Tendon injuries, especially Achilles tendinitis, cause pain and swelling that can last a long time. Researchers tested whether combining a special electrical treatment with natural supplements could help tendons heal faster. They studied rats with induced tendon injuries and gave some groups supplements containing olive extract, a compound from olive oil, and amino acids. The results showed that combining the electrical treatment with these natural supplements worked better than the electrical treatment alone. One supplement in particular—hydroxytyrosol from olive oil—showed the strongest healing benefits and reduced inflammation and damage in the tendons.

The Quick Take

  • What they studied: Whether natural supplements combined with electrical therapy could help injured tendons heal better and faster
  • Who participated: Laboratory rats with artificially created tendon injuries similar to Achilles tendinitis in humans. Different groups received different treatments over several weeks.
  • Key finding: Combining electrical therapy with natural supplements (especially hydroxytyrosol from olive oil) significantly improved tendon healing compared to electrical therapy alone, with reduced inflammation and tissue damage markers
  • What it means for you: This research suggests that natural compounds from olive oil may help support tendon recovery, though human studies are still needed. If you have a tendon injury, discuss these findings with your doctor before trying supplements, as this was animal research.

The Research Details

Researchers used laboratory rats to model Achilles tendinitis, a common tendon injury in humans. They created tendon injuries in the rats and then divided them into different treatment groups. Some rats received electrical therapy (called percutaneous intratissue electrolysis), some received dietary supplements containing natural compounds, some received both treatments, and some received neither as a control group. The supplements included hydroxytyrosol (a compound from olive oil), maslinic acid (another olive compound), and amino acids (glycine and aspartic acid). The researchers fed these supplements directly in the rats’ food at specific doses over the course of the study.

Tendon samples were collected at different healing stages to examine what was happening inside the tissue. The researchers used several laboratory techniques to look at the tissue structure, count different cell types, and measure inflammation and damage markers. They stained tissue samples to see collagen fiber organization and fibroblast cells, and used protein analysis to measure inflammatory chemicals and oxidative stress (cellular damage from harmful molecules).

This type of study design allows researchers to carefully control variables and observe healing processes that would be difficult to study in humans. However, results in rats don’t always translate directly to humans.

Understanding how tendons heal at the cellular level is important because tendon injuries are common and often heal slowly, causing long-term pain and disability. By studying the molecular changes during healing, researchers can identify which treatments actually promote tissue repair rather than just reducing pain temporarily. Testing combinations of treatments helps determine whether they work better together than separately.

This study has several strengths: it used a controlled animal model, measured multiple healing markers, examined tissue at different healing stages, and tested multiple compounds. However, the study was conducted in rats, not humans, so results may not apply directly to people. The abstract doesn’t specify the exact number of animals used, which would help assess statistical power. Animal studies are valuable for initial testing but require human clinical trials to confirm effectiveness and safety in people.

What the Results Show

The combination of electrical therapy plus nutritional supplements produced significantly better tendon healing than electrical therapy alone. Among the supplements tested, hydroxytyrosol (HT)—a natural compound extracted from olive oil—showed the strongest healing effects. The HT group demonstrated reduced inflammation markers, meaning fewer inflammatory chemicals were present in the injured tissue. Tissue examination showed better collagen fiber organization (the structural protein that gives tendons strength) and improved fibroblast density (the cells responsible for building new tissue).

The researchers also measured oxidative stress, which is cellular damage caused by harmful molecules called free radicals. The HT group showed significantly lower levels of MDA (a marker of oxidative damage), indicating that this compound protected the tissue from this type of damage. Maslinic acid, another olive-derived compound, also showed benefits but not as strong as hydroxytyrosol.

When electrical therapy was combined with supplements, the healing improvements were greater than either treatment alone, suggesting the treatments work together synergistically. The study examined tissue at multiple healing stages, showing that the benefits appeared throughout the recovery process.

The amino acid combination (glycine and aspartic acid) showed some benefit but less dramatic effects than the olive-derived compounds. The study measured several inflammatory and stress-related proteins in the tissue, and the supplement groups showed more favorable patterns in these markers. The tissue structure analysis revealed that supplemented groups had better organization of collagen fibers, which is important for tendon strength and function. The research also suggests that nutritional supplementation alone (without electrical therapy) may be a viable option for people who cannot receive electrical therapy due to medical contraindications.

This research builds on existing knowledge that inflammation and oxidative stress play major roles in tendon injury and slow healing. Previous studies have suggested that olive oil compounds have anti-inflammatory properties, but this appears to be one of the first studies systematically testing these compounds in tendon injury recovery. The finding that combining treatments works better than single treatments aligns with current thinking in regenerative medicine that multi-targeted approaches may be more effective.

This study was conducted in rats, and animal results don’t always translate to humans due to differences in metabolism, healing rates, and physiology. The exact number of animals in each group wasn’t specified in the abstract, making it difficult to assess whether the sample size was adequate. The study used artificially induced tendon injuries, which may not perfectly replicate naturally occurring tendon injuries in humans. The doses used in rats would need to be carefully adjusted for human use. Long-term follow-up data in humans would be needed to determine if benefits persist and whether there are any side effects with prolonged use.

The Bottom Line

Based on this animal research, hydroxytyrosol and maslinic acid (compounds from olive oil) appear promising for supporting tendon healing when combined with appropriate physical therapy or medical treatment. However, this is preliminary research in animals. If you have a tendon injury, work with your healthcare provider on evidence-based treatments. You might discuss whether olive oil-derived supplements could be a complementary addition to your treatment plan, but don’t rely on supplements alone without professional medical guidance. Confidence level: Low to Moderate (animal study only—human trials needed).

This research is most relevant to people with Achilles tendinitis or other tendon injuries, athletes dealing with overuse injuries, and healthcare providers treating tendon conditions. It may also interest people interested in natural anti-inflammatory compounds. This research should NOT be used to self-treat tendon injuries without medical supervision. People with olive allergies should avoid these compounds.

In the rat study, improvements were observed over several weeks. In humans, tendon healing typically takes 6-12 weeks or longer depending on injury severity. If these findings translate to humans, you might expect to see gradual improvements over weeks to months, not days. Patience and consistent treatment are important.

Want to Apply This Research?

  • If using supplements under medical guidance, track: (1) Pain level on a 0-10 scale daily, (2) Range of motion/flexibility weekly, (3) Swelling/inflammation observations, (4) Functional activities you can perform (walking distance, stairs, etc.), and (5) Supplement adherence (did you take it as planned?)
  • Work with your healthcare provider to: (1) Add olive oil-derived supplements to your routine if appropriate, (2) Combine supplements with prescribed physical therapy exercises, (3) Maintain consistent dosing and timing, (4) Track how your tendon feels during and after activity, and (5) Adjust activity levels based on pain and swelling
  • Create a weekly check-in routine: photograph any visible swelling, record pain levels at rest and with activity, note which movements are easier or harder, and assess overall function (can you do more than last week?). Share this data with your healthcare provider monthly to evaluate whether the treatment approach is working and adjust as needed.

This research was conducted in laboratory rats and has not been tested in humans. These findings are preliminary and should not be used as a basis for self-treatment. If you have a tendon injury or Achilles tendinitis, consult with a qualified healthcare provider (physician, physical therapist, or sports medicine specialist) before starting any supplement regimen. Supplements are not regulated the same way as medications and may interact with other treatments or conditions. This article is for educational purposes only and does not constitute medical advice. Always seek professional medical guidance for diagnosis and treatment of tendon injuries.