Dietitian Mailbox

This mailbox serves to provide a platform for the general public to raise their questions related to diet and nutrition with our registered dietitian, Patricia Chiu. Patricia is a registered dietitian (Australia) and current member of Dietitians Association of Australia, Hong Kong Nutrition Association and The Hong Kong Practising Dietitian Union.

Patricia has experience in providing nutrition consultations in elderly homes and private clinic. She has also taught nutrition courses for various organisations.

Submit your question - please email your questions to WCRF HK’s registered dietitian. Our dietitian will respond as soon as possible.

Frequently Asked Questions and Answers

What is trans fatty acid?
A: A process called hydrogenation forms trans fatty acid. This process is used to change the chemical structure of fatty acids, so that liquid oils are turned into solid fats. Trans fatty acids have been linked to increased risk of coronary heart disease. Studies have shown that trans fatty acids raise LDL (bad) cholesterol and lower HDL (good) cholesterol. The link between trans fatty acids and cancer is unclear. However, WCRF HK recommends limiting fat intake and choosing unsaturated fat where possible. Trans fatty acids are found in processed foods such as hard margarines, biscuits, cakes, pastry and fast foods. You can also check the food labels when buying foods, if an ingredient list includes ‘hydrogenated oils/fats’ or ‘partially hydrogenated oils/fats’, it probably also contains trans fatty acids.

What are phytochemicals and their role in cancer prevention?
A: Phytochemicals are chemical compounds found in plant foods that are protective to our health. During the past decade, researchers have identified hundreds of individual phytochemical and more are discovered all the time. Some well known phytochemicals include beta-carotene (present in carrots) and lycopene (present in tomatoes). Different phytochemicals help to prevent cancer through different mechanism. For example, some phytochemicals act as antioxidants in the body and may decrease inflammation and the growth of tumour cells. While others may stimulate the production of anticancer enzymes, thus increasing the body’s natural ability to ward off cancer.

Is it better to avoid drinking water during exercise if I want to lose weight?
A: No. If you exercise for 30 minutes or more and don’t drink any water, your weight will probably be down immediately afterward. But this weight loss is only a reflection of water loss during exercise and is only temporary. It is exercising a little longer and harder that will help you lose more body fat. Studies clearly show that people who drink fluid before exercise (and during exercise, if it is longer than 20 to 30 minutes) can perform faster, harder and longer than exercisers who do not drink fluid. Fuel yourself with a snack or meal two to three hours before exercise and drink plenty of fluid. In most cases water is the preferred beverage choice if you are trying to lose weight, unless you are exercising for an extended period of time.

All material on WCRF HK's website is intended for educational and informational purposes only and is not a substitute for individualized, professional medical advice. Please contact your health care professional consultant with any questions you may have regarding your individual health or medical concerns.

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Does chicken consumption affect cancer risk?
A: Studies have not linked chicken or other poultry consumption with increased cancer risk. However, chicken that is grilled or fried at high temperatures forms carcinogenic (cancer-causing) substance. For this reason, it is a good idea to cook chicken at lower temperatures, such as steaming and baking, and perhaps marinate it first. Some studies suggest that marinades may decrease the formation of carcinogenic substances.

Is it good for our health to use olive oil?
A: Olive oil is composed mainly of monounsaturated fatty acids. Monounsaturated fat has been shown to be a good fat by lowering the “bad” LDL cholesterol. This is good for our heart. Moreover, olive oil contains antioxidants called phenols. A recent study shows that olive oils with higher phenols level have a greater effect on raising “good” HDL cholesterol and decrease cell damage more effectively. The amount of phenols varies depending on how the oil is produced. Extra virgin and virgin oils contain higher levels of phenols than more refined light olive oils.

Can soy help to prevent breast cancer?
A: Soy has been associated with the inhibition of breast cancer cells in some, but not all, laboratory experiments. Several human laboratory studies have suggested that the consumption of soy early in life may help protect against breast cancer later in life. However, results are less encouraging for post-menopausal women. In fact, one recent analysis of available data concluded that soy consumption by adult women probably has little or no effect on breast cancer risk. However, soy has demonstrated a protective effect against bladder, cervix, lung and stomach cancer in other laboratory studies. It is recommended to eat soy products such as tofu, soymilk and soybeans in moderation for reducing the risk of these cancers. Request a copy of Reducing Your Risk of Breast Cancer.

WCRF HK recommends a plant-based diet, but I’ve heard that eating starchy foods such as rice, bread and pasta can make people gain weight, what should I do?
A: Starchy foods themselves do not cause weight gain. Eating excessive amounts of just about any food will add up to more calories than what is needed for the day, and that’s how you gain weight. Whole grains are recommended over refined grains because they contain more dietary fibre and nutrients. They are also digested more slowly and will keep you satisfied longer than refined grains. Whole grains, such as brown rice, whole-wheat pasta, oatmeal and whole-grain bread offer loads of nutrition and protective phytochemicals, and are also satisfying.

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What shall I do about the cravings I have for ‘unhealthy’ foods?
A: It would be hard if we never allowed ourselves to have a ‘treat’ now and then - this approach is unrealistic. Instead, you should think about changing your eating habits for life. You should allow yourself a treat such as chocolate bar from time to time. But try to just have one at a time and opt for the small size where possible. The great thing about a plant-based diet is that it will help to reduce cravings. You will be less likely to feel the need to indulge in high fat, or high sugar foods as much as you used to.

