Vitamin D Ineffective in Treating Osteoarthritis Of the Knee

Along with calcium, vitamin D helps maintain bone health by ensuring that the body creates and reabsorbs bone tissue at roughly the same rate, thus avoiding a net loss of bone. Although scientists are exploring a wide range of possible benefits of vitamin D unrelated to bone health, the results of their studies have remained mixed.

Previous studies had purported to show that higher vitamin D levels were associated with a slower progression of the characteristic joint damage associated with osteoarthritis (Osteoarthritis, sometimes referred to as “wear and tear” arthritis, is the most common type of arthritis and is usually related to either the aging of the joint or a prior injury.[1]) However, because these analyses were observational studies, the nature of their design could only determine that people with higher vitamin D levels happened to do better over time and not whether vitamin D was the actual cause of the improved outcomes.

In contrast, an article published in the Jan. 9, 2013, issue of the Journal of the American Medical Association (JAMA) cited a more rigorous, randomized controlled trial to evaluate the claim that vitamin D supplements benefit osteoarthritis patients. This study found that vitamin D supplements (CALCIFEROL) given to people with osteoarthritis of the knee were not effective in relieving their knee pain or slowing the damage to the knee joint.[2]

Study design and results

The study enrolled 146 elderly people suffering from knee pain due to osteoarthritis that was confirmed by magnetic resonance imaging (MRI). People already taking high doses of vitamin D (more than 800 international units [IU] a day) or other treatments for osteoarthritis were among those excluded.

Investigators gave half the subjects vitamin D and the other half a placebo and then followed them for two years. Those receiving vitamin D were started at a dose of 2,000 IU per day. This was gradually increased over the course of the study to achieve a target blood concentration of at least 36 nanograms per milliliter (ng/mL), the level at which vitamin D was thought to have an effect on the progression of osteoarthritis of the knee and hip in prior observational studies.[3] Most subjects given vitamin D reached these target blood levels.[4]

Subjects were followed for two years, during which time they filled out questionnaires and underwent MRI studies of their knee to determine how the pain and arthritic damage in the knee were progressing. These results were compared with those obtained pre-study.

Results showed that subjects given vitamin D and those given a placebo achieved about the same level of pain relief throughout the two-year study. Vitamin D supplementation also had no effect on the progression of cartilage loss in subjects’ knees.

Claims lack evidence

The recent JAMA study is the latest in a series of findings from rigorous studies demonstrating that the benefits of vitamin D supplementation are much more modest than previously believed. A 2012 randomized controlled trial, also published in JAMA, contradicted the earlier findings from observational studies suggesting that lower vitamin D levels increased the occurrence of upper respiratory infections (URIs), such as the common cold. The 2012 JAMA trial demonstrated conclusively that vitamin D supplements failed to prevent URIs or limit their duration or severity.[5]

In 2010, the Institute of Medicine (IOM), a nonprofit organization that, among other things, determines the recommended daily allowances used in food nutrition labels, reviewed more than 1,000 studies of vitamin D and calcium and found that the only health benefit demonstrated by reliable studies was the well-established benefit to bone health in certain people.[6]

This has been the typical trend for other vitamin supplements once touted as panaceas. In an interview published in Consumer Reports, Harvard Medical School professor Dr. JoAnn Manson, a member of the IOM committee that drafted the 2010 vitamin D report, pointed to the similarly failed promises of other supplements, such as vitamins C and E and the nutrient beta carotene.[7] All were thought at one time to prevent cancer or heart disease until rigorous clinical trials showed these theories to be false.

“These all looked beneficial in observational studies,” Manson told Consumer Reports. “But when subjected to rigorous testing, they were shown not to be of benefit.”[8]

Manson did mention that several large clinical trials of vitamin D for the prevention of heart disease, stroke and certain cancers are ongoing, including one that she is conducting. However, pending the results of these trials, as the IOM concluded, current evidence does not support these uses of vitamin D supplementation.

Skyrocketing sales

Despite the scant evidence of benefit, sales of vitamin D supplements in the U.S. rose more than 14-fold over the past decade, from $42 million in 2002 to $605 million in 2011, according to the Nutrition Business Journal.[9] Some have attributed this rise in vitamin D use primarily to a “pandemic” of vitamin D deficiency in the country.[10] Vitamin D is truly a problem for some: According to a national survey conducted by the Centers for Disease Control and Prevention (CDC), 8 percent of Americans are deficient in vitamin D,[11] many of whom are elderly persons living in nursing homes or other inpatient facilities, for whom vitamin D and calcium supplements can be beneficial in preventing bone fractures.[12]

However, this fact alone cannot begin to account for the recent enormous increase in vitamin D sales. The CDC survey showed that the estimated prevalence of true vitamin D deficiency in the U.S. population remained largely unchanged between 2001-02 and 2005-06, including in both women and those over age 60.[13]

Also, guidelines had recommended vitamin D for the prevention of osteoporosis in postmenopausal women for at least 10 years preceding the jump in sales.[14] The findings of the largest study to date of vitamin D in women, which revealed no benefit in preventing fractures in post-menopausal women without osteoporosis, were released at the height of the sales upsurge, in 2006.

