Prostate Research Campaign UK - People and Lifestyle article

People & Lifestyle story, July 2005

DIET AND PROSTATE CANCER

Advice from Heather Salomon Zeitz, RD, CDN (USA)

Received from: Andrea Kon

Five times more men die of prostate cancer in the United States or Britain than in Japan. In fact, the incidence and mortality rates of prostate cancer are significantly higher in the UK when compared to most Asian countries. Why? The answer, as research suggests, can most likely be found in the diet and lifestyle differences found across the globe.

In general, the British consume approximately 40 percent of total calories from fat, where fat intake in China and Japan is considerably lower, at 10 to 20 percent. The Asian diet is characteristically rich in fish and plant-based foods such as fruits, vegetables, whole grains, and soy foods, while the typical Western diet consists of significantly more processed, or "convenience" foods, and animal products. Evidence overwhelmingly suggests that it is healthier to have a diet low in fat (particularly saturated or animal fat), and high in fruits, vegetables, fibre, and soy protein. This article gives you an overview of the current dietary recommendations in the fight against prostate cancer and provides you with practical guidelines to incorporate these principles into your diet.

Fat Facts
Fat has been studied more thoroughly and linked more frequently to cancer than any other factor in our diets. Studies of the vast cultural differences in diet first identified total fat intake as a factor directly associated with the incidence of prostate cancer. The incidence of prostate cancer in the United States has increased significantly in the 20th century right along with the increased intake of red meat and hidden fats in oils, margarine, butter, and processed baked goods.

Saturated fats
While the evidence does support a diet that is on the whole low in fat-as low as 10 to 20 percent total calories from fat-more recent research suggests that the type of fat you consume can also make a difference. Several studies have found a direct association between saturated fat intake from meat and dairy products and prostate cancers. Saturated fats are animal in origin, such as fatty meats (i.e., beef, veal, pork, lamb), whole-milk dairy products, and butter. Even leaner animal products such as chicken or turkey can serve up a lot of saturated fat if you are choosing pieces with skin or dark meat.

Unsaturated fats
On the other hand, unsaturated fats are derived mainly from plants and fish. The two types of unsaturated fats include monounsaturated fats (fats from olive oil, canola oil, avocados, and peanuts) and polyunsaturated fats (omega-6 fatty acids from vegetable oils (i.e., corn and safflower oil), omega-3 fatty acids from fish and flax seeds). While all types of unsaturated fats have been shown to help cardiovascular health by lowering levels of LDL ("bad" cholesterol in the blood), laboratory tests have suggested that trying to increase omega-3 fatty acids while decreasing sources of omega-6 fatty acids can help control stimulation of tumor growth in prostate cancer.

Trans-fatty acids
Trans-fatty acids are unsaturated fats that have been chemically modified to become saturated and seem to carry the same risks as saturated fats where cancer and heart disease are concerned. These fats are found mostly in margarine and processed snacks or baked goods, which list "partially hydrogenated oil" as one of the first ingredients on the food label. Overall, in the fight against prostate cancer, your goal should be to lower the total fat in your diet-specifically saturated fats, omega-6 fatty-acids and trans-fats, while incorporating some omega-3 fatty acids for their potential protective effects.

Lowering Your Fat Intake is Easier Than You Think

Here are some tips for lowering your fat intake:

Eliminate fried foods.
Use low-fat cooking methods. Use cooking spray or a nonstick pan instead of oil. Grill, broil, roast, or poach fish and poultry. Trim all visible fat before cooking.
Choose only low-fat or fat-free dairy products. A low-fat product means there is no more than 3g of fat per serving and a "fat free" product has no more than ½ gram of fat per serving.
Eliminate fatty foods (i.e., cream sauces, poultry skin, cream soups, nuts, chocolates, gravies). Choose tomato-based sauces and soups instead of cream varieties.

