Nutritional, micronutritional and functional support for people with cancer calls for a rigorous, integrative and personalised approach. Cancers differ, medical protocols differ, and side effects vary widely from one person to the next. Within that framework, diet, micronutrition, physical activity, relaxation and psychological support all have an essential complementary role.
Understanding what characterises cancer cells
Cancer cells divide abnormally. Normally the body renews its cells through mechanisms that repair or remove faulty ones. When those systems are pushed beyond their limits, a cell can turn malignant.
Several features characterise tumour progression:
- cell proliferation that is out of control;
- inhibition of apoptosis, that is, of programmed cell death;
- mutations affecting oncogenes, anti-oncogenes or apoptosis genes;
- deregulation of cell metabolism;
- resistance to cell death;
- escape from immune surveillance;
- inflammation that favours the tumour;
- epigenetic reprogramming.
This biological picture helps explain why nutritional support can never come down to a single lever.
Why care remains complex
The medical strategy depends on the histological diagnosis, the stage, the cell type and the way the cancer behaves. Not all cancers progress at the same speed: some, such as prostate cancer, advance slowly, while others are far more aggressive.
Medical care often combines several stages:
- surgery;
- radiotherapy;
- chemotherapy;
- sometimes several successive chemotherapy regimens;
- sometimes consolidation or holding chemotherapy.
Chemotherapy acts on dividing cells or on the mechanisms that precede cell division. Immunotherapies use monoclonal antibodies to direct a targeted immune response. These approaches increase survival in certain cancers, but they remain demanding and toxic by nature: their effectiveness rests precisely on that controlled toxicity.
The side effects to watch for
Dr Jean Joyeux runs through the range of possible side effects:
- anaemia, clotting disorders, immunosuppression;
- digestive problems, liver and kidney toxicity;
- skin and mucosal lesions, mouth ulcers, wounds and fungal infections;
- muscle or joint pain, neurological and cardiac toxicity;
- profound fatigue, stress, anxiety and depressive states.
Weight loss and muscle wasting are a major risk: protein undernutrition weakens the person, reduces tolerance of the treatment courses and makes recovery between two sessions harder. Conversely, high-dose cortisone can drive weight gain and disturb metabolism.
The main principles of support during the treatment courses
The primary aim is to help the person cope better with the courses and the stress that goes with them, while avoiding needless loss of weight and lean mass.
1. Protect muscle mass
Maintaining muscle mass rests on an adequate protein intake, resistance work, physical activity matched to the person, and close monitoring of nutritional status. During chemotherapy, the speaker suggests a baseline of at least 1 g of protein per kilo of body weight per day.
2. Keep fluid intake high
Hydration plays a key role, particularly in view of renal toxicity: the aim is well diluted urine. When intravenous fluids are not given during the courses, a high oral fluid intake becomes necessary.
3. Adapt the diet
A low-carbohydrate or even ketogenic diet may interest some people, but it does not suit everyone and it assumes protein intake stays sufficient. Unjustified restrictions are best avoided, especially in someone who has already lost weight. The diet keeps a simple logic: high micronutrient density, low glycaemic index, low glycaemic load, and a Mediterranean slant wherever possible.
4. Maintain physical activity matched to the person
Adapted physical activity supports tolerance of the courses and recovery, while helping to preserve muscle mass. The level of effort is always adjusted to the person's condition.
5. Support mental wellbeing
Psychological support is essential. The diagnosis is a shock, and the side effects add further blows. Putting anxiety, anger or sadness into words helps people get through this period.
What is better avoided during the treatment courses
According to Dr Jean Joyeux, some practices call for caution, or are best avoided during chemotherapy:
- Omega-3: intake comes above all from food (fish, organic rapeseed oil, walnuts). The capsule form is not the priority during chemotherapy.
- Antioxidants: the treatment courses are seeking a pro-oxidant action on diseased cells. Supplementing with antioxidants during this period serves no purpose and risks interfering with the intended effect; these nutrients find their place later, during the rebuilding phase.
- Vitamins: these come first from food. During the courses, the essential thing is to steady the person's general condition without interfering.
- Detoxification or drainage: the period of the treatment courses is not the moment to embark on that kind of approach.
Plants and chemotherapy: interactions to know about
Interactions between herbal medicine and chemotherapy call for real caution: some plants alter how the drugs act by affecting cytochrome P450 enzymes, absorption or bioactivation. Among the combinations to avoid during chemotherapy:
- turmeric as a supplement, milk thistle, rosemary, St John's wort, rhodiola, chrysanthellum;
- aloe vera and clay taken orally;
- grapefruit and pomelo, pomegranate juice;
- a question mark over grape, mango, cranberry, guava, papaya and apple juices.
A single glass of grapefruit juice can lead to an overdose up to three days later. Vegetable juices are more useful, in small amounts and with a variety of vegetables.
Desmodium, a special case
Desmodium stands out for its low interaction with cytochrome P450 enzymes and acts mainly as a liver protectant: it helps limit nausea, support appetite and reduce the liver inflammation linked to certain courses. In practice, follow the liver work-up and stop it if that deteriorates. Its value is open to discussion during some chemotherapy regimens, though not in every context, and it remains more uncertain in liver cancer.
Probiotics, the microbiota and fungal infections
The gut and oral microbiota deserve particular attention, especially where there is immunosuppression and fungal infection, and bifidobacteria and lactobacilli hold an important place there. Bacterial probiotics can support the management of some fungal infections, particularly oral ones. One strain is an exception and remains contraindicated in a person who is immunocompromised: Saccharomyces boulardii, which can colonise an implanted port, enter the bloodstream and become life-threatening. Caution is essential.
Vitamin D, magnesium, glutamine: at what point?
Vitamin D
Vitamin D status is worth knowing, even if the blood level does not always reflect its activity; serum calcium and parathyroid hormone add a complementary picture. Its value is confirmed above all in the rebuilding phase, after the courses.
Magnesium
Magnesium is open to discussion, without being a priority during chemotherapy.
Glutamine
Glutamine does not feed cancer, contrary to a widespread idea: it mainly supports the enterocytes and repair of the gut lining. It becomes useful after the courses, often in the fortnight to month that follows, to help rebuild the intestinal barrier and calm digestive inflammation. Butyrate, for its part, acts mainly on the colonocytes and depends on the microbiota and on fibre.
After the courses: a more open phase
Once the courses are over, the priorities widen: rebuilding immunity, supporting the microbiota, working on metabolism, freer use of antioxidants, a detoxification approach that becomes possible again, a Mediterranean diet, work on the quality of what is on the plate, physical activity and psychological support. This is where glutamine, vitamin D and work on the intestinal barrier come into their own.
Key points
- support without interfering;
- protect body weight and muscle mass;
- hydrate properly;
- leave unsuitable supplements until after the courses;
- stay cautious with plants and juices;
- bring in the microbiota, vitamin D and glutamine at the right moment;
- build diet, physical activity and psychological support in as a matter of course.
The aim is never to replace medical care, but to support it with method, caution and consistency.
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