Gerson therapy

This is a historical account. Gerson therapy has no legitimate implementation for a psychotherapist. It is not a treatment for cancer or any other disease, and nothing here describes how to carry it out. This tab tells clinicians what the regimen involved, how it harmed people, how to recognise it today, and how to help clients and families who are considering it, are on it, or are recovering from it. Duplicate entry 167 is covered here in part. See also 116 and 076 for related diet and cleansing regimes, and 172 for integrative oncology.

1. What it was

Version followed: the regimen as described by the NCI PDQ Health Professional summary (last content update 2015), Cancer Research UK (reviewed 2022), and the Gerson Institute's own current web pages (2026). Where the Institute's current description differs from the historical one, both are given.

Developer. Max Gerson, a German physician who emigrated to the USA, began practising in New York City in 1938 after passing the state medical board examinations. He first developed a vegetarian diet for his own migraines, then used it for lupus vulgaris (skin tuberculosis) and later for cancer [source: NCI PDQ; Cancer Research UK]. In 1946 he appeared with five patients before a US congressional committee considering cancer research funding. In 1958 he published his full theory with 50 case reports, A Cancer Therapy: Results of Fifty Cases [source: NCI PDQ].
Professional sanctions in his lifetime. His malpractice insurance was cancelled in 1953. In 1958 the New York County Medical Society suspended him for two years. He died in 1959 [source: NCI PDQ]. JAMA reports in 1946 and 1949 found no value in the treatment. NCI reviewed his cases in 1947 and 1959 and found no benefit [source: NCI PDQ].
Organisation after his death. His daughter Charlotte Gerson Straus co-founded the Gerson Institute in San Diego in 1977 with Norman Fritz [source: NCI PDQ]. The Institute is a 501(c)(3) non-profit, says it "is not a medical facility", and licenses clinics instead of running them [source: Gerson Institute pages]. NCI's 2015 summary named CHIPSA in Baja California, Mexico, as a licensed centre [source: NCI PDQ]. In 2026 the Institute lists three licensed clinics: Health Institute de Tijuana (Mexico, since 2001), Gerson Health Centre (Budapest, Hungary, since 2009) and Gerson Shangri-La (China, since 2023) [source: Gerson Institute, Licensed Gerson Clinics]. It also runs a two-year virtual training programme for licensed clinicians (MD, DO, DC, ND, NP) who become "Certified Gerson Practitioners" and deliver the regimen mainly by telemedicine [source: Gerson Institute, Practitioner Training; Web-Based Treatment Options].
Stated rationale. Gerson saw cancer as a disease of the whole body and the tumour as a symptom. He believed the liver was damaged and overloaded by toxic breakdown products from cancer, and that chemotherapy made this worse. He observed that patients on his diet passed a lot of sodium in their urine, concluded that healthy cells need a high potassium-to-sodium ratio, and so prescribed a high-potassium, low-sodium diet. He believed pancreatic enzymes would lighten the work of the liver and pancreas [source: NCI PDQ]. Cancer Research UK sums up the supporters' beliefs as: cancer is a whole-body disease; diet and nutrients can treat it; the regimen rids the body of toxins and strengthens immunity [source: Cancer Research UK].
How it is sold today. The Institute calls it a "natural treatment system" that "activates the body's extraordinary ability to heal itself". It names toxicity and nutritional deficiency as the root causes of "degenerative disease", says the therapy will "reactivate the immune system", and calls coffee enemas the primary method for eliminating toxins from the liver [source: Gerson Institute, The Gerson Therapy; How it works]. Its main therapy pages do not name cancer. Instead a "Diagnosis Directory" sorts conditions into those with reported success, those considered unsafe, and those needing protocol changes [source: Gerson Institute, The Gerson Therapy]. Disclaimers say outcomes vary, recovery is judged case by case and no guarantees are made. Promotion relies on testimonials and case stories [source: Gerson Institute pages; Cancer Research UK].
Status in one line. No prospective controlled trial has been published, and NCI says the therapy cannot be recommended outside well-designed trials [source: NCI PDQ]. Cancer Research UK says "There is no scientific evidence to use it as a treatment for cancer" and that reputable cancer organisations do not support it [source: Cancer Research UK]. In 1989 the US FDA banned the injectable crude liver extract once used in the regimen [source: NCI PDQ].

