Who Found Vitamin D, and How Rickets Turned Sunlight Into a Supplement Story

Sunshine and cod liver oil both cured rickets before anyone knew the chemistry. This is how the vitamin D story moved from 1822 advice to Windaus's 1928 Nobel, and where today's intake limits sit.

The history of vitamin D starts with children's bones and two remedies that worked long before anyone knew why. In 1822, Sniadecki advocated sunshine as a treatment for rickets, and in the same period several British physicians advocated cod liver oil. Both approaches succeeded ([Miller and Imel, 2022](https://doi.org/10.1159/000527011)). Windaus's research, recognized with the 1928 Nobel Prize, explained the chemistry more than a century later. ## Why did children's bones soften before vitamin D was known? Rickets was a public health problem from Roman times, and medical descriptions date from the 17th century ([Miller and Imel, 2022](https://doi.org/10.1159/000527011)). The London of Dickens's time offers a vivid example. A historical article on that period reports that 60% of London children had rickets, and it links the problem to soot-blackened skies, crowded tenements and a limited diet ([Chesney, 2012](https://doi.org/10.1001/archpediatrics.2011.852)). The NIH Office of Dietary Supplements describes rickets as bone tissue that fails to mineralize properly, leaving bones soft and causing skeletal deformities ([NIH ODS](https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/)). In adults and adolescents, the same deficiency can lead to osteomalacia, in which existing bone is incompletely or defectively mineralized ([NIH ODS](https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/)). ## How did cod liver oil and sunlight become the first treatments? Cod liver oil and sunlight were both in clinical use before the chemistry was known. The turning point in the sources I checked is 1924, when work showed that exposure to UV light gave fats and other foods antirachitic properties ([Miller and Imel, 2022](https://doi.org/10.1159/000527011)). That gave the sunshine remedy a measurable chemical counterpart. The cod liver oil story has its own origin, covered in the [omega-3 history](/blog/history/history-of-omega-3-from-cod-liver-oil-to-epa-and-dha). ## Why did a Nobel Prize go to a sterol chemist? Adolf Windaus received the 1928 Nobel Prize in Chemistry "for the services rendered through his research into the constitution of the sterols and their connection with the vitamins" ([Nobel Prize](https://www.nobelprize.org/prizes/chemistry/1928/windaus/facts/)). He found that ergosterol, a sterol, could cure rickets, and he showed that vitamin D formed from ergosterol under ultraviolet light ([Nobel Prize](https://www.nobelprize.org/prizes/chemistry/1928/windaus/facts/)). Later work produced vitamins D2 and D3 by UV radiation of ergosterol and 7-dehydrocholesterol, respectively ([Miller and Imel, 2022](https://doi.org/10.1159/000527011)). ## Is vitamin D a vitamin or a hormone? The short answer is that it starts as a vitamin from food or sunlight, and the body converts it in two steps into a form that binds a nuclear receptor. In the liver, vitamin D becomes 25-hydroxyvitamin D. In the kidneys, that becomes 1,25-dihydroxyvitamin D, the active form, which binds the nuclear vitamin D receptor to exert its effects ([Charoenngam, Shirvani and Holick, 2019](https://doi.org/10.1016/j.jcot.2019.07.004)). The active form, calcitriol, was identified in the early 1970s ([Miller and Imel, 2022](https://doi.org/10.1159/000527011)). Once active, vitamin D promotes intestinal calcium and phosphate absorption, renal calcium reabsorption and calcium mobilization from bone ([Charoenngam, Shirvani and Holick, 2019](https://doi.org/10.1016/j.jcot.2019.07.004)). For the nutrient itself, see the [vitamin D3 monograph](/ingredients/vitamin-d3-cholecalciferol). ## What did the sunlight and latitude research find? In 1981, Michael Holick and colleagues exposed