Benefits
Weight loss alongside a hypocaloric diet (Di Pierro 2009, blinding not stated)
In a 90-day controlled trial in 100 obese adults, 300 mg/day Greenselect Phytosome plus a hypocaloric diet was reported to produce about 14 kg of weight loss versus about 5 kg on the diet alone, with BMI falling in step. Read the design alongside the number: the paper describes a controlled trial and does not state that it was blinded, so participants and staff may have known who was taking the extract, which matters a great deal in a diet study. This is the largest of the three trials but the weakest design, and a 14 kg loss in 90 days is a very large effect for an unblinded study. The comparison was against diet alone, not against a standard green tea extract, so the trial cannot show that phytosome absorption is why the groups differed.
Metabolic markers in borderline metabolic syndrome (24 week registry study)
In a controlled study of adults with borderline metabolic syndrome and raised oxidative stress markers (50 taking the extract, 50 controls), 300 mg/day (two 150 mg tablets) for 24 weeks was followed by 68 percent of the treated group no longer meeting the metabolic syndrome profile, against 20 percent of controls, with movement in weight, blood lipids, blood pressure and waist circumference. The abstract calls this a registry study while the methods describe a randomized, single-blind comparison with a blank tablet, so the paper contradicts itself on design. At most one side was blinded, and if people chose whether to take the supplement they may also have differed in diet, activity and motivation. Read this as a signal worth testing properly, not as evidence that the ingredient treats or reverses a diagnosed condition.
EGCG absorption: higher from the phytosome in one single-dose study
The only absorption reference cited here is a 1998 human study in which volunteers took a single dose of either Greenselect (free catechins) or Greenselect Phytosome, equivalent to 400 mg EGCG, about ten times the EGCG in the daily 300 mg dose. Catechins were absorbed more extensively from the phytosome, but the abstract gives no figure, so it cannot confirm that the phytosome more than doubles peak plasma EGCG at an equal 240 mg catechin dose. The underlying problem is real: EGCG is poorly absorbed from ordinary green tea extract, and complexing catechins with phospholipid is a reasonable way to try to improve that. But the size of the improvement quoted here is not backed by any citation on this page, so a reader has no way to check it.
Post-menopausal metabolism claim (uncited)
Nothing cited on this page supports this. The respiratory quotient, resting energy expenditure, carbohydrate oxidation and lipid oxidation results described for sedentary post-menopausal women at 150 mg/day do not come from any of the four references listed here, so a reader has no way to check who was studied, how many, for how long, or whether the changes were statistically significant. Treat it as unverified until a citation is attached.
Caffeine-free for evening/sensitive use
≤0.1% caffeine specification (vs 1-5% in non-decaffeinated green tea extracts) makes Greenselect Phytosome suitable for evening dosing schedules and caffeine-sensitive populations. The low caffeine figure is a specification of the raw material rather than a measured outcome: none of the cited trials tested sleep, alertness or jitteriness.
Weight maintenance after weight loss (the one double-blind trial, 40 women)
This is the only double-blind placebo-controlled trial on the page, and it is also the smallest: 40 obese women, 20 per group, taking 150 mg twice daily together with 15 mg piperine for 3 months following a period of weight loss. The treated group lost a further 1.0 kg on average while the placebo group gained 0.3 kg, and 75 percent versus 45 percent held on to at least 5 percent of their earlier weight loss at the one-month mark. Two things a buyer should weigh: the difference between the groups is only about 1.3 kg, and the capsules also contained piperine, so the trial cannot tell you how much of the result belongs to the catechins. It is still the best-designed evidence here.
Lower plasma free radicals over 24 weeks alongside diet and exercise
In one 24-week controlled study, adults borderline for metabolic syndrome with raised oxidative stress took 300 mg/day Greenselect Phytosome or a blank tablet with a diet and exercise plan. Plasma free radicals fell 33% vs 4% in controls (between-group P<0.022). It is a single trial from one research group, the paper calls itself both a registry and a randomized single-blind study, and the assay is a lab marker, not a felt outcome.
Mechanism of action
Phytosome bioavailability enhancement
Phytosome® technology complexes EGCG and other catechins with phosphatidylcholine, creating amphipathic structures that improve absorption through the intestinal epithelium. The one head-to-head study cited here, a 1998 single-dose study at a dose equivalent to 400 mg EGCG, reported more extensive catechin absorption from the phytosome than from free catechins, but its abstract gives no figure, so the size of the advantage is not documented here.
Catechin-COMT inhibition (norepinephrine extension)
EGCG and other catechins inhibit catechol-O-methyltransferase (COMT), the enzyme that degrades norepinephrine. Extended norepinephrine action prolongs sympathetic-driven thermogenesis and lipolysis. Without caffeine, this effect is milder but free of caffeine-related side effects.
Fat oxidation upregulation
Catechins upregulate fatty acid oxidation enzymes (CPT1, ACO) in skeletal muscle and liver, supporting use of stored fat for energy. Combined with the thermogenic effect, this shifts metabolism toward fat utilization.
Antioxidant protection
Catechins are potent antioxidants — EGCG has one of the highest antioxidant capacities of all polyphenols. Antioxidant capacity of this kind is measured mostly in test-tube assays and does not by itself tell you what happens in a person. In the 24-week controlled study, plasma free radicals fell 33% with 300 mg/day versus 4% in controls, and in the 1998 single-dose study both Greenselect forms raised plasma total radical-trapping capacity by 16 to 19% while briefly lowering plasma vitamin C and glutathione by 10 to 20%, at a dose far above the daily one. The antioxidant category on this page is measured in people, but in one small, at best single-blind trial.
Clinical trials
90-day clinical trial in 100 obese patients comparing 300 mg/day Greenselect Phytosome + hypocaloric diet vs hypocaloric diet alone.
100 obese patients
90-day clinical trial in 100 obese patients comparing 300 mg/day Greenselect Phytosome + hypocaloric diet vs hypocaloric diet alone. The phytosome group lost about 14 kg against about 5 kg in the diet-alone group, with a corresponding fall in BMI. Design caveat that belongs next to that number: the paper describes a controlled trial and does not state that it was blinded, so participants and staff may have known their allocation, and expectation effects are hard to rule out in a diet study. The comparison arm was diet alone, not a standard green tea extract, so the study cannot show that phytosome absorption is the reason for the difference, nor can it be compared with what standard extracts achieve. Reference: PMID 19594224, Di Pierro 2009, whose lead author is affiliated with Velleja Research.
Controlled study of Greenselect Phytosome versus a blank tablet, described in the abstract as a registry and in the methods as randomized and single-blind.
100 asymptomatic adults with borderline metabolic syndrome and raised oxidative stress markers (50 taking the extract, 48 of whom completed, and 50 controls), followed for 24 weeks.
300 mg/day Greenselect Phytosome (two 150 mg MonCam tablets) for 24 weeks, or a blank tablet, alongside a diet and exercise plan. Plasma free radicals fell 33% in the treated group vs 4% in controls (P<0.022 between groups). Outcome: 68% of treatment-arm subjects exited the metabolic syndrome profile vs 20% in controls. Improvements in weight, blood lipids, blood pressure, and waist circumference. Published in Evidence-Based Complementary and Alternative Medicine in 2013 (PMID 24348726). No side effects were reported. The abstract calls it a registry study while the methods describe a randomized, single-blind comparison with a blank tablet; with the paper contradicting itself and no double blinding, it cannot rule out that people who chose the supplement also changed diet or activity more than the controls did.