High levels of total cholesterol are linked to a heightened risk of tendon abnormalities and pain, according to a review of available evidence by Australian researchers.
Mechanical stress as a result of obesity or excess body fat distribution, and overuse during the course of exercise or work, are thought to be among the leading causes of tendinopathy.
But these factors do not explain a significant proportion of cases, said the researchers from Monash University in Melbourne.
“These findings provide significant support for a metabolic hypothesis of tendon injury and implicate lipid parameters as a potential link”
They noted that patients with familial hypercholesterolaemia seemed to be at greater risk of tendon pain. However, they said it was not clear if those with lower, but still high levels, might also be vulnerable to tendon injuries.
The study authors therefore trawled six medical research databases, looking for studies investigating links between blood fats and tendon abnormalities and related pain.
They identified 17 articles, involving 2,612 participants, to use in their analysis.
The results showed that, compared with people whose tendon structure was normal, those with abnormal tendon structure had a significantly more unfavourable lipid profile.
They had significantly higher total cholesterol, including higher low density cholesterol and lower high density cholesterol, and higher triglyceride levels.
In addition, people with an unfavourable lipid profile were much more likely to have tendon injuries and higher levels of pain associated with musculoskeletal problems in their arms.
Two studies that looked at Achilles tendon thickness found people with an unfavourable lipid profile had thicker tendons than those with lipid levels in the normal range.
“Together, these findings provide significant support for a metabolic hypothesis of tendon injury and implicate lipid parameters as a potential link,” stated the researchers in the British Journal of Sports Medicine.
There was good evidence to suggest a poor blood lipid profile may be harmful to tendons, they said, because people with familial hypercholesterolaemia had altered tendon structure throughout childhood and adolescence, and aggressive lipid-lowering treatment reduced tendon thickness.
High cholesterol levels were also known to stimulate the build-up of cholesterol in immune system cells, which in turn leads to low level chronic inflammation. People with tendinopathy have increased numbers of these immune cells in their tendons, said the researchers.
However, they cautioned that their research was an observational study and, therefore, no definitive conclusions could be drawn about cause and effect.