By Dr. Mercola
Vitamin D is a steroid hormone produced in your body with the help of cholesterol molecules when you expose significant amounts of skin to the sun. It is an essential vitamin that interacts with a number of different systems in your body.
One of the best ways to optimize your vitamin D blood levels is to get sensible sun exposure, taking great care never to get burned.
Deficiency is very common in the U.S. but many Americans mistakenly believe they are not at risk simply because they eat foods fortified with vitamin D, such as milk. Before 2000, many physicians had not considered the possibility you could be deficient in vitamin D.
With advancing technology and research, it has become clear that vitamin D deficiency in the U.S. is rampant and this deficiency significantly impacts the development of many different health conditions.
Researchers estimate 85 percent of children in industrial cities and well over half of adults and elderly suffer from deficiency.1
The elderly may be at greater risk as they not only spend less time outside, but also produce approximately 30 percent less vitamin D than a younger person with the same sun exposure. Limiting your outdoor exposure and consistently wearing sun screen may also increase your risk of vitamin D deficiency.
A recent paper in Dermato-Endocrinology reviewed the current science for the risks and benefits of sun exposure and found insufficient exposure in the U.S. has become a major public health problem.
Insufficient Sun Exposure Has Become a Public Health Risk
In the late 1950s Coppertone began marketing their product, designed to help you get a suntan without the burn.2 Over the subsequent years researchers have theorized exposure to the sun would increase your risk of skin cancers and have recommended sun protection anytime you're outside.3
However, this has overlooked the health benefits of sun exposure without burning. In response to public health recommendations to limit sun exposure, lead researcher Dr. David Hoel writes:4
"The body of science concerning the benefits of moderate sun exposure is growing rapidly, and is causing a different perception of sun/UV as it relates to human health.
Melanoma and its relationship to sun exposure and sunburn is not adequately addressed in most of the scientific literature."
Historically, research identified benefits of sun exposure, linking it with prevention of rickets and production of vitamin D. In further scientific inquiry researchers began to focus on health risks, specifically the development of skin cancers.
Research has also determined outdoor workers have a lower incidence of melanoma, the most aggressive form of skin cancer, than do indoor workers.5 In the past 15 years, thousands of studies have been published linking the production of vitamin D with protective health benefits.
However, there is still considerable controversy over the optimum level of vitamin D for health, and not just prevention of disease. In their paper, Hoel's team identified several effects that a deficiency in vitamin D may have on your health, half of which account for the top 10 leading causes of death in the U.S.6
With adequate sun exposure and vitamin D levels, public health officials may make a significant impact on the number of deaths attributed to these diseases. According to the authors:7
"Insufficient sun exposure has become a major public health problem, demanding an immediate change in the current sun-avoidance public health advice. The degree of change needed is small but critically important."
Deficiency Increases Your Risk of Some Cancers and Neurological Conditions
They estimated a 16 percent reduction in deaths from those diseases with an increase of vitamin D to 40 nanograms per milliliter (ng/mL) and a direct health cost reduction estimated at $130 billion per year.
The link between vitamin D and specific cancers has been demonstrated in more than 200 epidemiological studies.9 Optimizing your vitamin D levels could help prevent at least 16 different types of cancer, including pancreatic, lung, breast, prostate and skin cancers.
Vitamin D appears to increase the self-destruction of mutated cells that, when left to replicate, may lead to cancer. It also helps reduce the spread of cancer cells and improves differentiation in cells, as cancer cells often lack differentiation.10
A recent study demonstrated a strong link between vitamin D and breast cancer prevention and found in a study of over 1,500 women, those with the highest levels had superior breast cancer survival rates.11
Neurological conditions are also affected by levels of vitamin D in the body. An Egyptian research team evaluated the addition of vitamin D supplementation to the treatment plan for children with autism and found the children's symptoms were positively affected by the increased levels of vitamin D, and not by placebo.12
In their review of the literature, Hoel's team found research demonstrating links between vitamin D deficiency and an increased risk of developing Alzheimer's disease, dementia and cognitive decline in adults.13
The development of multiple sclerosis (MS) also appears to be impacted by low levels of vitamin D.14 In one study, women with low levels had twice the risk of developing MS in the following 10 years.
Vitamin D Protects Your Bones, Skin, Heart and Metabolism
Heart disease is the No. 1 cause of death in the U.S., responsible for killing 787,000 people in 2011 and claiming more lives than the combination of all forms of cancer.15 Every 34 seconds someone in the U.S. has a heart attack, and every 60 seconds, someone in the U.S. dies from heart related disease.
Research has recently demonstrated the role vitamin D plays in improving heart function in patients suffering from heart failure.16 Many patients suffering with heart disease were deficient in vitamin D and low levels were connected to worse outcomes and more severe disease. Experimental studies have also demonstrated a role in reducing inflammation, thrombosis and calcification.17
A review of the research demonstrates a link between people with levels of vitamin D below 20 ng/mL and the development of psoriasis.18 Vitamin D is also essential to the absorption and modeling of your bones, preventing osteoporosis as you age.19 The presence of vitamin D, MK-7 K2, calcium and phosphorus increase the likelihood of proper bone modeling and reduced risk of fracture.
