The replenishment notebook
Arizona IV Therapy: following the refill
NAD+ makes an appealing replenishment story. I want to follow it past the glass: through cell biology, IV experiments and the human trials.
Why NAD+?
Arizona puts a refill in my head: a glass, a basin, rain reaching dry ground. It is an inviting picture for anything described as replenishment. With NAD+, though, I mistrust how easily that picture supplies its own happy ending.
The biology deserves the interest. NAD+ carries electrons in cellular reactions and supplies enzymes involved in signalling; a coenzyme is a small helper molecule that lets an enzyme do its work. That is a substantial role. Whether giving something from outside produces a useful change is the question that sends me further into the papers.
Arizona IV Therapy is the title of this research notebook. There is no treatment business behind the name. The about page explains its limits.
At the cell surface
The most interesting refill here happens in a dish. In cultured human skin fibroblasts, extracellular NAD was broken down at the cell surface. Adenosine, a breakdown product, was taken up and converted to ATP inside the cells. These were laboratory cell cultures.
The fibroblast experiment scrambles my tidy picture of a refill. The thing added to the dish and the thing entering the cell need separate names. A glass filling up is too simple an image for those observations. Follow the cellular replenishment story.
The IV record
The intravenous papers take some sorting. An NAD+ experiment reduced heart injury in rats. The human studies discussed here used NADH in Parkinson’s disease: a small double-blind study found no significant difference from saline, while an open study reported improved clinical scores alongside conventional therapy.
My confidence shrinks when unlike experiments get bundled into one broad benefit claim. Their differences are the interesting material: the compound, the species, the comparison and the treatment setting. Open the IV papers.
The oral NMN results
Oral NMN gives the refill question a different set of measurements. A trial in prediabetic, postmenopausal women improved muscle insulin sensitivity; another in healthy middle-aged adults raised blood NAD+ and improved walking distance and quality-of-life scores versus placebo. Both used oral NMN.
Those particular findings give me reasons for interest. I distrust sweeping conclusions: a review of human ageing trials describes limited efficacy and sparse tissue-specific data. Read the oral trial ledger for the results and their boundaries, or go straight to the reading list.