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SPORTS MEDICINE: Vitamin D more vital than ever

SPORTS MEDICINE: Vitamin D more vital than ever


The current issue of Sports Health, an interdisciplinary medical journal, included two articles offering advice regarding COVID-19 and sports. However, the issue’s focus was on something else altogether — bone health — or was it?

Editor-in-chief Dr. Edward Wojtys set the tone in his introductory piece by warning, “Osteoporosis, a disease of bone fragility, can develop in childhood but may not present until the elder years.”

By the time victims realize they have it, though, it is too late for a cure. Instead Wojtys advises, “Optimizing bone development in childhood is critical to building strong bodies and avoiding the dreadful consequences of osteoporosis later in life.”

Those dreadful consequences include stress fractures — if one is fortunate. The less fortunate suffer compression fractures in the spine, and broken hips and wrists that necessitate surgical repair. A half-century ago, fractured hips were viewed as a death sentence. Today, they are less frequent due advances in preventive care. Still, when osteoporosis-related hip fractures do occur, nearly one-third of victims are dead within a year and fewer than half of the survivors return to the their previous level of activity.

The best opportunity for preventive care, according to Wojtys, occurs in the teenage years, decades before diagnosis. “Peak bone mass is dependent on 5 main factors: sex, race, hormones, nutrition and physical activity,” he wrote. “Sex and race are nonmodifiable, while nutrition, physical activity and hormones are.

“While all the first 20 years of life are important in bone development, approximately 40% to 60% of adult bone mass is achieved during adolescence. Interestingly, 25% of peak bone mass is acquired during the two-year span around peak height velocity: 12.5 years of age for girls and 14 years of age for boys. Nearly all (90%) peak bone mass will have accrued by the age of 18 years, often determining our fracture risk for the rest of our lives.”

Dietary calcium is key for developing strong bones.

Wojtys advises teenagers get 1,300 mg per day for optimal growth. “Keeping in mind that an 8-ounce serving of milk provides 300 mg of calcium” Wojtys wrote, “it is clear that the calcium demand for optimal growth is not easily met. I don’t know of many teenagers who drink four glasses of milk per day. For those restricted to vegetable diets and who do not consume milk or other calcium-fortified plant milks, the challenge to obtain enough calcium becomes much more difficult.”

To optimize absorption of calcium, Vitamin D is necessary. Without Vitamin D, bones are able to absorb only 10-15% of available dietary calcium, according to Wojtys. This vital substance is found in milk, eggs, fish, breakfast cereal and multivitamins. Play outside in warm weather, in a T-shirt and shorts, and the sun and your skin will combine to make it for you.

For those who do not get enough Vitamin D from sunlight or diet, supplementation helps but is overdosing a possibility?

Exposure to sunlight and/or a normal daily diet will never cause toxic levels. Nor will daily supplementation at doses as high as 4,000 IU per day, according to the Institute of Medicine.

For dark-skinned athletes and those who play their sports indoors and/or at cooler latitudes, deficiency is a problem. In fact, according to a study published in 2015 in the journal Sports Medicine, 56% of athletes had insufficient levels. A literature review published two years ago in the Journal of the American Academy of Orthopaedic Surgeons explained in detail the effects of vitamin D — or the lack of it — on athletic performance.

A British investigation of Royal Marine recruits determined that those who were vitamin D deficient were 60 percent more likely to suffer a stress fracture than those with normal levels. A look at American football pros determined that those who have suffered at least one fracture had significantly lower levels of vitamin D than those who had never had a broken bone.

Vitamin D provides benefits beyond those to bone. Daily supplementation has been shown to increase hand grip strength, bench press, leg press, vertical jump and squat, while improving sprint times.

One of the studies cited in the AAOS article found that, in a group of 80 American professional football players, 77 percent of them were vitamin D deficient. Furthermore, the lower the level of vitamin D, the greater the likelihood that the player would be released from his team prior to the start of the regular season due to injury or inadequate performance.

There is one more benefit to Vitamin D, very recently discovered. According to a study published last month in the online version of the Journal of the American Medical Association, “the relative risk of testing positive for COVID-19 was 1.77 times greater for patients with likely deficient vitamin D status compared with patients with likely sufficient vitamin D status, a difference that was statistically significant.”

Other recent studies have linked Vitamin D deficiency to severity of illness for those infected with COVID-19. Consequently, multiple medical experts from Harvard, the University of Chicago, and the Royal College of Surgeons are recommending Vitamin D supplementation. Thus a cheap and readily available substance, already acknowledged to boost athletic performance while preventing osteoporosis, is now another weapon to fight the pandemic.

John Doherty is a licensed athletic trainer and physical therapist. This column reflects solely his opinion. Reach him at Follow him on Twitter @JDohertyATCPT.


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