A supplement advertises a combined supplement containing 500 mg elemental magnesium plus 4000 mg sea salt (sodium chloride) per dose to 'optimize electrolytes.' Evaluate this product's safety for general adult use and identify which populations would be at particular risk.

• A. Only people with low dietary chloride will be at risk; magnesium excess is not a concern because supplements do not absorb into the bloodstream.
• B. Entirely safe for everyone because marine-derived sea salt contains beneficial trace elements that fully mitigate magnesium toxicity and sodium risks.
• C. Safe for young athletes only, because high magnesium will enhance performance and elevated sodium is desirable during rest periods; no clinical monitoring is needed.
• D. Not safe for general use: 500 mg supplemental magnesium exceeds the supplemental UL (350 mg) raising hypermagnesemia risk, and 4000 mg sea salt likely yields sodium and chloride above recommended limits increasing hypertension risk; high-risk groups include people with kidney disease, hypertension, older adults, and those on cardiovascular medications.

Answer: (D)