The role of Macronutrients in Health

Macronutrients (carbohydrates, lipids (fats) and protein) are the main components that make up our foods and contribute to our dietary energy intake (Vipercore-13, 2005). The three macronutrients are the only energy-yielding nutrients we consume in our diet and are known as macronutrients as we require them in relatively large amounts, daily (Whitney & Rolfes, 2019). The energy released from carbohydrates, fats and protein can be measured in joules, which is the international unit for measuring the energy in food (Whitney & Rolfes, 2019). Each of the macronutrients have a different chemical make-up and function in the body however, all three are equally as important to consume to ensure we are providing our bodies with energy to function. This report will further discuss the differences in the three macronutrients, including; the chemical composition, biological function, dietary sources and recommended daily intakes, as well as consequences and symptoms of over or under consumption.

CARBOHYDRATES  

The composition and biological function of carbohydrates

Most energy in the diet comes from carbohydrates (Slavin, 2013). The carbohydrate family includes simple carbohydrates and complex carbohydrates, depending on their structure.

Simple Carbohydrates:

Simple carbohydrates are composed of single sugars are known as monosaccharides, which include; glucose, fructose and galactose. When two single sugars (monosaccharides) are joined together, they form disaccharides, which include; maltose, sucrose and lactose. The monosaccharides most important in nutrition each contain 6 carbon atoms, 12 hydrogens and 6 oxygen atoms (written in shorthand as C6H12O6). (Whitney & Rolfes, 2019), which can be seen as an example in figure one (dlc.dcccd, "Carbohydrates"). Glucose is used by our bodies and brains as the main source of energy1. Glucose is stored in the muscles and liver as glycogen, which acts as an ‘energy reservoirs’ that can be used to supply the brain, muscles and blood with energy as well as to produce ATP.

Complex carbohydrates:

Complex carbohydrates are formed of three or more monosaccharides linked together. Compositions containing 3-10 monosaccharides are called oligosaccharides, whereas, if there are more than 10 single sugars strung together, it is called a polysaccharide. See an example of polysaccharide ‘Glycogen’ in figure two (Khan Academy, "The structure and function of glycogen."). Polysaccharides include glycogen, starches and fibres (TED-ED & Wood, 2016). To digest complex carbohydrates, our bodies break down the chains of monosaccharides using enzymes, to use directly as energy or store in the muscles and liver as glycogen for later use.

Dietary sources and the recommended daily intake of carbohydrates

It is recommended by the Australian dietary guidelines that our diets should be made up of 45-65% carbohydrates. This is the estimated Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates to reduce the risk of chronic disease (Eat for health, 2019). Simple carbohydrates can be found in dietary sources such as:

• Honey

• Some fruits

• Soft drinks

• Desserts

• Ready to eat cereals

Complex carbohydrates can be found in foods such as:

• Brown rice

• Legumes

• Potatoes

• Corn

• Whole wheat bread, pasta and flour 

Excessive and insufficient consumption of carbohydrates

Carbohydrate rich foods are a great source of energy for the body and many of them include lots of vitamins and minerals essential for good health (Gillaspy, 2018). However, over and under consumption of carbohydrate rich foods can lead to health serious health issues.

Excessive Consumption

When carbohydrates are digested, an increase of blood sugar occurs. In response to this, the pancreas stops secreting glucagon and releases insulin instead. The amount released is based off the body’s carbohydrate levels prior to the meal being digested, causing the blood sugar to remain elevated. This can be an issue as a second secretion of insulin will occur, causing more glucose to be transported to the cells and stored as reserved every called glycogen (Kolodziejski, K. 2018). Excessive supplies of stored glycogen may lead to weight gain, which could possibly lead to obesity. Obesity can cause server health issues such as heart disease, stroke and kidney problems.

There are 17 kilojoules (kj) in one gram of carbohydrate (Daily intake guide, 2011).

Insufficient consumption of carbohydrates

Hypoglycaemia occurs when glucose levels in the body are below normal. This can be caused by a lack of carbohydrate consumption (Sheehan, 2018). The body uses carbohydrates as it’s main source of energy, so not consuming enough foods rich in carbohydrate may cause symptoms such as;

• Lack of energy

• Weakness

• Dizziness

• Confusion

• Hunger

PROTEIN

The composition and biological function of Protein

Like carbohydrates, protein atoms are made up of carbon, hydrogen and oxygen, however, proteins also contain nitrogen atoms. These nitrogen atoms give the name amino (nitrogen containing) to the proteins, hence why they are known as amino acids (Whitney & Rolfes, 2019). The basic structure of a protein molecule is the same for all types of amino acids, the difference is in the nitrogen side group which is attached to the carbon atom which makes the type of protein unique (as shown in figure three).

