on June 24th, 2010 by admin
Dietary Fat – the fat in our diet or the amount of fat in the foods we eat each day – there are so many buzz words, so much advice, so many warnings. I find it sometimes difficult to keep up with all the information and to know what is best for one to eat. With so many terms, I decided to begin my investigation with definitions – saturated fat, polyunsaturated, monounsaturated, hydrogenated fat, partially hydrogenated fat, trans fat, cholesterol, fatty acids, omega-3 fatty acids, omega-6 fats. I tend to oversimplify things but have come up with simple definitions that make sense to me.
Some say we should eat a low fat diet, others say no fat, still others say some fat is good for us and we should eat the “good fats”. Wow – what’s one to do?
Dietary Fat and Oils – are organic compounds made of carbon, hydrogen and oxygen belonging to a group of substances called lipids, and are in solid or liquid form. They are composed of basic units termed fatty acids. Each type of fat or oil is a mixture of different fatty acids – both saturated and unsaturated fatty acids.
Saturated Fats - are often described as solid at room temperature and found mostly in foods from animal sources like meat and dairy products such as butter, cheese, whole milk, ice ceam and cream. Some vegetable oils such as coconut, palm kernel and palm oil also are high in saturated fat. These foods are usually associated with increased blood cholesterol levels. Saturated fats raise total and bad (LDL) cholesterol levels.
Polyunsaturated Fats – are usually liquid or soft at room temperature and found mainly in vegetable oils, fish and seafood. Included here are omega-3 and omega-6 fatty acids. Examples include fish, safflower, corn and soybean oils.
Monounsaturated Fats – are mainly in vegetable oils, nuts, seeds, olives and avocadoes. They are liquid at room temperature. Examples include olive and canola oil.
Hydrogenated Fats – are liquid vegetable oils that have been turned into solid fat through a chemical process. This is done to increase shelf life, i.e., they do not become rancid as quickly,it increases the melting point and so they can withstand heating and deep-fat frying and they give a creamy, smooth texture to foods. Originally they were believed to be a healthier choice as they were cholesterol free or lower in cholesterol.
Fats can be fully hydrogenated or partially hydrogenated.
Fully Hydrogenated – Oils that are fully hydrogenated retain almost no trans fats. The resulting fat is a hard, waxy solid at room temperature. Full hydrogenation increases the amount of saturated fat; however, it is converted by the body into a monounsaturated fat and does not raise the level of bad cholesterol.
Partial Hydrogenation - Vegetable oils that are partially hydrogenated will contain trans fatty acids or trans fats and are believed to be harmful to health, more harmful than saturated fats. Trans fats not only raise total and bad cholesterol levels in the blood but also strip levels of good (HDL) cholesterol, the kind of cholesterol that unclogs the arteries. Trans fats also increase triglyceride levels in the blood, increasing the risk of cardiovascular disease.
Trans Fats or Trans Fatty Acids – are made when vegetable oils are made into a solid fat through a chemical process called Partial Hydrogenation. (Small amounts of trans fat occur naturally in beef and dairy foods.) Common examples are margarine and vegetable shortening.
Dietary Cholesterol – is the fatty substance found in animal-based foods such as meat, poultry, egg yolks, and whole milk. We get cholesterol from the foods we eat and also our body makes cholesterol to use in normal body functions.
Blood Cholesterol – This is the total cholesterol in your blood. It includes HDL and LDL cholesterol. HDL Cholesterol – stands for high-density lipoprotein. It is often called the “good” cholesterol because it helps carry cholesterol away from your body’s organs to your liver where it can be removed. LDL Cholesterol – stands for low-density lipoprotein cholesterol. It is sometimes called the “bad” cholesterol because it is associated with a greater chance of heart disease. Too much cholesterol in the blood, or high blood cholesterol, can be serious. People with high blood cholesterol have a greater chance of geting heart disease. Cholesterol can build up on the walls of the arteries (blood vessels that carry blood from the heart to other parts of the body.) This build-up of cholesterol is called plaque. Plaque can cause narrowing of the arteries over time.