The dramatic increase in vitamin D sales was most likely due to a wave of news stories reporting on studies claiming to show a benefit of vitamin D for a number of conditions, from hypertension to cancer. These same studies were ultimately deemed by the IOM to be insufficient to support the claims of benefit, with the exception of effects on bone health.[15]

Nutraingredients.com, a website targeted primarily to food and beverage manufacturers and advertisers, acknowledged as much in a 2010 article. It attributed the “triple-digit” market growth of vitamin D supplement sales to “recent studies … highlight[ing] diverse benefits” of vitamin D on immunity, gut health and other functions and to “good work from talk show host Oprah Winfrey,” who reportedly told her viewers that adequate levels of vitamin D consumption could be five times higher than the recommended intake levels at the time.[16]

What You Can Do

If you have osteoarthritis, do not use vitamin D supplements to treat your symptoms. (For more information on the benefits and risks of vitamin D supplements for other conditions, see “Vitamin D and Calcium for Bone Health: Getting the Right Amount” in the January 2013 issue of Worst Pills, Best Pills News.)

Osteoarthritis is often a mild condition and may cause no symptoms or only occasional joint pain and stiffness. However, many patients suffer from more severe forms of the illness, which in some cases can be debilitating. The most severe form of osteoarthritis is the type that affects the joints that bear the body’s weight, such as the hips and the knees, which can progress to a point at which walking is difficult.

If you have osteoarthritis of the hip or knee and are obese or overweight, losing weight often can be the most effective treatment. Weight loss should be achieved through a combination of diet and exercise. Exercise should put an affected joint through its full range of motion while gently avoiding excessive stress on the joint. Swimming and walking are particularly helpful, but avoid running on hard surfaces, which can aggravate osteoarthritis of the hip or knee.

If your pain persists despite weight loss and gentle exercise, oral medications also can be used to treat osteoarthritis pain. Avoid topical skin creams, which are ineffective for osteoarthritis.[17] Two common pain relievers are aspirin and acetaminophen (TYLENOL). Two 325-mg aspirin tablets, taken twice a day, can be sufficient to control osteoarthritic pain in some adults. If you cannot take aspirin (for example, if it irritates your stomach or you are at high risk for bleeding), try acetaminophen (two 325-mg tablets, taken two to three times a day).[18]

Be aware that taking either aspirin or acetaminophen at high doses for prolonged periods of time can result in severe and potentially fatal side effects. Never take more than four grams of acetaminophen[19] or aspirin[20] per day, and do not take acetaminophen for more than 10 days, unless directed by a doctor.[21]

If weight loss and a short course of pain medicines do not relieve your symptoms, your osteoarthritis may be more severe. Cases of severe osteoarthritis are sometimes treated with physical therapy, orthopedic devices and, in extreme cases, surgery.

References

[1] Arthritis and inflammation. Worst Pills.org. /chapters/view/27. Accessed June 4, 2013.

[2] McAlindon T, LaValley M, Schneider E, et al. Effect of vitamin D supplementation on progression of knee pain and cartilage volume loss in patients with symptomatic osteoarthritis: a randomized controlled trial. JAMA 2013; 309(2):155-62.

[3] Ibid.

[4] Ibid.

[5] Murdoch DR, Slow S, Chambers ST. Effect of Vitamin D3 Supplementation on Upper Respiratory Tract Infections in Healthy Adults: The VIDARIS Randomized Controlled Trial. JAMA 2012;308(13):1333-1339.

[6] Institute of Medicine, National Academies. Dietary Reference Intakes for Calcium and Vitamin D, November 2010, Revised March 2011. http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Report-Brief.aspx.

[7] The vitamin D dilemma. Consumer Reports. Updated May 2011. http://www.consumerreports.org/cro/2012/04/the-vitamin-d-dilemma/index.htm.

[8] Ibid.

[9] Has Vitamin D Been Oversold? AARP. July 5, 2012. http://www.aarp.org/health/drugs-supplements/info-07-2012/how-much-vitamin-d-is-enough.html.

[10] Ibid.

[11] CDC’s Second Nutrition Report. Chapter 2: Fat-soluble vitamins. Page 98. http://www.cdc.gov/nutritionreport/pdf/Fat.pdf#zoom=100.

[12] Vitamin D and Calcium for Bone Health: Getting the Right Amount. Worst Pills, Best Pills News 19(1):6-7.

[13] CDC’s Second Nutrition Report. Chapter 2: Fat-soluble vitamins. Page 102. http://www.cdc.gov/nutritionreport/pdf/Fat.pdf#zoom=100.

[14] Jackson RD, LaCroix AZ, Gass M, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006;354(7):669-83.

[15] The vitamin D dilemma. Consumer Reports. Updated May 2011. http://www.consumerreports.org/cro/2012/04/the-vitamin-d-dilemma/index.htm and: Has Vitamin D been oversold? AARP. http://www.aarp.org/health/drugs-supplements/info-07-2012/how-much-vitamin-d-is-enough.html

[16] Global vitamin D boom remains elusive. Nutraingredients.com Markets. http://www.nutraingredients.com/Industry/Markets-Global-vitamin-D-boom-remains-elusive.

[17] Arthritis and inflammation. Worst Pills.org. /chapters/view/27. Accessed June 4, 2013.

[18] This recommendation translates to total daily dose of 1300-1850mg a day, well below maximum dose of 4g/day.

[19] Tylenol label: DailyMed (NIH database): 12 tabs x 325mg = 3900mg: http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=118de851-8c4e-4080-8218-310493286a11#nlm34068-7. Accessed June 4, 2013.

[20] Bayer aspirin label: Daily Med (NIH database): 12 tablets x 325mg = 3900 mg. http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=11086b35-760b-460d-b1b6-e20ad6baf764#nlm34068-7. Accessed June 4, 2013.

[21] Tylenol label: DailyMed (NIH database): “don’t take more than 10 days unless directed by a doctor”: http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=118de851-8c4e-4080-8218-310493286a11#nlm34068-7. Accessed June 4, 2013.