Supplements for cancer survivors

The cancer survivorship stack — rationale by ingredient

Vitamin D3 1,000–2,000 IU/day (test and correct)

Vitamin D deficiency is common in cancer survivors due to reduced sun exposure, treatment-related effects, and age. Adequate vitamin D supports bone health (particularly important with aromatase inhibitors, ADT, or long-term corticosteroids), muscle function (falls prevention), and possibly cancer-specific outcomes — VITAL ancillary analysis suggested reduced cancer mortality with vitamin D 2,000 IU/day; the SUNSHINE trial in advanced CRC showed potential PFS benefit at higher doses. Test 25-OH-D and correct to 30–50 ng/mL.

Calcium — dietary first; supplement only to fill gap

For survivors on aromatase inhibitors (breast cancer), ADT (prostate cancer), long-term corticosteroids, or with chemotherapy-induced premature menopause, bone health is a priority. Target total calcium 1,000–1,200 mg/day. See bone health 50+ guide for the full framework. Modest supplementation; avoid mega-doses.

Vitamin B12 — selective use based on testing

B12 deficiency commonly underlies post-treatment fatigue and peripheral neuropathy. Particularly relevant after gastrectomy, prolonged metformin (often used in obesity-related survivorship), chronic PPI use, and following ileal resection. Test serum B12 and methylmalonic acid; supplement if deficient.

Omega-3 (EPA/DHA) 1–2 g/day

Cardiovascular co-benefit — cancer survivors have elevated cardiovascular mortality risk (treatment cardiotoxicity, lifestyle factors). Modest signal for cancer-related cachexia at higher EPA doses (2 g/day). Reasonable as part of survivorship cardiovascular protection.

Protein 1.2–1.5 g/kg/day (target for active survivors)

Cancer treatment commonly causes loss of lean mass (sarcopenia, cachexia). Recovery is accelerated by adequate protein intake plus resistance training. Whey or plant protein supplementation to hit daily targets is well-tolerated. Distribute across meals.

Psyllium husk for bowel regularity

Bowel function is commonly disrupted post-treatment — constipation from opioids, diarrhea from chemotherapy, radiation enteritis. Soluble fibre supports bowel regularity, glycaemic control, and lipid profile. Generally very safe.

Magnesium glycinate 200–400 mg at bedtime

Many survivors have post-treatment sleep disturbance, fatigue, and constipation. Magnesium addresses several of these simultaneously. Glycinate form for tolerability.