. “We will find it necessary,” Haight wrote to Steenbock, “to limit our licenses to certain food products, perhaps not over a dozen, and as to each of these products, the field must be limited to one concern or one strong group of concerns.” Instead of a flat fee, he proposed a royalty system based on a percentage of sales with a guaranteed minimum of $60,000. After that, the sky was the limit.

General Foods had every reason to take the gamble of challenging WARF. The Sperti patent was different from Steenbock’s because of its use of “selective irradiation.” And any number of companies could be potential licensees because the country was going D crazy. In the 1930s, Jergens sold vitamin D cold cream. Schlitz produced a vitamin D beer. Lucky Strikes were touted in magazine ads as the more healthful cigarette because the tobacco was toasted with ultraviolet rays.

But WARF was a determined and tough adversary. It and its licensees heavily promoted themselves as the sole sources of and arbiters for vitamin D, often hailing Harry Steenbock for living on a humble professor’s salary while giving away vitamin D for the good of mankind. The promotion worked. By the mid-1930s, if you wanted to munch the Loose-Wiles Biscuit Company’s Graham Crackers, sip Ovaltine, eat cereal from Quaker Oats or bread made with flour from the nation’s largest milling companies (what is today Archer-Daniels Midland), swallow a Parke-Davis vitamin capsule, or simply drink milk that contained vitamin D, you had to become an indirect customer of WARF.

There was often more marketing than actual rickets prevention in many products, however. According to Margaret Irwin, one of Steenbock’s lab assistants, the professor didn’t really believe in most of the vitamin fortification WARF was licensing. “Many companies thought that that would be a good selling point,” she told an interviewer for a University of Wisconsin oral history program. “As time went on, it gradually became clear, I think to Dr. Steenbock particularly, that the only real good place to put vitamin D in food was in milk because of the calcium and phosphorus there.”

The vitamin D cartel organized by WARF was divided into product areas. Quaker Oats got cereal. Fleischmann (later Standard Brands) got yeast. A group of producers got evaporated milk. Dairies were selected by region to avoid overlap. Right off the bat WARF licensed five drug companies: Abbott Laboratories, E.R. Squibb & Sons, Mead Johnson & Company, Winthrop Chemical Company, and Parke-Davis & Company. Each agreed to the same royalty fee structure and to minimum retail price fixing so no company could undercut another. Retailers or wholesalers who discounted vitamin D products like Viosterol were blackballed. The five companies met regularly to decide which retailers and wholesalers to work with, which to blackball, and to discuss pricing and other policies. In return for the licensees maintaining high prices and paying the fat royalties, WARF acted as a hidden hand to enforce obedience, settle disputes, and to protect the group from interlopers.

WARF eventually attracted the attention of the federal government, which accused the foundation of a conspiracy to keep vitamin D prices high by illegally suppressing competition. The feds joined a lawsuit involving WARF and a vitamin supplement company in California. When the case was finally decided, in 1945, the Ninth Circuit Court of Appeals in San Francisco declared that Steenbock’s patents were invalid.

4   Further reading

5   References

[1](1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) Cari Romm. Feb 26 2015. Vitamin B.S. http://www.theatlantic.com/health/archive/2015/02/vitamin-bs/386126/
[2](1, 2, 3)

http://idlewords.com/2010/03/scott_and_scurvy.htm

Didn't fully take notes on this. Really great read though.

[3](1, 2, 3, 4, 5, 6, 7, 8) Office of Dietary Supplements (ODS). April 15, 2016. Vitamin D. Fact Sheet for Consumers. https://ods.od.nih.gov/factsheets/VitaminD-Consumer/
[4](1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)

Vitamin D. Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

Best source on the topic by far.

[5](1, 2, 3, 4, 5, 6, 7) Vitamin D. https://faq.soylent.com/hc/en-us/articles/203962069-Vitamin-D
[8]Brian Alexander. 2013-09-26. THE MILKMAN COMETH. http://www.cincinnatimagazine.com/features/the-milkman-cometh/

About half of adults take a daily multivitamin, according to industry data.

Sales over the last decade had been growing by about 4 percent annually. But this year, as more people are taking their health into their own hands, perhaps hoping to stave off doctor bills, vitamin sales are expected to grow by 8 percent to a total of $9.2 billion, according to Nutrition Business Journal, a market researcher and publisher.

