The science of nutrition is undoubtedly a multi-faceted field, largely focusing on dietary and health concerns surrounding foods and eating habits. Together with physical activity, they are the two most important components for our health and well-being for a number of reasons. But before getting into these, there are several simple but extremely important things on fundamental nutrition everyone can and, for me, should know in order to make their life healthier and, let’s admit it…easier! So, here are some of the highly important facts you should know on nutrition:

  1. Macronutrients

They are called so as they largely exist in our everyday diet. Macronutrients are divided in 4 categories: carbohydrates, fats, proteins and alcohol.

More specifically:


There are two types of carbohydrates present in foods: simple and complex. Simple carbohydrates are the common sugars which are further divided to intrinsic and extrinsic, sugars in whole fruits (fructose) and vegetables and sugars in dairy products e.g. lactose (milk sugar). Complex carbohydrates comprise of starch and fibre which is further discussed below. Starch can be found in bread, potatoes, rice and pasta. Glucose is the main unit of carbohydrates and is present in the majority of food items.

1 gram of carbohydrate provides approximately 4 kcal which means that complex carbohydrates are an important source of energy in our diets. Half of our everyday diet should be derived from a mix of starch, fruits and vegetables (~50-55% of total daily calories). However, evidence also suggests that the type of carbohydrate consumed can be definitive for diabetes and cardiovascular disease.


Fat is the most energy-dense nutrient present in foods providing 9 kcal per 1 gram. Therefore, only small amounts are necessary with regards to other macronutrients (~30-35% of total daily calories). Fats are essential components of diet as they are:

  • building blocks of body’s cells
  • vital for thermoregulation
  • major sources of energy
  • carriers of fat-soluble vitamis and essential for their absorption.
  • sources of omega-3 polyunsaturated and omega-6 polyunsaturated fatty acids.

Important sources of fat are: oils, olives, seeds and nuts, fatty fish and meats, avocados.


Proteins are fundamental elements of body’s cells as they support cells’ structure and fuction. They are also actively involved in human metabolism and are essential for human growth, trauma (repair) and overall health. 1 gram of protein provides 4 kcal of energy and 10-15% of body’s total dietary energy. It’s the second most abundant compound in the body (after water) and it’s found: ~45% in muscles, ~15% in skin and ~15% in blood.  The average requirement for protein in healthy individuals is 0.75-0.8g/kg of ideal body weight.

Important sources of protein are: grains, legumes, eggs, dairy products, tofu, seafood, fish, chicken, red meat, mushrooms, nuts and seeds.


Ethanol in alcohol provides about 7 calories per gram when broken down in our body. For this reason, it’s an important macronutrient which should not be underestimated when it comes to calorie counting. Its regular consumption should be as limited as possible.

  1. Vitamins

Vitamins are divided according to their solubility in water (blood) and fat (adipose tissue) in water-soluble and fat-soluble vitamins, respectively. Water-soluble vitamins are B-complex vitamins and vitamin C, which reduce stress, boost mood, reduce symptoms of anxiety and depression, convert nutrients into energy, promote growth of hair and nails and prevent ageing of skin.

Vitamins A, D, E and K constitute fat-soluble vitamins and their role in human metabolism is major as they are actually fats and are necessary for the exact same reasons fat is important.

Unlike fat-soluble vitamins, water-soluble vitamins are not stored in the body and, as a result, their daily intake through diet is essential. However, specific dosage should be determined based on gender, age and special, individual needs.

  1. Minerals

Minerals and trace elements are inorganic substances which are required in small amounts. They have important and different roles in the human body and their intake is ensured via a healthy, balanced diet without excluding ANY food group or even food item from it. Minerals and trace elements are: calcium, phosphorus, magnesium, iron, sodium, potassium, zinc, iodine, fluoride, copper, selenium, manganese, chromium and more.

  1. Dietary fibre

Fibre is a term used for carbohydrates other than starch and sugars and are predominantly found in plant-based food items (fruits, veggies, wholegrain), comprising soluble and insoluble fibre. They cannot be digested in the small intenstine that’s why they reach colon which is healthier and hence has numerous benefits increasing the body’s absorption in vitamins and minerals, promoting weight loss, maintaining pH balance in the bloodstream and decreasing the risk of bowel cancer.

Fibre also:

  • promotes digestion
  • prevents constipation
  • creates sense of early satiety
  • foods rich in fibre have low glycaemic index (GI) which means it prevents increased blood sugar levels- ideal for diabetics
  1. Energy intake and physical activity

Energy expenditure is the sum of the amount of energy expended while at complete rest (basal metabolic rate), the energy required for the digestion and absorption of food (thermic effect of food= TEF) and the energy expended via daily physical activity.

The cliché ‘calories in- calories out, reflects the amount of calories we get into our bodies by consuming our foods and drinks and the calories we burn via our level of physical activity per day. So in order to maintain a normal body weight one must ‘burn’ calories equal to the calories consumed, for weight loss expenditure should exceed intake and for weight gain intake should exceed energy expenditure.

According to Department of Health, physical activity for healthy individuals should be at least 30 minutes of moderate intensity activity on five or more days a week or more than 150 minutes a week. Alternatively, high intensity physical activity should constitute at least 75 minutes over a week. Overweight and obese individuals need to be moderately active for at least 40-60 minutes a day. Same guideline applies for overall prevention of obesity as well. Children are recommended to engage in at least moderate intensity exercise for at least 60 minutes every day.


Bruins, MJ, Van Dael, P, Eggersdorfer, M. (2019). The Role of Nutrients in Reducing the Risk for Noncommunicable Diseases during Aging.. Nutrients. 2 (11), 85.

Chen, Y, Michalak, M, Agellon, LB. (2018). Importance of Nutrients and Nutrient Metabolism on Human Health. Yale Journal of Biology and Medicine. 91 (2), 95-103.

Stephen, AM, Champ, MM, Cloran, SJ, Fleith, M, van Lieshout, L, Mejborn, H, Burley, VJ. (2017). Dietary fibre in Europe: current state of knowledge on definitions, sources, recommendations, intakes and relationships to health.. Nutrition Research Reviews. 30 (2), 149-190.

Wolever, TM. (2017). Effect of macronutrients on the glycemic index. The American Journal of Clinical Nutrition. 106 (2), 704-705.

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