supplements
7 interactions related to supplements
rosuvastatin + berberine
Rosuvastatin is taken into liver cells by the OATP1B1 transporter, and berberine has been shown to upregulate OATP1B1 in hepatocyte studies, increasing hepatic uptake of rosuvastatin. The clinical net effect (more LDL lowering vs. higher muscle/liver risk) is not well established in humans.
caffeine + ashwagandha
Ashwagandha is an adaptogen that lowers cortisol and reduces perceived anxiety; caffeine is a stimulant that raises cortisol and can increase anxiety. Taking them together can blunt caffeine's anxiety and jitter side effects while preserving its alertness benefit, but ashwagandha may also slightly dampen caffeine's peak stimulant effect.
atorvastatin + vitamin d
Vitamin D's active metabolite (calcitriol) can induce CYP3A4, which metabolizes atorvastatin. Small studies show vitamin D supplementation may reduce atorvastatin and metabolite plasma levels by up to ~55%, although LDL-lowering efficacy appears largely preserved.
simvastatin + berberine
Simvastatin is extensively metabolized by CYP3A4, and berberine inhibits CYP3A4 in vitro, which can raise simvastatin levels and increase the risk of myopathy and rhabdomyolysis. The interaction is bidirectional in some models (induction is also possible), making net effect unpredictable.
caffeine + creatine
Early studies suggested caffeine blunts the ergogenic effect of creatine on muscle phosphocreatine resynthesis and high-intensity performance, but subsequent randomized trials show the combination is generally additive or neutral; the original blunting effect appears specific to chronic co-ingestion during creatine loading rather than acute pre-workout use.
caffeine + vitamin d
In vitro and observational studies suggest high caffeine intake (>300 mg/day) may decrease vitamin D receptor (VDR) protein expression in osteoblasts and is associated with lower serum 25-hydroxyvitamin D levels in some NHANES data. The clinical effect is modest and most relevant for bone health in postmenopausal women with low calcium intake.
atorvastatin + berberine
Berberine inhibits CYP3A4 in vitro and can raise plasma levels of CYP3A4 substrates, including atorvastatin, which may increase the risk of muscle pain, liver enzyme elevation, and rhabdomyolysis. The interaction direction is complex — some animal data also show induction — but co-use is unpredictable.