The foods we eat can affect our risk of developing certain types of cancer. High energy and high fat diets can lead to obesity and are generally thought to increase the risk of some cancers. Plant-based diets high in fresh fruits, vegetables, legumes and wholegrain foods may help to prevent cancer.

Diet is just one of the lifestyle factors that influence the risk of developing cancer. Smoking, obesity, alcohol, sun exposure and physical activity levels are also important. Although some foods can affect cancer risk, there is no evidence that specific foods can cause or cure cancer.

Food and some common cancers
Some common cancers (and how they are affected by what we eat) include:

• Lung cancer – this is the leading cause of death from cancer in the world and smoking is mostly responsible. There is convincing evidence that diets high in vegetables and fruits are protective against lung cancer. It is thought that compounds called carotenoids (present in significant amounts in fruits and vegetables), as well as vitamin E, are probably responsible for some of this effect. However, the use of antioxidant supplements, such as beta-carotene and vitamin E, has not been proven to be effective in either prevention or treatment of lung cancer and may, in fact, increase the risk of developing cancer in those who smoke. While fruits and vegetables may offer some degree of protection, not smoking in the first place is by far the best prevention.

• Breast cancer – this is the most common type of cancer in women in the world. There is an increased risk of breast cancer with factors such as rapid early growth, greater adult height and weight gain in adulthood. Much of the risk of developing breast cancer involves factors that influence oestrogen levels during a woman’s reproductive life, such as age of menarche (first period), number of pregnancies and breastfeeding practices. Post menopausal women who are carrying too much weight, especially around their middle, have more than twice the average risk of breast cancer. Diets high in mono-unsaturated fat and high in vegetables and fruits may reduce the risk, while alcohol consumption increases the risk.

• Prostate cancer – a quarter of all new cancers diagnosed in men in UK is prostate cancer. Vegetables, soy in particular may decrease the risk, while a high fat diet that comprises mostly animal fat sources (such as dairy products, fatty meats and takeaway foods) may increase the risk. Lycopene is a potent antioxidant found in tomatoes, tomato-based products, watermelon and strawberries. It may also help lower the risk of prostate cancer.

• Bowel cancer – this is the fourth most common cancer in the world. Up to 70 per cent of cases can be prevented by following a healthy lifestyle. Keeping a healthy weight, being physically active and a diet high in vegetables and fibre are protective, while consuming a large amount of red meat (especially processed meat) and alcohol may increase the risk.

Foods to ‘eat less’
Foods to limit in your diet or eat less of include:

• Fatty processed red meats

• Highly processed foods that are low in fibre

• Heavily salted and pickled foods.

Foods to ‘eat more’
The strongest protective anti-cancer effect has been shown with:

• Vegetables, especially raw vegetables or salads

• Leafy green vegetables

• Carrots

• Tomatoes

• Citrus fruits

• Cruciferous vegetables like broccoli, cabbage, brussels sprouts, bok choy and other Asian greens.

Include more of these vegetables and fruits in your diet along with other varieties.

Seven a day
Eating seven or more serves daily of a variety of grains, grain products, legumes, roots and tubers will also provide protective benefits against cancer. The less processed the grains, the better. Diets high in refined starch and refined sugar may increase the risk of stomach cancer and bowel cancer.

Meat and bowel cancer
There is now convincing scientific evidence that eating processed meat increases bowel cancer risk. The World Cancer Research Fund (WCRF) has recently recommended that people avoid eating processed meat. Processed meats are any meat that has been preserved by curing, salting or smoking, or by adding chemical preservatives. These meats include hot dogs, ham, bacon and some sausages and burgers.

It is recommended that children are not given processed meats at all. This is because many of the habits we develop as children last into adulthood. Substitutes for processed meats that are recommended for children include poultry or fish, low fat cheese or small amounts of lean meat.

The WCRF also recommends limiting the amount of fresh red meat we eat to 500g (cooked weight) a week. This is because there is convincing evidence that red meat also increases a person’s risk of bowel cancer.

