Beating skin cancer
Protecting yourself against skin cancer involves more than just staying out of the sun. The right diet could mean the difference between life and death, MiNDFOOD reports.
Beating skin cancer
What do you think of when someone says ‘summer’? Usually it’s glorious images of searing sunshine, tanned bodies, surf, barbecues and the great outdoors. However healthy and appealing the image, in real life sunshine and long days at the beach can turn out be a death sentence. An overdose of UV rays can lead to skin cancer, and the most frightening skin cancer of all, melanoma.
Each year more than 50,000 New Zealanders and 370,000 Australians are diagnosed with the most common (and less deadly) skin cancers – squamous cell and basal cell carcinomas. Removed early, these skin cancers are no threat to life.
It’s the tiny inconsequential-looking mole on your arm, face, or even the sole of your foot that could turn out to be the calling card of the grim reaper … melanoma. Not only is melanoma the most aggressive form of skin cancer, it is also one of the most aggressive of all types of cancer. Living beneath the searing Antipodean sun, Australians and New Zealanders have a melanoma risk up to 10 times higher than many other parts of the world. Australia has the highest incidence of melanoma in the world, followed closely by New Zealand. Across the Australian population, the lifetime risk of developing melanoma is about one in 25. An individual’s risk may be much higher depending on their personal risk profile, such as skin and hair colour, family history of the disease, and history of childhood sunburn.
Personal vigilance and self-awareness is vital for finding melanoma at its earliest, hopefully curable, stage. But how do you know if you should be worried about the tiny little mole on your cheek, or anywhere else for that matter? Firstly, you need to know that melanomas can form virtually anywhere on your body … including the soles of the feet, your eyes, inside your mouth and even in your intestines. That’s why you need a buddy for a melanoma check, someone to look at your scalp, on your back, and yes, even inside your mouth. And what are you looking for? A mole … but not just any mole. Melanomas come in all colours and sizes, but often a melanoma mole is an interesting mix of different colours and usually has an irregular border. Unlike normal moles, these moles are often itchy and irritating. Pay attention to the feel and appearance of your moles, and if you notice a mole changing shape, size or colour, or becoming itchy or irritating, see your doctor immediately.
Melanoma is caused by excessive sun exposure, or at least that’s what we’re usually told. The truth is that it’s still not fully understood what causes melanoma. While sunshine exposure is significant in the risk equation, it’s probably not the full story. That’s why sometimes people are diagnosed with melanoma despite very little history of sun exposure, and also why melanoma can form on parts of the body that rarely or never come into contact with the sun, such as inside the mouth.
Although it takes more than just a history of sunburn and excessive sun exposure to trigger a melanoma, there are some people who are at increased risk of this cancer. They are usually fair skinned and have red or blond hair and blue eyes. With their low production of the tanning pigment melanin, these people are much more likely to burn quickly and have a 600 per cent greater chance of developing melanoma. Those who have a lot of moles on their body face a similar elevated melanoma risk. A family history of melanoma also places you at great risk.
Of course not everyone with fair skin or moles goes on to develop melanoma, even with sun exposure. Why this should be is an interesting question. Could it be that our nutrition has something to do with increasing or reducing our risk of developing melanoma? This is the case for many other forms of cancer including breast, bowel and prostate cancer.
Our understanding of how nutrition affects melanoma risk is still in its infancy. While researchers continue to search for all the possible links between our daily dietary practices and melanoma, many of the results have been confusing and contradictory. That said, there are some nutritional relationships that are starting to look fairly certain. Melanoma risk appears to be increased by: alcohol consumption; diets lacking in antioxidants, especially beta-carotene; and diets containing excessive omega-6 fatty acids and too little omega-3 fatty acids.
Skin cancers and melanoma have much to do with free radicals. While they sound like extremist terrorists, free radicals are actually unstable and destructive molecules produced by our own bodies. When we are exposed to excessive ultraviolet radiation, destructive free radicals are created, damaging the genetic material (DNA) within the melanocyte cells responsible for producing the brown pigment melanin that causes tanning.
As well as limiting sun exposure, we can further protect ourselves from free-radical mayhem by eating a diet rich in naturally occurring antioxidants. Some studies suggest that a diet rich in antioxidants can reduce our risk of skin cancers and melanoma. The antioxidants thought to be most protective include:
– Beta-carotene – found in yellow, orange and dark-green vegetables, such as carrots, yams, kumara, broccoli and oranges.
– Beta-cryptoxanthin – found in yellow and orange fruits and vegetables. Highest in pumpkin, squash, papayas and mandarins.
– Lutein – found in dark-green leafy vegetables and egg yolks.
– Lycopene – found in the red pigment in fruits and vegetables. Richest in cooked tomatoes.
There is also some evidence that diets high in fibre, B vitamins, folate, magnesium and zinc may lower our risk of melanoma.
