# Nutrition and diets in metastatic melanoma
In the treatment of metastatic melanoma, nutrition plays a supportive role. The treatments — especially immunotherapy — put the body under severe strain. Research increasingly focuses on how nutrition can help support the immune system, relieve side effects, and keep body weight stable. What works varies per person and per phase of treatment.
Weight management and caloric intake
ResearchediPositive results in clinical studies, not yet standard treatment
In cancer treatment — especially immunotherapy — maintaining a healthy body weight is important. Excess weight is linked in research to worse treatment outcomes and more side effects, while severe weight loss weakens the body and complicates treatment.
Weight loss in metastatic melanoma can result from the disease itself, medication side effects (many immune medications cause abdominal problems), fatigue, or reduced appetite. Some patients struggle to maintain their weight.
The CANOBESE study (2026) examines weight management in obese cancer patients undergoing curative active treatment. It shows that gentle, personalized guidance on nutrition and exercise during intensive cancer treatment is feasible and many patients succeed in keeping their weight reasonably stable. Undernutrition and severe overweight can both cause problems; it is about balance.
**Risks and interactions:** Strict dieting during immunotherapy can be counterproductive — the body needs energy to cope with treatment. Some nutritional supplements (see below) can interfere with certain immunotherapies.
Antioxidant-rich foods (vegetables, fruit, nuts, seeds)
ResearchediPositive results in clinical studies, not yet standard treatment
Vegetables, fruit, nuts, and seeds are rich in vitamins, minerals, and substances that fight oxidative stress. In theory, this could help the immune system. In practice, evidence in melanoma treatment is still limited and nuanced.
Research suggests that mild antioxidant intake (through normal eating) can be beneficial, but very high doses via supplements (especially in pill form) can sometimes interfere with immune medications. The body does need antioxidants, but too much can also suppress the immune response.
Many patients feel better with an eating pattern in which vegetables and fruit have a natural place, without extremes.
Omega-3 fats (fish, flaxseed, oils)
ResearchediPositive results in clinical studies, not yet standard treatment
Omega-3 fats from oily fish (salmon, mackerel, herring) or plant-based sources (flaxseed, walnuts) have anti-inflammatory and immune-supporting properties. In small studies, patients with omega-3-rich diets seem better able to maintain their immune function.
In melanoma treatment, nutrition with adequate omega-3 is sometimes recommended to keep inflammation in balance — this can moderate side effects of immunotherapy (which can also be inflammatory in nature).
**Risks:** Very high supplemental doses can increase bleeding tendency, which is relevant if you are also receiving chemotherapy. Discuss this with your care provider.
Protein-rich nutrition
ResearchediPositive results in clinical studies, not yet standard treatment
Adequate protein is essential: the body uses it for immune cells, tissue repair, and maintenance of muscle mass. In cancer treatment, much energy goes to healing, and protein deficiency weakens resistance.
Sources are meat, fish, eggs, dairy, legumes, nuts. With reduced appetite from side effects, frequent small amounts of protein help — for example, yoghurt, meat soup, or nuts between meals.
Research into specific protein dosages in melanoma treatment is limited, but clinical experience shows that patients who maintain their protein intake well have less tissue breakdown and recover better.
Periodic fasting and intermittent fasting
ExperimentaliOngoing in study setting, outcome still unknown
Periodic fasting — for example, eating within a specific time window — is being investigated as a possible supporter of immune function. In theory, it could stimulate autophagy (cellular self-cleaning) and sharpen the immune response.
There are some small preclinical studies suggesting this, but human trials on melanoma treatment are still sparse. Some patients report feeling better with a fixed eating/fasting period, particularly if this helps their digestion during immunotherapy.
**Risks:** Fasting can worsen weight loss and take away energy your body needs for healing. With severe side effects, it can cause further exhaustion. This is definitely not suitable for everyone.
Mediterranean dietary pattern
ResearchediPositive results in clinical studies, not yet standard treatment
The Mediterranean pattern — plenty of vegetables, fruit, fish, olive oil, whole grains, moderate meat and dairy intake — is described as favorable in much cancer research. It contains many beneficial substances and does not burden the body with extremes.
Patients with metastatic melanoma who follow this pattern often report fewer severe side effects, better energy and fluid balance, and more stable blood values. The pattern aligns well with caution and balance.
This is not a strict diet, but rather a lifestyle that fits well with long-term treatment.
Ketogenic diet (low carbohydrate, higher fat)
ExperimentaliOngoing in study setting, outcome still unknown
The ketogenic diet — very low in carbohydrates, high in fat and protein — has been investigated as possible cancer support, based on the theory that cancer cells prefer carbohydrates. Some preclinical studies suggest an effect, but human trials on melanoma are very limited.
Some patients report higher energy on ketogenic nutrition, others experience more side effects. The evidence for melanoma specifically is lacking.
**Risks:** Ketogenic eating is intensive and can cause weight loss and fluid balance disruption — precisely what is risky during cancer treatment. It can also interact with certain medications. This is certainly not a standard approach.
Nutritional supplements (vitamins, minerals, herbs)
Cautiously investigated partly discouraged
Many patients use supplements hoping to help their immune system further. Some are unlikely to be harmful, others can interfere with immunotherapies.
**Specific points of attention:**
- **High doses of vitamin C, E, selenium:** These very strong antioxidants can in large doses slow down the immune response of antibody therapy.
- **Probiotics:** Investigated, but cautiously — some strains can cause bacterial sepsis in patients with weakened immunity.
- **Herbs (astragalus, reishi, medicinal mushrooms):** Popular, but interaction with immunotherapies not well understood; caution is warranted.
- **Bromelain (from pineapple):** A 2026 study on healing after skin incision surgery showed modest effect, but application in melanoma treatment is lacking.
Many supplements are unproven to be safe alongside modern immunotherapy. This is really something you discuss with your treating physician beforehand.
Fluid balance and electrolytes
ResearchediPositive results in clinical studies, not yet standard treatment
Immunotherapies and chemotherapy often cause diarrhea, vomiting, or reduced fluid intake. This quickly leads to dehydration and electrolyte imbalance, which is serious.
Regular drinking — water, tea, fluid from food — is essential. With much diarrhea, isotonic drinks (with salt and glucose) work better than plain water. Some patients benefit from regular small fluid portions rather than large amounts at once.
This is not a diet, but a daily concern that has major impact on side effects and wellbeing.
Lean diet (low fat) and digestion
ResearchediPositive results in clinical studies, not yet standard treatment
Many immunotherapies (antibody therapy) cause gastrointestinal side effects — diarrhea, abdominal pain, nausea. Food that is easily digestible helps: cooked vegetables, lean meat, white fish, rice, grated apple, yogurt.
Fatty, spicy, or heavy food is often poorly tolerated. This is not a permanent diet, but rather cautious eating during periods of active side effects.
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Final note
Nutritional choices for metastatic melanoma are highly personal. What works well for one patient may not work for another. Your treatment phase, your medications, your side effects, your body weight and your preferences determine what is sensible.
A specialized oncology dietitian (dietitian with experience in cancer treatment) can help adapt nutrition to your situation, relieve side effects and ensure that your body gets enough to cope with treatment. This is not a luxury; it is part of good oncology care.
_This information never replaces the judgment of a doctor. Always discuss your nutritional choices with your own doctor or oncology dietitian._