Vitamin D was discovered in the early part of the 20th century. Large numbers of children were developing rickets, a softening and weakening of the bones that often caused significant deformity and multiple fractures. When a researcher found that cod liver oil could prevent rickets, he named the nutritional factor in it that promoted calcium deposition, vitamin D.
Since rickets was thought to be another vitamin-deficiency disease like scurvy or beriberi, the cure was given the next letter in the vitamin alphabet, following the already existing A, B and C. We now know that vitamin D should probably never have been labeled a vitamin at all.
Sources of Vitamin D
Vitamin D has long been recognized as the “sunshine vitamin” because it is naturally produced when skin is exposed to sunlight’s UVB rays. Actually, exposure to sunlight is the only natural source of significant amounts of vitamin D. However, getting enough sun exposure to produce adequate amounts of vitamin D can be difficult. It can vary greatly depending upon the time of day, season, latitude, age, skin pigmentation and the amount of skin not covered with clothing or sunscreen.
Dietary intake is not a good option for vitamin D because, with the exception of oily fish and fish-liver oil, vitamin D does not naturally occur in food. Milk and other dairy products, orange juice and breakfast cereals have been fortified with small amounts of vitamin D, but it is virtually impossible to get adequate amounts through your diet. It would take 5 cans of tuna, 10 eggs, 10 glasses of milk, or up to 17 cups of breakfast cereal to get 1000 IU of vitamin D.
Because it is so difficult to get adequate amounts of vitamin D from natural sources, supplementation is usually the most practical solution.
Dangers of a D-ficiency
Many years ago it was thought that the only significant danger from a vitamin D deficiency was the development of rickets in children. That is why milk and other foods first began to be fortified with vitamin D as far back as the 1930s. As it turns out, rickets was just the tip of the iceberg.
Next, vitamin D deficiency was found to be a key factor in other bone diseases like osteopenia (thinning bones), osteoporosis (porous, brittle bones), and osteomalacia (a softening of bones in adults, often starting with insidious muscle weakness and aches and pains in the lower back & thighs, later spreading to arms and ribs).
In more recent years scientists have discovered that a vitamin D deficiency may contribute to an even wider variety of health problems. Michael F. Holick, PhD, MD, in a 2006 report in the journal Mayo Clinic Proceedings, stated, “Many lines of research support the concept that inadequate vitamin D may be involved in the pathogenesis and/or progression of several disorders, including cancer, hypertension, cardiovascular disease, neuromuscular diseases, osteoarthritis, diabetes, and other autoimmune diseases.”
Who is at Risk for Vitamin D Deficiency?
As it turns out, almost everyone is at risk of having a vitamin D deficiency. A 2009 epidemiological study found that an astounding 77% of Americans have insufficient levels of vitamin D. The numbers are even higher in Europe and higher still in the Middle East, where women especially tend to stay covered when outdoors.
Although virtually everyone has some risk, following are specific groups who have an especially high risk for vitamin D deficiency:
- Adults over 50 – As we age, the skin cannot synthesize vitamin D as efficiently and the kidney is less able to convert it to its active hormone form.
- People with limited sun exposure – If you’re homebound, wear clothing that covers most of your skin, or live in northern latitudes that get
- little sunlight part of the year, it’s unlikely that you get adequate amounts of vitamin D.
- People with dark skin – The pigment melanin, which results in darker skin, also reduces the skin’s ability to produce vitamin D from exposure to sunlight.
- People who have fat malabsorption problems – Vitamin D is fat soluble and therefore requires some dietary fat in the gut for absorption. Some medical conditions associated with fat malabsorption include some forms of liver disease, cystic fibrosis and Crohn’s disease.
- Tobacco smokers – Tobacco smoking is associated with significantly reduced vitamin D levels.
- People who are obese – Greater amounts of subcutaneous fat sequester more of the vitamin D and alter its release into the circulation.
- People who have had gastric bypass surgery – Part of the upper small intestine where vitamin D is absorbed is bypassed, which may lead to inadequate levels.
Measuring Vitamin D Levels
The only way to know for sure if you are deficient in vitamin D is by a blood test that measures serum 25(OH)D concentrations. 25(OH)D or 25-hydroxyvitamin D is a metabolite of vitamin D. There is considerable disagreement among experts as to exactly what 25(OH)D levels should be. Norms will vary between labs but the following chart will give you a general idea of what to look for:
|Severely Deficient||< 8 ng/ml|
|Deficient||8 – 19 ng/ml|
|Insufficient||20 – 29 ng/ml|
|Sufficient||30 – 49 ng/ml|
|Optimal||50 – 99 ng/ml|
|Excessive||100 – 150 ng/ml|
|Potentially toxic (yet to be proven)||>150 ng/ml|
Vitamin D’s Role in Chronic Pain, Fibromyalgia and ME/CFS
An important vitamin D connection that has only recently begun to be recognized and emphasized is the link between low vitamin D and chronic pain. Although a number of experts have recommended that vitamin D deficiency be considered in the differential diagnosis of patients with musculoskeletal pain, fibromyalgia, and ME/CFS, this is still not known – or ignored – by many healthcare professionals.
Following are just a few examples of research examining the role of vitamin D in a variety of pain conditions:
Fibromyalgia: A 2009 study looked at 139 patients with fibromyalgia and/or non-specific musculoskeletal pain. Three-quarters of them were deficient in vitamin D. Following vitamin D supplementation, clinical improvements were observed in 90% of the patients.
Neuropathy (Nerve Damage): A 2008 study examined 51 patients with diabetic neuropathy. After supplementing with approximately 2000 IU of vitamin D each day for three months, there was a 50% decrease in pain scores.
Migraines: Case reports have shown that two months of supplementation with vitamin D combined with calcium dramatically reduced both the frequency and intensity of migraines in post- and pre-menopausal women.
