Although there is no strong evidence linking fat consumption to breast cancer, we know that high consumption of fat can lead to obesity and there is a strong link between obesity and breast cancer in post-menopausal women. However, fats have many essential functions in the body and help with the absorption of essential vitamins such as vitamin A, D, E and K. Consuming fat moderately is part of a healthy diet and eating the right type of fat is crucial.
The World Health Organisation suggests that less than 30% of our total energy intake should come from fats. Foods containing a high content of unsaturated fats (mono or polyunsaturated) can be a major source of energy and some are even essential, since the body cannot make them, and they must be obtained through diet.
You can find these in vegetable oils (for example olive oil), seeds, avocados and nuts, but also fish. These fats are much healthier and, in many cases, provide key benefits. If you have a diet high in saturated fats, try to replace these fats with unsaturated fats, which can also lower blood cholesterol levels.
Fats with a high content of unsaturated fatty acids are liquid at room temperature.
Try to avoid saturated fats and limit your intake of trans fats of all kinds. Your intake of saturated fats should be reduced to less than 10% of total energy intake and trans fats to less than 1% of total energy intake.
Trans fats are often found in fast food, cakes and biscuits. They have no known health benefits and even small amounts of trans fats can harm health, so you should try to avoid them. Eating foods rich in trans fats promotes inflammation, which is linked to many diseases.
Saturated fats are normally found in animal and dairy products such as red meats, butter, and cream. Fats with a high content of saturated fatty acids tend to be solid at room temperature.
There is evidence that processed meat slightly increases breast cancer risk. Processed meat is meat that has been altered through salting, curing, fermentation, smoking or other processes to enhance flavour or improve preservation. Examples include ham, sausages, bacon, beef jerky, tinned meat. The World Health Organisation has classified processed meats as a Group 1 carcinogen (known to cause cancer).
Some studies suggest increased red meat consumption may increase breast cancer risk but evidence remains inconclusive.
If you eat red meat, the World Cancer Research Fund recommends limiting consumption to no more than about three portions – about 350–500g (12–18oz) cooked weight per week. If you want to eat meat, try pure organic poultry meat.
Although meat is a source of protein, which is an important part of your diet, you can easily replace it with other sources of protein, including certain legumes, nuts, eggs, fish, tofu or mycoprotein (a meat substitute). A vegetarian diet can be healthy and balanced too. Just ensure you are getting enough protein, vitamin B12, iron, zinc, calcium and omega-3-fatty-acids.
Try to avoid processed meat altogether and if you can’t, consume only a little, and infrequently.
Though red meat isn’t specifically linked to breast cancer, the health drawbacks of eating red meat are well known.
Many studies indicate that a diet high in fruit and vegetables provides protection against breast cancer. For example, there appears to be a correlation between eating high quantities of non-starchy vegetables and a decreased risk of oestrogen receptor negative (ER-) breast cancer; and between consuming lots of foods high in carotenoids and a decreased risk of breast cancer. Certain studies suggest a vegetarian diet can reduce the risk of getting breast cancer – but evidence is inconclusive.
The World Health Organisation recommends eating at least three portions of non-starchy vegetables and two portions of fruit (in total 400g) each day.
Fruits and vegetables provide a mixture of health-promoting ingredients such as fibre, phytochemicals, vitamins and minerals. No single fruit or vegetable provides all the nutrients we need to be healthy, so we should eat plenty of different varieties every day. Vegetables, with their usually high water and low sugar content, are a great low-calorie substantial dish and can help to control body weight.
Put special emphasis on consuming:
♦Tip They are usually best absorbed when mixed in an oily base or eaten together with an oily accompaniment (such as egg yolks, or a bit of olive oil) and if the preparation (mixing, heating) destroys the cell walls of the plant.
Any excess calories can lead to being overweight and fruit usually has more calories than vegetables, so emphasis should be placed on eating more vegetables than fruit. It’s also important to pay attention to the preparation of fruit and vegetables. Vegetables shouldn’t be deep-fried but steamed with tasty spices or lightly fried in olive oil at low temperatures.
Although there’s no specific link between breast cancer and diets high in sugar (sucrose) or other carbohydrates, we know that consuming too much sugar can promote weight gain and being overweight increases the risk of post-menopausal breast cancer. You can reduce your risk of getting breast cancer by making healthy choices and lowering the amount of added sugar in your daily meals in order to maintain a healthy body weight.
Carbohydrates provide your body with a primary energy source, glucose, which fuels everything you do. But the quality and the quantity matter.
When it comes to carbohydrates it’s best to consume higher amounts of “complex carbohydrates”, rather than “simple carbohydrates” such as sucrose and fructose. Although simple carbohydrates can be found in fruit and, to a lesser extent, in vegetables, you shouldn’t leave them out completely as they supply vital nutrients like vitamins, as well as fibre. Try to make these part of your five-a-day (see more in the fruit and vegetables section above).
