MACRONUTRIENT SERIES: FATS PART 2

From a nutritional point of view, Essential Fatty Acids, EFA’s, are important for several health related aspects and for optimal functioning of the human body. EFA’s are not just a source of energy; The fats you eat give your body energy that it needs to work properly. During exercise, your body uses calories from carbohydrates you have eaten. But after 20 minutes, exercise then depends on calories from fat to keep you going. EFA’s also function as structural building blocks of the body, carry fat-soluble vitamins. You also need fat to keep your skin and hair healthy. Fat also helps you absorb vitamins A, D, E, and K, the so-called fat-soluble vitamins. The involvement in vital physiological processes in the body is a key component to EFA’s, as they fill your fat cells and insulate your body to help keep you warm. This is highly important to babies and infants as their bodies haven’t developed thermoregulation of the body; this won’t happen until early childhood.

The fats your body gets from your food give your body essential fatty acids called linoleic and linolenic acid. They are called “essential” because your body cannot make them itself, or work without them. Your body needs them for brain development, controlling inflammation, and blood clotting. Making them indispensable for a number of important biological functions including growth and development. The importance of dietary fats is explained in more detail below.

Why are Dietary Fat so Essential to the Human Body?

Fat has 38kj per gram, more than 2 times the number of kjs in carbohydrates and protein, which each have 17kj per gram. All fats are made up of saturated and unsaturated fatty acids. Nutrition nourishment has explained these different types of fatty acids that are a part of the diet. If you are interesting in finding out more about these types of fats, please view our Part 1 series on Macronutrients: Dietary Fats blog.

Structural component
The membranes around the cells in our body physically separate the inside from the outside of the cell, and control the movement of substances in and out of the cells. They are mainly made of phospholipids, triglycerides and cholesterol.  Both length and saturation of the fatty acids from phospholipids and triglycerides affect the arrangement of the membrane and thereby its fluidity. Shorter chain fatty acids and unsaturated fatty acids are less stiff and less viscous, making the membranes more flexible. This influences a range of important biological functions such as the process of endocytosis in which a cell wraps itself around a particle to allow its uptake.

The brain is very rich in fat (60%) and has a unique fatty acid composition; docosahexaenoic acid (DHA) is the major brain fatty acid. The lipids of the retina also contain very high concentrations of DHA.

Carrier of vitamins
In the diet, fat is a carrier for the fat-soluble vitamins A, D, E and K, and supports their absorption in the intestine. Consuming sufficient amounts of fatty foods that contain these vitamins is thus essential for adequate intake of these micronutrients.

Provision of energy
EFA’s are a source of energy in the human diet, Fat has 38kj per gram, more than 2 times the number of kjs in carbohydrates and protein, all which form the three macronutrients of the body, which each have 17kj per gram respectfully. Fat can be stored in the body’s fat tissue, which releases fatty acids when energy is required

Other biological functions
Our bodies cannot produce the polyunsaturated fatty acids (PUFA) linoleic acid (LA) and alpha linolenic acid (ALA). Without these essential fatty acids some vital functions would be compromised, thus they must be provided by the diet. LA and ALA can be converted to longer chain fatty acids and compounds with hormone-like or inflammatory properties (such as prostaglandins or leukotrienes, respectively). As such, essential fatty acids are involved in many physiological processes such as blood clotting, wound healing and inflammation. Although the body is able to convert LA and ALA into the long chain versions arachidonic acid (AA), eicosapentaenoic acid (EPA), and, to a lesser extent, to docosahexaenoic acid (DHA), this conversion seems limited. The longer chain fatty acids EPA and DHA are said to be “conditionally essential” and it is recommended to consume direct sources of these particular long chain fatty acids. The richest source of EPA and DHA is oily fish, including anchovy, salmon, tuna and mackerel.

 An in-depth look into Cholesterol. 

Cholesterol has a bad name. It has been linked to risk of heart disease, cancers, types 2 diabetes and obesity. As this may be truth, it is grossly …… Cholesterol is an important compound in the body. See below for the roles that cholesterol play in the human body to improve your understanding.
All animal cells contain cholesterol, a lipid that plays a role in the membrane’s fluidity and permeability. Cholesterol is also a precursor of vitamin D, adrenal and sex steroid hormones, and bile salts that emulsify and enhance absorption of fats in the intestine. The main dietary sources of cholesterol are cheese, eggs, beef, pork, poultry and (shell) fish.

Dietary cholesterol helps to maintain a stable pool of cholesterol, but cholesterol is also synthesised by the liver. The human body regulates its cholesterol status. When the cholesterol intake is very low (as in vegans who consume no animal products), both gut absorption and synthesis increase. When cholesterol intake is high, the body’s synthesis is suppressed and excretion via bile salts is increased. The amount of cholesterol, which passes daily through the small intestine, which is the sum of dietary cholesterol and produced cholesterol, is between 1 and 2 g.  The blood cholesterol level is the net result of the absorption in the gut and the synthesis in the liver, minus the excretion via the faeces (as cholesterol, bile salts and products resulting from bacterial transformation) and the use of cholesterol by cells.Cholesterol in the blood is carried by lipoproteins: LDL (low density lipoprotein) and HDL (high density lipoprotein).
Importantly, for most people, eating foods that contain cholesterol has little effect on blood cholesterol level, as recent research has noted. However, a small number of people (15-25% of the population) may be ‘hyper-responders’ to dietary cholesterol, and are advised to limit their cholesterol intake.

Did you know??

Your liver contributes to most of the cholesterol in your body? Around 75-80% in fact. With your liver producing 2,000-3,000mg of cholesterol each day!

We hope you enjoyed the SECOND PART of the Fats- Macronutrients Series, and have developed a greater understanding of how Essential Fatty Acids contribute to a range of biological needs in the body. If you would like to read more about fats in the diet, clink the links below!

http://lpi.oregonstate.edu/mic/other-nutrients/essential-fatty-acids

https://www.nrv.gov.au/nutrients/fats-total-fat-fatty-acids

http://www.nutritionmd.org/nutrition_tips/nutrition_tips_understand_foods/fattyacids.html

https://www.msdmanuals.com/professional/nutritional-disorders/undernutrition/essential-fatty-acid-deficiency

Stay tuned for our final Part Three of Fats- Macronutrients series, where nutrition nourishment will explore in detail the Polyunsaturated Fats including Omega 3 & 6, DHA and EPA, known as the ‘Fish Oils’,  how they relate to good health and signs of a deficiency.

Healthiest Regards

Nutritionnourishment

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