Phyto-Power: Fruit and Vegetables
"Eat your fruit and vegetables." We’ve all heard these words our entire lives, and we can safely assume that our elders really had no idea just how valuable this advice was! A substantial and growing amount of research has suggested that fruits and vegetables contain nutrients and compounds that help the body destroy cancer-causing agents (carcinogens) before they damage cells, thereby reducing cancer risk. While the exact mechanism remains unclear, it has been suggested that the antioxidant properties (the ability to neutralize harmful free-radicals in the body) of certain vitamins such as vitamin A and vitamin C seem to offer protection. The most valuable sources of these vitamins include dark green leafy vegetables (such as spinach, kale, and romaine), yellow/orange/red vegetables (such as tomatoes, carrots, red and yellow peppers, and sweet potatoes), and citrus fruits (such as oranges and grapefruit).

Along with valuable vitamins and minerals, these colourful fruits and vegetables are rich in plant chemicals (phytochemicals) that are currently the subject of a great deal of research. For example, lycopene (responsible for the red colour of tomatoes) consumption from tomato-based sauces, drinks, and spreads is associated with a reduced risk of prostate cancer. Garlic, onions, shallots, leeks, and other allium vegetables contain organosulphur compounds that have been shown in some laboratory studies to prevent tumour cell growth. Both of these phytochemicals are best absorbed with a little processing (i.e., cooking or crushing) which releases their valuable properties. Also, another family of vegetables called the cruciferous vegetables (including broccoli, cauliflower, Brussel sprouts) contain indoles, which also seem to block carcinogens from your body cells.

How many fruits and vegetables should I eat?
The list of these proposed compounds goes on and on. From my review of the research, I believe there is much value in the synergy of all of these compounds in how they may work together to fight all cancers-including prostate cancer. I counsel the importance of a variety of fruits and vegetables with a focus on the groups mentioned above. While your initial goal should be to eat at least five servings of fruits and vegetables per day, shooting for at least nine servings per day should be a long-term goal for yourself, given all the benefits. One serving can be defined as 1 cup of raw vegetables, ½ cup of cooked vegetables, 1 medium-sized fruit, ¾ cup juice, ½ cup canned fruit, = ¼ cup dried fruit. The best choices are raw and cooked vegetables and whole fruits for their fibre content.

It’s Easy to Add Fruits and Vegetables...The Secret is a Colourful Plate and a Little Creativity

Here are some suggestions for how you might incorporate fruits and vegetables into your diet:

Include fruits and vegetables with every meal.
Snack on fresh or dried fruits and raw vegetables instead of biscuits and cakes.
When eating out, order a steamed side vegetable or a mixed salad with dark greens to add to your meal.
To avoid extra fat, you can steam or cook vegetables in broth and/or add herbs and spices for increased flavour.
Try sprinkling buttered flavoured granules, lemon, or vinegar on cooked vegetables.

Fitting in Fibre
Although fibre is a non-absorbable carbohydrate, benefits are found in the ability of dietary fibre to promote the clearance of hormones and fats from the body via the gastrointestinal tract. In other words, they help you stay regular. Reproductive hormones such as testosterone circulate throughout the body and reduction in the level of these hormones may have a dramatic impact on the progression of prostate cancer. One study showed plasma testosterone levels to be significantly lower in middle-aged men who ate high levels of dietary fibre from cereals, grains, fruits and vegetables when compared to men eating a typical American diet filled with processed foods, and hence a much lower fibre content.

Most of the richest sources of fibre come from foods that have undergone minimal or no, processing, such as whole grain breads and cereals, legumes, whole fruits and vegetables. While the typical American diet averages about 10 grams of dietary fibre per day, the general recommendation is an intake of 25 to 35 grams of fibre per day. If you are not used to a high-fibre diet, introducing fibre-rich foods too quickly, and without adequate fluid, can cause gas, cramping and bloating. My suggestion is to start slowly and work your way up to the recommended intake. Gain Dietary Fibre Gradually - One Step at a Time.

Here are some tips to help you catch up on your recommended daily portion of dietary fibre:

Experiment with whole grains. Use brown rice, barley, bulgur, and whole-wheat pasta in soups and casseroles, or as a side dish.
Eat more legumes. Add peas, beans, and lentils to main dishes, soups, or salads.
Eat a high-fibre breakfast. Choose breakfast cereals with more than three to five grams of fibre per serving or mix half of your favourite low-fibre cereal with bran flakes.
Choose breads, cereals and pastas with "whole wheat" or "whole grain" as the first ingredient on the food label.
Choose breads with at least 2 grams dietary fibre per slice.

