Light Makes a Difference
Make vs. Take

Sunlight is Essential 

Like most life on earth, humans require fresh air, water, food and sunlight to survive. All life evolves to exploit nutrients available in the environment, and instinctively, most of us know this includes the power of the sun. There is an abundance of compelling scientific research that validates our innate desire to get outside on a sunny day to soak up those rays. This research proves that the vitamin D our bodies create using sunshine is essential to our wellbeing and survival. 

Recent medical research has focused on vitamin D and its role not only in bone health, but in preventing depression, cancer, and other diseases. These studies consistently show that elevated vitamin D from sunlight is associated with improved physical, mental and immune system function. Yet vitamin D supplementation studies don’t show the same health effects. Why are oral vitamin D supplements not sufficient? Why, in fact, do supplements sometimes even exacerbate the problem or, as the latest research shows, cause new ones? 

The answer lies in understanding the complex system our bodies naturally utilize to provide us with vitamin D efficiently and safely. Our bodies evolved to create several beneficial hormones, including vitamin D, when our skin is exposed to sunlight. When we spend a day in the sun, we may be concerned about sunburn, but we never worry about overdosing on vitamin D. 

Impressively, the body has developed a foolproof system for protecting us from getting too much vitamin D when it is made by sunlight and synthesized in our skin. In fact, vitamin D regulation in the human body is performed only when vitamin D is created in the skin, while vitamin D ingested through the stomach bypasses this essential protection. 

Vitamin D Binding Protein (DBP) 

At the heart of this system lies the Vitamin D Binding Protein (DBP). This protein is the guiding force in ensuring we always have exactly the amount of vitamin D that we need. DBP controls the delivery and bioavailability of vitamin D and calcitriol, a pro-steroid hormone that is the active form of vitamin D. DBP is a multifunctional protein found at work everywhere in the body: in blood, ascitic fluid and cerebrospinal fluid, as well as on the surface of many cell types.[1] The principal role of DBP is to maintain stable serum stores of vitamin D metabolites and moderate the rates of its bioavailability, activation and delivery at a cellular level.[2,3] DBP binds to vitamin D3 and all of its 37 known metabolites (including liver-produced 25- hydroxyvitamin D and kidney- produced calcitriol), and transports them to target tissues.[4,5] 

 Vitamin D supplements vs sunshine

When skin is exposed to the sun, specifically light in the ultraviolet B (UVB) spectrum, it kicks off a slow, sustained release of vitamin D yielding consistent, elevated concentrations of vitamin D over many days. When light hits the body, it converts a cholesterol found in the uppermost layers of the skin into previtamin D3. However, DBP will not bind to this form of vitamin D for transport. First, the skin must convert previtamin D3 into vitamin D3. Only then will DBP pick it up for carefully measured delivery from the skin into the blood stream over the course of several days.[6] These internal controls result in a deliberately slow and steady trickle of vitamin D3 to the liver lasting more than two weeks. The body has evolved to ensure that vitamin D3 is not delivered to the liver too quickly. After arriving in the liver, vitamin D requires two metabolic conversions to become the active hormone calcitriol: often referred to as the Master Hormone due to its significant impact on systemic health.[7,8]  Finally, calcitriol, carried almost exclusively by DBP, binds to vitamin D receptors in every cell in the body to modulate gene transcription and keep the important functions of the body in working order.[7,8] 

Ingested vitamin D, on the other hand, bypasses all of the body’s regulatory processes and allows transport and uptake of vitamin D by the liver in a meager few hours.[9-11] This delivery is facilitated primarily by fat-soluble chylomicron remnants and LDL cholesterol (bad cholesterol). Vitamin D3 that is delivered to the liver via DBP enters slowly and steadily as part of a water-soluble molecule, while vitamin D3 coming from the stomach arrives on the back of cholesterol and fat in one massive deposit demanding immediate processing. In this way, vitamin D supplements bypass the natural regulators of production and distribution in the body.[12] With no DBP to monitor delivery or uptake, oral vitamin D supplements provide a rollercoaster-like, feast or famine in the availability of vitamin D.[9] In extreme cases, sudden large increases of vitamin D due to ingested supplements can cause over absorption of calcium in the blood (hypercalcemia) and overburden the liver and kidneys, which were not designed to receive such concentrated doses. While vitamin D toxicity is rare, it has been seen as a result of taking large doses of supplemental vitamin D for extended periods of time. Supplements provide a sporadic, undependable and short- lived supply of vitamin D. 

Do vitamin D supplements work?

Oral vitamin D supplements are not effective for a surprisingly large number of people. The human body was designed to make vitamin D through the skin when exposed to sunlight, as opposed to absorbing this important hormone through the digestive system. It has been demonstrated that supplemental ingestion of vitamin D does not bind correctly, with no more than 60% ever binding to DBP in humans. 

Additionally, nearly 32 million Americans have a fat malabsorption condition (cystic fibrosis, Crohn’s disease, celiac, liver disease, etc.) that prevents them from absorbing fat soluble vitamin D supplements, yet their bodies can successfully produce significant amounts of vitamin D from UVB light. Because supplements circumvent the body’s natural process for regulating vitamin D and do not correctly bind to DBP, they are not effective for supporting systemic health in the same way as vitamin D derived from sunlight. 