Of course, it’s controversial whether we should be taking vitamins at all. Recent studies have indicated that taking a multivitamin won’t protect you from heart disease or cancer. And experts maintain that if you eat well, you don’t need vitamin supplements.

For example, if you don’t get enough vitamin D — many people who live in the northern states or who wear sunscreen everyday are low on this crucial vitamin — then buy just a D supplement. Standard multivitamins will probably not have the levels of D you require (many doctors suggest taking 1,000 to 2,000 international units a day).

Vitamins and minerals are commodity items, and every manufacturer has access to the same ingredients. For that reason, researchers and scientists say paying more for a name brand won’t necessarily buy you better vitamins.

Purchase your vitamins from well-known retailers that do a brisk business and restock frequently, whether that’s Costco or Drugstore.com. Vitamins lose their potency over time and must be stored at, or below, room temperature. If bottles are sitting on a shelf in warm room or in direct sunlight, they may degrade even before their expiration date.

PRICE MAY NOT MEAN QUALITY While the Food and Drug Administration regulates vitamins as part of the nutritional supplement industry, it does not test them before they are put on the shelves. The F.D.A. places the responsibility on the manufacturer to ensure that its dietary supplement products are safe before they are marketed. All of which means that no matter what the price, quality is not assured.

ConsumerLab.com, a company based in White Plains that tests hundreds of vitamins each year, finds that 30 percent of multivitamins have a quality problem: the pills might have more or less of a stated ingredient, or they might not dissolve properly.

Mr. Shao said that the F.D.A. allowed for “a reasonable amount of variation” — which he characterized as up to 15 percent more of an ingredient than the label might indicate. Mr. Shao said that manufacturers frequently add slightly more of an ingredient to ensure that the amount is at least at the level claimed on the label as the product nears the end of its shelf life.

In any case, ConsumerLab.com says it has found a few patterns that consumers may find helpful. Products sold by vitamin chains tend to be more reliable than drugstore brands, and Wal-Mart and Costco’s vitamin lines are usually worth considering.

CERTIFICATION SYMBOLS One quality check you can make, although it is not a perfect screening, is to see whether a product is certified by one of several nonprofit organizations that check supplements for purity and quality.

The two most commonly used groups are the United States Pharmacopeia (www.usp.org) and NSF International (www.nsf.org), according to Mr. Shao. Manufacturers voluntarily submit a product for review and, if it passes, the product can bear an approval seal, such as USP or NSF.


If you are a healthy adult with no known nutritional deficiencies, save your money.

An independent panel convened by the National Institutes of Health concluded that evidence is lacking for or against the ability of a multivitamin to prevent chronic disease. The American Cancer Society, the American Heart Association and the United States Preventive Services Task Force, among others, have found no role for a one-a-day supplement to prevent cancer or heart disease; they recommend instead a balanced diet with a variety of foods as likely to be more effective than any capsule.

This does not mean that people shown to be deficient in one or another nutrient should refrain from taking a medically recommended supplement. For example, now that doctors routinely test for vitamin D levels, especially in older adults, nearly everyone I know, myself included, is taking 1,000 international units or more of this nutrient every day, primarily to support bone health. Without sufficient vitamin D, the body doesn’t absorb enough calcium and phosphorus from the diet to keep bones strong. Nonetheless, it has not yet been proved that vitamin D supplements prevent fractures.

People’s calcium levels, too, may be problematic following a significant decline in Americans’ milk consumption in recent decades, even though calcium sources like yogurt, cheese and ice cream remain popular.

Then there’s fish oil, usually taken in hopes of preventing heart disease and cognitive decline. The supplements contain two key omega-3 fatty acids important to brain function and preventing inflammation, a significant factor in heart disease. I began taking fish oil supplements many years ago hoping to counter the effects of a rising cholesterol level.

However, a 2013 study of more than 12,000 patients at high risk of a heart attack found no protection from fish oil supplements. And another major study that year linked fish oil supplements to a raised risk of prostate cancer, especially an aggressive form of the disease, suggesting that men may be better off getting these fatty acids from a serving or two a week of an oily fish.