Some research suggests that eating burnt or charred meat may increase cancer risk, but the evidence is unclear.

Fats and cancer
There has been a great deal of interest in the possible association between fat and cancer. Current evidence does not indicate a direct link between fat intake and particular types of cancer (with the possible exception of prostate cancer). However, a high fat diet may lead to obesity, which is a risk factor for several cancers including cancer of the colon, breast, kidney, oesophagus, gallbladder and endometrium.

Supplements are not the answer
Results of studies that show a protective effect of foods containing certain nutrients should not be taken to mean that these nutrients, when isolated and taken as supplements, will provide the same benefits for cancer prevention. In some cases, there has been an increased risk of cancer in those people who take nutrient supplements at doses higher than the amount of that nutrient normally eaten in foods.

Suspect foods examined
While a high energy, low fibre diet may increase a person’s risk of developing cancer, some individual foods have also been singled out as potentially causing cancer (carcinogenic). These include:

• Artificial sweeteners – such as aspartame, saccharin and cyclamate. Laboratory rats can develop bladder cancer if fed huge amounts of saccharin or cyclamate, although this is at levels thousands of times greater than a normal diet. International studies agree that humans aren’t affected in the same way. Artificial sweeteners are considered safe to eat.

• Cured, pickled or salty foods – there is no conclusive evidence that red meat causes cancer. However, bacon and other cured or pickled meats contain a substance called nitrate, which has the potential to cause cancer in laboratory animals when eaten in huge doses. How this research relates to humans isn’t clear. To be on the safe side, it is best to limit the amount of cured meats in the diet because they are generally high in fat and salt. Salt has also been associated with an increased risk of stomach cancer and should be consumed in limited amounts.

• Burnt or barbecued foods – a group of carcinogenic substances called polycyclic aromatic hydrocarbons (PAHs) can be produced if foods are overheated or burnt. Although charred or smoked foods could contain traces of PAHs, experts agree that the amount in the average UK diet is too low to be considered a significant cancer risk. However, when cooking, it’s best to use relatively low temperature methods wherever possible. These include steaming, boiling, poaching, stewing, casseroling, braising, baking, stir-frying, microwaving or roasting. Avoiding char-grilled meats and foods would also be smart.

• Peanuts – some laboratory animals can develop cancer after eating peanuts that are contaminated with toxin-producing moulds. However, peanuts sold in the UK are generally uncontaminated and contamination is routinely screened for.

• Alcohol – consuming alcohol increases the risk of cancers of the mouth, pharynx, larynx, oesophagus, breast and liver. The risk is even greater in those people who smoke. Alcohol has also been associated with colon, breast and rectal cancers. Men should drink less than two standard drinks a day and women less than one standard drink a day.

Treating cancer with food
While food plays an important role in preventing some cancers, the therapeutic value of food in treating existing cancer is less clear. It is true that a person with cancer needs excellent nutrition in order to better cope with the physical demands of the illness and the rigours of medical treatment. However, claims that particular foods, vitamins or micro nutrients can kill cancer cells should be viewed with scepticism To date, there is little scientific proof that a particular food or supplement can cure cancer or destroy cancer cells.

Recently some Japanese studies have found that green tea may delay the development and spread of certain cancers. Other studies have suggested that soy may also have a similar effect. Although this work is preliminary, it may suggest a more important role for food in the treatment of cancer in the future.

Nutrition for the person with cancer is important for many reasons, including:

• The immune system needs bolstering to fight at full strength.

• The diet may be adjusted to cope with various symptoms, such as constipation, diarrhoea or nausea.

• Loss of appetite or an increased metabolism means that high energy foods may need to be included in the daily diet.

• Extra protein may be needed to help prevent loss of muscle from weight loss.

Things to remember

• High fat, low fibre diets may increase the risk of many cancers, including bowel, lung, prostate and uterine cancers.