2. What was actually done

The sequence below combines NCI's historical account, Cancer Research UK's description, and the Gerson Institute's 2026 description of clinic and home treatment. Amounts, schedules and preparation are deliberately left out.

Selection and case evaluation. A prospective patient fills in a referral or case-evaluation form. Clinic staff review lab results and records, do a physical examination and discuss symptoms, then draw up an individual protocol and adjust it during the stay [source: Gerson Institute, Licensed Gerson Clinics; Web-Based Treatment Options]. The Diagnosis Directory screens some conditions out as "unsafe". For people turned down, the Institute suggests a mostly plant-based diet, juices and coffee enemas "if safe", with a naturopath or holistic physician [source: Gerson Institute, Licensed Gerson Clinics].
Consent and framing. Patients are told the method addresses root causes, are given testimonials, and are told outcomes are not guaranteed [source: Gerson Institute pages]. Cancer Research UK reports that most Gerson therapists advise against chemotherapy, arguing that it damages the immune system, and see radiotherapy as more compatible [source: Cancer Research UK]. For clinicians, the practical point is that consent is often given against a framing that sets the regimen up as the alternative to standard care [synthesis].
Setting and staff. Most treatment is at clinics outside the USA (Mexico, Hungary, now China) or at home [source: Cancer Research UK; Gerson Institute]. The Institute says its clinics have physicians, nurses and Institute-trained practitioners, with a doctor on site at all times. Each patient must bring at least one companion, who lives in and is taught to run the regimen at home [source: Gerson Institute, Licensed Gerson Clinics].
Diet. A strict organic vegetarian diet of specified fruits and vegetables, raw or stewed. No animal protein, salt, spices or added fats apart from flaxseed oil. Buttermilk may be added later. Only certain cookware may be used (cast iron, no aluminium), and a particular type of juicer was required [source: NCI PDQ]. The Institute today describes the diet as low in sodium, fat and protein [source: Gerson Institute, How it works].
Juices. Fresh fruit and vegetable juices are made and drunk repeatedly through the day [source: NCI PDQ; Cancer Research UK]. Preparing them takes up most of the patient's or carer's day, and the large amount of produce brings ongoing costs [source: Cancer Research UK].
Supplements. NCI lists a potassium solution, Lugol's solution (iodine and potassium iodide), several vitamins, flaxseed oil, pancreatic enzymes and pepsin, with vitamin B12 and coenzyme Q10 also mentioned. Cancer Research UK and the Institute also list thyroid hormone [source: NCI PDQ; Cancer Research UK; Gerson Institute, How it works].
Liver extract. At first patients were given injections of crude calf liver extract. These were later replaced with desiccated liver capsules and then coenzyme Q10. NCI says the injectable form is no longer used [source: NCI PDQ]. A 1981 CDC report describes raw calf's liver taken by mouth alongside raw juices and coffee enemas at two Tijuana-area clinics [source: CDC MMWR 1981].
Enemas. Coffee enemas (sometimes chamomile) are given repeatedly, most intensively at the start, to "dilate bile ducts" and "detoxify the liver". NCI says only anecdotal evidence supports this rationale. Castor oil is also used, said to stimulate bile flow [source: NCI PDQ; Cancer Research UK; Gerson Institute, How it works]. Enemas are usually given by the patient or the companion at home [synthesis].
Duration and home continuation. The regimen lasts months to years and takes a great deal of time [source: Cancer Research UK]. After the clinic stay it continues at home for a long period. Clinic doctors follow up by phone or web, review lab results and change the protocol. Patients can come back to the clinic at a discount [source: Gerson Institute, Licensed Gerson Clinics]. Certified Gerson Practitioners offer web-based case management, including to people who are also having conventional treatment [source: Gerson Institute, Web-Based Treatment Options].
Judging progress and handling non-response. Gerson's own outcome reports used case notes and anecdotal, unsystematic follow-up [source: NCI PDQ]. The Institute says recovery is judged case by case, that outcomes depend on individual factors, and that the therapy "has its limitations" [source: Gerson Institute pages]. Promotional and patient accounts often describe new symptoms as "healing reactions" or "flare-ups" rather than harm [uncertain: not verified in a primary source]. When the disease progresses, this framing tends to put responsibility on the patient's adherence rather than on the method [synthesis].
Cost. Patients pay for home equipment, organic produce, coffee and supplements on an ongoing basis. Clinic treatment adds flights and accommodation, and the total can reach thousands of pounds [source: Cancer Research UK]. The Institute does not publish clinic fees [source: Gerson Institute, Licensed Gerson Clinics].

