After her melanoma, my mother did what a lot of people do: she went looking for something she could control. The surgeon had done his part, the pathology was clear, and she was told to come back in six months. Six months is a long time to sit with a diagnosis and do nothing. She came to my kitchen with a printed list of "anti cancer foods" from a website that also sold the supplements, and asked me, because I am the one in the family who reads the studies, whether any of it was real.
Some of it was. Most of it was not. This article is the answer I wish I had been able to hand her that afternoon: what the evidence says about food and skin cancer, which nutrients have been properly tested, which have been oversold, how alcohol and body weight fit in, and how to exercise when your doctor has told you to stay out of the sun. It is written for three groups of people: those who want to lower their risk, those going through treatment, and those on the other side of it who want to stay there. No shame, and sources for everything.
First, the honest framing
Food does not cause skin cancer and food will not cure it. Around 86 percent of melanomas and 90 percent of non melanoma skin cancers are caused by ultraviolet light (Parkin et al., British Journal of Cancer 2011). If you eat perfectly and burn twice a summer, the burns win. Everything below sits on top of the basics in our prevention guide: daily sunscreen, shade at midday, no sunbeds, monthly skin checks.
That said, the skin is an organ under constant oxidative attack, the immune system is what clears the cells that UV damages every day, and there is now a reasonable body of research on which foods help those two systems do their job. One nutrient has a proper randomised trial behind it. Several others have consistent observational evidence. And there are two things, alcohol and excess weight, that nudge risk in the wrong direction.
The one supplement with trial evidence: nicotinamide
Nicotinamide is a form of vitamin B3. It helps skin cells repair UV damaged DNA and prevents the local immune suppression that UV causes. In the ONTRAC trial, 386 Australians who had already had at least two non melanoma skin cancers in the previous five years took either 500 mg of nicotinamide twice a day or a placebo for a year. The nicotinamide group developed 23 percent fewer new basal and squamous cell cancers and 13 percent fewer actinic keratoses, the rough pre cancerous patches (Chen et al., NEJM 2015). The benefit stopped within six months of stopping the tablets.
Important caveats. It has not been shown to prevent melanoma. It has not been shown to help people who have never had a skin cancer. It is nicotinamide, not niacin (nicotinic acid), which causes flushing and can strain the liver at high dose. It is cheap, available in any pharmacy, and it is now recommended by many dermatologists for people with a history of multiple non melanoma skin cancers or on immunosuppressant drugs. Ask before starting it if you have kidney or liver disease. My mother takes it, and the interval between her basal cells has, for whatever it is worth in a sample of one, lengthened.
Foods to eat: what the cohort studies point to
Oily fish and omega 3 fats
Omega 3 fats dampen the inflammatory response to UV and appear to reduce UV induced immune suppression in the skin. In a Nurses' Health Study analysis of more than 75,000 women, higher fish intake was associated with a lower risk of squamous cell carcinoma, and a randomised trial in which volunteers took 4 grams of omega 3 a day for three months found their skin's immune response to UV was significantly better preserved (Pilkington et al., American Journal of Clinical Nutrition 2013). Two portions of salmon, mackerel, sardines or trout a week is the practical target.
Carotenoids: tomatoes, carrots, sweet potato, peppers
Lycopene and beta carotene accumulate in the skin and absorb some UV energy. In a small but well run trial, volunteers who ate 40 grams of tomato paste with olive oil daily for ten weeks had 40 percent less reddening from a standard UV dose, equivalent to about SPF 1.3 (Stahl et al., Journal of Nutrition 2001). That is not sunscreen. It is a small, permanent, whole body baseline that food gives you and cream does not. Cooked tomatoes with fat, carrots, butternut squash, red peppers and dark leafy greens are the sources. Do not take high dose beta carotene tablets: in smokers they increased lung cancer in two large trials (Omenn et al., NEJM 1996).
Green tea and coffee
Green tea catechins (EGCG) and coffee both have plausible mechanisms and modest cohort evidence. In a pooled analysis of more than 447,000 people, those drinking four or more cups of coffee a day had a 20 percent lower risk of melanoma than non drinkers (Loftfield et al., Journal of the National Cancer Institute 2015). Decaffeinated coffee showed no effect, which suggests caffeine itself rather than a lifestyle difference. This is not a reason to start drinking coffee, but it is a reason not to stop.