Is it important to have breakfast?
A: Breakfast is an important meal of the day. It gives the body energy to get going in the morning. Studies have found that eating breakfast is related to our weight status, general well-being and longevity. Some simple breakfast choices include whole wheat bread, fruits and low fat dairy products.

My kids don’t like to eat vegetables, is there any way that I can encourage them to eat more?
A: It is important to help our kids develop healthy eating habits early in life. Here are some tips for encouraging kids to eat more vegetables. First, you have to be a good role model. Children like to copy the eating habits of other family members, therefore, your kids are more likely to eat vegetables if you do. Second, let your kids help with preparing foods with vegetables. You will be delighted to see how they enjoy the vegetables they cooked. Moreover, do not use foods as rewards or punishments. Don’t blame your kids when they refuse to eat vegetables, this will only make them reject this group of food more.

Salty food I heard in the news that more and more people in Hong Kong are suffering from colon cancer. What lifestyle factors can lower my risk?
A: Physical activity, as well as eating a mostly plant-based diet with adequate dietary fibre, can help decrease your risk of developing colon cancer. Limiting red meat and fat intake is also important. Recent research also points to colon cancer being higher in individuals who eat large amounts of processed meats such as deli meats, bacon and sausage. Thus, limiting consumption of these foods can also lower your risk.

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I am not having enough fruits and vegetables; can drinking fruit or vegetable juice help?
A: A 150ml glass of fruit or vegetable juice can be counted as one serving/portion of fruits and vegetables. WCRF HK recommends eating at least 5 servings of fruits and vegetables per day for lower cancer risk. Note that, no matter how much juice you drink in a day, it will only count as one serving. This is because juice contains fewer nutrients than whole fruits and vegetables. There is less fibre, vitamins and minerals in juice when compared to whole fruits and vegetables. Also, fruit juice contains a lot of natural sugar, which may make us gain weight if we drink too much juice.

Can drinking green tea help to prevent cancer?
A: Laboratory studies have shown that green tea can slow or completely prevent cancer development in colon, liver, breast and prostate cells. Other studies involving green tea have shown similar protective effects in tissues of the lung, skin and digestive tract. Studies that track the diets of human subjects over several years, particularly studies conducted in Asia where green tea consumption is common, have associated regular usage of green tea with lower risk for bladder, colon, stomach, pancreatic and esophageal cancers.

Am I at increased risk of cancer if I am overweight?
A: Yes. There is a lot of concern about the effects of excessive weight on disease risk. And research clearly shows that obesity is not only a risk for diabetes and heart disease, but also for several types of cancers. Losing as little as 10 percent of your body weight can make a difference to your disease risk. That means if you weigh 180 pounds, just losing 18 pounds can offer significant health benefits and protection. Click here to request a copy of The Truth about Weight and Cancer.

I’ve heard that eating tomatoes could help to prevent cancer, is this true?
A: Tomatoes are rich in lycopene, an antioxidant that can help protect against the kind of damage that gets cancer started. There is evidence that the protection from lycopene is increased if tomato is consumed in a processed form such as tomato sauce, tomato juice and tomato paste. This is because cooking allows this natural compound to be released and more easily absorbed.

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Can grilled foods really cause cancer?
Grilled food A: Research studies done on animals show that exposing meats to direct flame, smoke or intense heat (like when you grill or broil) can cause the formation of carcinogens (cancer-causing substances). Cooking methods that involve less heat, such as microwaving, baking, steaming and poaching, do not promote the formation of these substances. If you grill, there are several strategies that can be used to cut down on carcinogen formation. Marinating can significantly protect animal proteins such as beef, chicken and fish from carcinogen formation. Flipping frequently, removing excess fat from meat before cooking, and decreasing exposure by microwaving for part of the cooking time may also be helpful. Most experts agree that plant-based foods do not form these undesirable substances. So for delicious and healthy options, try grilling vegetables and fruit slices and cut down on meat, fish and poultry.

Is it necessary to buy organic fruits and vegetables?
A: Recent science indicates that the benefits of eating a wide variety of vegetables and fruits each day far outweigh any risks associated with pesticide residues. To date, there is not enough evidence to indicate that organic fruits and vegetables are better for our health. Their nutritional values are similar to conventionally grown produce. But if you are very concerned about pesticide residues, you may want to purchase organic produce now available in specialty stores and most supermarkets. Be aware that they are more expensive.

What vitamins should I be taking to help prevent cancer?
A: There is no scientific evidence that vitamin supplements are cancer protective. It is clear that supplements cannot take the place of a mostly plant-based diet that contains a large variety of vegetables and fruits. The thousands of phytochemicals (protective plant substances) cannot be found in a simple pill. If you follow the Diet and Health Recommendations of WCRF HK, it is not recommended, and probably unnecessary, to take any dietary supplements.

What does eating salt and salty foods have to do with cancer?
A: Diets containing a large amount of salted foods (such as those readily available in Hong Kong) increase the risk of stomach cancer. It is recommended that we decrease our intake of processed foods, such as salted vegetables, canned foods and sauces, since they contain the greatest source of salt found in the Chinese diet.

Which vegetables are especially good for preventing cancer?
A: In general, a wide variety of vegetables and fruits offers a wide variety of phytochemicals. Each individual produce item offers its own profile of these protective substances, so include as many different ones as possible each day for a powerhouse of protection.

All material on WCRF HK's website is intended for educational and informational purposes only and is not a substitute for individualized, professional medical advice. Please contact your health care professional consultant with any questions you may have regarding your individual health or medical concerns.

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