is there mutation cause glutathione deficiency Metabolism - an overview Frontiers | Glutathione: Pharmacological aspects
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Some people may experience temporary redness, swelling, or irritation at the injection site, while others might notice changes in appetite, water retention, joint aches, or mild fatigue

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Studies integrating Ayurveda with pharmacogenomics are being piloted in India under the Centre for Ayurgenomics and other national research bodies

You might try mixing the Vitamin B12 with a small amount of wet food and see if he will eat it
