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Is diet important after breast cancer?
There is convincing evidence that nutrition and lifestyle factors affect the development and recurrence of breast cancer. It is natural to be unsure about what to eat after your breast cancer treatment has finished, as there is so much information available. It is important that the advice you follow is based on scientific evidence and does not have the potential to cause adverse effects.
It is recommended that cancer survivors follow the same guidelines used for cancer prevention. The strongest evidence suggests that the most important things to prevent cancer returning are maintaining a healthy weight, doing regular exercise and eating a healthy, balanced diet. There are no special foods you should eat, diets you should follow or specific foods you should avoid to prevent your cancer returning.
This fact sheet incorporates the latest research findings to help you choose a healthy diet after your treatment and for the years to follow.
What is a balanced diet?
A balanced diet means that you eat regular meals during the day and that the meals consist of the correct proportions of protein, fat and carbohydrate. A balanced diet allows you to obtain all the nutrients your body requires and is the best way to achieve weight loss or maintain your weight.
Your protein requirements depend on your body weight. Generally one to two serves of protein foods each day are adequate. Good sources of protein include lean meat, chicken, fish, dairy foods and beans and legumes.
While a high-fat diet is not recommended, there are essential fats called polyunsaturated and monounsaturated fatty acids that our body needs. Most of the fat we need can be obtained from foods such as fish, nuts, seeds, avocados and polyunsaturated plant oils such as olive and canola oil.
Carbohydrate is required for muscles to contract and for the brain and heart to function. Carbohydrates are needed to stop your body breaking down muscle to supply the glucose required for these organs. Low-carbohydrate diets should be avoided for this reason, also because they are high in saturated fat and do not contain enough fibre.
Your carbohydrate requirement depends on how much energy your body needs, but most women need at least four serves each day. The best sorts of carbohydrate foods to eat are those that are digested slowly. These are referred to as low glycaemic index foods. These foods include wholemeal and grain breads, wholegrain cereals and pasta.
It is important for women to get two to three serves of foods containing calcium each day to keep their bones healthy. Good sources of calcium include low-fat milk, cheese and yoghurt, canned salmon with bones, sesame seeds, brazil nuts, almonds and soy products such as tofu and soy milk.
Fruit and Vegetables
A plant-based diet has been found to be protective against cancer development. This is because plant foods contain numerous vitamins, minerals and other protective substances known as phytonutrients, and are generally high in fibre and low in calories. It is important to eat many different plant foods to obtain a wide variety of these nutrients. You should aim to have at least five serves of different vegetables and two serves of fruit each day. One serve of fruit is 150g fresh fruit (eg 1 medium apple) and 75g of fresh vegetable (half a cup of cooked vegetables).
Diets that claim to prevent cancer returning, by recommending large amounts of any one particular food (including supplements and herbal products), are not based on scientific evidence and may cause your diet to be unbalanced which can lead to nutrient deficiencies. It is a good idea to talk to your doctor and an Accredited Practising Dietitian (APD) if you are thinking of following a special diet.
Guidelines for a healthy diet
Here are the guidelines for a healthy diet for Australian adults:
- To achieve and maintain a healthy weight, be physically active and choose amounts of nutritious food and drinks to meet your energy needs
- Enjoy a wide variety of nutritious foods from the five food groups every day
- Limit intake of foods containing saturated fat, added salt, added sugars and alcohol
- Encourage, support and promote breastfeeding
- Care for your food; prepare and store it safely.
Maintaining a healthy weight after your cancer treatment
Weight gain during treatment
Many women find that they gain weight during their treatment. This can occur for a variety of reasons including being less active than usual, frequent snacking to prevent nausea, eating more fatty foods than usual or taking medicines such as steroids and chemotherapy.
Research has shown that women who are overweight have an increased risk of their cancer coming back. This emphasises how important it is to try to maintain a healthy weight. It also will benefit your overall health and help prevent many other chronic diseases such as diabetes, heart disease and other types of cancer.
Your body mass index (BMI) is a number used to tell you if your weight is in the healthy range. You can work this out by dividing your weight (in kilograms) by your height (in metres) squared.
For example, for a woman who weighs 63 kg and is 165 cm tall:
BMI = 63/(1.65)2
While there are many diets that claim to help you lose weight, most of these are not effective in the long term. The most effective way to lose weight is by consuming fewer calories from foods and drinks combined with expending more energy by being physically active. To maintain weight, energy intake should be equal to energy expenditure. It is important that any eating plan you follow meets your requirements for all essential nutrients such as calcium, iron, essential fats and fibre. An Accredited Practising Dietitian (APD) is able to advise on how to tailor an eating pattern to your individual needs.
What is a healthy BMI?
Less than 18: underweight
18–25: healthy weight range
Benefits of exercise after your treatment
Physical activity is not only an essential component in maintaining a healthy weight, but has also been shown to directly reduce the risk of cancer returning by reducing the levels of hormones such as insulin and oestrogen in the body. Although certain amounts of these hormones are required by the body, high levels are believed to be involved in breast cancer. The American Cancer Society recommends at least 30 to 45 minutes, preferably up to 60 minutes, of physical activity at least five days each week. Any activities such as brisk walking, swimming and cycling are beneficial.
Other nutritional information
Should I eat red meat? Lean meat is a good source of protein and iron and can be included as part of a healthy diet. The association between red meat and breast cancer is unclear. Although some large studies have shown that red meat increases the risk of breast cancer development, others have shown that the risk is not increased. The World Cancer Research Fund recommends limiting red meat to 500g per week.
There is convincing evidence that alcohol increases the risk of breast cancer developing, but the association between alcohol and breast cancer recurrence is less clear. The World Cancer Research Fund and Cancer Council Australia recommend limiting alcohol intake. If you choose to drink it is recommended that women
There is no evidence to suggest that taking vitamin supplements reduces the risk of breast cancer returning. A diet high in vegetables, fruits, wholegrain breads and cereals is proven to be protective against cancer developing. However, these beneficial effects are not seen when the nutrients are taken in supplement form. In fact, some research shows that certain vitamins when taken in high doses may actually increase the risk of certain cancers. Ideally, you should try to get all the nutrients your body needs from foods, but certain vitamins may be helpful if the diet is inadequate. An ADP can assess whether you would benefit from taking supplements.
In recent years, there has been much discussion about soy products and the natural compounds they contain (phyto-oestrogens). There is a theory that a high intake of phyto-oestrogens may protect against breast cancer, but this has not been supported by scientific evidence. Phyto-oestrogens may have a cancer-protective effect, but there is also evidence that they might cause hormone-sensitive cancers to grow. Therefore, it is recommended soy foods can be included as part of a healthy diet, but avoid supplements containing high doses of phyto-oestrogens.
What can I do to improve my chances of surviving breast cancer?
Following the recommendations in this fact sheet can help reduce the risk of your cancer returning. Regular breast checks with your doctor and mammograms every year are also important to stay healthy after breast cancer.
Further information Dietitians’ Association of Australia. www.daa.asn.au NHMRC Australian Dietary Guidelines – Eat for Health. www.nhmrc.org.au United States Department of Agriculture www.choosemyplate.gov
[This information guide is also available in PDF format to download.]