Fatty Acids – are the long chains of carbon atoms, with hydrogen atoms, that form the fat. The chain can vary from 10-30 carbons. Fatty acids differ from one another not only by the number of carbons in the chain but also by the number of double bonds between carbon atoms. There are two groups of fatty acids – saturated and unsaturated. Saturated fatty acids have all carbon atoms filled (saturated) with hydrogen atoms and are solid at room temperature. Unsaturated fatty acids have carbon atoms in the chain that are not filled – double bonds- (unsaturated).
Common saturated fatty acids are lauric, palmitic, stearic. Common unsaturated fatty acids are oleic, linoleum, linolenic and arachidonic.
Omega-3 Fatty acids are polyunsaturated fats and are referred to as “essential fatty acids” because they are necessary for our health and we must get them from our diet as our body is unable to produce them. There are three important omega-3 fatty acids: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). They are believed to be important in prevention of heart disease by controlling blood clotting, healthy cell membranes and lowering cholesterol and triglyceride levels, anti-inflammatory, and critical for proper brain and nerve development in babies. Omega-3 fatty acids are found in fatty fish including salmon, herring, mackerel, sardines, anchovies, canned (albacore) tuna, flax seeds, flax seed oil, walnuts, soybeans and some dark green leafy vegetables.
Omega-6 fatty acids, linoleic acid (LA) are also essential – that is they need to be consumed in our diet as the body is unable to produce them and they are essential for health. They are the precursors for pro-inflammatory molecules, which help avoid infection and promotes healing and also believed to help lower LDL cholesterol. Omega-6 fatty acids are in vegetable oils – corn, safflower and soybean oils. As these oils are found in many processed foods, most Americans consume them in abundance.
Each type of fat or oil is a mixture of saturated, monounsaturated and polyunsaturated fatty acids, although we usually name them by the predominant fatty acid they have. (Safflower oil and Canola oil contain small amounts of saturated fat. However since they contain mostly monounsaturated fat we refer to them as monounsaturated. Likewise lard and chicken fat have small amounts of polyunsaturated fat and the saturated fat; however, they contain mostly saturated fat and thus are referred to as saturated fats.)
Fat is a component in food. Some foods such as fruits and vegetables have almost no fat, whereas other foods have much fat – beef, nuts, oils, butter, etc. Because of the scientific studies in recent years indicating that fat contributes to heart disease and other health problems, we sometimes think of fat as a bad food and something to avoid or eliminate from our diet. However fat is an important part of a healthy diet. Little children need a certain amount of fat in their diets so the brain and nervous system develop properly. That’s why toddlers need to drink whole milk, which has more saturated fat.
Fat adds flavor to food, satieity (keeps us from getting hungry between meals) and is essential to the health and proper functioning of the body.
Healthy skin and hair are maintained by the fat in the diet. Fats helps the body absorb the fat soluble vitamins, which are necessary for life. Fats are also the building blocks of hormones and they insulate the nervous system tissue in the body. Fats are also a means by which the body can store energy. (Of course too much “stored energy” is overweight.) Also as mentioned previously, Omega-3 and Omega-6 fatty acids are “essential” to health and they must be consumed in the diet.
With all this review on fats, what fats should we eat and what should we avoid.
As we have seen some fats, saturated and trans fats, are harmful to the body. However, some fats are necessary for good health and some fats are essential (must be included in the diet) to the body.
It is recommended that we consume 20-35 percent of our caloric intake as fat. Using your recommended energy intake, one can determine the amount of fat one should consume daily. You may like to check with your physician or dietitian. As a guide, one may refer to the following table:
Recommended calorie intake for men and women of varying ages:
| Women
|
Men
|
| 19-50 years old – 2200 calories
|
19-50 years old – 2900 calories
|
| 51 years and up – 1900 calories
|
51 years and up – 2300 calories
|
Based on a light to moderate activity level.
