Medical research conducted in Venezuela by Kalvatchev, Walder, and Garzaro, 1997, examined the flowers of Calendula Officinalis for potential "ability to inhibit the human immunodeficiency virus type 1 (HIV-1)." The conclusion of their study was that organic extracts of Calendula "exhibited potent anti-HIV activity in an in vitro MTT/tetrazolium-based assay."

     The summary also reports that "in the presence of the organic extract … the uninfected Molt-4 cells were completely protected for up to 24 h from fusion and subsequent death, caused by co-cultivation with persistently infected U-937/HIV-1 cells." Also, "the organic extract from Calendula officinalis flowers caused a significant dose- and time-dependent reduction of HIV-1 reverse transcription (RT) activity." This reports shows "an 85 % RT [reverse transcription] inhibition achieved after a 30 min treatment of partially purified enzyme in a cell-free system."

     The Herb Research Foundation quotes that "In vitro (test tube) research has shown that calendula contains antimicrobial compounds that inhibit certain strains of Staphylococcus and Candida, as well as E. coli and some protozoa, such as Trichomonas (Mayes, 2001)." More research discussed by Mayes "suggests that calendula gently stimulates the immune system and promotes lymphatic drainage, reduces inflammation and pain, lowers cholesterol and triglycerides, and inhibits tumor growth." Another benefit attributed to this herb are stimulation of the digestive system, caused by the "bitter green calyx that surrounds the flower." Finally, the "lycopene" found in the Calendula flowers "has recently been shown to be beneficial to prostate health," reports Mayes. Mayes also points out that "Calendula is perhaps best known for its effectiveness in healing skin problems such as wounds, burns, insect bites, eczema, skin ulcers, and rashes."