human skin to simulated solar ultraviolet radiation and measured the previtamin D3 it made ([Holick et al., 1981](https://doi.org/10.1126/science.6256855)). Synthesis leveled off at about 10 to 15 percent of the original 7-dehydrocholesterol. During prolonged exposure, previtamin D3 was also photoisomerized into two biologically inert isomers. Higher skin melanin or higher latitude required longer exposure to maximize formation, but did not change the total content. The paper ranked the limits in order: photochemical regulation first, then pigmentation, then latitude ([Holick et al., 1981](https://doi.org/10.1126/science.6256855)). Its title states the finding plainly: skin pigment is not an essential regulator. The NIH fact sheet adds that D2 and D3 both raise serum 25-hydroxyvitamin D, and most evidence shows D3 raises it further and keeps it higher for longer ([NIH ODS](https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/)). ## How much do adults need, and what did fortification change? Vitamin D occurs naturally in fatty fish, fish liver oils, beef liver, egg yolks and cheese. In American diets, fortified foods such as milk and breakfast cereals provide most of it ([NIH ODS](https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/)). The Recommended Dietary Allowance for adults runs from 15 to 20 mcg (600 to 800 IU) a day, depending on age. The Tolerable Upper Intake Level for everyone 9 and older is 100 mcg (4,000 IU) a day from all sources ([NIH ODS](https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/)). The [dosage guide](/health/vitamin-d-complete-guide/vitamin-d-dosage-guide) and the [food sources guide](/health/vitamin-d-complete-guide/vitamin-d-food-sources) cover those numbers in more detail. Three Mt. Angel Vitamins products carry vitamin D3, at three different doses. Everyday Liquid Sunshine D3 1,000 IU provides 25 mcg (1,000 IU) per drop, with 1,400 one-drop servings per 1 fl oz bottle at $25.99, under 2 cents a day ([product page](https://mtangelvitamins.com/products/everyday-liquid-sunshine-bone-imm?utm_source=learn_hub&utm_medium=content&utm_campaign=blog_post&utm_content=history-of-vitamin-d-from-rickets-to-sunshine-vitamin)). Good Vitamin D provides 50 mcg (2,000 IU) per capsule with 200 mg of bromelain, 60 capsules at $17.99, about 30 cents a day ([product page](https://mtangelvitamins.com/products/good-vitamin-d-60-caps?utm_source=learn_hub&utm_medium=content&utm_campaign=blog_post&utm_content=history-of-vitamin-d-from-rickets-to-sunshine-vitamin)). Everyday Liquid Sunshine 2 provides 5,000 IU (125 mcg) of D3 and 120 mcg of vitamin K2 per dropper squeeze, about 70 servings per 2 fl oz bottle at $25.99, about 37 cents a day ([product page](https://mtangelvitamins.com/products/everyday-liquid-sunshine-2-d3-k2?utm_source=learn_hub&utm_medium=content&utm_campaign=blog_post&utm_content=history-of-vitamin-d-from-rickets-to-sunshine-vitamin)). Vitamin D helps the body absorb calcium and supports healthy bones.† *†These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.* The reaction Windaus showed for ergosterol still happens in skin, with 7-dehydrocholesterol as the starting sterol ([Holick et al., 1981](https://doi.org/10.1126/science.6256855)). Sniadecki's 1822 sunshine treatment depended on the same ultraviolet light that drives that reaction, long before anyone had the chemistry. **Next reads** - [Vitamin D complete guide](/health/vitamin-d-complete-guide): the reference page for vitamin D, from dosage to food sources. - [Vitamin D3 with K2](/health/vitamin-d-complete-guide/vitamin-d3-k2-combination-benefits): what the D3 and K2 pairing does and does not have trial evidence for. ### Related reading - [the vitamin E origin story from fertility factor to tocopherol](/blog/history/history-of-vitamin-e-from-fertility-factor-to-tocopherol) - [the vitamin K origin story from Danish blood clotting to K2](/blog/history/history-of-vitamin-k-from-danish-blood-clotting-to-k2)