Basic dietary principles for patients with prostate cancer
Why nutrition matters during the treatment of prostate cancer?
You have probably been wondering what your diet should look like after you've been diagnosed, and whether nutrition can contribute to the outcome of your treatment and to the quality of your life during treatment. Yes, nutrition can support your normal body constitution, physical shape and wellbeing during the period of demanding oncological treatment. But most of all, proper nutrition will reduce adverse effects of treatment that can have an impact on dietary habits, boost the functioning of your immune system, and improve the outcome of treatment. Therefore it is very important to pay extra care and attention to your diet during the time of disease and treatment.
Cancer is a disease that alters metabolism in the body. There are various causes of metabolic changes. The most important one is the reaction of an organism to stress – to illness itself. Other important causes are adverse events of treatments and the direct impact of the tumor, which can secrete substances that alter the metabolism. These metabolic changes contribute to the development of a syndrome of cancer cachexia. Some tumors cause only very small changes that do not affect the metabolism much, while other changes can be significantly greater and very important for the treatment of a patient. The main characteristic of metabolic changes is increased decomposition and poor regeneration of protein structures in the body (cells, muscles and other body tissues and organs). Insufficient nutrition further accelerates the process of cachexia and contributes to the development of undernourishment.
There are various kinds of prostate cancer treatments, including surgery, radiation therapy, chemotherapy and hormone therapy (withdrawal of testosterone – male sex hormone). Patients undergoing hormone therapy can experience different adverse events of treatment, e.g. hot flashes, night sweating, reduction of bone density, weight gain, or changes in the composition of body structures (muscles and fat deposits). Due to metabolic changes and hormone therapy, patients with prostate cancer tend to lose muscle mass and gain body fat.
Because of these changes in body structures and bone density it is important that you pay attention to your diet and maintain an active lifestyle, which includes regular exercise, predominantly strength training in combination with endurance training.
If your diet does not reflect your demand for energy and proteins, the consequence will be weight loss resulting from the reduction of muscle mass and depletion of fat reserves in your body. The greater your weight loss is and the poorer your nourishment, the higher the risk of complications during oncological treatment can become. Your doctor or clinical dietitian is qualified to assess your nutritional status with a nutritional examination.
Even if you're not losing weight during treatment or are actually gaining weight, it is nevertheless important that you consume food rich in proteins, adhere to basic principles of protective diet, and remain physically active in order to promote the proper functioning and regeneration of your body.
What should be the basis of your diet?
The basis of a good diet during treatment is a healthy and balanced nutrition where daily food intake is usually spread over 5 meals (breakfast, morning snack, lunch, afternoon snack, dinner). It is important that larger meals contain protein food sources with high biological value (milk, meat, eggs, fish), while almost every meal should also include carbohydrates (bread, pasta, rice, potatoes, etc.). It will suffice if you consume from 450 g to 650 g of fruits and vegetables over the day.
You should pick various kinds of food from every dietary group, such as grain products and starchy foods, fruits and vegetables, lean meat and meat products, skim milk and milk products, eggs, fish, beneficial fats e.g. olive and canola oil. It is important that your diet contain as little processed foods as possible, therefore it's best that you prepare your own meals from fresh food sources and use only the smallest amount of preservatives, additives and salt.
Which nutrients are important?
Proteins, carbohydrates, fats, vitamins, minerals and trace elements are substances needed by cells, tissues and organs of your body in order to build, regenerate and function.
Proteins are a source of amino acids that facilitate the regeneration of the body and reduce increased decomposition of proteins in the body (cells, muscles, other tissues and organs). Insufficient intake of proteins forces the body to use its own amino acids as supplementary fuel, which accelerates the loss of lean body mass, i.e. muscles. A balanced protective diet of a cancer patient will therefore focus on the intake of proteins with high biological value, e.g. eggs, skim milk, lean meat and fish, which can be used with greatest efficiency by the organism because they contain all of the essential amino acids. Biological value of amino acids is determined by the quantity and ratio of essential amino acids.
