Abstract In cancer patients, appetite and immune status are significantly weakened. Two experimental fermented formulations without (group A, named as FSWW08) and with (group B, FSWW08) an extract from yam root were investigated against a placebo formulation with casein (group C) in a clinical study conducted in six cancer hospitals where cancer patients underwent radio or chemotherapy (patients undergoing radiation therapy n=78, patients undergoing chemotherapy n=184, total 262). IgG and IgA were increased by formulation A in patients despite receiving radio- or chemotherapy. Group A experienced statistically significant increases in lymphocyte transformation rates, whereas group B and group C did not. Formulations A and B either inhibited or lessened statistically significant decreases in white blood counts, whereas the placebo group experienced substantial decreases. Hemoglobin and platelet decreases were inhibited in group A, although not statistically significantly. Patients in group A received no blood transfusions, whereas many patients from the placebo group received blood transfusions. Appetite loss was reduced in group A from 57.9% to 13.3% and in group B from 70% to 35.8%. In the placebo group, an increase in appetite loss was detected under chemo and radiation therapy from 41.8% to 70.9%.