Researchers looked at 10 studies to understand whether vitamin D helps tendons heal better after surgery. Tendons are tough cords that connect muscles to bones, and they heal slowly because they don’t get much blood flow. The review found that people with low vitamin D levels seemed to have slower healing and more problems after tendon surgery, especially for rotator cuff repairs in the shoulder. However, the studies weren’t very high quality, so scientists need more research to be sure. This could eventually help doctors decide if vitamin D supplements should be part of recovery plans for tendon injuries.

The Quick Take

  • What they studied: Whether having enough vitamin D in your body helps tendons heal better after surgery, and what happens if you don’t have enough.
  • Who participated: The review looked at 10 different studies involving adults who had tendon repair surgery. Most studies focused on shoulder tendon (rotator cuff) repairs, with very few looking at other tendons like the Achilles or knee tendons.
  • Key finding: People with low vitamin D levels appeared to have slower healing, more tendon re-tears, and weaker recovery after surgery compared to those with normal vitamin D levels. However, the evidence quality was low, meaning we can’t be completely certain yet.
  • What it means for you: If you’re having tendon surgery, maintaining healthy vitamin D levels may help your recovery, but this isn’t proven enough to make it a standard recommendation yet. Talk to your doctor about your vitamin D status before and after surgery. Don’t start high-dose supplements without medical guidance.

The Research Details

This was a scoping review, which means researchers searched through medical databases to find all available studies on vitamin D and tendon healing. They looked through three major medical databases (Embase, OVID Medline, and Emcare) for studies published through November 2024. They included both observational studies (where researchers watched what happened to people) and randomized controlled trials (where people were randomly assigned to different groups).

Two independent reviewers read through all the studies to decide which ones qualified and to pull out the important information. When they disagreed, a third reviewer helped settle it. The researchers then looked at how good the quality of each study was using a standard scoring system. Because the studies were very different from each other, they couldn’t combine the numbers mathematically, so they described the findings in words instead.

This approach is important because it gives us a complete picture of what scientists currently know about vitamin D and tendon healing. By looking at all available studies together, researchers can spot patterns and identify what we still need to learn. This type of review helps doctors and patients understand the current state of evidence before making treatment decisions.

The overall quality of evidence was low. Most studies were retrospective, meaning researchers looked backward at medical records rather than following people forward in time. A major concern is that half the studies used the same large database, so some patients may have been counted multiple times. The review focused heavily on shoulder tendons (8 out of 10 studies), leaving big gaps in knowledge about other tendons. These limitations mean we should be cautious about applying these findings until better research is done.

What the Results Show

The review found a consistent pattern: people with vitamin D deficiency (low levels) had worse outcomes after tendon surgery. Specifically, they experienced slower healing, higher rates of the tendon tearing again after surgery, and less functional improvement during recovery. The studies that looked at how vitamin D works in the body suggested it helps by reducing inflammation and helping the body rebuild the tendon tissue properly.

Most of the evidence came from rotator cuff repairs, which are surgeries on the shoulder tendon. These studies showed the clearest connection between low vitamin D and poor healing. However, the researchers emphasized that while the pattern was consistent, the quality of the studies wasn’t strong enough to say with certainty that vitamin D deficiency causes worse healing.

The mechanistic studies (research looking at how vitamin D actually works) suggested that vitamin D helps tendons heal by controlling inflammation and helping cells rebuild the tissue structure. This provides a plausible explanation for why vitamin D might matter, but these were mostly laboratory or animal studies rather than human studies. The review also noted that no studies looked at whether vitamin D supplements could actually improve healing—all the studies just compared people who naturally had different vitamin D levels.

This review builds on previous knowledge that vitamin D is important for bone and muscle health. The new finding is that it may specifically help tendon healing after surgery. However, most previous research focused on bones, not tendons. This review highlights that tendon research is much newer and less developed than bone research, which is why the evidence quality is lower.

The biggest limitation is that most studies were retrospective (looking backward) rather than prospective (following people forward). This makes it harder to prove that low vitamin D actually caused the poor healing rather than just being associated with it. Half the studies used the same database, which means some patients might have been included multiple times, making the evidence seem stronger than it actually is. Almost all research focused on shoulder tendons, so we don’t know if these findings apply to other tendons like the Achilles or knee tendons. Finally, no studies tested whether giving people vitamin D supplements actually improved their healing—they only looked at people’s natural vitamin D levels.

The Bottom Line

Current evidence suggests maintaining adequate vitamin D levels may support tendon healing after surgery, but the evidence is not strong enough to make this a standard medical recommendation yet (Low confidence). If you’re having tendon surgery, ask your doctor to check your vitamin D level beforehand. If you’re deficient, correcting it through supplements or sunlight exposure may be reasonable, but this should be done under medical supervision. Don’t assume high-dose supplements will speed healing—that hasn’t been proven.

Anyone planning tendon surgery, especially rotator cuff repair, should care about this research. People with known vitamin D deficiency should definitely discuss this with their surgeon. However, this research is less relevant for other types of tendon injuries (Achilles, patellar, flexor tendons) since almost no studies looked at those. People without tendon injuries don’t need to change their behavior based on this review alone.

If vitamin D deficiency is affecting your healing, correcting it would likely take several weeks to show effects, since vitamin D builds up in your body over time. Most tendon healing takes 3-6 months, so any benefit from vitamin D would be part of that longer timeline. Don’t expect immediate improvements from starting vitamin D supplements.

Want to Apply This Research?

  • If you’re recovering from tendon surgery, track your vitamin D supplementation (dose and frequency) alongside your pain levels and functional recovery (like range of motion or ability to perform specific activities). Record this weekly to see if there’s a pattern.
  • Set a daily reminder to take vitamin D supplements if your doctor recommends them after checking your levels. Also track sun exposure time, since natural sunlight helps your body make vitamin D. Aim for 10-30 minutes of midday sun several times per week (depending on your skin type and location).
  • Have your vitamin D levels checked before surgery and again 6-8 weeks after surgery to see if supplementation is working. Track your surgical recovery milestones (like when you can return to normal activities) and note your vitamin D status alongside these achievements. Share this data with your doctor to help inform future treatment decisions.

This review summarizes current research on vitamin D and tendon healing, but the evidence quality is low and mostly limited to shoulder tendon repairs. These findings should not replace professional medical advice. Before starting vitamin D supplements or making changes to your recovery plan after tendon surgery, consult with your orthopedic surgeon or healthcare provider. Individual vitamin D needs vary based on age, location, skin type, and medical history. This information is educational and not a substitute for personalized medical recommendations.