It now seems fairly certain that the delicious glass of wine or ice-cold beer at the end of the day may be doing more than improving the health of your cardiovascular system. When it comes to alcohol, it’s certainly not all good news because while your heart may benefit, your risk of melanoma may increase. Drinking more than four drinks a week could as much as double your risk of melanoma. If you’re a woman, the evidence suggests you’re even more sensitive to this alcohol-induced increase in risk.
Then there’s the question of fat. It’s common knowledge now that the amount and type of fat in our diet can influence the risk of developing a number of different cancers, including cancer of the breast, prostate and colon. Some studies suggest that we can add melanoma to this list too. To safeguard your skin, limiting total dietary fat is a smart move that will also benefit your cardiovascular system and waistline. It’s also important to choose the right kinds of fats.
As far back as 1994, experiments with hairless lab mice showed that our daily fat choices can protect or punish our skin. Two groups of hairless mice were fed identical diets, except that the diet of one group contained 20 per cent butter (a saturated fat) and the other group a diet containing 20 per cent margarine (polyunsaturated fat). By the end of the study, the group eating the polyunsaturated fats had developed significantly more skin cancers after exposure to UV light.
Omega-6-rich polyunsaturated oils (found in safflower, sunflower, corn oil and margarine) contain a lot of linoleic acid, thought to suppress the immune system’s cancer fighting abilities when taken in high amounts. Other polyunsaturated fats contain higher concentrations of omega-3 fatty acids and have just the opposite effect, working to protect the skin from skin cancer and melanoma.
When lab mice are fed diets rich in omega-3, not only do they have much greater resistance to skin cancer, they are also able to spend twice as long under sun lamps before they begin to burn. In the real world of people, observational studies have found that people who regularly eat omega-3-rich fish are 40 per cent less likely to develop skin cancer.
An equal balance between omega-6 and omega-3 fatty acids is important for skin health. Too many omega-6 oils disturbs our ability to absorb and use the cancer-protective omega-3 fatty acids.
TOP TIPS FOR LOWERING MELANOMA AND SKIN CANCER RISK
Avoid excessive sun exposure
Cover up with clothing, a hat and sunblock during peak UV times.
Use a sunblock of at least SPF15 that contains physical sunblockers such as titanium or zinc oxide to reduce UVA exposure.
More fruit and veg
Increase fruit and vegetables in your diet to boost antioxidant intake. Have a generous daily serving of yellow or orange and green fruits and vegetables to increase beta-carotene intake.
Keep dietary fats low
Avoid trans fats (listed as hydrogenated fats in ingredients).
Minimise omega-6 fats such as sunflower, safflower, soy and corn oil and margarine.
Increase omega-3 fatty acids such as oily fish, avocado, nuts and seeds. Eat oily fish such as salmon, sardines, herrings and tuna three to four times a week.
Keep alcohol intake low
Just four drinks a week could double your risk of melanoma.
Have your vitamin-D levels checked with a 25-hydroxy-vitamin D blood test. If your levels are below 50-80ng/ml, ask your doctor about supplementing with D3. Vitamin D is made in your body in response to sunlight exposure. Exposing unprotected skin for 10 minutes in peak UV times will boost vitamin D levels if they are low. If you are fair skinned, have red or blond hair and blue eyes or have lots of moles or a family history of melanoma, use D3 supplements instead of relying on sun exposure.
IS YOUR MOLE A MELANOMA?
Check your moles regularly and have a regular mole check with your doctor or dermatologist. To decide if your mole is suspicious and needs further medical investigation, use the ABCD rule:
A FOR ASYMMETRY
Moles are usually symmetrical and round. Melanomas often have irregular borders and shapes.
B FOR BORDER
Moles usually have smooth, regular borders. Melanomas often have uneven borders or scalloped edges.
C FOR COLOUR
Moles are usually one colour, often brown. Melanomas are often unusual colours or mixed colours, including reds, blues and white.
D FOR DIAMETER
Melanomas often grow larger than moles, and can easily grow to the size of a pencil eraser.
UVA V UVB – WHAT’S THE DIFFERENCE?
When we are in the sun, our body is bathed in UV light made up of different wavelengths. UVB causes tanning and sunburn, and is effectively blocked by sunscreen. UVA is traditionally only weakly blocked by sunscreen and it is this wavelength that’s thought to be more closely associated with melanoma formation.
The latest sunscreens contain ingredients which also partially block UVA. Check the label on your sunscreen to ensure that it contains titanium dioxide, zinc dioxide or avobenzone (trade name Parsol 1789) or Mexoryl SX (trade name Tinosorb). Even with these ingredients, UVA blockage appears to be greatly inferior to UVB blockage, so sunbathing will still increase your exposure to UVA rays associated with melanoma.
The solution to the dilemma? Restrict peak-hour sun exposure and cover up with clothing and hats instead of just relying on sunblock.