Chronic Back Pain: In 2003 researchers studied 360 patients with chronic back pain. After three months of vitamin D supplementation, symptom improvement was seen in 95% of all subjects and in 100% of those who were severely deficient in vitamin D at the start of the study.
Vitamin D Impacts a Wide Range of Illnesses
In addition to chronic pain conditions, a deficiency in vitamin D has been linked to many other illnesses, such as:
Bone Disease (Osteopenia, Osteoporosis and Osteomalacia): It is widely known that a combination of Vitamin D and calcium supplements can help decrease postmenopausal bone loss and prevent osteoporosis. A major function of vitamin D is to maintain serum calcium concentrations. When vitamin D levels are low, calcium concentrations are inadequate, resulting in bone disease. A 2005 meta-analysis of randomized controlled trials found that oral vitamin D supplementation in the range of 700 to 800 IU/d should reduce the risk of hip or any nonvertebral fracture by approximately 25%.
Colds, Flu and Other Respiratory Tract Infections: Because of reduced sunshine in fall and winter months, a study was undertaken to determine if low vitamin D levels correlated with the incidence of acute viral respiratory tract infections. The researchers found that individuals with a serum 25(OH)D concentration of less than 38 mg/ml were three times more likely to become ill with an acute respiratory tract infection.
Type 2 Diabetes: According to a new study, vitamin D deficiency is highly prevalent in patients with Type 2 diabetes and may be associated with poor blood sugar control. The study, which looked at 124 patients with Type 2 diabetes, found that 91% had a vitamin D deficiency or insufficiency. Investigators also found an inverse relationship between vitamin D levels and hemoglobin A1c values – those with lower vitamin D levels had higher A1c levels. Co-author Esther Krug, MD, concluded, “This finding supports an active role of vitamin D in the development of Type 2 diabetes.”
Rheumatic Conditions (Rheumatoid Arthritis, Osteoporosis, Osteoarthritis, etc.): Two new studies have shown that vitamin D deficiency is common in patients with a range of rheumatic diseases.
- A UK study showed that 58% of individuals with a rheumatic condition had low vitamin D levels,
- An Italian study reported that 85% of rheumatic patients not taking vitamin D supplements had insufficient levels – as did 60% of those who were taking recommended doses of vitamin D.
A third study assessing response to vitamin D supplementation found that taking the traditionally recommended daily dose did not normalize vitamin D levels in rheumatic disease patients, indicating that higher doses would probably be necessary.
Cardiovascular Disease: Noticing that people in sun-deprived regions suffered more heart attacks than did those in sunnier locales, scientists began to suspect that vitamin D may have some relationship to cardiovascular health. Investigating that theory, New Zealand researchers found that people who had suffered heart attacks had significantly lower vitamin D levels than controls who had no heart attacks.
A few years later, UK researchers conducted an exhaustive worldwide study that demonstrated a consistent relationship between sunlight exposure and heart disease. The further north people lived, the more frequently they experienced heart attacks, suggesting that vitamin D, which is activated by sunlight, reduces the risk of heart disease.
Multiple Sclerosis: Several epidemiological studies have shown that exposure to sunlight during early life may have a protective effect regarding the development of multiple sclerosis in later years. And a recent longitudinal study confirmed that vitamin D supplementation reduced the life-time prevalence of MS in women. It is thought that the white matter of the brain affected by MS contains vitamin D receptors, and that inadequate vitamin D in the early years of life may predispose these cells to an early death.
A new 2010 retrospective study also found that lower vitamin D levels are associated with a substantially increased relapse rate in pediatric-onset multiple sclerosis.
What Kind of Vitamin D Should You Take?
There are two main types of vitamin D – D2 (ergocalciferol) and D3 (cholecalciferol). The best supplement to take is vitamin D3 because it is the form that also is produced naturally in the skin from sun exposure. Vitamin D2 is produced by irradiating fungi, and is less efficient as a precursor to the active vitamin D metabolite calcitriol.
How Much Vitamin D Is Enough? …Too Much?
The recommended dosages of vitamin D3 are currently in the state of flux due to the abundance of new and on-going research on the subject. Ever aware of their ethical precept, “First, do no harm,” clinicians often lean toward recommending the lower levels of supplementation.
The US Institute of Medicine’s Food and Nutrition Board is currently revising its recommendations on Vitamin D dosing. It is generally thought that the new recommended dose will be 2,000 IU/day for healthy adults. If you have a vitamin D deficiency-associated disease, however, you will need significantly more.
In his dosing and testing suggestions, Dr. Stewart B. Leavitt of Pain-Topics.org cites the vitamin D recommendations of two practitioners with the Canadian Centre for Integrative Medicine: “Ko and Arseneau note that recommended vitamin D3 dosing for healthy adults by various authorities, such as the Canadian Cancer Society, is 5,000 IU/day.
“Other leading authorities, such as Reinhold Veith, PhD, suggest that oral supplementation is safe for infants at 1,000 IU/day, for children at 2,000 IU/day, and for adults at 5,000 IU/day. More aggressive dosing (up to 10,000 IU/day) may be useful but should be checked with more frequent lab testing (every 3 months).”
There also continues to be a great deal of disagreement among medical professionals as to the maximum safe dosage. The current “official” limit is 5000 IU/day, but the Vitamin D Council insists that doses up to 10,000 IU/day are not even remotely toxic.
One protocol successfully used by many doctors if you are deficient in vitamin D is to take 50,000 IU/week for approximately three months or until your 25(OH)D3 levels are in the optimal range – and then switch to a maintenance dose of 5,000 IU/day. Of course, having your 25(OH)D3 serum levels checked regularly is the best way to ensure you are taking the right dose of vitamin D3 for you.