Side-by-side: what's in the tablet?
Per typical daily dose: • Berocca Performance (1 effervescent tab): vitamin C 500 mg, B-complex, magnesium 100 mg, zinc 10 mg, sodium ~ 270 mg. No vitamin A. Designed as an energy/immunity drink, not a multivitamin. • Centrum Advance (1 tab): vitamin A 800 µg as retinol, vitamin D 5 µg, vitamin C 80 mg, full B-complex, calcium 162 mg, magnesium 100 mg, potassium 125 mg, phosphorus 100 mg. • Sanatogen A–Z Complete (1 tab): vitamin A 800 µg as retinol, full B-complex, calcium 162 mg, magnesium 100 mg, potassium 40 mg, phosphorus 48 mg. • Tesco / Boots A–Z (1 tab): broadly mirrors Centrum, retinol-based vitamin A, 100% NRV across most micronutrients, ~ 30–125 mg potassium, ~ 50–100 mg phosphorus. • Kidney Vitality (1 dose): vitamin A as beta-carotene only, vitamin D3 25 µg, vitamin C 60 mg, renal B-complex (B1 50 mg, B6 10 mg, folate 1 mg, B12 6 µg), no added potassium, no added phosphate, modest zinc and selenium, no magnesium loading.
Why retinol vitamin A is the biggest single concern
Vitamin A as retinol (the form in Centrum, Sanatogen and most A–Z multivitamins) is fat-soluble and excreted via the kidneys. In CKD, plasma retinol can rise to 2–4× the upper reference range even on a standard 800 µg daily dose. Documented consequences include hypercalcaemia, bone resorption, hepatotoxicity and skin changes. Beta-carotene is the safer alternative: the body converts it to retinol only as needed, with no toxicity ceiling. Every renal multivitamin should use beta-carotene — not retinyl palmitate or retinyl acetate.
Added potassium and phosphate: small per tablet, big over time
100–125 mg of added potassium per tablet sounds modest — but it sits on top of dietary potassium and any potassium in salt substitutes (LoSalt, Solo). In stage 4–5 CKD with a 2 g/day potassium target, a multivitamin can quietly consume 5–7% of the daily allowance. Added phosphate is worse. Inorganic phosphate in supplements is ~ 90% absorbed (versus ~ 40–60% from food). 100 mg per tablet contributes ~ 90 mg of bioavailable phosphate per day — clinically significant against an 800–1000 mg phosphate target in advanced CKD, and a driver of vascular calcification.
Mega-dose vitamin C and oxalate
Berocca delivers 500 mg vitamin C per tablet — more than 5× the NRV. Vitamin C is metabolised in part to oxalate, which deposits as calcium oxalate in renal tubules. Case reports of oxalate nephropathy from chronic high-dose vitamin C are well documented. CKD patients should keep total vitamin C intake under ~ 100 mg/day from supplements.
Magnesium accumulation in advanced CKD
Centrum, Berocca and most A–Z formulas contain 100 mg elemental magnesium per dose. Healthy kidneys excrete excess magnesium effortlessly. In stage 4–5 CKD, magnesium can accumulate and cause hyporeflexia, hypotension and cardiac conduction effects. Renal multivitamins should avoid magnesium loading entirely or keep doses modest (< 50 mg).
What a renal-safe multivitamin actually looks like
• Vitamin A as beta-carotene — no retinol • No added potassium, no added phosphate • Vitamin C ≤ 100 mg • Renal B-complex: B1 50–100 mg, B6 5–10 mg, folate 0.8–1 mg, B12 ≥ 6 µg (covers haemodialysis losses) • Vitamin D3 25 µg (helpful in CKD; check 25-OH-D) • Modest zinc (8–15 mg) and selenium (50–100 µg) • No magnesium loading • No herbal additions (cranberry, nettle, dandelion are not safe in CKD without supervision) Kidney Vitality is formulated to this exact specification by a UK Consultant Nephrologist (Professor Mohammed Mahdi Althaf, GMC 7216325).
