Macro and Micro-nutrients: Why are they important?

Food typically provokes a broad and often polarising range of views in broader society. Many of these are often contradictory and leave us in a mental (and sometimes physical) war between what foods are ‘good’ or ‘bad’, and what foods we actually want to eat. From a nutrition perspective, our bodies need variety. This not only helps to keep food interesting, but it also assists with the overall bioavailability of nutrients in our bodies. Bioavailability refers to the absorption and usage of nutrients in your body. These nutrients can be categorised into two primary groups: macronutrients and micronutrients.

Macronutrients – or ‘Macros’ – are the larger nutrients that, when combined, equal the amount of energy you consume each day. These can be protein, carbohydrates, fats and, in moderation, alcohol. Micronutrients, on the other hand, are all of our vitamins and minerals which are also found in the foods we eat on a daily basis in varying quantities. All of these macro- and micro-nutrients have multiple individualised roles in our body that are constantly interacting with each other in different ways to allow us to live and function efficiently. Many people, even those well-educated with regards to nutrition, struggle with the scientific recommended daily intake (RDI) for nutrients, especially when having to consider other factors such as time, accessibility, and taste and texture preferences. So, let’s break down what the RDI’s actually mean and how you can start to put these together to hit the balance of enjoying nutritious food without breaking into a cold sweat and questioning whether you’re hitting your all-important ‘macros’.

When considering which macronutrient split might be optimal for health or body composition, we need to consider our baseline requirements. Current recommendations regarding health are 0.8-1.0 grams of protein per kilogram of body weight (AGHE) each day, in addition to other recommendations from literature reviews that suggest 2-3 grams per kilogram of body weight for carbohydrates and a minimum of 30-40 grams of total fats. These measurements are based on minimum requirements to sustain basic bodily functions. Generally, we are all consuming amounts above and beyond this to supply our body with enough physical food for life-sustaining daily activities, such as breathing and organ functions (quantified as Basal Metabolic Rate), and elements of consciousness including muscle movements (quantified as Resting Metabolic Rate). Further to this, we are often consuming surplus to requirements based on how much we are moving around, whether that be incidental within our daily schedule or with planned exercise.

Protein

Protein is required to match your body’s natural turnover of enzymes and hormones, as well as providing the resources for regeneration of organ and muscle tissues. Generally, most of us in Australia are well and truly above the minimum protein amount we need, so much so that many are approaching too much protein! People that are often low on protein, however, are those of us who follow a strict plant-based diet without purposefully replacing animal-based products with high-protein plant-based alternatives, as well as those following limited energy or other restrictive diets.

When looking at protein intake more closely, protein quality is of utmost importance. This is because there are nine essential amino acids (EAAs) that the human body cannot make itself, which means that we are reliant on foods to provide these each day. Animal-based foods do a great job of providing each of these EAAs. However, when looking at protein rich plant-based foods, tofu, amaranth and quinoa are the only sources that contain all EAAs, which means that protein pairing of other protein-rich plant-based foods are needed. For example, lentils paired with chia seeds or hemp seeds, and legumes with rice or wheat.

Carbohydrates

Carbohydrates are important to supply the body with the primary fuel source for your brain, red blood cells and, when exercising at or above 65% of VO2max, your muscles. Carbohydrate-rich foods often get slammed by many diets for promoting fat storage and chronic illness such as diabetes, however, this is generally only the case when ‘simple’ carbohydrates are consumed consistently in large quantities. In reality, when carbohydrates, particularly complex carbohydrates, are consumed in moderation (45-65% of daily energy intake). This promotes good gut health through fibre, which promotes ideal body composition for health, increases serotonin and decreases inflammation. Fibre requirements for males are 25-30g and for females are 20-25g each day. These positive health benefits occur when opting for more whole grains such as brown rice, quinoa, bran, legumes, rolled oats and vegetables and fruits with the skin left on, rather than white varieties of grains, soft drinks, pre-made juices and lollies.

