Of all the vitamins and nutrients which are required by the human body, there are 13 of which that are considered essential nutrients. That means they can’t be produced within our bodies.
One of those vitamins can be produced in our bodies, but it requires a little bit of help to make it.
It is a vital component of human health, yet an enormous percentage of the world is deficient in it.
Learn more about Vitamin D, aka the Sunshine Vitamin, on this episode of Everything Everywhere Daily.
Before I get into the weeds about what vitamin D is and how it works, I should start with the history of vitamin D.
The history of the vitamin begins in the ancient world with the diagnosis of the disease we know as rickets.
Rickets is a disease that afflicts the bones of children when they are growing. It can result in deformities, soft bones, bow-leggedness, exaggerated foreheads, and in severe cases, death.
Rickets was first recorded in the second century by Soranus of Ephesus, who was a doctor who practiced medicine in Alexandria and Rome. He noted the deformity of bones in certain infants.
In 1645, the English doctor Daniel Whistler identified rickets as a specific disease, not just as symptoms that afflicted children.
Rickets would appear in children throughout history and no one was sure what caused it. Jon Snow, the man who famously figured out how to stop cholera outbreaks, thought that he came from bread treated with alum.
It wasn’t until the 20th century that researchers began to discover treatments for rickets that actually worked.
The first came from the German doctor Kurt Huldschinsky who, immediately after the first world war, discovered that rickets would be treated with exposure to ultraviolet lamps.
Around the same time, a British doctor by the name of Edward Mellanby found that he could treat rickets in dogs by feeding them cod liver oil. Mellanby assumed that the substance which cured the dogs was newly discovered vitamin A, which is found in cod liver oil.
However, in 1922, one of the co-discoverers of Vitamin A, American Elmer McCollum, repeated the experiment with dogs but removed the vitamin A from the cod liver oil. The dogs still recovered, indicating that it wasn’t the vitamin A that was treating rickets.
McCollum named the new substance Vitamin D, as it was the fourth vitamin to be identified.
Technically, vitamin D is not a vitamin, although it is always treated as one. It is technically a fat-soluble steroidal hormone.
If you remember back to my episode on vitamins, many vitamins are really vitamers that have several different forms, and this is the case with Vitamin D.
The first type, which was dubbed vitamin D1, was later founded to be a collection of different molecules, so D1 is no longer used.
There are two main types of vitamin D: D2 and D3.
D2 is known as ergocalciferol, and D3 is known as cholecalciferol.
There are technically vitamins D4 and D5, but they are of minor and relatively little importance.
When vitamin D is referred to generically, it is referring to both D2 and D3.
So what does vitamin D do? The reason why cod liver oil was a treatment for rickets is that it was a powerful source of vitamin D, and vitamin D deficiency was the primary cause of rickets.
Of the many things that vitamin D does is facilitate the absorption of minerals such as calcium, magnesium, and phosphate. When a child is developing, they are constantly growing new bone mass. Without sufficient vitamin D, their bodies can’t develop bones properly.
This is the main reason why a generation of children was given cod liver oil by their mothers.
If vitamin D deficiency could explain why rickets developed in children, then how was it that Kurt Huldschinsky was able to treat rickets with exposure to ultraviolet lamps?
In the 1920s, German researcher Adolf Windaus and American Alfred Hess found that when a substance found in our skin known as 7-dehydrocholesterol is irradiated with ultraviolet light, in particular, wavelengths of UV-B light, it produces vitamin D3.
As Hess succinctly put it: “Light equals vitamin D.”
In addition to sunlight, the other sources of vitamin D are dietary. The only major natural source of vitamin D comes from animal-based foods. Seafood is particularly high in vitamin D, including salmon, sardines, and oysters. Eggs, and beef liver also contain vitamin D.. There are also some species of mushrooms that can produce small amounts of vitamin D as well.
Consumption of fatty fish is one of the reasons why people such as the Inuit who live in polar regions are able to get enough vitamin D, even though they go through much of the year without sunlight.
Once vitamin D was discovered and its importance, especially for children, was known, many foods began being fortified with vitamin D. Milk, breakfast cereals, and orange juice are the foods most commonly fortified with vitamin D.
