Diet Fat Content of Foods
Information - Diet Nutrition
- Saturated Fat - Monounsaturated
Fat - Polyunsaturated
Types of Dietary Fat in Foods
Fats and oils contain different types of fatty acids which affect dietary health in varying ways. They are classified into two main types: saturated and unsaturated (inc. mono-unsaturated and poly-unsaturated fats). Fat is saturated when its molecules hold the maximum amount of hydrogen; monounsaturates hold less hydrogen, while polyunsaturates have the least.
Our Dietary Fat Needs
Neither saturated nor monounsaturated fat is needed in our diet, as our body can manufacture its own from carbohydrate, protein or alcohol. We only need to eat certain polyunsaturated fats which our body cannot make for itself. These polyunsaturates are known as essential fatty acids (EFAs).
Recommended Dietary Allowance (RDA) For Fat
There is no RDA for fat. US government guidelines state that fats should be eaten "sparingly", while most nutritionists and dietitians recommend a daily fat intake of about 30 percent of calories - about 50 grams of total fat on a 1600-calorie diet. More important is to restrict your intake of saturated fat, including trans-fats, to no more than 5-10 per cent of calories. This equates to a maximum of 22g of saturated fat per day on a 2000-calorie diet. Heart associations typically advise that people with raised blood cholesterol, elevated blood pressure, or a history of family heart disease, should eat less than 30 percent of calories in the form of fat, and should restrict their consumption of saturated and trans-fatty acids to a minimum. For this category of people, regular physical exercise is also highly recommended.
Fats and Healthy Eating Habits
Saturated fatty acids - the "bad fats" - are found mainly in animal foods (eg. meat, cheese) and are solid at room temperature. Saturates also include "trans-fats". These are "transformed" from polyunsaturated vegetable oils into saturated fats by an industrial process called hydrogenation. They are found in processed foods like cookies, pies, cakes, candy and chips.
Saturated fats (including trans fats) are the least healthy type of dietary fat. An excessive intake of saturated fat is linked to elevated cholesterol levels, clogging of the arteries leading to coronary heart disease and stroke. With a couple of exceptions, (palm oil, coconut oil) saturates are found only in animal foods and is typically solid at room temperature. Since our body manufactures its own saturated fat we don't need to include any in our diet. For optimum heart health reduce your saturated fat intake, especially if you suffer from hypertension or high serum cholesterol, or have problems with fat-metabolism.
Monunsaturated fatty acids are liquid at room temperature. With the exception of essential fatty acids, monounsaturated fat is probably the healthiest type of dietary fat, although it is still calorie-dense and should therefore be eaten in small amounts. Monounsaturated fats have none of the adverse effects associated with saturated fats, hydrogenated fat, trans-fats or omega-6 polyunsaturated vegetable oils. Good sources include olive oil, peanuts and avocado. The dietary and nutritional health benefits of monounsaturates are best seen in Mediterranean-style diets.
Polyunsaturated fatty acids remain liquid at room temperature, or when chilled. Polyunsaturated fat is an essential element in our diet because it includes the family of essential fatty acids.
There are two basic types of essential fatty acids: linoleic acid (omega-6) and alpha-linolenic acid (omega-3). When eaten in the right ratio (3 grams omega-6, to one gram of omega-3), these EFAs have powerful healing properties and may assist weight control. An excellent food source of Omega-3 fat is oily fish, or flaxseed oil.
Diet Nutrition - Nutritional Benefits of Fat
Along with protein and carbohydrate, essential fatty acids are highly nutritious and provide a range of health and nutritional benefits. For example, Omega-3 fats reduce inflammation and regulate a wide variety of chemical reactions and metabolic functions. They also help to maintain a healthy weight. Also, without sufficient dietary fat we cannot absorb the fat-soluble vitamins A,D,E and K.
Health Dangers of Excessive Fat Intakes
As stated above, eating too much saturated
or trans-fat leads to an increased risk of cardiovascular disease. But
overeating of any fat is likely to lead to an excessive calorie-intake.
This is because fat (9 calories per gram) contains twice the calorie content
of protein or carbs (4 calories per gram). Thus, notwithstanding the alleged
fat-burning qualities of ketogenic diets like Atkins Diet, overweight
and obesity may result from a high fat diet. So for optimum heart health
and weight management, follow the fat RDA guidelines.
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