Fats

Fat is another macronutrient that has been demonised from time to time, being blamed for increasing risk of heart disease and many chronic illnesses. This definitely can be the case if our diets consist of a large amount of saturated fats, found commonly in animal-based products, coconut oil, and fried products, while also in the presence of ‘simple carbohydrates’. Conversely, if our diets consist of a healthy balance of fats that contribute 20-35% of our daily energy intake and are largely coming from plant-based fats such as nuts and seeds, olives, avocado and the like, hormonal control, cellular health and even a decrease in inflammation ensues.

Similar to protein, we also have ‘essential’ fats that the human body cannot make. These are the omega-3 and omega-6 fats. Both of these fats can have anti-inflammatory effects in your body. However, too many omega-6 fats can contribute to inflammation. In western societies, we are generally consuming too many omega-6 and omega-3 fats. Omega-6 fats are found in eggs, meats, seafood, sunflower oil and even some vegetables such as corn. Omega-3 fats are found more selectively in oily fish, walnuts, chia seeds, flaxseeds and walnuts. Overall, if we have largely plant-based fats and limit animal-based fats by choosing lean meat sources, while also more consciously eating a mixture of omega-3 rich foods, health in the short and long-term is supported.

Micronutrients: Vitamins and Minerals

Vitamins and minerals play essential roles in all functions of the human body, from cellular oxygen delivery to allowing your body to use energy easily. Vitamins are broadly categorised into two groups based on whether they are ‘fat soluble’ or ‘water soluble’. Fat soluble vitamins include vitamins A, D, E and K. Each of these vitamins play key roles in your body including vision and organ function, bone health, skin integrity and blood clotting. These vitamins are absorbed alongside fats and are stored in our fat stores in our body. If we’re meeting daily fat requirements and are exposing our skin to 15mins of sun each day for vitamin D, we are meeting most of our daily vitamin requirements. People groups that are at risk therefore are those of us who follow a very low fat, low energy diet or have a fat malabsorption disorder. Please note that toxicity can occur with these vitamins so gain advice from your doctor or an APD prior to any supplementation.

Water soluble vitamins include vitamin C, thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate (B9) and cobalamin (B12). Overall, these vitamins have limited abilities to be stored by your body. As a result, we are more reliant on daily intake to meet our requirements. Foods that are rich in these nutrients include a variety of vegetables, fruits, legumes, grains, as well as dairy, eggs and meats for B12 more specifically. These vitamins play key roles in how the human body uses energy sources (macronutrients), copes with inflammation, produces of red blood cells and DNA, and the health of skin and nerves.

Minerals are found in different foods and are required by the human body in varying amounts. Generally speaking, minerals are better stored in comparison to water soluble vitamins, however we still do have recommended daily intake measures for each nutrient based on current research. Often, multiple minerals are found in the same food sources such as dairy, meats, seafood and sea vegetables, eggs, grains, nuts and seeds.

Major minerals that we require include calcium, phosphorus, magnesium, sodium, potassium, chloride and sulphur. Each of these nutrients play key roles in a variety of areas in the human body such as bone health, nerve transmission, electrolyte balance, blood pressure and decreasing chronic inflammation. These minerals are considered major minerals because the human body requires a larger amount each day to optimise body functions in comparison to trace minerals.

Trace minerals include iron, manganese, copper, iodine, zinc, cobalt, fluoride and selenium. Despite requiring a smaller amount each day, these nutrients still play essential roles in our body such as oxygen delivery to cells, energy metabolism, thyroid hormone production and use as well as the health of nerves, blood vessels, bones and immune system.

Overall what we can take away from this is that regardless of what ‘diet’ we choose to follow, the best evidence for a long healthy life shows that having variety in the foods we eat helps to provide the human body with a larger variety of nutrients, which better supports basic function and performance. If you, or anyone that you know, could benefit from more targeted diet education, please don’t hesitate to get in touch with one of us at Inspire – we’d love to help!

NHMRC 2013, Eat for Health Australian Dietary Guidelines, Commonwealth of Australia, Canberra

Satija, A, Bhupathiraju, SN, Spiegelman, D, Chiuve, SE, Manson, JAE, Willett, W, Rexrode, KM, Rimm EB & Hu FB 2017, ‘Healthful and Unhealthful Plant-Based Diets and the Risk of Coronary Heart Disease in U.S. Adults’, J Am Coll Cardiol, vol 70, no. 4, pp. 411–422.