While rickets was the historical disease that brought vitamin D to the forefront, it turns out that vitamin D is involved with far more metabolic functions than just bone growth.
Vitamin D deficiency has been linked to a whole host of ailments including:
Increased risks of certain types of cancer, including skin melanomas, breast cancer, and liver cancer. A study out of Michigan State University found a 13% increased survival rate among cancer patients who took a vitamin D supplement vs those who took a placebo.
Vitamin D deficiency has been linked to reduced cognitive function, including everything from brain fog, reduced memory, and recall, to increased rates of schizophrenia.
While vitamin D deficiency can cause rickets in children, it also can cause bone problems in adults. Osteoporosis, brittle bones, and reduced bone mineral content have all been linked with low vitamin D as well.
One of the biggest areas of current vitamin D research has to do with vitamin D’s role in the immune system. In addition to aiding bone growth, it appears vitamin D plays a role in the activation of T-cells. T-cells being the cells that hunt down foreign pathogens in your body.
There are many other ailments, such as multiple sclerosis, which have been linked to vitamin D. This isn’t a health podcast, and I’m not a doctor, so for any individual ailments, I suggest you consult a doctor and do research on your own.
However, in the course of doing research for this episode, I was shocked at the number of ailments of all types which were correlated with low vitamin D levels.
What is undeniable is that vitamin D is really important to the functioning of the human body, and it is involved in multiple metabolic functions within our bodies, some of which we probably still don’t even know about.
While vitamin D is important, so are many other vitamins. I could have done episodes on any of them, all of which can result in problems if you are deficient.
So why vitamin D?
It is because vitamin D deficiency has become one of the biggest health problems in the world. According to the World Health Organization, the number of people globally who suffer from some degree of vitamin D deficiency may be one billion people, and some estimates put the number as double that.
Almost everything in the modern world, it seems, is designed to reduce our levels of vitamin D.
The biggest culprit, by far, is the fact that people spend more time indoors and not enough time outdoors.
Vitamin D deficiency is starting to appear in places with lots of sunlight. Doctors in Kuwait recently warned that vitamin D deficiency becoming a problem. Cyprus, Greece, and Australia, all sunny countries, have seen increased rates of vitamin D deficiency.
Air conditioning and white-collar jobs keep people indoors during the day when our ancestors would have been outside working. Video games and computers keep kids inside when they would otherwise be outdoors playing.
However, there are other contributing factors as well. Some pharmaceutical products can block the effectiveness of vitamin D. Obesity can result in an increase in the amount of vitamin D, which is necessary. People are eating foods with less vitamin D, and many of the foods, such as factory-produced eggs, chicken, and salmon, have less vitamin D than more natural variants.
When people do go outside, they will often cover themselves in sunscreen, which blocks UV-B rays, which are responsible for the production of vitamin D.
Some researchers have suggested that increasing levels of vitamin D might be the single easiest thing we can do to improve health across the entire population.
So, what can you do? The simple answer is to get outside more often. That’s it.
How much sun exposure do you need to create adequate levels of vitamin D?
There is no single answer to that question because there are a host of variables involved.
The time of day, the time of year, the latitude you live at, the amount of skin exposed, and how dark your skin is all factor into how much exposure you need.
For most people in most latitudes, the amount of exposure you need each day probably doesn’t have to be more than 10-20 minutes. This is a level of exposure that was trivial for our recent ancestors but is actually a problem for many people today.
Personally, I was talking to a friend of mine a few years ago who lived in New York City. She said she went to a doctor and was diagnosed with vitamin D deficiency. As she described her symptoms of feeling sluggish, tired, and sore, I realized that I suffered from many of those things.
I set myself on a course of consuming more foods rich in vitamin D and making it a point to take a walk outside every day. The treatment was incredibly simple, but the results were dramatic.
Vitamin D deficiency affects a large number of people around the world and statistically speaking, many of the people listening to this podcast right now.
Thankfully, the solution to the problem is incredibly simple and requires no prescriptions. Just go outside and get yourself some sun.