Macronutrients = Protein, Carbohydrates and Fats
Protein
Your body uses protein to build and repair tissue. You need it to make enzymes, hormones and other body chemicals. It’s an important building block of bones, muscles, cartilage, skin and blood.
Protein-rich foods are often rated in terms of how ‘complete’ their amino acid profile is in relation to needs for essential amino acids. As we are biologically much closer to a cow than a cauliflower, the cow’s protein content is much more like ours. Therefore, food that we get from animals and animal products (meat, fish, eggs, dairy) usually score highly on their amino acid profile and are subsequently regarded as high-quality proteins. Proteins from these food sources supply all the essential amino acids.
However, vegetables are also perfectly good sources of protein and good amino acid profiles can be obtained from appropriate combinations, such as cereals (e.g. bread, pasta, rice) combined with legumes (beans, peas, lentils.) This is the basis of many traditional diets which have evolved to provide the right balance. When neither animal foods or a traditional balance is available, traditional diets have adopted less usual foodstuffs like seaweed, as rich source of amino acids.
The best nutrition viewpoint is about achieving the right balance of nutrients from an attractive variety of foods and meals. See below for the following examples of protein sources which are easy food combinations and achieve the required essential amino acid profiles:
- Pulses – beans, peas, lentils with dairy products e.g. milk, cheese = baked beans with grated cheese, lentil dhal with natural yoghurt
- Whole grains – brown rice, noodles, couscous, whole-wheat bread with pulses – beans, peas, lentils = baked beans on toast, risotto with peas, mexican tortilla with refried beans
- Pulses – beans, peas, lentils with seeds and nuts = hummus (chick peas with sesame seed oil), mixed bean salad with flax seed oil dressing.
- Dairy – milk, cheese with whole grains – brown rice, noodles, couscous, whole-wheat bread = cheese sandwich with wholemeal bread, porridge with milk.
Protein can also assist with keeping you feeling fuller for longer.
Carbohydrates
Carbohydrate is a key nutrient that our body needs. It is an organic compound made up of carbon, hydrogen and oxygen. Carbohydrates are the main energy source for our body and are the energy that gets used first (before protein, fat and alcohol.) It is recommended by most sources – including the Guideline Daily Amounts, that about 45-60% of our energy intake should come from carbohydrates.
They have important roles in our body including:
- An energy source that gives us most of the energy that our body needs;
- Part of many proteins and fats (lipids) that our body needs for many bodily processes;
- Providing nutrients for the good bacteria in our intestines that helps us digest our food;
- Protecting our muscles because carbohydrates are the first source of energy for our body. Without it, protein from our muscles will be consumed meaning that our body will effectively eat its own muscles!
Carbohydrates should be the body’s main source of energy in a healthy balanced diet. They are broken down into glucose (sugar) before being absorbed into the bloodstream. From there, the glucose enters the body’s cells with the help of insulin. Glucose is used by your body for energy, fuelling all your activities, whether that’s going for a run or simply breathing.
Unused glucose can be converted to glycogen found in the liver and muscles. If more glucose is consumed than can be stored as glycogen, it is converted to fat for long-term storage of energy. High fibre, starchy carbohydrates release sugar into the blood more slowly than sugary foods and drinks. Most carbohydrates occur naturally in plant-based foods such as grains. Food manufacturers also add carbohydrates to processed foods in the form of starch or added sugar.
Carbohydrates can be found in –
- Sugar is the simplest form of carbohydrate and occurs naturally in foods such as fruits, vegetables, milk and milk products. Types of sugar include fruit sugar (fructose), table sugar (sucrose) and milk sugar (lactose).
- Starch is a complex carbohydrate, meaning it is made of many sugar units bonded together. Starch occurs naturally in vegetables, grains and cooked dry beans and peas.
- Fibre is also a complex carbohydrate. It occurs naturally in fruits, vegetables, whole grains, and cooked dry beans and peas.
Whilst we can most certainly survive without sugar, it would be quite difficult to eliminate carbohydrates entirely from your diet. Carbohydrates are the body’s main source of energy. In their absence, your body will use protein and fat for energy. It may also be hard to get enough fibre, which is important for a healthy digestive system and to prevent constipation. Healthy sources of carbohydrates such as starchy foods, vegetables, fruits, legumes and lower fat dairy products are also an important source of nutrients such as calcium, iron and B vitamins.