• You can reduce your risk of developing cancer by eating more fresh fruits, leafy green vegetables and wholegrain foods.

• Even though diet can influence your risk of developing cancer, there is little evidence that special foods can be used to cure existing cancers.

                                  

Along with a balanced diet and regular exercise, multivitamins are a good way to stay in good health. For just pennies a day, they may help lower your risk of cancer, heart disease and osteoporosis as well as prevent some birth defects. When undertaking body weight management, taking a multi-vitamin will keep you strong and healthy. Since you are changing your eating habits in one way or another, you want to make sure you are getting in a good amount of your essential vitamins and minerals. Look to include vitamins: A, D, E & B-Complex (B1, B2, B6, B12), minerals: calcium, magnesium, potassium, copper, manganese, chromium, zinc, iodine, boron, iron & selenium in addition to an anti-oxidant. There are many misconceptions about vitamins and the health benefits they offer.
Vitamins play an important role in keeping the body healthy. However, taking large doses of certain vitamins can actually be harmful. For most people, it is best to get the vitamins our bodies need from eating a variety of healthy, unprocessed foods rather than by taking supplements. Vitamin supplements are frequently misused and taken as a form of medicine to treat ailments such as colds or to counteract lifestyle issues such as stress. Contrary to popular belief, vitamins aren’t drugs or miracle cures. They are organic compounds that participate in various metabolic functions. High-dose supplements should not be taken unless recommended under medical advice. Isolating the ‘active ingredient’ is not the answer Proper balance and adequate levels of essential nutrients is important for a range of complex processes in our body. When vitamins are taken as supplements, they are introduced into the body at levels that could never be achieved by eating even the healthiest of diets. They are also sent in ‘alone’. When they occur in food, vitamins have many other companions to help them along the way. For instance, provitamin A (beta-carotene) in food is accompanied by hundreds of its carotenoid relatives. Simply taking a vitamin pill is not an instant fix for feeling run down or lacking in energy. It is the combination of a whole range of compounds (most of which we probably don’t even know about) in plant foods that gives us the protection. When you artificially remove one of them and provide it completely out of context, it may not be as effective and, in the case of some vitamins, can have negative effects
Recommended dietary intakes
 Many people mistakenly believe that since small amounts of vitamins are good for you, then large amounts must be better. In the case of vitamins, it is better to follow the rule of ‘less is more’. The vitamins A, D, E and K are fat soluble, which means they can be stored in the body. Taking high doses of these vitamins, especially vitamin A, over a long period of time can result in harmful levels in the body unless you have a medically diagnosed deficiency. Some of the water soluble vitamins can also cause side effects in high doses. For instance, vitamin B6 has been linked with nerve damage when taken in large doses. For a healthy adult, if supplements are used, they should generally be taken at levels close to the recommended dietary intake (RDI). High-dose supplements should not be taken unless recommended under medical advice. Deficiencies and illness
The human body is able to store vitamins. The fat soluble vitamins A, D, E and K can be locked away in the liver and body fat and stored for a long time. The water soluble vitamins, including B-complex and vitamin C, are mostly only stored for a shorter period of time. A vitamin deficiency takes weeks or months before it will affect your health. For instance, it would take months of no vitamin C before you developed scurvy. An occasional lapse in good eating will not harm you if your usual diet consists of a wide variety of fresh foods.
Sometimes supplements are needed
 Supplements do have a role to play for some groups of people. For instance, people on long-term restrictive weight loss diets or people with malabsorption problems such as diarrhoea, coeliac disease, cystic fibrosis or pancreatitis can benefit from supplements. Folic acid supplements are strongly recommend for women planning a pregnancy to reduce the risk having a baby with neural tube defects, like spina bifida. People who are advised by their doctor that they need to take vitamin supplements are encouraged to consult an accredited dietitian, who can work with their doctor to provide dietary advice related to the person’s situation. If you need to take a supplement, it is best to take multivitamins at the recommended dietary level, rather than single nutrient supplements or high-dose multivitamins.