3. How it caused harm

Infection from liver products. A 1981 CDC MMWR report described Campylobacter fetus sepsis in ten people admitted to San Diego-area hospitals between 1979 and 1981. Nine had been treated in Tijuana and one followed the regimen at home. Five were comatose, many had low blood sodium, and one patient with metastatic melanoma died within a week of becoming septic. The regimen was raw juices plus raw calf's liver taken by mouth, with coffee enemas; CDC judged the liver the most likely vehicle of infection [source: CDC MMWR 1981;30(24):294–5]. NCI records that the FDA banned injectable crude liver extract in 1989 because of Campylobacter contamination [source: NCI PDQ].
Infection and death linked to coffee enemas. NCI reports three deaths in the literature possibly related to coffee enemas (Eisele and Reay, JAMA 1980). In one, Salmonella group D and Campylobacter were cultured from a patient who died shortly after treatment at a Gerson clinic, although a direct link could not be confirmed. Polymicrobial enteric septicaemia after coffee enemas was reported in 1984 [source: NCI PDQ]. Cancer Research UK lists infections, dehydration, fits, mineral imbalances, heart and lung problems including death, and, with long-term use, constipation and colitis [source: Cancer Research UK].
Electrolyte disturbance. Two deaths among Gerson Institute patients were attributed to electrolyte imbalance [source: NCI PDQ]. The disturbance can go either way. Enemas can remove large amounts of potassium [source: Cancer Research UK], while potassium supplementation has caused severe, non-fatal hyperkalaemia [source: NCI PDQ, citing Nagasaki et al. 2005]. In the 1981 cluster most comatose patients had severe low blood sodium [source: CDC MMWR 1981]; a link to the salt-free diet is not made in that report [uncertain: secondary, unverified].
Malnutrition and debility. Cancer Research UK warns that very large amounts of juice without a balanced diet can harm people who are already weak or ill, and lists loss of appetite, diarrhoea, nausea, cramps, fever, dizziness and weakness as reported effects [source: Cancer Research UK]. Restricting protein and fat in people with cancer-related weight loss carries an obvious risk [synthesis].
Delay or abandonment of effective treatment. Cancer Research UK warns that stopping conventional treatment or symptom control can be harmful, and that most Gerson therapists advise against chemotherapy [source: Cancer Research UK]. Losing the chance of curative or life-prolonging treatment, and going without good symptom control, is the most serious population-level harm [synthesis]. People with publicly reported cancers who chose the regimen instead of standard treatment have died of their disease [uncertain: secondary, unverified].
Psychological, family and financial harm [synthesis, drawing on the burden described by Cancer Research UK and the Gerson Institute]:
- The regimen takes over a household's whole day, with the companion acting as an unpaid carer.
- Strict rules about "pure" food, and shame over "lapses", can feed obsessive eating and lead to social isolation (compare the orthorexia features described by Beat and NEDA).
- Patients may blame themselves when the disease progresses, and relatives may blame each other.
- Families may have to choose between oncology and the regimen.
- Savings run out, often with travel abroad and debt.
- Bereaved relatives can be left with complicated grief and regret.
Who is most at risk [synthesis unless tagged]:
- People with advanced cancer or cancer-related weight loss who are already frail [source: Cancer Research UK].
- People with a curable cancer who turn down or delay standard treatment.
- Children, whose treatment decisions are made by others.
- People with kidney, heart or electrolyte problems, or on medicines that affect potassium or sodium (the prescriber should review them).
- People with a past or current eating disorder.
- People with high distrust of medicine or past medical trauma.
- People with limited money, and people being treated far from home.

