Understanding Nutrition A beginners guide What is Nutrition? We refer best to nutrition as food food is composed of nutrients, the most well-known are macronutrients protein, carbohydrate and fats. Food also contains micronutrients such as water, vitamins, minerals. Each of these all contribute to our physiological function (the way our body works). Once absorbed, we break these down into smaller units to become usable by our cells amino acids from protein, glucose from carbohydrates and fatty acids from fats. Although digestion and hormonal response can vary, once the subunits enter the general circulation, the actual food source doesn t matter, as the body can t differentiate what food it came from anyway. Although this is fact it doesn t mean the quality of food is unimportant for our health, performance and body composition. Our bodies will physiologically respond better to higher quality of food. Understanding the nutrients that make up our food is a fundamental part of understanding and learning nutrition. When discussing good nutrition it s important to talk in terms of whole foods, as whole foods are digested and absorbed more slowly due to a higher fibre content which results in less glucose appearing in the blood, less insulin being released and less chance of fat storage. The main sources for energy production are the macronutrients and the amount of energy from these are referred to as calories. The important criteria for all good nutrition behaviours include: 1. Good nutrition properly controls energy balance 2. Good nutrition provides nutrient density (food containing large amounts of key nutrients) 3. Good nutrition achieves health, body and performance goals 4. Good nutrition is honest and outcome based 5. Good nutrition is sustainable for us and the planet.
Nutrition and the Digestive process. A healthy digestive tract can digest and absorb about 97% of the food we eat and after processing ends up with the eventual fate of either; storage, energy production or excretion. The digestive system starts at the mouth and ends at the anus and bends and twists to 25 feet in length through our bodies. The digestive process begins in the mouth with the process of mastication (chewing) which is then mixed with secretions of fluid to form bolus (soft, partially chewed food) the bolus then travels down the esophagus and enters the stomach. The chewing process triggers the stomach and supporting organs to trigger specific acids, mucous, enzymes and bile. This digestive action is to break down the bolus while extracting the nutrients and moving them to the small intestine. Here, the nutrients can be absorbed through the intestinal cells. In order for absorption to occur, the digested food must travel slowly through the intestines to give the GI system time for the nutrients to come into contact so the nutrients can be grabbed and transported into blood circulation. If nutrients are bound with fibre they will usually pass unabsorbed and later secreted as waste. Absorption can also be compromised by irritation to the intestines; coeliac, introlerances etc. once absorbed into circulation they are passed to the liver where they are passed on to where they are required. The whole digestive system is governed by two organ systems of the body: the endocrine (hormonal) system and the nervous system. As diverse and complex as it seems, the digestive process has one goal: to deliver nutrients into our bloodstream to use in our cells. We eat, we digest, we absorb, we circulate, we store, we transfer energy, we use the energy and then we repeat. Nutrients are required for ATP (energy) production which is required for nearly every action in the body. We need it to move our skeletal muscles, contract our digestive muscles and produce enzymes. We need it to carry molecules across cell membranes and to form even more energy production.
Micronutrients Micronutrients (meaning small amount) provide the foundation for our metabolic and physiological functions within the body. They are known primarily as vitamins and minerals, and when the body doesn t receive enough of these it will start to show symptoms of deficiencies. Even though we need these to function there is also risk of micronutrient toxicity when too much of a vitamin or mineral is present in the body. VITAMINS Vitamins are organic compounds that are needed in trace amounts in the body to enable several important regulatory functions such as growth, digestions, energy transfer, nervous system function and more. Vitamins are categorized into water soluble and at soluble Water soluble dissolve in water and are usually excreted through our urine as they will not store in the body these are the B&C vitamin group. Fat soluble dissolve in fat, are absorbed in our GI tract and usually excreted through our faeces these include vitamins A,D,E & K MINERALS Like vitamins, minerals are also essential in the body but not for direct energy. Minerals serve as building blocks for body structures such as the teeth and bones and can assist in constructing other cells and enzymes. Minerals can act as electrolytes which are critical to the regulation of muscle contraction, establishment of fluid balance and generation of nerve impulses. Micronutrients should be sourced primarily from whole food sources rather than dietary supplements to receive greater health benefits.
Macronutrients Macronutrients (carbs, proteins and fats) are our primary source of energy and influence our energy levels on a daily basis. They assist in our ability to work, recover from exercise, chronic disease, body composition and more. Our intake of macronutrients highly influences our energy levels and knowing them more in depth can give you a better understanding of why they re important to our overall health. I will discuss each macronutrient more in depth. Carbohydrates Carbohydrates (carbs) are a collection of carbon, hydrogen and oxygen molecules. Sugar starches and fibres are all considered carbohydrate sources. Carbohydrate digestion breaks down more complex carbs into their simpler form for eventual release into the bloodstream as glucose. As soon as we bite into carbs our salivary amylase (enzyme that breaks down starch) helps to break down the carbohydrate chain, but only accounts for about 20% of the breakdown depending on how long the food stays in the mouth. Once broken down the simple carbs pass through and exit the intestinal cells into the blood vessels that then transports them to the liver before entering general circulation. The liver takes what it needs for energy transfer and glycogen storage and ships the rest out into circulation to be taken up by the cells. The liver can store up to 100g of glycogen and the muscles can store up to 600g (depending on muscle mass) beyond this any additional glucose will usually turn to fat storage. Glucose is essential to life, both the brain and nervous system prefer a continuous supply for fuel. The body can transfer energy through the production of ketones when carb supply is low, but a suggested intake of 130g carbs per day is recommended to meet daily energy needs but of course individual context will alter this recommendation. A diet consisting of refined carbohydrates and added sugars enter the body at a rapid pace which can elevate blood sugar, LDL (bad) cholesterol and cause insulin resistance, where unrefined carbohydrates can benefit by; increasing micronutrient intake, greater fibre intake, enhanced satiety (feeling full), higher thermic (burning calories) effect and controlled blood sugar levels. Rapid digesting carbs can benefit physically active people during or after exercise due to the fact insulin sensitivity is high and the liver and muscle glucose uptake is rapid. Carbohydrates are important and required for optimal functioning, it should be proportional with dietary fat intake eg. If fat intake is high, carb intake should be lower and vice versa.