Digestible complex carbohydrates (e.g. starch) are found in foods like potatoes, cereals, legumes, tubers, fruits and seeds.
When you eat digestible complex carbohydrates they are released more slowly into the bloodstream, so the blood sugar levels rise more slowly after eating these and you stay full longer. This is because they need to be broken down before they can be absorbed. So you end up eating less and are more likely to stay a healthy weight.
Indigestible complex carbohydrates are found in whole grain foods, vegetables, fruit and pulses.
Because your body is unable to digest indigestible complex carbohydrates like fibre, this helps you feel full, meaning you are less likely to over-eat. It’s also good for your gut health. The recommended amount of dietary fibre is 30 grams per day.
Because soft drinks, biscuits and cakes are high in simple carbohydrates (like sucrose), they are missing the vital nutrients you find in fruits and vegetables, and therefore contain ’empty calories’. Try to only have them as a treat, or on special occasions.
Dairy products are foods produced from the milk of mammals such as cows and sheep. They include milk, butter, cheese, yoghurt and cottage cheese.
In order to get maximum benefit from dairy products, try to opt for natural products with no added sugar. Organic natural yogurt, cottage cheese and reduced fat milk contain high quality protein and lots of calcium, zinc and iodine as well as vitamins B2 and B12, vitamin A and D. Yogurt also contains beneficial bacterial cultures, making it a source of probiotics which are beneficial for gut health. You can make your own sweet-tasting yogurt by adding some berries and a little bit of honey.
When buying milk, try to buy organic grass-fed cow’s milk since it contains a better omega-6/omega-3-fatty-acid balance and a higher amount of total omega-3-fatty-acids.
Try to avoid sugar traps, such as puddings, colourful yogurts for the children, and milk drinks. They are high in calories and can be heavily sweetened.
Despite breast cancer incidence being lower in Asian countries where a high amount of soy is consumed, it is unclear whether a soy rich diet is protective against breast cancer. There is no evidence that soy increases risk.
The soybean is a legume and has its origin in Asia. It’s rich in isoflavones, compounds found in soy which have properties that can be both protective and cancer-promoting. Although researchers studying cells in the laboratory have found that individual isoflavones may stimulate breast cancer growth, studies observing people consuming soy foods over a long period of time show either a protective, or neutral effect, which suggests moderate soy consumption is safe.
Soybeans are a good source of unsaturated fats, vitamin B, iron, calcium, zinc and other compounds beneficial to your health. They are easily digested. Soy is the only available plant protein that has been shown to contain protein of high quality. It is similar to protein found in cow’s milk and eggs, traditionally used as standard references and considered a complete protein source, as it contains all nine essential amino acids that must be obtained from the diet.
Moderate consumption of soy products is considered positive for our health – especially if it replaces unhealthy meat meals. Soybeans are mainly processed into tofu, soy sauce, soymilk and soy yoghurt, but can also be bought as dried or tinned beans and are also consumed as edamame (young soybeans). Because soy is consumed in a variety of different ways, it’s useful to consider how much isoflavone content you are eating (see table below). Approximately 25 – 50mg of isoflavone per day is considered safe for everyone, including those who have, or have had, breast cancer.
|Soy type||Approx. Isoflavone content per 100g|
|Soybeans (ripe, raw)||104 mg|
|Soy yoghurt||33.2 mg|
|Tofu (solid or cooked)||22.1 mg|
Try to aim for natural soy products such as tofu, edamame and tempeh (fermented soybeans). They are often low in fat as well as high in protein and nutrients, compared to red and processed meat, or other animal sources of protein which are higher in saturated fat.
It is always advisable to seek medical advice before taking isoflavone supplements.
Aim for natural, rather than highly processed soy products which may contain additives. Even highly processed soy is preferable to unhealthy processed meat. Keep an eye on the fat and salt content though.
Drinking alcohol is a serious risk factor for breast cancer. It is thought to contribute to around 4,400 cases of breast cancer every year in the UK alone. Alcohol (ethanol) may increase oestrogen levels, which affects your risk of getting breast cancer. It’s broken down into by-products which can damage cells and cause DNA mutations which may lead to breast cancer.
All alcoholic drinks increase breast cancer risk. For more information see our briefing on “Alcohol and breast cancer“.
Drinking any amount of alcohol increases breast cancer risk. There is no lower limit. The higher the intake the greater the risk. The more alcohol a woman drinks, the more likely breast cancer will come back after initial treatment. Drinking alcohol during pregnancy may raise the lifetime risk of breast cancer in your female child.
UK government guidelines recommend drinking less than 14 units of alcohol per week for both men and women and suggest you limit the amount you drink on any one occasion. If possible, try to follow these guidelines as a minimum, and aim for less if you can.
Try and eat organic – Although there is no conclusive evidence that organic food offers protection against breast cancer, some studies suggest it may. Organic food contains less pesticide residue and therefore it is less likely to contain hormone disrupting chemicals which may be linked to breast cancer.
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