Benefits
Food source of apigenin that reaches the bloodstream
Parsley is rich in apiin, a sugar-bound form of apigenin. After a single large serving of blanched parsley, apigenin rose in the blood of healthy adults and peaked about seven hours later, and a dried parsley drink led to apigenin metabolites in urine. Only a small share of the apigenin eaten was recovered, and results varied widely between people.
Antioxidant enzyme activity in a controlled diet study
In a randomized crossover study of 14 adults on a strictly controlled low-flavonoid diet, a week with added parsley raised the activity of two red blood cell antioxidant enzymes, glutathione reductase and superoxide dismutase, compared with the plain diet, partly offsetting a decline in enzyme activity seen over the two weeks. Two other enzymes and a marker of protein oxidation did not change. The study was small and short.
Supplies vitamin K and vitamin C as a fresh herb
According to USDA food composition data, 100 g of fresh parsley provides about 1,640 mcg of vitamin K1 and 133 mg of vitamin C. A tablespoon of chopped leaf (about 3.8 g) adds roughly 60 mcg of vitamin K, while a cup (about 60 g) adds close to 1,000 mcg, several times the daily adequate intake for adults.
Traditional use as a diuretic
Parsley has a long folk reputation for increasing urine flow. Support comes from rats: animals drinking a parsley seed extract passed more urine over 24 hours, and the extract raised urine flow in a perfused rat kidney. No study in people has measured urine output after parsley, so the effect in humans is unknown.
Freshening garlic breath
In a laboratory study that measured garlic odor compounds on human breath, raw parsley was among the foods eaten after raw garlic that reduced the volatiles, alongside raw apple, spinach and mint. The authors attributed this to enzymes in the fresh leaf that oxidize its polyphenols. The study tested single servings right after garlic.
Body measures and blood lipids in a parsley seed bread diet study
In 85 women with obesity, four weeks of bread made with ground parsley seed, eaten as part of a low-calorie diet, was followed by lower body measures, blood lipids and creatinine. The values rose again when ordinary bread replaced it. With no separate control group and a diet change at the same time, the effect of parsley itself cannot be isolated.
Mechanism of action
Apiin is absorbed slowly as apigenin metabolites
Parsley's apigenin is mostly bound to sugars as apiin. In people, apigenin from parsley peaked in the blood about 4 to 7 hours after eating, which points to absorption lower in the gut, and it circulated as glucuronide and sulfate metabolites. Taking dried parsley with yogurt delayed the peak to about 6 hours.
Kidney sodium pump inhibition in rats
A parsley seed extract lowered the activity of the Na+/K+ ATPase pump in rat kidney tissue. The authors propose this reduces sodium and potassium reabsorption so that water follows into the urine. In a separate rat study, parsley seed extract reduced net water absorption in perfused colon, the proposed basis of parsley's folk use as a laxative.
Alkenylbenzenes in the volatile oil
Parsley oil contains apiol and myristicin, alkenylbenzenes that are concentrated in the seed (apiol 11.3 to 67.5 percent of seed oil). Risk assessments of parsley teas and parsley based supplements found margins of exposure that flag concern for daily use over long periods, though not for short-term use.
Polyphenol oxidase acting on odor compounds
Raw parsley contains enzymes that oxidize its own polyphenols when the leaf is chewed. The oxidized polyphenols are thought to deodorize garlic sulfur volatiles such as allyl methyl disulfide and diallyl disulfide, lowering what reaches the breath. This is a proposed mechanism from one food science study.
Clinical trials
Randomized crossover trial in which a strictly controlled diet low in flavones and other natural antioxidants was given for 2 weeks, with parsley added in one of the weeks (Nielsen et al. 1999, Br J Nutr)
14 adults (7 men and 7 women).
Urinary apigenin rose during the parsley week, with about 0.58 percent of the apigenin eaten excreted in urine. Red blood cell glutathione reductase and superoxide dismutase activity rose compared with the plain diet (P < 0.005), while catalase, glutathione peroxidase and a plasma protein oxidation marker did not change. Enzyme activity drifted down over the 2 weeks overall, and the authors say parsley partly offset that decline.
Randomized crossover study that fed onions, dried parsley or a placebo for 7 days each, alongside laboratory tests of apigenin on platelets (Janssen et al. 1998, Am J Clin Nutr)
18 healthy volunteers; the parsley period gave 5 g dried parsley a day, providing 84 mg apigenin a day.
Parsley had no significant effect on platelet aggregation, thromboxane B2, factor VII or other clotting measures, and plasma apigenin could not be measured. Apigenin blocked platelet aggregation in the test tube only at very high concentrations (2500 micromol/L), which the authors conclude cannot be reached by eating it.
Single-dose bioavailability study of blanched parsley after an apigenin-free and luteolin-free diet, with blood sampled over 28 hours and urine collected for 24 hours (Meyer et al. 2006, Ann Nutr Metab)
11 healthy adults (5 women, 6 men) aged 23 to 41; one serving of 2 g blanched parsley per kg body weight.
Plasma apigenin peaked at an average of 127 nmol/L about 7.2 hours after eating, with large differences between people, and fell below detection within 28 hours. Only about 0.22 percent of the ingested apigenin appeared in 24-hour urine. The authors conclude that a small portion of apigenin from food reaches the circulation.
Registered absorption and excretion study (NCT03526081) comparing pure apigenin, a dried parsley drink, dried parsley in yogurt and chamomile tea (Borges et al. 2022, Free Radic Biol Med)
Healthy adult men; 17 enrolled according to the trial registry. The parsley drink was 3.2 g dried parsley in 300 mL hot water.
Pure apigenin was poorly absorbed, with metabolites equal to 0.5 percent of intake in urine. After the parsley drink the main metabolite peaked at 4 hours and urinary metabolites equaled 11.2 percent of intake; parsley in yogurt pushed the peak to 6 hours. Chamomile tea peaked at 2 hours with 34 percent recovered.
Two-phase nutritional intervention: 4 weeks of ground parsley seed bread plus a low-calorie balanced diet, then 4 weeks with ordinary baladi bread at equal calories (Essa et al. 2024, Clin Nutr ESPEN)
85 women with obesity (average BMI 35.7).
During the parsley seed bread phase, body measures, blood lipids, creatinine, osteopontin and IL-1 beta fell and eGFR and IL-10 rose; the values returned toward baseline after the bread was replaced. The abstract describes no separate control group, and the bread was paired with a calorie-restricted diet, so the change cannot be attributed to parsley seed alone.
Laboratory study measuring garlic sulfur volatiles on human breath by selected ion flow tube mass spectrometry after raw garlic followed by different foods and drinks, plus headspace tests of blended mixtures (Munch et al. 2014, J Food Sci)
People eating raw garlic followed by a test food; participant numbers are not given in the abstract.
Raw parsley was among the treatments that lowered garlic volatiles, which the authors attribute to enzymatic oxidation of polyphenols, as with raw apple, spinach and mint. Chlorophyllin and whey protein did not deodorize. Headspace results did not correlate well with breath results.