Knee osteoarthritis: no demonstrated additional benefit from active vitamin D3 or vitamin E alongside exercise

Three groups to test the value of adding vitamins

The trial randomly assigned 88 postmenopausal women with symptomatic knee osteoarthritis, radiographic grade 2 to 4, to three groups. Their mean age was 71.9 years. One group performed only lower-limb exercises at home, another also received active vitamin D3, and the third received vitamin E.

The isometric exercises were performed twice a day for 24 weeks. The primary outcome measure was the Japanese Knee Osteoarthritis Measure questionnaire, or JKOM. The researchers also measured muscle strength, performance on a 10-meter walk test, inflammatory markers and bone mineral density. In total, 80 participants completed follow-up.

Improvements, but no demonstrated advantage between groups

In all three groups, JKOM scores, quadriceps strength and walking test performance improved statistically significantly. However, between-group comparisons showed no significant advantage from adding vitamins for symptoms, muscle strength or physical performance.

Grip strength improved significantly only in the active vitamin D3 group. Inflammatory markers also decreased in the vitamin E group. These within-group changes are not enough to establish a benefit from the supplement: the corresponding between-group differences were not significant.

The abstract reports a between-group difference in bone mineral density without specifying its direction or magnitude. It therefore provides no basis for a practical conclusion.

What this trial tells us

This trial provides no compelling evidence for routinely adding these vitamins to exercise to improve knee osteoarthritis. However, it does not assess all populations or formulations: the vitamin D3 studied was an active form, not interchangeable with ordinary vitamin D3 supplements.

The pilot design and small sample size limit the ability to detect modest differences. The abstract does not provide doses, effect sizes or confidence intervals. It also does not allow an assessment of adverse effects, funding or conflicts of interest.

What we can take away

In this trial, adding active vitamin D3 or vitamin E to exercise did not demonstrate any additional improvement in symptoms or physical abilities.