Friday 9 October 2015

DIETARY FATS (The pros and cons)

SATURATED, UNSATURATED FATTY ACIDS AND TRANS FATS

Just like carbohydrate and protein, fat is an important macro nutrient and form an integral role in nutrition of human body. Fats are hydrophobic, soluble in organic compounds and insoluble in water. Fats function as most dense source of chemical energy to the body with one gram providing 9 kilo calorie.[1]

Fats energy release is more than two folds to what either protein or carbohydrate provides per gram. [2] This translates to what health professional say that consuming more energy dense food (fats) can lead to rapid weight gain with an imminent sequelae of being overweight.[4]

Fats are composed of saturated or unsaturated fatty acids and glycerol.[3]
According to the number and bonding of carbon atoms in fats, fats can be classified in the following categories to include:-

  • Saturated fats- they have single bonds between carbon atoms saturated with hydrogen atoms. Mostly found in animal products like milk and milk products, cheese, butter oily fish [3]
  • Unsaturated fats- they have one or more double bonds between carbon atoms mostly found in most vegetable oils. [3]
SATURATED FATS

According to American Heart Association, saturated fats increase the 'bad' cholesterol (LDL) in the body increasing the risks to heart diseases and stroke.[4]

Saturated fats increase total blood cholesterol, triglycerides and LDL cholesterol and lowers the 'good' cholesterol -HDL. Saturated fats affects the entire lipid profile increasing risks to heart diseases, stroke and type 2 diabetes mellitus. [5]

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American Heart Association recommends eating little saturated fatty acids to give a total of 5- 6% of the total daily caloric requirement. [6]
TRANS FATS.

Trans fats are produced during industrial process by partial hydrogenation of liquid vegetable oils in the attempt to make them more solid. They give food desirable taste, used for deep frying in fast-food outlets on the grounds that oils with trans fat do last for longer.

According to American Heart Association, trans fats raise the 'bad' cholesterol (LDL) and lower the 'good' cholesterol (HDL) level in blood which is a risk factor for development of heart diseases, stroke and type 2 diabetes.

Trans fats are found in foods like cakes, pizza, biscuits, cookies, pie crusts.

The Michigan F.D.A (Food and Drug Administration) has already given a grace period of 3 years (ending 2018) for the food industry to eliminate trans fats in the food they produce. Trans fat clog arteries increasing risks for heart diseases [8] and type 2 diabetes mellitus. [9]

UNSATURATED FATS.

These fats contain one or more double bound between the carbon atoms. They are divided into two forms:-

Monounsaturated fats- they have one double bond between the carbon atoms. [10] Sources of monounsaturated fats include:-

  • Avocado
  • Sufflower oil
  • Sunflower oil
  • Olive oil
  • Nuts
  • Vegetable oil[11]

Polyunsaturated fats- they contain more than one double bond between the carbon atoms.[10]
Polyunsaturated fats are further divided into:-
  • Omega-3 fats
  • Omega-6 fats

Omega-3 fats are cardio-protective in that they help in lowering the bad cholesterol in the body, lowers blood triglycerides and lower the systemic blood pressure. Sources are;

  • Eggs
  • Oily fish like salmon, sardines
  • Lean meat.
  • Chicken.
  • Flaxseed, walnut, soybeans, canola oil.
When omega-6 fats are consumed in place of trans fats and saturated fats, they help to lower risks of heart diseases and stroke. Food sources of Omega-6 fats include;

  • Margarine spreads
  • Sufflower oil
  • Sunflower oil
  • Soybeans
  • Sesame oil
  • Walnuts[12]

The American Heart Association recommends consumption of monounsaturated and polyunsaturated fats in place of trans fats and saturated fats because of their health benefits of lowering the bad cholesterol, lowering triglycerides, lowering the blood pressure and enhancing heart health. [13]


OUR RECOMMENDATIONS IN KENYAN DIET:-

Due to the aggressive nature of industries to make cheaper fats that most of the population can afford, it is our own responsibility as consumers to check food labels and ascertain and appreciate the fact that different fats and oils have different composition of fats. We discredit use of solid fats as they have high levels of saturated fatty acids (SFA) with almost all of them having zero trans fat to use of oils with higher levels of Polyunsaturated fatty acids (PUFA) and Monounsaturated fatty acids (MUFA) and low levels of saturated fatty acids (SFA) as low as 10%.

References:
1. Fat- Wikipedia, The Free Encyclopedia. Last edited: May 17, 2015. Address: https://en.wikipedia.org/?title=Fat. Viewed on: 17/06/2015.
2. Normal Values, Diet- Ross and Wilson textbook of Anatomy and Physiology in health and illness. 10th Edition, 2006 by Ann Waugh, Allison Grant. Page 464.
3. Introduction to nutrition, fats- Ross and Wilson textbook of Anatomy and Physiology in health and illness. 10th Edition, 2006 by Ann Waugh, Allison Grant. Page 373.
4. Fats 101- American Heart Association. Address: http://www.heart.org/HEARTORG/GettingHealthy/FatsAndOils/Fats-101_UCM_304494_Article.jsp#mainContent. Viewed on: 17/06/2015
5. Saturated fats- Wikipedia, The Free Encyclopedia. Edited on: June 13, 2015 by Jefr. Address: http://en.m.wikipedia.org/wiki/saturated-fat. Viewed on; 17/06/2015.
6. Saturated fat- American Heart Association. Address: http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/Saturated-Fats_UCM_301110_Article.jsp#mainContent. Viewed on:17/06/2015.
7. Saturated fats- Heart Foundation. Viewed at: http://www.heartfoundation.org.au/healthy-eating/fats/pages/saturated-fats.aspx. viewed on: 17/06/2015.
8. F.D.A sets 2018 Deadline to Rid Foods of Trans Fats- NYTimes.com by Sabrina Tavernise. June 16, 2015. Address: http://mobile.nytimes.com/2015/16/17health/fda-gives-food-industry-three-years-eliminate-trans-fats.html?_r=0&reference=. Viewed on 17/06/2015
9. Trans fats- American Heart Association. Address: http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/Trans-Fats_UCM_301120_Article.jsp#mainContent. Viewed on: 18/06/2015.
10. Unsaturated fats- Wikipedia, the free encyclopedia. Edited: 17th April, 2015 by Deli nk. Address: http://www.en.m.wikipedia.org/wiki/unsaturated_fat. Viewed on 18/06/2015.
11. Nutrition for Everyone: Basics: Unsaturated fat|DNPAO|CDC. Address: http://www.cdc.gov/nutrition/everyone/basics/eat/unsaturatedfat.html. Viewed on: 18/06/2015.
12. Unsaturated fats|Dietitians Association of Australia. Address: http://daa.asn.au/for-the-public/smart-eating-for-you/nutrition-a-z/unsaturated-fats/. Viewed on: 18/06/2015.
13. Polyunsaturated fats- American Heart Association. Address: http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/Polyunsaturated-Fats_UCM_301461_Article.jsp#mainContent. Viewed on: 18/06/2015.