The following definitions are provided for quick reference. Full context for each appears in the relevant section of the guide.
Adaptogen
A category of herbal compounds, including ashwagandha, marketed for supporting the body's response to stress. Evidence quality varies substantially by specific compound and extract.
Bioavailability
The degree to which a supplement's active ingredient is actually absorbed and usable by the body — the reason specific forms (e.g. magnesium glycinate over oxide, triglyceride-form omega-3 over ethyl ester) are recommended over others.
Menaquinone (Vitamin K2)
The form of vitamin K found in fermented foods and some animal products, distinct from the K1 found in leafy greens. Associated with directing calcium toward bone rather than arterial tissue.
NAD+ (Nicotinamide Adenine Dinucleotide)
A molecule essential for cellular energy production and DNA repair, which reliably declines with age. NMN and NR are precursor supplements that raise NAD+ levels — see the Longevity guide for the full evidence picture.
Proprietary Blend
A supplement formulation that discloses a combined total dose of several ingredients without specifying each ingredient's individual amount. See Section 8 for why this is treated as a red flag in this guide.