Vegetables, fruit and the Mediterranean pattern
An Italian case control study found that people eating the most vegetables, fruit and fish, in a pattern close to the Mediterranean diet, had roughly half the odds of melanoma compared with those eating the least, after adjusting for sun exposure and skin type (Fortes et al., International Journal of Epidemiology 2008). Case control studies have their weaknesses, but the finding fits everything else we know about this eating pattern, including its effect on the cancers covered in our kidney cancer and gallstone guides. Cruciferous vegetables (broccoli, kale, cabbage) contain sulforaphane, which in small human trials switches on the skin's own antioxidant enzymes.
Vitamin D: from a tablet, not a sunbed
People with low vitamin D at melanoma diagnosis tend to have thicker tumours and worse outcomes (Newton-Bishop et al., Journal of Clinical Oncology 2009). Whether correcting it changes outcomes is being tested, but there is no downside to keeping your level in the normal range. Ten micrograms (400 IU) a day from October to March at UK latitudes is the standard advice, and year round if you now cover up carefully. A tablet costs pennies. A sunbed is a group 1 carcinogen.
Foods and habits to limit
Alcohol
A meta analysis of 16 studies found each standard drink a day raised melanoma risk by about 20 percent, with the strongest effect on melanomas of the trunk, the skin that gets intermittent intense exposure on holiday (Rota et al., British Journal of Dermatology 2014). Part of that is behaviour: people who drink on the beach burn on the beach. Part of it may be direct, since alcohol metabolites make skin more sensitive to UV. Either way, the holiday combination of sun, sangria and a nap on the lounger is the single most dangerous afternoon most people have all year.
Processed meat and citrus peel
Processed meat shows a small, inconsistent association with melanoma. More interesting is citrus: in two large US cohorts, people consuming the most citrus fruit and juice had a 36 percent higher melanoma risk, thought to be due to psoralens, compounds in citrus peel and oil that make skin photosensitive (Wu et al., Journal of Clinical Oncology 2015). Later studies have been mixed, and the effect, if real, is small. Do not give up oranges. Do wash your hands after handling limes in the sun, because lime juice on skin plus sunlight causes a real and nasty burn called phytophotodermatitis.
Body weight, BMI and skin cancer
The relationship between weight and skin cancer is odder than for most cancers. Men with obesity have about 31 percent higher melanoma risk, while the link in women is weak (Sergentanis et al., European Journal of Cancer 2013). Higher BMI is also associated with thicker melanomas at diagnosis, probably because it is harder to see and check all of your own skin. Yet among people already being treated for advanced melanoma with immunotherapy, those with obesity lived longer in a pooled analysis of 1,918 patients, a finding called the obesity paradox that researchers are still trying to explain (McQuade et al., Lancet Oncology 2018).
The sensible reading of all this is: aim for the healthy range because it lowers your risk of getting melanoma and of every other major disease, do not crash diet during cancer treatment because your body needs the reserves, and do not let a number on a chart frighten you either way. Our BMI calculator gives you the standard figure and the lower Asian and Black thresholds, and the obesity diet and exercise plan on this site is written for people with a lot to lose who need a gentle, realistic start.
Exercise and skin cancer: how to move when you have been told to avoid the sun
This is where many people get stuck. You have been told to stay out of the sun. You have also been told, correctly, that exercise is one of the most powerful things you can do for cancer outcomes. Regular physical activity after a cancer diagnosis is associated with around 35 percent lower cancer mortality across cancer types (Friedenreich et al., JAMA Oncology 2020), it improves natural killer cell activity, which is the immune system's first response to abnormal cells, and in people on immunotherapy it reduces fatigue, the most common and most wearing side effect. The American College of Sports Medicine's 2019 roundtable concluded that 150 minutes a week of moderate activity plus two strength sessions is safe and beneficial during and after treatment for essentially every cancer (Campbell et al., Medicine and Science in Sports and Exercise 2019).
