l-carnitine and coq10 Nature's Bounty CoQ10, 100mg Plus L-Carnitine, 60 Softgels MRM CoQ10 with L-Carnitine Liquid

It is generally well-tolerated, with the following side effects [9][18]: GI symptoms (most common): Nausea, vomiting, diarrhea, and abdominal discomfort, particularly at doses above 1,200 mg/day Sulfurous taste/smell: NAC has a distinct sulfur odor and taste that some find unpleasant Headache: Occasionally reported Anaphylactoid reactions (IV use only): Infusion-related reactions including flushing, itching, bronchospasm, and hypotension occur in approximately 10-20% of patients receiving IV NAC for acetaminophen overdose [18] Upper limit: There is no established UL for NAC

Certain allium vegetables are a great source of sulfur as well

Neurochem Res 33:25402546 Mandal PK, Tripathi M, Sugunan S (2012) Brain oxidative stress: detection and mapping of anti-oxidant marker 'Glutathione' in different brain regions of healthy male/female, MCI and Alzheimer patients using non-invasive magnetic resonance spectroscopy

Since blood contains only 0.8% of total body free thiamine, its an unreliable marker