Contributions from Medical and Allied Health

CONTRIBUTIONS FROM MEDICAL AND ALLIED HEALTH

NUTRITION

WATCHING YOUR DIET - ALL ABOUT FATS AND SODIUM
Pauline Chan
Consultant Nutritionist and Dietitian
Food and Nutrition Specialists Pte Ltd

The number of Singaporeans suffering from cancer, heart disease and stroke has increased dramatically in the last 10- 20 years. In Y2005 alone, these three major killer diseases contributed more than half of the total deaths in Singapore.

While these diseases are all unique with their own etiology, they all share many common risk factors such as smoking, obesity, physical inactivity, stress and most importantly, an unhealthy diet. For example, a high fat diet will not just cause weight gain but also increase the risk of cancer, heart disease and stroke. Similarly, diet high in sodium is linked to high blood pressure, especially among sodium-sensitive individuals, which in turn can lead to stroke, heart attack and kidney failure. Healthy changes in current dietary patterns and habits among Singaporeans could impact greatly on the reduction of the rate of these diseases.


FAT AND HEALTH
Fat, unlike what most people think, is an essential nutrient. In fact, 2 – 5% of our total energy intake must come from fat. The common term "fat" refers to solid fats like butter, margarine and ghee as well as the liquid oils. Fats and oils may be of vegetable, animal, or marine origin. Fatty acids are the building blocks of fats. All dietary fats consist of a mixture of three families of fatty acids namely, saturated, monounsaturated and polyunsaturated fatty acids. For public education purpose, we group fats and oils based on the composition of the fatty acids present in them.


Saturated fats (SFA): Found mostly in foods of animal origin, and they are usually solid at room temperature. These include the fat in whole milk, cream, cheese, butter, meat and poultry. Vegetable fats and oils, such as cocoa butter, coconut oil and palm kernel oil also fall in to this category.

Monounsaturated fats (MUFA): Primarily found in foods of plant origin, and they are liquid at room temperature. Olive, peanut and canola oil are some of the common examples of oils that are a good source of MUFA.

Polyunsaturated fats (PUFA): Found in plants, and are also liquid at room temperature. Sunflower, corn, soybean, cottonseed and safflower oils are vegetable fats high in polyunsaturated fatty acids. Margarine made with vegetable oil, some fish and cod liver oil are also rich in PUFA.

Trans fat is formed during the hydrogenation of vegetable oils - a commercial process to harden oil for production of fats like shortening and hard margarine. Hydrogenation causes the liquid oils to become semisolid, more stable at room temperature and more saturated.

A small amount of trans fat is found naturally in animal-based foods such as meat and milk. However, the main sources of trans fat in our diet are processed foods such as vegetable shortenings, some margarines, and commercially fried and baked foods such as pastries, cakes, cookies and biscuits, salad dressings, and any other products made with partially hydrogenated vegetable oils.


Trans fat content in some common foods:

Name of food items Portion Weight Trans fat per portion
Sardine puff (pastry) 82 g 1.11 g
Sardine puff (pastry) 90 g 0.96 g
Table margarine, regular 20 g 0.86 g
Jackfruit chips 70 g 0.55 g
Chicken pie (pastry) 100 g 0.52 g
Whipped margarine 4 g 0.44 g
Apple strudel 128 g 0.29 g
Butter 25 g 0.26 g
Chocolate eclair 40 g 0.14 
2 in 1 white coffee 12 g 0.11
Peanut butter 34 g 0

Source: Health Promotion Board website www.hpb.gov.sg

Fat and Obesity
Studies carried out in past have shown a definite and positive link between fat and obesity. Fat provides 9 Kilocalories per gram which is twice the amount of energy obtained from the other 2 calorie-contributing nutrients, carbohydrate or protein. Hence people who regularly eat high fat diets, are likely to exceed their energy needs, and the fat get stored very efficiently in the body so they gain weight. Being overweight and obese will increase the risk of heart disease, stroke, diabetes, hypertension and certain types of cancer.

Fat and Heart Disease
Both the amount and type of fat consumed by an individual will influence the blood cholesterol levels. In the case of heart health, high level of blood cholesterol is a major cause of blocking the arteries, supplying blood to the heart, and leading to fatal heart attack.

  • A high intake of fat, especially of saturated fat, raises blood cholesterol more dramatically than dietary cholesterol itself. Cutting back on saturated fats will help to maintain a healthy heart.
  • Replacing saturated fats with polyunsaturated fats and monounsaturated fats while keeping the total intake within recommended level, have shown positive effect on the blood cholesterol levels. Unsaturated fats have shown to lower the LDL cholesterol (bad cholesterol) while either maintaining or raising the HDL cholesterol (good cholesterol).
  • Recent research in nutrition suggests that specific polyunsaturated fatty acids like Omega-3 and Omega-6, found especially in fish and fish oils or vegetable sources such as flaxseed may benefit heart health.
  • Intake of trans fatty acids has the same detrimental effect on the blood cholesterol levels as saturated fats. Limiting its intake is therefore beneficial.

