DIGOXIN-LIKE FACTORS IN HERBAL TEAS

Forty-six commercially packaged teas and 78 teas prepared from purchas ed herbs were assayed for digoxin-like factors (DLF) by their crossrea ctivity with digoxin antibody (immuno-crossreactive DLF) and by their inhibition of ouabain binding to membrane Na,K-ATPase (NKA inhibitory DLF). Three packaged teas and 3 herbs gave NKA inhibitory DLF values > 30 mug digoxin equivalents/cup. Two packaged teas and 3 herbs gave imm uno-crossreactive DLF values >.050 mug digoxin equivalents/cup. One he rb, pleurisy root, had a crossreactive DLF value of 187 mug/cup and NK A inhibitory DLF equivalent to 3658 mug/cup. Plasma digoxin-like facto rs were measured after ingestion of the 3 commercially packaged herbal teas with highest values for NKA inhibitory DLF. After ingestion of e ach of the 3 teas, plasma NKA inhibitory DLF increased, in one case mo re than 100-fold. Two teas produced a measurable increase in plasma im muno-crossreactive DLF after ingestion. Some digoxin-like factors in h uman plasma may have a dietary source.