Using the recommended calorie level for you or using the guide in the Table above, refer to the chart below for your recommended daily fat allowance in grams:
| Calories
|
Fat (grams)
|
| 1200
|
40
|
| 1500
|
50
|
| 1900
|
63
|
| 2000
|
65
|
| 2200
|
73
|
| 2300
|
77
|
| 2500
|
83
|
| 2900
|
97
|
| 3000
|
100
|
So how can one know the amount and type of fat in processed food? Food Labels. Read the labels for the Nutrition Facts on the packaged foods. The upper portion of the Nutrition Facts label contains information specific to that product – the serving size, calories for the serving size, and the nutrient information. The lower portion of the label gives the recommended Daily Values, for the nutrients listed for a 2000 calorie diet and for a 2500 calorie diet. Start with the serving size – one cup, 15 pieces, etc., and the number of servings in the container. This is to be used as a guide. If the recommended calorie intake for you is above or below the 2000 or 2500 calorie listings, then adjust up 
or down as necessary.
The information in the upper portion of the label will be the amount for the serving size stated. (If you eat twice the size serving then double all the amounts given.) The label will list the amount of Total Fat, Saturated Fat, trans Fat, and Cholesterol contained in the size serving listed for the food for each nutrient. The percent of Daily Value will also be listed in a column to the right of the nutrient. (A rule of thumb for percentage of Daily Value suggests 5% or less is low and 20% or more is high. For example if Total Fat is listed at 18% of the recommended daily value that is not low. However if this food is one main entree then it is 18% of one entire daily intake and is acceptable.
Food labels can list a food as “Fat-Free” if it has less than 0.5 grams of fat per serving, with no additional fat or oil. Labels may also list a food as ”Saturated Fat Free” if the product has less than 0.5 grams of saturated fat and less than 0.5 grams of trans-fatty acids per serving. Labels may list “Cholesterol-Free” if the product contains less than 2 mg. cholesterol per serving. Thus the size serving is important. If one eats a portion that is 2,3,4 or more times the serving size indicated on the label, then one can be consuming 2,3,4 times 0.5 grams of fat or saturated fat (or 2,3,4 or more times the 2 mg of cholesterol.)
Many food processors, food manufacturers and restaurants have spent much time and money to reformulate recipes and provide the public with foods that are lower in saturated and trans fats and to provide the nutrient information for their products. I sometimes hear very negative and nasty remarks condemning these food establishments for using saturated and trans fats. However we must realize that it has not been that long ago (1970′s) that science was telling them to switch from animal fats to vegetable oils, which they did in an effort to provide people with the “most healthy” foods. As industrious as they are, they developed hydrogenation, which at the time was believed to be an excellent solution. However science has now learned that these hydrogenated fats may be more dangerous than the fats they were replacing. So food businesses have again, in a few short years, stepped up to help their consumers by reformulating recipes and providing foods and nutrient information on their products so that the public can make informed choices.
In conclusion, most current writings suggest that Saturated Fat, Trans Fat and Cholesterol are harmful to health and therefore should be omitted whenever possible and if consumed, choose foods with the lowest possible numbers.
Fat is necessary for the proper functioning of the body. Adults should be aware of the fat content of the food they eat. By knowing the type and amount of fat in their food, individuals can make choices to consume more monoumsaturated and polyunsaturated fats and less saturated and trans fats.
Recommendations are:
Keep total fat intake to 20-35% of total calorie intake.
Limit saturated fats to less than 10% of daily calories (200 calories for a 2000 calorie diet.)
Limit trans fats to 1% of calories (2 grams per day for a 2000 calorie diet).
Limit choleserol to 300 mg per day.
Monounsaturated fats include olive oil, canola oil, peanut oil, sesame oil, walnut oil, flaxseed oil, macadamias, hazelnuts, pecans, almonds, cashews, pistachios, peanuts, sesame seeds, pumpkin seeds, flaxseed, sunflower seeds, avocado, black olives and green olives.
Poluunsaturated oils include corn, soybean, sunflower oil, safflower oil and fish oils.
Selected plant sources of omega fatty acids are: flaxseed oil (raw-not used in cooking), walnut oil, canola oil, soybean oil, flaxseeds, walnuts, pecans.
Tags:
cholesterol,
dietary fat,
fat in foods,
fatty acids,
food labels,
hydrogenated fats,
monounsaturated fats,
omega-3 fatty acid,
omega-6 fatty acid,
polyunsaturated fats,
saturated fats,
trans fats | Posted in
Nutrition