Legumes such as peas and beans, which are characterized as protein-carbohydrate food sources, are also a source of some essential amino acids. Legumes and grains have a lower biological value since they do not contain all of the essential amino acids. However, we can combine several food sources with lower biological value in order to achieve a higher biological value. For example, combining peas with rice will result in a mixture of amino acids and proteins with a higher biological value that can replace proteins obtained from virtually the same amount of meat.
Cancer patients undergoing specific oncological treatment are advised to consume more protein than is recommended for a healthy individual, namely from 1.2 g to 2 g per kilogram of body weight of protein per day. All of the three main meals should include sufficient amount of protein, namely from 25 g to 30 g.
Carbohydrates are nutrients providing energy – glucose, which is needed for normal functioning of the body. Their decomposition in the body releases energy needed for cellular work and generation of body heat. Grains and grain products, rice, barley, oatmeal and other cereals, bread, potatoes, pasta, legumes, sugar and honey are important mainly as a source of carbohydrates. Additionally, whole grains and their products are an important source of dietary fiber that provides many benefits and improves digestion.
Fats are an important source of energy. While fats provide energy, they are also a source of various fatty acids (saturated and unsaturated) and fat-soluble vitamins A, D, E and K. Fats include: oils, lard, butter, margarine, cream and mayonnaise.
Diet of a cancer patient should emphasize the use of unsaturated fatty acids and deemphasize the use of saturated fatty acids. We recommend the use of vegetable oils (olive, sunflower, canola and others), which contain predominately unsaturated fatty acids, while saturated fatty acids in butter and cream should be added only as a supplement to other food in order to increase its caloric value if you are experiencing a loss of appetite and therefore consume smaller amounts of food than usual.
By increasing the consumption of lean red med, skim milk, products from skim milk, and by decreasing the consumption of lard and butter you can decrease the quantity of saturated fatty acids in your diet.
Unsaturated fatty acids perform various functions in the human body and are therefore essential for its proper performance. The body is able to synthesize some of them from other fatty acids. Others (omega-6 fatty acids – found mainly in plant oils – and omega-3 fatty acids) cannot be synthesized in the body and should therefore be consumed as food. Omega-3 fatty acids in particular have a special place in the diet of a cancer patient. The best source of these acids is fish oil. They play a role in reducing chronic inflammation and in boosting the immune response, so you should definitely include them in your meals. Fish rich in omega-3 fatty acids are mackerel, anchovy, salmon and tuna. A correct ratio of omega-3 to omega-6 fatty acids in the diet of a cancer patient is especially important. This ratio can be achieved by following the previous advice for increasing the consumption of unsaturated fatty acids and decreasing the consumption of saturated fatty acids, as well as including sea fish in your weekly diet plan. It is recommended that you substitute red meat for an equal amount of sea fish at least twice per week.
Vitamins and minerals are micronutrients involved in many metabolic processes in the organism and are needed for optimal functioning of every cell. Their main food sources are fresh foods and vegetables. The main role of fruits and vegetables in the diet is to provide vitamins, minerals, antioxidants and nutrients. Antioxidants are known as "scavengers of free radicals", which are products of normal metabolism that multiply during periods of great stress and burden. Many have external causes: cigarette smoke, polluted environment, UV and gamma rays, low-quality food, etc. Free radicals destroy or alter healthy cells. Antioxidants on the other hand inhibit and/or prevent the action of free radicals, and thwart the generation of new ones. Of greatest dietary importance are vitamins A, C and E, beta carotene, and minerals selenium and zinc.
Recommended daily quantity of fruits and vegetables in a balanced protective diet is about 400 g of vegetables and from 250 g to 350 g of fruits. We advise that you are "picky" when buying fruits and vegetables. Take your time, visit a farmers' market and purchase fresh fruits and vegetables that are in season. Try to consume most fresh, at least a third or a half of them. On average, 50% of water-soluble vitamins are lost during thermic processing (mainly by cooking), as well some important minerals. It is best to steam the vegetables in a small amount of water.