Thirteen studies were included in the review: five outcome evaluations (approximately 647 participants) and eight process evaluations (number of participants not reported). Only one of the five studies that were appraised for quality was assessed as having avoided selection, attrition and selective reporting biases. As a result, this was the only outcome evaluation study included in the narrative synthesis.
Outcome evaluations (five studies): A cluster randomised controlled trial (304 participants) of a peer-led cooking club for adults aged 65 years or more living in sheltered housing in socially deprived areas was included. At one year follow-up the intervention participants had increased the percentage of energy obtained from carbohydrates and had lower levels of vitamin D in their diet than the control participants. The intervention participants were more likely to perceive their diet as being healthier than it actually was. There was no evidence that the cooking club had any effect on knowledge, attitudes, physical health or any other dietary aspects measured.
The four remaining studies were reported as having considerable constraints that included difficulties in relation to recruitment of participants and drop-outs, so it was not possible to determine whether the outcome findings could be attributed to the cooking courses being evaluated.
Process evaluations (eight studies): One cluster randomised trial (304 participants, same as in outcome evaluations) reported that participants enjoyed the courses (largely due to social reasons) and appreciated learning from people of similar ages and levels of authority. A common barrier to participation was difficulty accessing the cooking ingredients. The findings from other studies included difficulties from limited facilities and lack of motivation among volunteers.