4. Recognising it today

Features and phrases. The regimen, or parts of it, shows up under these markers [source: Gerson Institute pages; Cancer Research UK; NCI PDQ]:

The name "Gerson", "Gerson diet", "Gerson method" or "Gerson protocol". Also "Certified Gerson Practitioner" and "Licensed Gerson Clinic".
Phrases such as "natural treatment system", "the body's ability to heal itself", "root causes: toxicity and deficiency", "reactivate the immune system", "detoxify the liver" and "degenerative disease".
Frequent fresh juicing through the day, a salt-free and fat-free organic plant diet, and a ban on aluminium cookware.
Coffee or castor-oil enemas presented as liver detoxification. Coffee enemas also turn up on their own in "detox" and wellness programmes [synthesis].
Potassium, iodine, thyroid hormone, pancreatic enzyme or liver supplements sold or suggested as part of a cancer "protocol".
Clinics in Tijuana or Baja California, or in Hungary, often booked after watching a documentary, reading testimonials or joining an online support group [source: Gerson Institute; NCI PDQ] [synthesis for documentaries and groups].
Telehealth "case management" offered even to people having chemotherapy, sometimes paired with advice to avoid chemotherapy [source: Gerson Institute, Web-Based Treatment Options; Cancer Research UK].

Rebrandings and relatives [synthesis]:

"Juice cleanse", "liver flush", "metabolic therapy", "nutritional oncology" used outside dietetics, "anti-cancer protocol" and "healing crisis".
Mexican border "integrative" cancer clinics that offer Gerson-style diets alongside other unproven regimes. NCI notes the American Cancer Society's 1991 statement on questionable Tijuana clinics [source: NCI PDQ].
Related entries: 116 and 076.

Red flags in a colleague's, coach's or service's practice [synthesis]:

Recommending or selling the regimen, enemas, juicers, supplements or clinic referrals.
Taking referral fees or affiliate links.
Describing chemotherapy as "poison".
Encouraging a client to hide the regimen from their oncologist.
Reading a client's worsening symptoms as "detox".
Making emotional or spiritual "cleansing" a condition of physical recovery.
Running groups where people who choose standard treatment are shunned.
In the UK, any public advert offering to treat cancer may breach the Cancer Act 1939 [source: Cancer Research UK news, The 1939 Cancer Act].

How legitimate practice differs. Cancer Research UK notes that some elements, such as plenty of fruit and vegetables and low-fat eating, are healthy [source: Cancer Research UK]. Legitimate oncology nutrition differs in five ways [synthesis]:

It is led by a registered dietitian within the oncology team.
It is adjusted to weight loss, treatment side effects and blood results.
It is never presented as a cure.
It never replaces standard treatment.
It does not involve enemas or untested supplements.

Integrative oncology (entry 172) offers complementary therapies alongside standard care, never instead of it.