Achieving Proper Balance 

Our bodies are programmed to define their own optimum levels of vitamin D and work with sunlight to keep us in perfect balance. It is well known that higher circulating vitamin D concentrations are associated with a lower risk of several chronic illnesses, including common cancers, autoimmune diseases, infectious diseases and cardiovascular disease.[13] However, there are several studies that have shown a confounding U-shaped association, where both low and high levels of vitamin D result in an increased risk of certain cancers, adverse cardiovascular outcomes and mortality.[14-17] In many cases, research has even shown that while higher vitamin D levels created by the sun are useful in preventing breast cancer and depression, vitamin D supplements provide no such benefit. This indicates that although low vitamin D is problematic, too much vitamin D obtained through supplements is not helpful and can also cause issues. This research shows that we must be cautious not to raise vitamin D levels too high using supplements, as we bypass the optimal zone in the middle and end up causing new unforeseen problems at a cellular level, or in extreme cases toxicity. As with any hormone, vitamin D levels need to be finely tuned to assist the body properly and this only comes from exposure to the correct spectrum of sunlight. 

To make things more complicated, that coveted spot in the middle that helps fight illness and prevent disease is different for each individual. Our bodies have evolved to regulate, manufacture, and distribute the unique amount of vitamin D an individual needs. This makes it virtually impossible to pinpoint and maintain one’s ideal optimal level with oral supplementation. The only way to reach true vitamin D optimization for the best systemic health is to allow the body to do what it does best: self-regulate production and delivery through skin exposure. 

Benefits of sunlight 

When human skin is exposed to sunlight it produces several hormones and peptides that contribute to systemic health and wellness. Substances made from chemical reactions with sunlight are called photoproducts. While vitamin D is the most universally recognized health benefit humans receive from sun exposure, it is just one of many important photoproducts. 

In addition to vitamin D3, other healthy photoproducts made in the same UVB wavelength range include: Calcitonin Gene Related Peptide, Neuropeptide Substance P, Adrenocorticotropic Hormone, Melanocyte Stimulating Hormone, Calcitriol, and Beta Endorphin.

These photoproducts have widespread impact on the body and are involved in regulating the immune system, promoting proper blood flow, reducing inflammation, acting as natural pain killers, and more. All of these substances contribute to that relaxed, happy feeling we get when we are regularly exposed to the sun. 

Should I take vitamin D pills?

Before turning to vitamin D supplements to support health, you should consider the differences between vitamin D pills vs sunlight. The correlation between higher blood levels of vitamin D and disease prevention in epidemiological research is actually measuring sun exposure and not supplemental vitamin D. Population studies have repeatedly demonstrated that sun exposure is a larger contributor of vitamin D concentration than oral consumption.[18,19] Therefore, at a population level, vitamin D is actually a measure of sun exposure, and higher serum concentrations are an indicator of greater skin contact with the sun’s light.[20] 

The assumption that vitamin D level in the body from an oral supplement represents the same health benefits as vitamin D derived from light fails to take into consideration the impact sunlight has on human health outside of vitamin D production. It is important to consider that there are other vital photoproducts that contribute to our systemic health in addition to vitamin D. 

Can you get too much vitamin D?

If you can get too much vitamin D all depends on the source of your vitamin D: sunlight vs supplements. You cannot overdose on vitamin D3 that is stimulated by light and produced in your skin. If you have enough vitamin D, your body will simply produce less. Using light to make vitamin D allows your body to self-regulate production and make as much as it needs to stay healthy, without any risk of overdose or toxicity. Oral supplementation, be it vitamin D pills, liquids, or sprays, introduce the risk of vitamin D toxicity and potentially dangerous symptoms. 

What happens when you take too many vitamin D supplements?

Before taking an ingestible vitamin D supplements it’s important to ask, “How much vitamin D should I take?” Treatment guidelines for low vitamin D vary greatly between different medical authorities. The Institute of Medicine’s (IOM) recommended dietary allowance is 600 International Units (IU) per day. Many vitamin D researchers disagree with this recommendation and say that the IOM’s recommended allowance isn’t enough to prevent deficiency or support bone health. Generally, 4,000 IU or less per day is considered safe, as long as your blood values are being monitored.

It is critical to avoid excessive doses of oral vitamin D. If vitamin D intake is too high, it can cause vitamin D toxicity, also known as hypervitaminosis D. Vitamin D toxicity can cause dangerously high levels of calcium in the blood, known as hypercalcemia. Vitamin D toxicity is fairly rare but has been observed as a side effect of high dose vitamin D pills if taken for long periods of time. 

Symptoms of too much vitamin D supplementation

When taking oral vitamin D supplements, it is important to know and be able to recognize the symptoms of vitamin D toxicity. What happens when you take too much vitamin D can vary person to person. Side effects of ingesting too much vitamin D can include diarrhea, constipation, and stomach pain. Digestive distress, excessive thirst, or frequent urination may all be signs of taking too much vitamin D.

If you experience any of these side effects when taking oral vitamin D tablets, pills, sprays, or liquid, you should contact your doctor as these may be signs of elevated calcium levels and vitamin D toxicity.