Cutting out carbohydrates from your diet could put you at increased risk of a deficiency in certain nutrients, leading to health problems, unless you’re able to make up for the nutritional shortfall with healthy substitutes. Replacing carbohydrates with fats and higher fat sources of protein could increase your intake of saturated fat, which can raise the amount of cholesterol in your blood, therefor a risk factor for heart disease.
When you are low on glucose, the body breaks down stored fat to convert it into energy. This process causes a build-up of ketones in the blood, resulting in ketosis. Ketosis as a result of a low carbohydrate diet can be linked, at least in the short term to headaches, weakness, nausea, dehydration, dizziness and irritability.
Fats
Fat doesn’t directly make you ‘fat’ however excessive calorie consumption will. It’s all about getting the right balance.
Fat has had bad press to the extent that some foods are designed and marketed as ‘fat-free.’ But it isn’t all bad. In fact, getting some fat from our diet is absolutely vital. Virtually all-natural foods contain some fat, this is due to both plants and animals using fats as the most economical way to store energy. It’s needed for their growth, development and function when there is a shortage of food supply (or a shortage of sunlight in the case of plants.)
Certain specific dietary fats have other essential functions. We are much like other animals so we do actually need some fat from our diet to survive. And while in general, as with most things, too much fat is bad, a certain amount is perfectly compatible with good health.
The main unsaturated fats are monounsaturated, found particularly in foods such as olive oil, rapeseed oil, peanuts and avocados.
Polyunsaturated fats are mostly found in plant foods such as nuts, seeds and vegetable oils and in cold-blooded sea-foods. In natural foods they come protected with antioxidant vitamins. There are two main classes of polyunsaturated fatty acids, omega-3 and omega-6. These include the essential fatty acids. Oily fish such as herring, salmon and mackerel, is a good source of omega-3, while omega-6 is mainly found in plant foods such as sunflower oil and rapeseed oil.
Trans fats can be natural or artificial. They are mostly artificially created through a process known as hydrogenation – which involves heating and chemical structure change. Artificial trans fats are mostly found in fast foods, fried foods and commercial baked products such as cookies and are the most unhealthy fats (even worse than saturated fats!) Natural trans fats can be found in small amounts in milk and beef and in large quantities in cheese.
We need fat in our diets for –
- A source of energy – Our body uses the fat we eat and fats we make from other nutrients in our bodies, to provide the energy for most of our life-functions
- Energy store – The extra calories that we consume, but do not need to use immediately, are stored for future use in special fat cells (adipose tissue)
- Essential fatty acids – Dietary fats that are essential for growth development and cell functions, but cannot be made by our body’s processes
- Proper functioning of nerves and brain – Fats are part of myelin, a fatty material which wraps around our nerve cells so that they can send electrical messages. Our brains contain large amounts of essential fats
- Maintaining healthy skin and other tissues – All our body cells need to contain some fats as essential parts of cell membranes, controlling what goes in and out of our cells
- Transporting fat-soluble vitamins A, D, E and K – via the bloodstream, distributing to where they are needed
- Forming steroid hormones – crucial to regulate many bodily process
Fibre
I want to touch on fibre as many of us don’t get enough of it. Fibre is an important part of a healthy balanced diet and it can help prevent heart disease, diabetes, weight gain and some research which suggests some cancers. It also plays a large part in improving digestive health.
Fibre is only found in foods that come from plants. Foods such as meat, fish and dairy products don’t contain any fibre.
There are two different types of fibre – soluble and insoluble. Each type of fibre helps your body in different ways, so a normal healthy diet should include both types. Eating wholegrain cereals and plenty of fruit and vegetables helps to ensure both adults and children are eating enough fibre.
However, if you have a digestive disorder such as irritable bowel syndrome (IBS), you may need to modify the type and amount of fibre in your diet in accordance with your symptoms. Your GP or a dietician can advise you further about this.
Soluble fibre
Soluble fibre dissolves in the water in your digestive system. It may help to reduce the amount of cholesterol in your blood. If you have constipation, gradually increasing sources of soluble fibre, such as fruit and vegetables which help relived symptoms. Alongside consuming oats and golden linseeds which help soften your stools and make them easier to pass.
