Understanding the molecular mechanisms of cancer prevention by dietary phytochemicals: From experimental models to clinical trials

Table 3 Evaluation of dietary phytochemicals in clinical trials

Compounds	No. of clinical trials		Chemopreventive agent administered		Target organs	Efficacy	Bioavailability/toxicity issues	Ref.
	Conducted	Results reported	High risk individuals/patients1	Route-dose range
Curcumin	52	3	-/+	Oral: 0.036-8 g daily	Multiple organ sites	+(2)/-(1)	+(1)/-(3)	[105-107]
Genistein	29	7	-/+	Oral: 160-600 mg/d	Breast, urothelial bladder, Mammary gland	NR	+(1)/-(1)	[108,109]
Indoles	4	0	-/+	Oral: 2 serving (½ cup/serving) daily	Prostate, breast, blood	NR	NR/NR	NR
Tocopherols	28	9	+/+	Oral: 50-500 mg/d, 400-1000 IU/d	Prostate, lung	NR	NR/+(2)	[110]
Dially Sulfide	0	0	-/-	NR	NR	NR	NR/NR	NR
Resveratrol	5	2	-/+	Oral: 20-80 mg/d	Colorectal, colon	+(2)	+(1)/-(2)	[32,111]
Retinoids	102	17	+/+	Oral: 1-80 mg/d	Lung, blood, prostate, kidney, skin, blood, head and neck, liver	+(3)/-(7)	NR/+(2)	[112,113]
Capsaicin	2	0	-/+	Oral: 112 mg twice daily for 6 mo, one capsaicin lozenge 4 times daily	Prostate, head and neck	NR	NR/NR	NR
PEITC	9	1	-/+	Oral: Broccoli (300 g) soup four times daily for 5 d, Broccoli seed extract (250 mg), 40 mg PEITC capsules 4 times a day	Lung, oral	-(1)	NR/-(1)	NR
Lycopene	26	24	-/+	Oral: 15-90 mg/d	Prostate	+(1)/-(1)	+(2)/NR	[114,115]
Green tea	85	6	-/+	Oral: 400-2000 mg twice a day, (daily dose is equivalent of 9 cup-of-green tea per day (0.9 g/d GTE, 0.6 g/d EGCG)	Blood, colorectal, prostate, pancreas	+(3)/-3	+(3)/-(3)	[116-118]

¹Study cohort is exclusively of cancer patients. Source: https://clinicaltrials.gov. +: Present; -: Not observed; NR: Not reported; PEITC: Phenethyl isothiocyanate.