Introduction - What's in my food?
A new week calls for the start of a new feature on Taste & See! This has been in the making for a while now, so I'm really glad to finally be sharing my first 'Nutrition Basics' post. The idea behind this series is to inform, educate, and empower you to understand more about the food that you eat, as well as how the body uses each food component to build, maintain, fuel, and heal itself. Today I'll be introducing each of the different components that can be found in most of the foods that we eat. Now most of this information may seem a bit simple and straightforward, but I really want to try and share it in a way that makes a lot of sense, is enjoyable to read, and can help guide you through the maze of nutrition information out there :)
Food is something that we require for fuel, growth, repair, and maintenance of important bodily processes. Without it, we wouldn't be able to survive. One of the first steps to understanding nutrition is gaining an understanding of the components found in the food that we eat.
So, what's in my food?
Food, on the most basic level, is made up of six main components:
Each of these components can be broken down further into different organic and inorganic compounds that each play a different role in the body. Foods also contain phytonutrients in addition to these major components. Nutrients are generally classified as macro- (major, required in larger amounts) or micronutrients (minor, required in much smaller quantities). Furthermore, nutrients can be classified as essential, which are required in our diets, or non-essential, which are not required in our diets due to the fact that the body is able to synthesise them to some extent from other components.
Carbohydrates are responsible for being a major source of energy for the body, providing 4 kcal/g of carbohydrate. Excess carbohydrates can be stored in limited amounts as glycogen in the liver and muscles, or in adipose (fat) tissue around the body. The most important dietary carbohydrates are classified as monosaccharides, disaccharides & oligosaccharides (simple sugars), as well as polysaccharides (complex carbohydrates). Disaccharides are made up of two monosaccharides that are bonded together, for example, sucrose (a disaccharide) is composed of one molecule of glucose and one of fructose. Oligosaccharides are made up of 3-10 monosaccharide units, whilst polysaccharides are large molecules made up of more than 10 monosaccharides. Dietary fibre, which refers to non-digestible plant components, also forms part of the carbohydrate family. Although not digestible by the body, different types of dietary fibre have been shown to have many beneficial physiological functions. Carbohydrates are mainly found in plant foods, such as grains, legumes, fruits, and vegetables. Milk contains the lactose, a disaccharide composed of one glucose and one galactose molecule.
Proteins are complex organic molecules that are unique in the fact that they contain nitrogen, in addition to carbon, hydrogen, and oxygen. Proteins are important in our food for proper growth, particularly in young children and teenagers, as well as for repairing body tissues in the body. Proteins function in the body as:
Enzymes, which catalyse biochemical reactions in the body
Hormones, which regulate various body functions
Carrier proteins, such as haemoglobin which transports oxygen
Contractile proteins in muscles, which are responsible for movement
Structural proteins, such as collagen
Immune system components, which protect our bodies by fighting infections
Proteins can be found in both plant and animal sources. Animal protein sources contain higher quality protein, supplying all of the amino acids required by the body, whilst plant-based proteins need to be combined in order to supply all of the essential amino acids.
Fats are a large, diverse group of organic molecules that provide the body with energy (9 kcal/g). For this reason, they are stored in various fat deposits around the body. Common dietary fats include monounsaturated, polyunsaturated, and saturated fatty acids. Fats are found in animal products, such as butter, cheese, eggs, and meat, as well as plant sources, such as avocado, seeds, and nuts. Despite the long-held belief that fats are bad for you, they are required for general health, the absorption of fat-soluble vitamins, and cell structure. Unsaturated fats for example, which are mainly found in plant sources, are generally considered to be better for your health than trans fats and saturated fats. There are two essential fatty acids that are required in the diet - alpha-linolenic acid and linoleic acid. All other lipids that are needed by the body can be synthesised from these.
The human body is made up of almost two-thirds of water, so this molecule is incredibly important for the body to function properly. Water is not considered a macronutrient, as it does not supply the body with energy, however it is required in large amounts as part of one's diet for many different processes such as digestion, transport, and metabolism. On average, humans consume about 20% of the water we need each day from the food that we eat. Some foods, such as watermelon, are made up of nearly 100% water, so this amount varies depending on the types of foods that a person eats.
