To investigate the effects of either a 7-day fast or a 7-day ketogenic diet upon serum interleukin-6 (IL-6) and dehydroepiandrosterone sulphate (DHEAS) in RA patients.
We measured serum concentrations of DHEAS and IL-6 in 23 RA patients with active disease, 10 of whom followed a 7-day sub-total fast and 13 of whom consumed a ketogenic diet (isoenergetic, carbohydrate < 40 g/day) for 7 days. Clinical and laboratory variables were measured at baseline, on day 7 and after re-feeding on day 21. Correlation analyses were used to assess the associations between serum IL-6, DHEAS and disease activity variables at each timepoint.
Fasting, but not the ketogenic diet, decreased serum IL-6 concentrations by 37% (p < 0.03) and improved disease activity at day 7. Both fasting and the ketogenic diet increased serum DHEAS levels by 34% as compared with baseline (both p < 0.006). Levels of IL-6, but not DHEAS, correlated with several disease activity variables.
Both fasting and a ketogenic diet significantly increased serum DHEAS concentrations in RA patients. Only fasting significantly decreased serum IL-6 levels and improved disease activity. As the increases in serum DHEAS were similar in response to both fasting and a ketogenic diet, it is unlikely that the fall in serum IL-6 or clinical improvements after fasting were directly related to increases in serum DHEAS. The fasting-induced fall in serum IL-6 may underlie the fall in CRP and ESR observed in RA patients in response to a 7-day fast.