Serve Up Soy
Many researchers strongly believe the significantly lower incidence and slower progression of prostate cancer in Asian countries is largely due to a diet rich in soy-based foods such as tofu, tempeh, and soy milk. Recent studies focus on the properties of specific phytochemicals in soy called isoflavones (genestein and daidzein), which can only be found naturally in soy foods. Isoflavones have estrogenic properties that may counteract the development of hormone-sensitive tumours such as in prostate cancer. Additionally, genestein has been shown in laboratory studies to inhibit the growth of both hormone-dependent and independent prostate cancer cells.

Despite the convincing evidence, the introduction of soy into the diet is usually met with some resistance because it seems foreign to many. An initial goal can be to incorporate an average of one serving of soy per day, with an ultimate goal of 25 to 40 grams of soy protein per day. The fact is, certain soy foods are also excellent low-fat sources of antioxidants and fibre, and with the variety of foods now available, it is easier than you think to enjoy both the taste and health benefits of soy foods.

Here are some common soy foods and tips to get you started

SOY FOOD, PREPARATION AND STORAGE TIPS:

Soybeans are legumes that have a nutty flavour.

Soaking dry soybeans shortens the cooking time and improves the flavour and texture.
Cooked soybeans can be refrigerated for about one week.
Dried soybeans have a shelf life of about six months.
Cooked (canned) soybeans are available in both yellow and black (lower in fat) varieties.
Add cooked soybeans to salads, chillies, and soups.
Replace or mix with other beans in recipes.

Soy milk (soy beverage) is made from grinding soaked, cooked soybeans.

Once opened, soy milk should be refrigerated and consumed within one week.
Brands fortified with calcium and vitamin D are good milk substitutes for those who are lactose intolerant.
Pour over hot or cold breakfast cereal.
Try plain or flavoured soy milk as a refreshing drink.
Use low-fat soy milk in milkshakes and smoothies.
Use to replace milk and cream in recipes.

Tofu (bean curd) is a soft cake of curdled soy milk. Tofu is available in extra firm, firm, soft and silken consistencies, as well as regular and low fat varieties.

Opened tofu should be rinsed and covered with fresh water for refrigerated storage. Change the water daily to keep it fresh, and use within one week
Add chunks of firm tofu to well-seasoned soups, stews, stir-fries, taco/fajita mixes, and burritos.
Grill or bake marinated tofu and use as a meat replacement in salads, sandwiches, and entrees.
Use soft or silken tofu in dips, smoothies, shakes, or as the base for creamy soups and salad dressings.
Mash tofu with breadcrumbs, onions, and seasonings to create tofu burgers.

TVP Texturized Vegetable (Soy) Protein (or TSP) is a granular product that takes on the texture of ground beef when rehydrated with water.

To rehydrate: mix boiled water one-to-one with TVP (i.e., 1cup water to 1 cup TVP)
Dehydrated TVP has a shelf life of about one year. Once rehydrated, it should be refrigerated and used within 3 to 4 days.
Replace some or all of the ground meat or poultry in meatloaf, meatballs, chili, sloppy joes, casseroles, hamburgers and tacos.
Add TVP to well seasoned sauces, soups, and pasta dishes.

Tempeh is made from cooked soybeans (sometimes mixed with other whole grains) which are fermented into a dense cake.

Tempeh is found in frozen, vacuum-sealed plastic wrapped patties. It can be frozen for up to one year, or refrigerated for about ten days.
Bake, grill, or broil marinated tempeh and use it to replace meat in sandwiches and entrees.
Use crumbled tempeh instead of ground beef in soups, casseroles, burgers, sauces, and chili.
Add grilled tempeh to salads.

Remember, diet changes do not happen overnight. The best thing to do now is set small goals for yourself. Review the guidelines above and choose one area at a time. You may want to concentrate on the fat in your diet first and once you’ve reached that goal, move on to fruits and vegetables. Each food that you add or eliminate is yet another success in using your diet to prevent or fight prostate cancer.

By: Heather Salomon Zeitz, RD, CDN
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