Low levels of vitamin D are linked to metabolic syndrome and insulin resistance.20 Obesity, also linked to metabolic syndrome, increases your risk of vitamin D deficiency as the vitamin is sequestered in adipose tissue. According to recent research, vitamin D deficiency affects your glucose metabolism and may actually be more closely linked to diabetes than obesity.21
In a study of 118 people, those with low vitamin D levels were more likely to have type 2 diabetes, pre-diabetes or metabolic syndrome, regardless of their weight. Another study22 published in 2013 found that type 2 diabetics given 50,000 IUs of oral vitamin D3 per week for eight weeks experienced "a meaningful reduction" in fasting plasma glucose and insulin.
Signs You Might Be Vitamin D-Deficient
Vitamin D is used in neuromuscular and immune functioning, reducing inflammation in your body, absorbing calcium, modulation of cell growth and assisting your muscles and nervous system to function properly. Many of the clinical signs you may be deficient are linked to these functions.
However, the only way to know definitively if you are deficient is to have a simple blood test. If any of the following signs apply to you, you may want to get tested sooner rather than later.
✓ Darker Skin
African-Americans are at greater risk of deficiency as darker skin requires as much as 10 times more sun exposure to product the same amount of vitamin D as skin that is paler.
✓ Feeling "Blue"
Serotonin, a brain hormone associated with mood elevation, rises and falls in association with sun exposure. In 2006, scientists evaluated the effects of vitamin D on mental health of 80 elderly patients and found those with the lowest level were 11 times more prone to be depressed than those with healthy doses.23
✓ You Are 50 or Older
As you age your skin doesn't make as much vitamin D and your kidneys become less efficient converting vitamin D into a form your body uses.
✓ You Are Obese or Have Higher Muscle Mass
Vitamin D is a fat-soluble, hormone-like vitamin, which means body fat acts as a "sink" by collecting it. If you're overweight or obese, you're therefore likely going to need more vitamin D than a slimmer person. The same also holds true for people with higher body weights due to muscle mass.
✓ Your Bones Ache
People suffering from aches and pains, especially in combination with fatigue, frequently end up being misdiagnosed as having fibromyalgia or chronic fatigue syndrome when in fact they may be vitamin D deficient.
✓ Head Sweating
One of the first, classic signs of vitamin D deficiency is a sweaty head. In fact, in years past physicians used to ask new mothers about head sweating in their newborns for this very reason. Excessive sweating in newborns due to neuromuscular irritability is still described as a common, early symptom of vitamin D deficiency.24
✓ Gut Problems and Bowel Diseases
Remember, vitamin D is a fat-soluble vitamin, which means if you have a gastrointestinal condition that affects your ability to absorb fat, you may have lower absorption of fat-soluble vitamins like vitamin D as well. This includes gut conditions like Crohn's, celiac and non-celiac gluten sensitivity and inflammatory bowel disease.
Sun Exposure Is the Best Way to Optimize Your Vitamin D Levels
Most vitamin D researchers agree that sensible sun exposure is the ideal way to get your vitamin D. Supplements do not confer the identical effects as the vitamin D your skin generates in response to UV exposure. Secondly, sun exposure has additional health benefits that are unrelated to vitamin D production.
For example, UVA exposure produces nitric oxide (NO), which has a blood pressure-lowering effect. In fact, the entire solar spectrum is important for optimal health. We're not dependent solely on the narrowband wavelength of about 295 nanometers (nm), which is where vitamin D is made.
However, unless you make a concerted effort, chances are you're simply not getting enough sun exposure to raise your vitamin D level. Your lifestyle, location, age, ethnicity, time of year, weather conditions and a number of other factors influence how much vitamin D your skin will make in response to sun exposure. The fact that vitamin D insufficiency and deficiency is widespread even in sundrenched areas like India attests to this difficulty.25
When You May Want to Take a Vitamin D3 Supplement
The worst thing you could do is to bake in the sun for hours on end on the weekends. You definitely want to avoid burning your skin, as this will only cause skin damage that could potentially increase your risk for skin cancer.
If sensible sun exposure is either not feasible or isn't sufficient to raise your vitamin D to a healthy level, then you may choose to take an oral vitamin D3 supplement. If you opt for this route, remember you will also need more vitamin K2, MK-7. The biological role of vitamin K2 is to help move calcium into the proper areas in your body, such as your bones and teeth. It also helps remove calcium from areas where it shouldn't be, such as in your arteries and soft tissues.
The only way to know how your sun exposure is affecting your vitamin D level is to get your vitamin D tested. I recommend doing this twice a year, in January and June/July, to get a reading on your lowest and highest levels. This will tell you whether you might be in need of a supplement. It will also guide you in terms of dosage.
In short, your ideal dosage is one that will help you maintain a clinically relevant vitamin D level of 40 to 60 ng/ml year-round. For some this may be 2,000 IUs a day, while others may require 8,000 IUs a day or more to maintain appropriate blood levels.