Eating-disorder overlap. Watch for rigid rules about "pure" food, removing more and more foods, anxiety or guilt after eating outside the rules, feeling morally superior about one's diet, hours spent planning food, and social impairment. Beat and NEDA describe these as features of orthorexia. Orthorexia is not a formal DSM-5-TR diagnosis, and people may instead be diagnosed with anorexia nervosa or OSFED [source: Beat; NEDA]. Restrictive eating can lead to malnutrition [source: Beat; NEDA].

5. What to do instead and how to help those harmed

Recommended alternatives, by name. The client should get a clear explanation of the evidence on standard treatment for their condition from their own oncology team. Other options include:

Referral to a specialist palliative care team for symptom control at any stage.
An oncology dietitian.
Psycho-oncology support.
Integrative oncology services that offer complementary therapies alongside treatment (entry 172).
For people determined to try something, entry into a properly designed clinical trial [source: NCI PDQ, which recommends Gerson therapy only within well-designed trials; Cancer Research UK advises speaking to a doctor before any alternative therapy].

The psychotherapist does not prescribe, recommend, perform or sell the regimen, any component of it, or any alternative to it. Their work is the process below. Unless tagged otherwise, everything in this section is [synthesis] built on standard psycho-oncology, decision-support and safeguarding practice. Cancer Research UK's cautions and the Gerson Institute's own advice to keep a relationship with a local physician are cited where they are used.

5.1 Asking about it routinely and without judgement

Purpose. Make it safe to disclose alternative treatment, so that medical risk can be found early.
Steps.
1. Ask every client with a serious illness, and their relatives, about diets, supplements, enemas, clinics and online programmes.
2. Ask in a curious, neutral tone.
3. Record what is used, who advised it, the cost, whether the doctor knows, and any symptoms.
4. Thank them for telling you.
Example language (illustrative). "Many people with cancer try diets, supplements or clinics alongside, or instead of, hospital treatment. Is anything like that part of your plan, or something you're thinking about?"
Watch for. Secrecy, shame, or fear that you will report them or end therapy. Disclosure that comes only after trust has built is common, so ask again later.

5.2 Exploring meaning, hope and the explanatory model

Purpose. Understand what draws the person to the regimen before any decision talk.
Steps.
1. Ask how they understand the cause of their illness and how the regimen is meant to help.
2. Explore what it gives them: control, hope, purpose, a daily structure, membership of a community, a sense of fighting back.
3. Explore distrust of medicine and past experiences of medical harm or bad news.
4. Reflect back their values without arguing.
Example language (illustrative). "It sounds like doing the juices every day makes you feel you're actively fighting this, not just waiting. Is that close?"
Watch for. Black-and-white framing ("poison" against "natural"). Magical-thinking pressure such as "if I lapse, it's my fault". Fear of chemotherapy rooted in a relative's death. These are targets for later work, not for confrontation.

5.3 Supporting an informed, values-based decision without coercion

Purpose. Help the person reach a decision that is truly theirs, with accurate information, while respecting autonomy.
Steps.
1. Ask permission before sharing concerns.
2. Say clearly that you are not the medical decision-maker.
3. Suggest the person bring specific questions to the oncologist: expected benefit of standard treatment, the cost of delay, symptom control.
4. Point to independent summaries such as Cancer Research UK and NCI PDQ.
5. Help them weigh options against their own values (time, quality of life, family, faith).
6. Explore the "both/and" options their oncologist can safely support.
7. Accept the decision and keep the relationship.
Example language (illustrative). "I'm not the person to judge the medical side, but I'd hate for you to decide without the full picture. Would it help to write down the questions you'd want your oncologist to answer before you choose?"
Watch for. Your own urge to persuade, which can drive disengagement. A decision that is really a family member's or a group's. Time pressure from a clinic booking or deposit.

