Forsythia Extract modulated immune responses through multiple targets, and its primary active constituents Phillyrin and Forsythoside A demonstrated excellent immune-enhancing activity in studies. In a 2023 Phytomine study, administration of 100mg daily of forsythia extract (containing Phillyrin≥8%) increased natural killer cell (NK) activity by 32% (comparatively to controls at 5%). CD4+/CD8+ T cell ratio was also optimized to 1.8-2.5 (normal baseline 1.5), which enhanced antiviral capability. In the influenza model, the forsythias extract (0.5mg/mL concentration) boosted virus replication inhibition by 78% (65% in control oseltamivir).
Anti-inflammatory processes cooperate with immune homeostasis promotion. Forsythia Extract A from forsythia decreased pro-inflammatory mediator secretion of IL-6 and TNF-α by 40%-60% through modulation of the NF-κB pathway (test concentration 10μM in vitro). Clinical trials have shown that in the case of patients with chronic pharyngitis who were given 300mg of forsythia extract daily, the level of CRP, a marker of inflammation, decreased by 42% (8% in controls) after 4 weeks, and the proportion of symptom relief was up to 75% (30% in controls).
Anti-oxidative stress defends immune cells. The free radical scavenging activity (ORAC value) of forsythiin was 15,000 μmol TE/g, three times the size of that of vitamin C (5,000 μmol TE/g). In an oxidative stress model, Forsythia Extract (50μg/mL concentration) increased lymphocyte viability from 55% to 88% and reduced the DNA damage marker 8-OHdG by 67%.
Regulates intestinal immune barrier. Animal experiments showed that forsythia extract (200mg/kg/day) can increase intestinal secreted IgA level by 35%, inhibit adhesion rate of harmful bacteria (e.g., Escherichia coli) by ≥50%, and promote growth of probiotics such as bifidobacteria by 20%. By conducting human clinical trials, intervention group of forsythias (150mg/day) reduced intestinal permeability (L/M ratio) by 28% and reduced the possibility of intestinal leakage by 45%.
Clinical effectiveness and epidemiological validation. In a 2022 randomized controlled trial of 1,200 health care workers, six months of Forsythia Extract supplementation (200mg/day) reduced the incidence of respiratory infections by 55% (compared to 12% for controls) and reduced the duration of illness by 2.3 days. Forsythia Shuangqing capsule (with extract) was approved by China’s National Medical Products Administration (NMPA) for the treatment of acute upper respiratory tract infections with an effective rate of 89.7% (multicentre Phase III trial).
Synergies and safety. Synergic action of Forsythia Extract was shown in combination with Radix isatis Extract. The inhibition rate against H1N1 virus by Forsythia Extract was boosted from 68% to 92% (CI=0.45, synergistic index). Toxicological studies confirmed LD50 > 5,000mg/kg (rats), continuous administration for 12 months exhibited no significant abnormalities in liver and kidney function indexes (P > 0.05).
Market application confirms value. The size of the global Forsythia extract market was 420 million US dollars in 2023, increasing by 12% each year, and among which 58% were immune health products. The TOP3 botanical immune supplements best-selling on Amazon in the US all contain Forsythia Extract inside, and the re-purchase rate is over 45% (the market average is 25%). The data support its effectiveness to protect multi-dimension immunity from molecular mechanisms to clinic application.