Both essential (cannot be synthesised) and non-essential (can be synthesised) proteins can be found in the body. Essential amino acids must be consumed through dietary sources, however, in extreme cases when essential amino acids are not available, the body can use non-essential amino acids to synthesise essential ones.

Amino acids in the body act as both building blocks of proteins and as intermediates in metabolism. They have both structural and functional properties (Capra, 2006). Proteins catalyse most of the reaction in living cells and control all cellular processes (Dayhoff, 2003).

Dietary sources and the recommended daily intake of protein

It is recommended by the Australian dietary guidelines that our diets should be made up of 15-25% protein (Eat for health, 2019). Some examples of dietary sources of protein include:

• Lean meat, poultry, fish

• Eggs

• Legumes

• Nuts and seeds

• Dairy products

Excessive and insufficient consumption of protein

Excessive Consumption of protein

Just like carbohydrates, excessive consumption of protein can cause health issues. Some symptoms of consuming too much protein short-term include:

• Dehydration

• Exhaustion

• Headache

• Irritability

• Intestinal discomfort

This can happen as the body does not use excess protein efficiently, meaning the body needs to work harder to digest and deal with excess protein. This may impose a metabolic burden on the bones, kidneys and liver (Delimaris, 2013).

Excessive consumption of protein in the long term however may lead to:

• Cardiovascular disease

• Liver and kidney injuries

• Blood vessel disorders

• Seizures

There are 17kj in one gram of protein (Daily intake guide, 2011)

Insufficient consumption of protein

Protein is the building block for our muscles, skin, enzymes, hormones and all body tissues (Arnarson, 2017), under consumption can be extremely detrimental. Most foods contain some protein so true deficiency is extremely rare in developed countries2. Protein deficiency can be identified by symptoms such as:

• Oedema

• Fatty liver

• Weak or problematic skin, hair and nails

• Loss of muscle mass

• Stunted grown in children

A protein deficiency disease ‘Kwashiorkor’ effects mostly children in developing countries, where there is a great lack in nutrient dense foods.

LIPIDS

The composition and biological function of Lipids

Lipids are insoluble biomolecules and just like carbohydrates and protein, they are essential as the third macronutrient in our diets. They play a role in many cellular processes such as energy storage, structural support, protection and communication (dlc.dcccd, "Lipids"). There are two main divisions of lipids; saturated and unsaturated. The difference between the two is in the structure of the cell. Saturated fat contains no double bonds between in the fatty acid chain whereas, unsaturated fat contains at least one double bond (as shown in figure four). Saturated fats are known as the ‘bad’ fats in our diet as they solid at room temperature. Whereas, unsaturated fats are known as ‘good’ fats and are liquid at room temperature. There are monounsaturated and poly unsaturated fats which are both good for you. ‘Trans’ fat however is a unsaturated fat which like unsaturated fat, not great for your health if excessively consumed.

Dietary sources and the recommended daily intake of protein

It is recommended by the Australian nutritional guidelines that our diets should be made up of 20-35% lipids (Eat for health, 2019). However, this should be predominantly from consumption of unsaturated fats. The amount of fat we eat doesn't impact our weight, cholesterol or our risk of heart disease nearly as much as what kind of fat we eat (Zaidan, 2013).
Examples saturated fats in our diet include:

• Avocado

• Fatty fish

• Nuts and seeds

• Olive oil

Examples unsaturated fats in our diet include:

• Animal fat

• Dairy products

• Palm and coconut oil

• Biscuits and pastries

   

Many Australians currently eat too much saturated fats. For good heart health, the heart foundation recommends saturated fat to be less than 10% of your total energy intake (The Heart Foundation, 2018).

Excessive and insufficient consumption of Lipids

Excessive Consumption of Lipids

Over consuming saturated fats can be very detrimental to your health. Eating a lot of saturated fat increases your blood cholesterol, in particular the bad (LDL) cholesterol (The Heart Foundation, 2018), which can lead to heart disease or stroke. Excessive consumption can also lead to weight gain and obesity3.

Consumption of unsaturated fats however, such as foods rich in omega-34 have the potential to lower cholesterol. This means unsaturated fats should be consumed at a much higher frequency than unsaturated fats to maintain good health.

Insufficient consumption of Lipids

Our bodies need fats for energy and other functions in the body.5 Under consumption of fats may cause disruption to bodily processors and therefore lead to poor health. Symptoms of under consumption of fat include:

• Weight loss

• Hunger

• Dry skin

• Mental fatigue

• Poor body temperature regulation

It is apparent that macronutrients are essential components in our what we eat. To achieve a healthy, balanced diet, a person should be consuming carbohydrates, protein and lipids in the recommended amounts, daily. Due to each macronutrient having a different chemical make-up and function in the body, it is essential to ingest all three to avoid over consumption or deficiencies. 