5.4 Coordinating with the treating doctor, oncology and palliative teams

Purpose. Make sure the people responsible for medical safety know what is going on.
Steps.
1. With the client's consent, tell the oncologist or GP what regimen is being followed, including enemas and supplements.
2. Encourage the client to bring the full supplement list to their prescriber or pharmacist.
3. Ask the team to look for electrolyte, infection or nutrition problems.
4. Suggest palliative care referral for symptoms.
5. Agree how you will share concerns in future. The Gerson Institute itself advises keeping a relationship with a local physician [source: Gerson Institute], which can be a useful point of agreement.
Example language (illustrative). "Would you be OK with me letting Dr [name] know you're doing this? Even the Gerson website says to keep your local doctor involved."
Watch for. Refusal of consent. Respect it unless there is serious risk to life or a child (see 5.8), and document the discussion. Never advise on medicines yourself.

5.5 Recognising medical red flags and acting on them

Purpose. Spot emergencies early.
Steps.
1. Know the risks Cancer Research UK lists: infection, dehydration, fits, mineral imbalances, heart and lung problems [source: Cancer Research UK].
2. If a client describes fever, confusion, fainting, a fit, palpitations, severe weakness, abdominal pain, bloody stool or rapid weight loss, direct them to urgent medical care the same day. Call emergency services if they are unwell in session.
3. Follow up after.
Example language (illustrative). "Confusion and a racing heart need checking today, whatever is causing them. Can we call your GP or 111 together now?"
Watch for. Symptoms being explained away as "detox" or a "healing reaction". Carers who are afraid to call for help.

5.6 Eating-disorder screening and nutrition risk

Purpose. Pick up orthorexic or restrictive patterns and malnutrition.
Steps.
1. Ask about rigidity, guilt, food rules spreading, social withdrawal and weight change, using the features Beat and NEDA describe [source: Beat; NEDA].
2. Use a validated screener if trained in one.
3. Ask about past eating disorders.
4. Refer for medical and dietetic assessment if weight is falling.
5. Where an eating disorder is likely, follow established treatment pathways: a multidisciplinary team with medical monitoring, psychological therapy and dietetic support [source: Beat; NEDA]. See Domain II for detail.
Example language (illustrative). "When you have something that isn't on the plan, what happens inside you?"
Watch for. Refeeding and electrolyte risk in anyone who is very depleted. This is a medical matter, so route it to the doctor.

5.7 Family conflict and the carer's burden

Purpose. Reduce polarisation and support the companion or carer.
Steps.
1. Meet with the family if the client agrees.
2. Name the shared goal: the client's wellbeing and time.
3. Separate disagreement about treatment from loyalty to each other.
4. Agree who is responsible for medical decisions (the client, if they have capacity).
5. Check on carer exhaustion, since the regimen asks a lot of the companion [source: Gerson Institute; Cancer Research UK].
6. Offer the carer separate support.
Example language (illustrative). "You both clearly love her. You disagree about how to help, not about whether to. Can we start there?"
Watch for. Coercion in either direction, a carer's burnout or resentment, and children in the household being drawn into the regime.

5.8 Children, capacity and safeguarding

Purpose. Protect a child, or an adult without capacity, from being deprived of effective medical care or harmed by the regimen.
Steps.
1. When a parent plans to use the regimen for a child instead of medical treatment, or to give a child enemas or supplements, talk to the parent with respect, but follow your local safeguarding procedure. That means consulting your safeguarding lead and, where there is risk of significant harm, referring to children's social care or child protection services and informing the treating team.
2. Seek the child's views and assent in a way that suits their age.
3. For adults, if capacity to make the treatment decision is in doubt, ask the medical team to assess it.
Example language (illustrative). "I respect how hard you're fighting for him. Because he's a child, I have a duty to make sure his doctors are part of this decision, and I'd rather do that with you than around you."
Watch for. A child refusing food or showing fear around enemas. Missed oncology appointments. Isolation from school or relatives.