The common cold and vitamin C
Many people think that vitamin C helps prevent the common cold. Despite exhaustive research across the world, there is still no strong evidence to prove this. Some studies have shown that taking large doses of vitamin C (more than 1,000mg per day) continuously or at the start of a cold may ease some of the symptoms and the duration, on average, making it about half a day shorter. It does not prevent you catching a cold. You also need to consider the health risks associated with taking large doses of vitamin C. Large doses may cause nausea, abdominal cramps, headaches, fatigue, kidney stones and diarrhoea. It may also interfere with your body’s ability to process (metabolise) other nutrients – for example, it could lead to dangerously raised levels of iron. Excessive amounts of vitamin C in the body can also interfere with medical tests, such as diabetes tests, giving a false result. Adults need about 45mg of vitamin C per day and any excess amount is excreted. Stress, depression and anxiety Some vitamin and omega-3 fatty acid deficiencies can lead to emotional disturbances. However, if you are feeling run down, it is more likely to be due to stress, depression or unhealthy lifestyle habits (such as insufficient sleep or smoking) rather than a vitamin deficiency. Feeling under pressure doesn’t automatically lead to a vitamin deficiency, so taking a vitamin supplement won’t necessarily make the stressful feelings go away. More serious mental illnesses, such as schizophrenia and bipolar disorder, aren’t caused or prevented by vitamins, although a healthy diet and good nutrient intake can help support a person to better cope with their condition.
Vitamin E and heart disease
Vitamin E is widely promoted as a beneficial antioxidant that can help prevent heart disease. Unfortunately, several large-scale reviews have conclusively found no evidence that vitamin E supplements prevent death from heart disease. In fact, there may be greater risk of all-cause death from taking such supplements.
Cancer cures
Vitamin A in large doses does not cure cancer and can be toxic, particularly if taken as pills rather than food. There is some evidence that vitamin E could play a small role in preventing some cancers although, equally, there is evidence that it could hasten the onset of other types of cancer; however, this has not been conclusively proved or disproved. While it is argued by some that megadoses of antioxidants can help with the effectiveness of conventional cancer treatments, such as chemotherapy and radiotherapy, the evidence is far from supporting this. In fact, it has been shown that megadoses of antioxidants can actually interfere with some medical treatments of cancer by helping to protect the cancer cells that the therapies aim to eradicate.
Some research findings
A number of studies into supplement use have shown negative findings. For instance: Vitamin A (beta-carotene) was thought to reduce the risk of some cancers but has been linked to an increase in others, such as lung cancer in smokers, if taken in supplement form. Several long-term studies have shown that prostate, breast and lung cancer risk are not decreased by taking high-dose supplements containing vitamins E or C or selenium. People taking high-dose vitamin E supplements have been found to have higher rates of early death (mortality).
Anti-ageing vitamins
Vitamin E is often singled out as the potential fountain of youth. However, there is no evidence that taking large doses of any vitamin can either stall or reverse the effects of ageing. Neither can any one vitamin restore a flagging sex drive or cure infertility. Vitamins and chronic disease
In developed countries, vitamin deficiency is rare but the inadequate intake of some vitamins is not so rare and has been linked to a number of chronic diseases. These include cardiovascular disease, cancer and osteoporosis. There is ongoing research to study the effects of taking vitamin supplements to prevent chronic disease, and evidence around nutrition and diet is constantly changing. It is important you consult with your doctor before taking vitamin supplements in high doses.
Things to remember
Vitamins are not drugs or miracle cures. Taking large doses of vitamins can be harmful because your body only needs vitamins in very tiny amounts. Eating plenty of fruits, vegetables, whole grains and cereals will give your body most of the vitamins your body needs at the right level and in the right balance. Vitamin supplements can’t replace a healthy diet, but a general multivitamin may help if your diet is inadequate.
People who may need vitamin supplements include pregnant and breastfeeding women, people who consume alcohol in amounts over the recommended level, drug users and the elderly.