APPENDIX:

1. The brain uses approximately 120g of glucose per day at a resting state (Hill.S, 2019).

2. A protein deficiency disease ‘Kwashiorkor’ effects mostly children in developing countries, where there is a great lack in nutrient dense foods.

3. There are 37kj in one gram of fat (Daily intake guide, 2011), which is substantially higher when compared to the energy in one gram of protein or carbohydrates.

4. A type of polyunsaturated fat

5. Such as cell growth, protection of our organs and to keep us warm. Fats also help our bodies absorb some nutrients and produce important hormones as well (Heart.org, 2019).

REFERENCES:

1. Vipercore-13. (2005, January 1). Macronutrient Balance. Retrieved from https://www.nrv.gov.au/chronic-disease/macronutrient-balance

2. Whitney, E. N., & Rolfes, S. R. (2019). Understanding nutrition. Boston, MA, USA: Cengage. from https://ebookcentral-proquest-com.ezproxy.laureate.net.au/lib/think/reader.action?docID=5024519

3. Slavin, J. L. (2013). Carbohydrates, Dietary Fiber, and Resistant Starch in White Vegetables: Links to Health Outcomes. Advances in Nutrition, 4(3). doi: 10.3945/an.112.003491

4. Wood, R. J. (2016, January 11). Retrieved August 15, 2019, from https://www.youtube.com/watch?v=wxzc_2c6GMg

5. S. H. (2019). SUGAR & SWEETENERS EXPLAINED [Web log post]. Retrieved July 21, 2019, from https://plantproof.com/sugar-sweeteners-explained/

6. Carbohydrates. Retrieved from https://dlc.dcccd.edu/biology1-3/carbohydrates

7. The structure and function of glycogen. Retrieved from https://www.khanacademy.org/test-prep/mcat/physical-sciences-practice/physical-sciences-practice-tut/e/the-structure-and-function-of-glycogen-

8. National Health and Medical Research Council, Eat For Health. (2019). Australian dietary guidelines: Summary. Retrieved July 21, 2019, from https://www.eatforhealth.gov.au/sites/default/files/content/n55_australian_dietary_guidelines.pdf.

9. Gillaspy, R., Dr. (2018). Health Effects of the Excessive Consumption of Carbohydrates. Retrieved August 17, 2019, from https://study.com/academy/lesson/health-effects-of-the-excessive-consumption-of-carbohydrates.html

10. Kolodziejski, K. (2018, December 12). What Happens if a Person Consumes an Excess Amount of Carbs? Retrieved August 17, 2019, from https://healthyeating.sfgate.com/happens-person-consumes-excess-amount-carbs-4591.html

11. Sheehan, J. (2018, December 07). What Can Happen From a Lack of Carbohydrates? Retrieved August 17, 2019, from https://healthyeating.sfgate.com/can-happen-lack-carbohydrates-5999.html

12. Dayhoff, M. O., Dr. (n.d.). Amino Acids. Retrieved August 17, 2019, from http://www.biology.arizona.edu/biochemistry/problem_sets/aa/aa.html

13. Capra, S. (2006). New nutrient reference values for Australia and New Zealand: Implementation issues for nutrition professionals. Nutrition Dietetics,63(2), 64-65. doi:10.1111/j.1747-0080.2006.00053.x

14. Delimaris, I. (2013). Adverse Effects Associated with Protein Intake above the Recommended Dietary Allowance for Adults. ISRN Nutrition,2013, 1-6. doi:10.5402/2013/126929

15. Arnarson, A. (2017, October 31). 8 Signs and Symptoms of Protein Deficiency. Retrieved August 17, 2019, from https://www.healthline.com/nutrition/protein-deficiency-symptoms

16. Lipids. (n.d.). Retrieved August 18, 2019, from https://dlc.dcccd.edu/biology1-3/lipids

17. Zaidan, G. (2013). Transcript of "What is fat?" Retrieved August 18, 2019, from https://www.ted.com/talks/george_zaidan_what_is_fat/transcript?language=en#t-246964

18. The Heart Foundation. (2018). Saturated and trans fat. Retrieved August 18, 2019, from https://www.heartfoundation.org.au/healthy-eating/food-and-nutrition/fats-and-cholesterol/saturated-and-trans-fat

19. The Heart Foundation. (2018). Five ways to lower cholesterol. Retrieved from https://www.heartfoundation.org.au/news/five-ways-to-lower-cholesterol

20. Daily intake guide. (2011). Healthy eating, made easy. Front-of-pack labelling for food and drink in Australia. - Energy. Retrieved from http://www.mydailyintake.net/energy/

21. Heart.org. (2019). Dietary Fats. Retrieved from https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/dietary-fats