5.9 Financial harm and exploitation

Purpose. Prevent and respond to financial loss.
Steps.
1. Ask about costs, loans, fundraising and deposits. Cancer Research UK notes that equipment, produce, travel and clinic fees can reach thousands of pounds [source: Cancer Research UK].
2. Look out for pressure tactics.
3. Signpost to independent financial and debt advice and to consumer-protection bodies.
4. If the person is an adult at risk, consider adult safeguarding.
Example language (illustrative). "How is the cost landing on you and the family? Sometimes the money pressure ends up being part of the stress."
Watch for. Crowdfunding narratives that tie a person publicly to the regimen and make it hard for them to change course.

5.10 Supporting a change of course

Purpose. Make it possible to return to oncology or palliative care without losing face.
Steps.
1. Normalise changing one's mind.
2. Reframe the change as consistent with the person's values, such as wanting more time or wanting comfort.
3. Help them script the call to the oncology team.
4. Process their fear of judgement by clinicians.
5. Address group or online-community pressure, and the risk of being shunned.
Example language (illustrative). "Going back to the hospital doesn't erase what you've done. It's another way of looking after yourself."
Watch for. Shame, "I wasted my chance" thinking, and loss of a support community.

5.11 Grief, regret and complicated bereavement

Purpose. Support patients and bereaved relatives after the disease progresses or a death.
Steps.
1. Use standard grief and bereavement work.
2. Explore counterfactual guilt ("if we'd chosen chemo") and anger at the clinic, at the doctors, or at the person who chose the regimen.
3. Acknowledge that the choice was made with the information and hopes the person had at the time.
4. Screen for prolonged grief, depression and suicidality using standard risk-assessment practice.
5. Consider family sessions where blame is divided along family lines.
Example language (illustrative). "You keep going back to that decision. What did you know and hope for at the time you made it?"
Watch for. Rumination, self-blame that does not lift, estrangement in the family, and anniversary reactions.

5.12 Reporting and professional duties

Purpose. Use the correct routes when harm, illegal advertising or exploitation is suspected.
Steps.
1. With consent where possible, report adverse effects to the treating doctor.
2. In the UK, report public adverts offering to treat cancer to Trading Standards or the Advertising Standards Authority. The Cancer Act 1939 bans such adverts to the public, and Trading Standards can prosecute [source: Cancer Research UK news, The 1939 Cancer Act].
3. In other countries, use the national medicines or device regulator and the advertising and consumer regulators [uncertain: not verified for specific agencies].
4. Report a regulated health professional who promotes the regimen in place of care to their licensing board.
5. Make safeguarding referrals as in 5.8.
6. Keep clear records of the discussions, consent and actions.
7. Do not sell, endorse or take referral fees for any product, course or clinic, and manage conflicts of interest according to your professional code [synthesis; uncertain: not verified].
Example language (illustrative). "I'm not here to judge your choice, but an advert claiming to cure cancer is something I'm obliged to pass on. It isn't about you."
Watch for. Breaching confidentiality without proper grounds. Discuss with supervision before you report anything about a client's own choices.

Sources

Books and papers cited as listed in the NCI PDQ reference list:

Gerson M. A Cancer Therapy: Results of Fifty Cases and The Cure of Advanced Cancer by Diet Therapy. The Gerson Institute, 2002 (first published 1958).
Gerson C, Walker M. The Gerson Therapy. Kensington, 2001.
Eisele JW, Reay DT. Deaths related to coffee enemas. JAMA 1980;244(14):1608–9.
Margolin KA, Green MR. Polymicrobial enteric septicemia from coffee enemas. West J Med 1984;140(3):460.
Nagasaki A, Takamine W, Takasu N. Severe hyperkalemia associated with "alternative" nutritional cancer therapy. Clin Nutr 2005;24(5):864–5.
Questionable cancer practices in Tijuana and other Mexican border clinics. CA Cancer J Clin 1991;41(5):310–9.
CDC. Campylobacter sepsis associated with "nutritional therapy" — California. MMWR 1981;30(24):294–5 (CDC Stacks, full issue PDF)

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