The sun and the exercise are not in conflict. They just need a timetable.
| Activity | Sun safe version | Notes |
|---|---|---|
| Walking, 30 to 45 minutes daily | Before 10am or after 4pm; shaded routes at midday | The single best evidenced activity. Wide hat, UPF long sleeves. |
| Swimming | Indoor pool, or outdoor early morning with a rash vest | Water reflects UV upward; sunscreen washes off in 40 to 80 minutes. |
| Cycling | Early or late, or an indoor trainer | Neck, ears and backs of hands are classic missed spots. |
| Strength training, twice a week | Indoors, any time | Preserves muscle during treatment; helps arm swelling after node surgery. |
| Gardening | Morning or evening; long sleeves; hat with a neck flap | Gardeners have high rates of ear and neck skin cancers. |
| Yoga, Pilates, tai chi | Indoors or shaded | Good for anxiety, sleep and scar tissue mobility. |
If you have had lymph node surgery
Lymphoedema, swelling of the arm or leg after nodes are removed, affects up to a quarter of people after full node dissection and a smaller number after sentinel node biopsy. For years patients were told not to lift anything heavy with the affected limb. The PAL trial reversed that: women who did supervised, slowly progressive weightlifting had half as many lymphoedema flare ups as those who avoided lifting (Schmitz et al., JAMA 2010). Start light, add weight slowly, wear your compression garment if you have one, and ask for a referral to a lymphoedema physiotherapist if the limb changes.
If you are on immunotherapy
Exercise is safe and helps with fatigue and mood. Two cautions. Report any new joint pain, breathlessness on exertion or muscle weakness the same day, because these can be early signs of immune related side effects rather than ordinary training soreness. And on the days you feel flattened, a ten minute walk still counts. The evidence for exercise and fatigue shows that the worst thing for cancer related fatigue is complete rest.
If you have just had skin surgery
Keep the wound dry and avoid stretching it for about two weeks (longer on the lower leg, where healing is slow and my mother learned the hard way that a brisk walk on day three reopens things). Upper body work is fine after a leg excision and vice versa. Once healed, keep the scar covered or under SPF 50 for a year, since new scar tissue pigments badly in the sun.
A sample sun safe day
- 7:00 Forty minute walk, hat and long sleeves optional this early. Coffee after.
- 8:00 Porridge with berries and walnuts, or eggs with tomatoes and spinach. Sunscreen on face, neck, ears and hands before leaving the house.
- 13:00 Lunch indoors or under cover: grilled salmon or sardines on toast, big salad with olive oil, carrot and pepper sticks.
- 15:00 Green tea, a piece of fruit. Reapply sunscreen if going out.
- 17:30 Strength session indoors, or gardening now that the shadow is longer than you are.
- 19:00 Dinner: chicken or beans with roasted sweet potato and broccoli, tomato sauce made with olive oil. One glass of wine if you want it, not three.
- Bedtime Nicotinamide if your dermatologist has agreed it; vitamin D in winter.
My mother did not adopt the printed list. She adopted roughly the day above: fish twice a week, more tomatoes than she used to eat, a morning walk with a hat she calls ridiculous, and a tablet she can pronounce. It did not cure anything. The surgeon did that. What it gave her was six months between appointments that felt like living rather than waiting, and that turns out to matter a great deal.
Read next
- How to prevent skin cancer: risk factors, sunscreen evidence and self checks
- Is skin cancer curable? Treatment and survival by type and stage
- BMI calculator with Asian and Black thresholds
- Obesity diet and exercise plan for people with a lot to lose
Frequently asked questions
What foods help prevent skin cancer?
Oily fish, cooked tomatoes and other carotenoid rich vegetables, leafy greens, cruciferous vegetables, green tea and coffee are all associated with lower risk in cohort studies. None replaces sun protection.
Does vitamin B3 prevent skin cancer?
Nicotinamide 500 mg twice daily reduced new basal and squamous cell cancers by 23 percent in people who had already had at least two, in a randomised trial. It has not been shown to prevent melanoma or to help people with no history of skin cancer.
What should I avoid eating with skin cancer?
Limit alcohol, which raises melanoma risk by about 20 percent per daily drink and encourages burning. Avoid high dose beta carotene supplements. Be aware that citrus peel and lime juice on the skin increase sun sensitivity.
Can I exercise outside if I have had skin cancer?
Yes. Exercise before 10am or after 4pm, use shade at midday, wear a wide brimmed hat and UPF clothing, and apply SPF 30 or higher to exposed skin. Indoor strength training and swimming are unrestricted.
Does being overweight cause skin cancer?
Obesity is linked to about 31 percent higher melanoma risk in men and a weaker link in women. Oddly, among people treated for advanced melanoma, those with obesity have had better outcomes in some studies. A healthy weight is still the sensible aim.
This article is for general information and does not replace advice from your own medical team. Do not start supplements during cancer treatment without checking with your oncologist.
