Packaging and labeling dont always make the distinction obvious to a casual reader, and the terms get used loosely in conversation, online forums, and even some product listings
If blood tests show clearly low levels (thresholds vary by lab, but often below roughly 200 pg/mL) or there are signs of anemia, a provider may recommend weekly injections for the first several weeks as a correction or "rescue" phase
Considering the recent X-ray crystallography and cryo-EM data, which revealed that GSH and Glu could bind to different domains of GLR3.4 for ion channel activation 30 , it would be intriguing to investigate whether GSH binds to GLR3.3 and further determine the potential relationship between GSH and Glu in activating GLR3.3

Copper Sun Tanning & Firming Lotion: Water, ethylhexyl palmitate, hydrolyzed soy protein*, squalane, cetyl alcohol, stearic acid, PEG-100 stearate, glyceryl stearate, glycerin, butylene glycol, PPG 2 myristyl ether propionate, phenoxyethanol, polysorbate 80, methylsulfonylmethane, C10-30 cholesterol/lanosterol esters, titanium dioxide (CI 77891), allantoin, polysorbate 20, cupric chloride, leucine, Lavandula Angustifolia (lavender) oil, copper tripeptide-1 (GHK-Cu), aloe barbadensis (aloe vera) powder, vitamin E TPGS (tocophersolan), vitamin E (as d-alpha tocopherol plus mixed tocopherols: d-beta, d-delta and d-gamma tocopherol), ubiquinone (CoQ-10), xanthophyll (Lutein)
Pregnant or breastfeeding individuals should also seek medical guidance before supplementation