The results presented here support this idea because, after the intervention with the synbiotic, a significant physiological increase in cortisol is observed, together with a decrease in DHEA, particularly in the group without previous diagnosis of CFS, clearly suggesting that the synbiotic generated an activation of the HPA axis (cortisol/DHEA ratio) to compensate for the low-grade inflammation (elevated IL-8) observed in FM patients, also particularly relevant in those without previous diagnosis of CFS. The gene discussed is CXCL8; the disease is myalgic encephalomeyelitis/chronic fatigue syndrome.