FAT Fats are organic molecules made up of carbon and hydrogen elements joined together in long groups called hydrocarbons, the arrangement and interaction of these with each other determines fat type. The simplest unit of fat is known as a fatty acid and is generalized into two forms saturated fatty acids and unsaturated fatty acids. To digest fat, the body breaks down triglycerides into fatty acids and glycerol which are repackaged various ways before entering the bloodstream, occurring mainly in the small intestine. Absorbed fat enters the bloodstream several hours after fat consumption due to the lengthy breakdown and transport process. Dietary fat has 6 major roles: 1. Provides an energy source (most energy dense macronutrient) 2. Helps manufacture and balance hormones 3. Forms our cell membranes 4. Forms our brain and nervous systems 5. Helps transport fat soluble vitamins A,D,E & K 6. Provides two essential fatty acids that cannot be made by the body (omega 3 & 6) Fat sources are made up of a combination of saturated, polyunsaturated and monounsaturated fatty acids. Higher saturated fatty acids tend to be solid at room temperature where as higher unsaturated fatty acids tend to be soft or liquid at room temperature. Our overall health is always determined by the balance of these consumed fatty acids. One unique group of fats known as trans-fat is a hydrogenated form of unsaturated fat, the only benefit this has is to big $$ companies as it makes their product taste better and last longer, but can pack into cell membranes of our bodies and can increase coronary heart disease and other conditions so beware of this ingredient on your food label. A good balance of healthy fats including omega 3 & 6 are the most beneficial to a healthy functioning body.
PROTEIN Proteins are made up of carbon, hydrogen and nitrogen molecules as part of their amino groups. When amino acids join together they are called peptides or peptide chains which make up the primary protein structure. Because proteins are digested into small peptides and amino acids, we evaluate protein quality based on amino acid content, and with adequate amino intake in the diet all the proteins for optimal physiological functioning can be formed later. Protein digestion begins in the acidic environment of the stomach and carries on into the small intestine where small peptides and amino acids are produced to be transported for absorption. Different aminos are absorbed in different ways such as BCAAS (branched chain amino acids) are absorbed faster than smaller amino acids, but once absorbed there are a few different ways aminos and peptides can go in our system. Some examples of protein use is for energy or to synthesis new proteins such as hormones, new digestive enzymes or the like. The liver is the primary site for amino uptake after a meal 60g of every 100g of aminos are catabolized in the liver. Dietary protein is so important as it plays so many important roles in the body such as our structure, hormones, enzymes, immune chemicals and encourages our metabolic process, not to mention provides us with 8 essential amino acids that our body cannot produce. A sedentary protein intake would range around 0.8g per kg of body weight per day, where a more active intake would be around 1.4-2.0g per kg of body weight per day, again dependent on the individual requirements of the person. Animal proteins such as meat, poultry, eggs, fish, milk and cheese rank highest on the protein measure while plant proteins rank lower, so it s important to eat a varied intake to get all the essential amino acids. Now you have a better understanding of the Macronutrients and basic process of digestion and nutrient uptake in the body you can see how important a healthy balance of quality food is important for our physiological and phsychological growth. I have outlined below the best sources of the macronutrients as well as recommended intakes for both men and women on daily basis.
PROTEIN CHART Serving Size Timing Food Sources Size of Palm (for women) Size of 2 Palms (for men) Each meal Lean Meats ground beef, chicken, turkey, venison Fish salmon, tuna, cod Eggs Dairy Cottage cheese, greek yoghurt, cheese Beans, peas, legumes, tofu, tempeh Protein Supplements Whey, casein, milk protein blend Plant Based Pea, hemp, rice or soy CARBOHYDRATE CHART Serving Size Timing Food Sources 40G raw or ½ cup cooked *note: your carbohydrate intake will be dependent on your individual needs, the above is merely a guideline Best within 3 hours after exercise Sprouted or wholegrain breads/pastas Corn Sweet potatoes/pumpkin Quinoa Amaranth Oats Long grain rice FAT CHART Serving size Timing Food sources 10-20G or 1-2 Tablespoons per meal *note: your fat intake will be dependent on your individual needs, the above is merely a guideline No specific requirement here but each meal is a good habit Saturated Fats: (animal fats) eggs, dairy, meat, butter cheese. Coconut Oil Monosaturated Fats: Macadamias, pecans, almonds, cashews, pistachios, tahini, pumpkin seeds, hazelnuts, olives, olive oil, avocado Polyunsaturated fats: Fish oil, hemp seeds, safflower oil, sunflower seeds, peanuts, canola oil, walnuts, flaxseeds, falx oil, chia seeds, brazil nuts.
FRUIT & VEGETABLES Serving size Timing Food sources VEGETABLES: 75-100G 5 serves per day (women) 6 serves per day (men) Asparagus, bean sprouts, beans, brussel sprouts, cabbage, carrot, capsicum, cauliflower, celery, cucumber, eggplant, garlic, ginger, horseradish, kale, mushroom, onion, peas, spinach, squash, tomato, zucchini FRUITS: 150G 2 serves per day Apple, apricot, banana, blueberries, cranberries, grapefruit, grapes, kiwifruit, lemon, lime, mango, nectarine, orange, peach, pear, plum, pineapple, raspberries, strawberries, watermelon.