LDN, vitamin D and immune supplements

Prepared 4 September 2026 by Kya at her partner's request, for her partner and the patient. Her partner heard a podcast on the drive to Southampton making three claims: that low-dose naltrexone is a potent anti-inflammatory that starves a tumour and makes it far more sensitive to treatment; that vitamin D3 levels should be pushed very high; and that the innate immune system can be boosted. Each claim is checked against the evidence in research thread 13, which cites the manufacturer's product information, the trials and the registries. No prognosis figures. Nothing here argues for changing the standard plan of biopsy, surgery and proton therapy.

The short answer

• Low-dose naltrexone cannot be used while the patient needs pain relief or is heading for surgery. Naltrexone blocks opioids. Its own product information lists opioid painkillers as a contraindication, requires five to ten opioid-free days before starting, and warns that trying to override the block with bigger opioid doses can cause fatal overdose. Anaesthetists want it stopped three days before any operation. On the cancer claims: the only placebo-controlled trial, 110 brain tumour patients in 2022, was negative; there is nothing in chordoma or chondrosarcoma; and the "half-dose chemotherapy" idea comes from a dish experiment in bowel cancer cells run by a group holding patents on it. Chordoma is not treated with chemotherapy anyway.
• Vitamin D: test it and correct it to the normal range, and stop there. Large trials show that modest daily doses may reduce cancer deaths slightly in the general population, that high or bolus doses do not help and trended to harm, and that in cancer patients high-dose was no better than standard. There is no chordoma data. "A hundred" is the trap: 100 nmol/L is a good level; 100 ng/mL is two and a half times that and the toxicity threshold. Too much vitamin D raises calcium and damages kidneys, which matters on diclofenac and if dexamethasone is started.
• Immune support: the real version is sleep, pain control, protein, walking and vaccines, plus a dietitian. Nothing in a capsule has been shown to help a tumour like this. Antioxidant supplements during radiotherapy were linked to more recurrences in a 540-patient head and neck trial, so supplements are a question for the proton centre, not a default.

The podcast claims, one by one

• "Naltrexone is a potent anti-inflammatory." Exaggerated. The idea rests on an eight-woman blood study and cell experiments. No randomised trial shows it lowers any inflammatory marker, and the best fibromyalgia trials, in 2024 and 2026, found no meaningful effect.
• "It shuts off the fuel to the cancer." False as stated. No such mechanism exists in the scientific literature for any human cancer. Chordoma has no known dependence on opioid signalling. The one randomised cancer trial was negative, and 1980s mouse work showed that the wrong dose speeded tumours up.
• "Half the chemotherapy dose with the same effect." A dish result in bowel cancer cells; never tested in a person; contradicted in a 2025 study on oral cancer cells; and irrelevant here because chordoma is treated with surgery and protons, not chemotherapy.
• Correction, 12 Oct 2026 (Kya): that is true only of conventional chordoma, and I put it as an absolute (first corrected to her partner 26 Sep). Dedifferentiated and poorly differentiated (INI1-loss) chordoma, and sarcomas, are treated with chemotherapy. On 6 Oct the surgeon said the patient's tumour may be INI1-lost or a form of sarcoma, so chemotherapy may well be on the table for her. The LDN claim is still untested in people. 13 Oct 2026: the diagnosis is poorly differentiated chordoma, so chemotherapy is on the table. The evidence that it helps in this type is weak: small case series and case reports, no trials.
• "Get D3 levels through the roof." Being replete matters; higher is not better; "through the roof" levels are dangerous for her kidneys and calcium.
• "Make the cancer more receptive to whatever treatment." Unsupported. Nothing sensitises a tumour to surgery or protons in this way. What genuinely improves her odds of good treatment is in the cutting-edge document: tissue handled right, joint surgical and proton planning at the national MDT.

What to do, and when

1. Nothing that blocks opioids while she needs pain control or in the three days before any operation or procedure. That rules out naltrexone now, through surgery and recovery, and probably through proton therapy. If it ever comes back on the table, it is for residual nerve pain, off opioids, with the pain team.
2. Vitamin D: ask for 25-hydroxyvitamin D, adjusted calcium and kidney function on her Southampton bloods. If low, standard daily replacement to reach 50 to 100 nmol/L, then 800 to 2,000 IU a day. Not more than 4,000 IU a day without a doctor checking calcium, and never aiming for 250 nmol/L (100 ng/mL) under any protocol's name. If dexamethasone starts, ask what calcium and vitamin D cover they want, since steroids thin bone.
3. Immune supplements: no, especially around surgery and radiotherapy. Declare anything she already takes. Put the effort into the dietitian, sleep, walking and flu and COVID vaccination timed around treatment.
4. Everything she swallows goes on the medication list that Southampton, the anaesthetist and the proton centre see.

Questions for the team

1. Can 25-hydroxyvitamin D, adjusted calcium and kidney function be added to her bloods, and will you prescribe standard replacement if she is low?
2. If dexamethasone is started, what calcium and vitamin D cover do you want, and for how long?
3. What is your policy on supplements during surgery and proton therapy, especially antioxidants and mushroom or "immune" products?
4. After treatment and off opioids, is there any circumstance in which you would consider low-dose naltrexone for residual nerve pain, and who would prescribe and monitor it?
5. Is she up to date with flu and COVID vaccination, and when should they be given relative to surgery and radiotherapy?
6. Can she see a dietitian this week, given 12 to 15 percent weight loss?

Key sources

• Naltrexone Summary of Product Characteristics (contraindications, opioid-free interval, overdose warning). Peters 2022 (placebo-controlled LDN trial, 110 glioma patients, negative). Liu 2016 (LDN and oxaliplatin in colorectal cells). Kazmi 2025 (oral cancer cells, antagonism). FINAL 2024 and INNOVA 2026 (fibromyalgia). Hegde 2025 meta-analysis (adverse events). PubMed: no naltrexone or OGF papers in chordoma or chondrosarcoma.
• VITAL (Manson 2019, NEJM); D-Health; Kuznia 2023 individual patient data meta-analysis (104,727 people); SOLARIS 2026 (JAMA, high-dose versus standard in cancer patients). NHS, NICE and BDA vitamin D guidance; toxicity threshold 250 nmol/L.
• Bairati 2005 (antioxidant supplements during head and neck radiotherapy). PSK trials in Japanese gastrointestinal cancer (not the turkey tail sold online).
• Full list with links: research thread 13, em-research/13-ldn-vitamin-d-immune.md. A few secondary pages could not be fetched tonight and are marked "verify" there.