Vitamins are complex organic compounds that are needed for overall wellbeing and health. They play an important role as catalysts, or 'helpers', which assist the body in maintaining normal growth, health, vision, metabolism of macronutrients, and life in general. Vitamins are classified on the basis of their solubility in water, as either:
Water-soluble - vitamin B-complex and vitamin C
Fat-soluble - vitamins A, D, E & K
Most of these vitamins cannot be made by the body, so we need to consume them in the foods that we eat to ensure that we have an adequate supply of each of them at all times. Deficiencies of any of these vitamins can result in illness and poor health, for example, vitamin C deficiency can result in scurvy and poor immune function. Overconsumption of vitamins, such as vitamin B6 or vitamin A, can result in toxicity which also has serious negative health effects. Each of these amazing compounds will get its own blogpost in good time :)
Minerals are vital for good health, and just like vitamins both excessive doses and deficiencies can result in negative health effects. Minerals are needed to build strong bones, teeth, the formation of red blood cells, and for the proper functioning of enzymes. Some minerals, such as sodium, calcium, and phosphorous, are required in larger amounts than others and are thus classified as macrominerals. Others, such as cobalt, zinc, manganese, and selenium, are required in much smaller amounts and are thus classified as micro- or trace minerals.
Plant foods contain thousands of chemical compounds known as phytonutrients or phytochemicals. Phytonutrients are not essential to keep you alive, however, they have been shown to prevent disease, maintain health, and prevent oxidation in the body. Examples of a few of the thousands of phytonutrients found in foods include:
Carotenoids - act as antioxidants in the body and provide yellow/orange/red colour to fruits and vegetables
Ellagic acid - may have protective effects against cancer
Flavonoids - may have anti-cancer, anti-inflammatory, and anti-oxidative effects
Resveratrol - acts as an antioxidant and anti-inflammatory in the body, and may have protective effects against the development of heart disease
Glucosinolates - found in cruciferous vegetables such as broccoli and may have protective effects against the development of cancer
These compounds each deserve an entire blogpost to themselves :) A lot of current research is being done on determining the exact mechanisms of many of these compounds.
So, what's the best way to get all of these nutrients into your diet?
Choosing nutrient-rich foods isn't all that difficult, and achieving a good balance and achieving a healthier overall diet can be quite simple to do. Healthy eating forms a key pillar of maintaining a healthy lifestyle and good health. For this reason dietary guidelines, such as the South African Food-Based Dietary Guidelines (FBDGs), have been developed in order to promote dietary recommendations that speak in terms of food rather than nutrients. Guidelines such as these translate evidence-based nutrient guidelines into information that guides consumers in making healthier food choices. The most up-to-date FBDGs recommend the following:
Enjoy a variety of foods
Make starchy foods part of most meals
Eat plenty of vegetables and fruit every day
Eat dry beans, split peas, lentils and soya regularly
Have milk, maas or yoghurt every day
Fish, chicken, lean meat or eggs can be eaten daily
Drink lots of clean, safe water
Use fats sparingly
Use sugar and foods and drinks high in sugar sparingly
Use salt and food high in salt sparingly
I also found a really cool resource from Eat Right (The Academy of Nutrition and Dietetics) that highlights a few easy tips to help you make good choices in your daily food choices, ensuring that you consume sufficient amounts of most nutrients every day. Take it or leave it, it's up to you, but following these tips will help you to nourish your body and keep you healthy in the long run :)
Choose brightly coloured fruits and vegetables
Eat at least one serving of dark green leafy vegetables each day
Choose to eat whole-grains and fibre-rich foods
Enjoy lean meats, poultry, fish, eggs, beans, and nuts each day
Serve meals that include a variety of different ingredients all in the same dish
Choose to drink water, low-fat milk, or small amounts of 100% pure fruit juice rather than soft drinks
 SFGate. 6 Components of Nutrition [Internet]. San-Fransisco: SFGate. Date unknown - [cited 2016 Dec 10]. Available from: http://healthyeating.sfgate.com/6-components-nutrition-2761.html.
 WebMD. Phytonutrients [Internet]. 2016 - [cited 2016 Dec 10]. Available from: http://www.webmd.com/diet/guide/phytonutrients-faq#2.
 Vorster HH, Badham JB, Venter CS. An introduction to the revised food-based dietary guidelines for South Africa. S Afr J Clin Nutr. 2013;26(3):S1-S164. Available from: http://sajcn.co.za/index.php/SAJCN/issue/view/67/showToc.
 Vorster HHE. The new South African food-based dietary guidelines in perspective [Internet]. Date unknown - [cited 2016 Dec 10]. Available from: http://www.nutritionsociety.co.za/index.php/11-useful-information/26-the-new-south-african-food-based-dietary-guidelines-in-perspective.
 Denny S. Tips for Choosing a Nutrient-Rich Diet [Internet]. 2015 Jul 6 - [cited 2016 Dec 10]. Available from: http://www.eatright.org/resource/food/vitamins-and-supplements/nutrient-rich-foods/choosing-a-nutrientrich-diet.