Foods that contain soluble fibre include:
- oats, barley and rye
- fruit, such as bananas and apples
- root vegetables, such as carrots and potatoes
- golden linseeds
Insoluble fibre
Insoluble fibre doesn’t dissolve in water. It passes through your gut without being broken down and helps other foods move through your digestive system more easily. Insoluble fibre keeps your bowels healthy and helps prevent digestive problems. If you have diarrhoea, you should limit the amount of insoluble fibre in your diet.
Good sources of insoluble fibre include:
- wholemeal bread
- bran
- cereals
- nuts and seeds (except golden linseeds)
Eating foods high in fibre will help you feel fuller for longer. This may help if you are trying to lose weight. See the weight loss guide for more.
If you need to increase your fibre intake, it’s important that you do so gradually. A sudden increase may make you produce more wind (flatulence), leave you feeling bloated and can cause stomach cramps.
Sugar
The instant ‘lift’ we get from sugar is one of the reasons we turn to it at times of celebration or when we crave comfort or reward. However, even those of us without a sweet tooth may be eating more than we realise because so many everyday processed foods, from cereals and bread to pasta sauce and soups, contain sugar.
But it’s not all bad news – sugar is a carbohydrate found naturally in a host of different foods from lactose in milk to the fructose in fruit and honey. In fact, if you’re very active and exercise regularly some sugar in your diet helps supply ready energy to fuel your muscles and keep your brain active.
The problem for the majority of us is that many of the processed foods we eat have added sugar which supplies energy in the form of calories and very little else, so we end up consuming more than we need. This means our body has to draw on the nutrients from the rest of our diet to process the sugar and this can affect our health, including our immunity – leaving us more susceptible to bugs and colds.
A high intake of sugar causes our blood sugar levels to shoot up, giving us that feel-good ‘high’ followed by a crashing slump which leaves us tired, irritable and craving more sugary foods. It’s a vicious cycle that may be contributing to our weight problems as well as health conditions like diabetes and heart disease.
Low-fat and ‘diet’ foods often contain extra sugar to help improve their taste and palatability and to add bulk and texture in the place of fat. Even savoury foods, like ready-made soups and sauces may contain added sugar. A can of soft drink, on average, contains the equivalent of seven teaspoons of sugar. The natural sugar in some fruit, including apples, has increased as new varieties (including Pink Lady, Fuji and Jazz) are bred to satisfy our desire for greater sweetness.
Micronutrients
Micronutrients are different from macronutrients (like carbohydrates, protein and fat) because they are necessary only in very tiny amounts. Nevertheless, micronutrients are essential for good health and micronutrient deficiencies can cause serious health problems. Micronutrients include such dietary minerals as zinc and iodine and are necessary for the healthy functioning of all your body’s systems, from bone growth to brain function.
Micronutrients are what are commonly referred to as ‘vitamins and minerals.’ Micronutrients include such minerals as fluoride, selenium, sodium, iodine, copper and zinc. They also include vitamins such as vitamin C, A, D, E and K, as well as the B-complex vitamins.
As mentioned, micronutrients are different from the macronutrients protein, carbohydrate and fat. Micronutrients are called ‘micro’ – nutrients because your body needs only very small quantities of them for survival. However, if your body doesn’t get the small quantities of micronutrients that it needs, serious health problems can result.
Micronutrients play a vital role. Sodium, for instance, is responsible for maintaining the proper fluid balance in your body; it helps fluids pass through cell walls and helps regulate appropriate pH levels in your blood. Here are some of the ways that other micronutrients help maintain your body’s systems:
Manganese promotes bone formation and energy production and helps your body metabolise the macronutrients, protein, carbohydrate and fat.
Magnesium helps your heart maintain its normal rhythm. It helps your body convert glucose (blood sugar) into energy. It is also necessary for the metabolisation of the micronutrients calcium and vitamin C.
Iron helps your body produce red blood cells and lymphocytes.
Iodine helps your thyroid gland develop and function. It helps your body to metabolise fats and promotes energy production and growth.
Chloride helps regulate water and electrolytes within your cells, as well as helping to maintain appropriate cellular pH.