Fat Intake Recommendation
Health professionals recommend the intake of fat for healthy Singaporean adults should provide not more than 25-30% of the total energy intake. This would amount to 60 gm of fat (12 teaspoon per day) for a moderately active man. Of this, less than 10% should come from saturated fat, less than 1% from trans fat, up to 10% each from polyunsaturated fat, and the remaining from monounsaturated fat.

Tips to reduce fat

Eating at home
Use small quantities of a variety of unsaturated cooking oils that suit your taste preferences like corn, canola, olive, soybean, sunflower, safflower and peanut oils to cook your food.
Reduce intake of saturated fat by substituting high fat meat with lean meat. Trim the visible fat from red meat. Remove the skin from the poultry. Grill, roast, broil, bake, stir-fry, stew, or braise meat instead deep-frying.
Refrigerate meat soups and gravies to solidify the fat. Remove the fat layer from top and use these low fat soups and gravies in your food.
Switch from whole milk to low fat milk or skim milk. Do the same for other milk and dairy products like cheese and yogurt. Increase the use of evaporated non-fat milk instead of cream to prepare desserts. Use skim milk yogurt to prepare gravies instead of coconut milk.
Look out for the invisible fat in foods like chocolates, pastries, biscuits, cookies, potato chip, and deep fried foods.

Eating out

Ask for less oil and fat in food.
Ask for skin to be removed from poultry and fat be trimmed from fatty meat.
Choose soupy dishes instead of fried or dried dishes.
Ask for plain rice over flavoured rice such as chicken rice, nasi lemak or nasi briyani.

Shopping

Read food labels carefully for the fat content of the food. Choose low fat items by comparing between the two products.
Choose products labeled with the “Healthier Choice” Symbol.

SODIUM AND HEALTH
Sodium is an essential mineral that is vital to the balance of body fluids. However, studies have shown that excessive intake of sodium may result in fluid retention in the body, causing blood volume to expand. This exerts pressure on the walls of blood vessels, raising blood pressure. Uncontrolled high blood pressure (hypertension) will lead to stroke.

A review of many scientific studies suggests that a reduction in sodium intake of 2,300/day would lower systolic blood pressure by about 5-6 mm Hg and diastolic pressure by 1-2 mm Hg among hypertensive individuals. In addition, many who are not yet hypertensive respond to sodium reduction, particularly those whose blood pressure is in the high normal range.

How much sodium do you need?
The World Health Organization recommends that individuals maintain a salt intake of no more than 5 g a day or a sodium intake of no more that 2000 mg a day. A reduction of 1000 mg of dietary sodium would lead to a 50% decrease in the number of people requiring anti-hypertensive therapy. This reduction may also decrease death rate from stroke by 22 %.

It is important to note that the recommendation is not the minimum requirement needed; rather, it is the maximum limit that should not be exceeded.

Food Sources of Sodium
Sodium occurs naturally in food and can be added to food. Most of the sodium Singaporeans consume comes from salt added during preparation at eateries, at home, or during food processing. The National Nutrition Survey (2004) estimated that processed foods contribute about 17% of the sodium in our diets, the rest from cooked foods.

Sodium is found in seasonings such as soy sauce, fish sauce, black sauce, oyster sauce and monosodium glutamate. In addition, sodium is also present in food additives such as baking powder, sodium benzoate and sodium nitrate / nitrite.

The sodium content of some of the most commonly used seasonings are as listed below:

Sodium content of seasonings 
Seasonings Sodium per tsp (mg)
Salt 2000
Stock cube 920
Salt substitute 865
MSG 615
Fish sauce 316
Dark soy sauce

324

Light soy sauce 325
Oyster sauce 345
Chilli sauce 57
Tomato sauce 48

Tips to reduce sodium intake

Eating at home

  • Gradually cut down on salt and seasonings used in cooking and at the table
  • Flavour food with natural seasonings such as lemon juice, herbs and spices

Eating out

  • Ask for less sauce and gravy
  • Taste food first. Use salt, sauce and pickles only if needed

Shopping

  • Choose fresh over processed food
  • Choose less salt-preserved, cured and smoked foods
  • Read labels to compare the amount of sodium in processed foods and choose foods labeled as reduce slat, low sodium, lightly salted, light in sodium, no added salt, no salt added or unsalted and those with “ Healthier Choice” Symbol.
Disclaimer: The information given here should not be used as a substitute for a consultation or visit with your physician. We would like to remind you that proper medical advice could be obtained only in the context of overall clinical assessment so medical consultation is important for diagnosis of condition.

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