Macronutrients are nutrients that provide calories or energy and are required in large amount by our body to maintain body functions and carry out the activities of daily life. They are the main nutrients that make up the foods we eat.
There are three broad classes of macronutrients: Carbohydrates, Essential fatty acids and Proteins. Let us know about these macronutrients in some details.
Carbohydrates are the macronutrients which constitute the major source of energy in our diet.
The simplest form of carbohydrates is monosaccharides which include glucose, fructose and galactose.
Disaccharides include sucrose, maltose and lactose.
Together, the monosaccharides and disaccharides are referred to as simple sugars or simple carbohydrates because they are easily broken down and absorbed in our body.
Polysaccharides are complex carbohydrates which include starch, glycogen and cellulose or dietary fiber.
Even more complex form of carbohydrates is oligosaccharides which includes Raffinose and Stachyose. Hence, our body do not easily absorb these.
The primary function of carbohydrates is to provide energy to our body. Our red blood cells and most parts of our brain derive all their energy from carbohydrates.
An adequate consumption of carbohydrates also allows our body to use protein and fat for their necessary requirements, it prevents ketosis, it provides fiber and it is the source of sweetness in our food.
Impact on physical health
The major health implication of a deficiency of carbohydrate intake is the production of ketones. Consumption of less than 50 to 100 grams of carbohydrate per day can lead to ketones.
Carbohydrate consumption in excess, specifically excess intake of simple carbohydrates, which can lead to obesity and increased insulin production.
Consumption of high fructose soft drinks can lead to increased body weight and obesity.
Excess consumption of foods with simple carbohydrates can lead to increased levels of blood glucose and serum insulin.
Diets with high glycemic index (GI) foods (i.e. foods that raise blood glucose to high levels quickly) such as simple sugars causes the increased risk of diabetes and heart diseases.
Diets high in complex carbohydrates (low GI) and fiber cause lower body weight and low cholesterol levels.
Higher intake of complex carbohydrates leads to improved gastric emptying, hormonal response, weight loss and reduce the risk for type 2 diabetes.
Sources and Recommended Intake of Carbohydrates
Carbohydrates content are high in foods such as grains, starchy foods like potatoes, cereals, rice etc.
Recommended consumption of a minimum of 50 to 100 grams of carbohydrates per day because it helps to prevent ketosis.
Fiber intake should make up approximately 45% of total energy intake. So, recommended amount is 20 to 35 grams per day for adult and 5 grams per day for children.
It is important to emphasize the need to include complex carbohydrates and limit simple sugars. Also, It is necessary to limit the consumption of processed and refined foods.
Natural and unprocessed foods contain the fiber necessary for maintaining cardiovascular and gastrointestinal health as well as other health promoting nutrients.
Processing removes fiber as well as vitamins and minerals. This usually results in the addition of additional sugar high fructose corn syrup and fat to the food to make it more pleasant.
Essential Fatty Acids
Essential fatty acids are the polyunsaturated fats omega-3 (alpha-linolenic acid) and omega-6 (linolenic acid) fatty acids.
These are the macronutrients essential for optimal health but we need to consume these from the food we eat because our body cannot produce them.
These fatty acids are precursors (a substance from which another is formed, especially by metabolic reaction) to longer and highly unsaturated fatty acids which are essential in cell membrane formation.
Impact on physical health
There is a rare deficiency of essential fatty acids. Moreover, Omega-6 fatty acids are plentiful in food sources, particular in vegetable oils.
However, omega-3 fatty acids are less plentiful in our food supply and relative deficiencies or imbalances between the two fatty acids may be more common and problematic.
Consumption of omega-3 fatty acids has been linked to reduce blood pressure, improve morning stiffness and joint tenderness in rheumatoid arthritis, lower incidence of dementia, lower the risk of stroke and possibly have an impact on depression.
Moreover, Fish derived omega-3 fatty acids are effective in prevention of coronary heart disease.
However, you should note that high intake of omega-3 fatty acids may increase the risk of prostate cancer.
Sources and Recommended Intake for Essential Fatty Acids
Omega-6 fatty acids are available in large amounts from foods such as grains, plant based oils, poultry, eggs.
Omega-3 fatty acids are primarily present in fatty fish (tuna, salmon, mackerel, and sardines), flax seed, hemp seed, walnuts, soybeans, canola oil.
The recommended intake of total fat is between 20% and 35% of total caloric intake with polyunsaturated fats comprising approximately 10% of total calories coming from foods such as fish, nuts, and vegetable oils.
Optimal balance of omega-3 and omega-6 fatty acids is 1:1
Protein is one of the macronutrients that is essential in the body to build muscle mass.
When protein is broken down in the body it helps to fuel muscle mass which help metabolism. They provide the necessary constituents for cell formation. Thus protein is also called as building block of the body.
The basic structure of protein is a chain of amino acids. A total of 20 different amino acids exist in proteins and hundreds to thousands of these amino acids are attached to each other in long chains to form a protein.
Of the 20 amino acids needed by the body, 9 are considered essential. The essential amino acids are histidine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Our body cannot produce Essential amino acids and hence must come from our diet. Two amino acids, cysteine and tyrosine, are considered as semi-essential because they can be synthesized by the body from methionine and phenylalanine respectively.
Proteins are the macronutrients essential for cell and tissue growth. It regulates and maintains body functions blood clotting, fluid balance, enzyme and hormone production. It also builds antibodies necessary for our immune system.
Impact on physical health
Protein deficient diets are also energy deficient diets and results in increased infections.
Severe deficit of protein-energy may result in marasmus and kwashiorkor.
When a diet is energy deficient, protein is catabolized for energy, which reduces the availability of protein for other functions. Deficiencies in protein will result in impaired functioning and seriously compromised immune and regulatory systems.
Sources and Recommended Intakes of Protein
A complete protein is that source of protein which contains all of the essential amino acids. Animal proteins from foods such as meat, poultry, seafood, eggs are complete protein for their higher proportions of essential amino acids.
However, most plant based proteins or vegetarian sources of protein will contain all 20 amino acids but tend to have limited amount of certain essential amino acids.
The incomplete proteins (vegetables, grains and nuts) can become complete when they combine with protein from sources with complementary limiting amino acids such as beans, rice, cereal and milk.
For example, consuming rice (limited in lysine and thiamine but high in methionine) combined with beans (limited in methionine but high in lysine and thiamine) will help meet essential amino acid requirements and thus complete protein.
Our body does not store amino acids the way it stores carbohydrates and fats. Thus it becomes essential to consume protein from our diet each day.
In individuals of healthy body weight, 0.8 grams of protein is needed for each kilogram of weight.
Proteins comprise approximately 16% of body weight and supply 4 kcal/g of energy. Adults require approximately 15% of their total protein to be essential amino acids and typically consume 50% of their protein as essential amino acids.
Children require 35% of their dietary protein to be in the form of essential amino acids.
All the three macronutrients are essential and our body needs them in large quantities. They are the energy providing nutrients and are essential for cellular growth, immune function, repair and develop new tissues and overall body growth. So, you should consume macronutrients in varying amount and a diet that includes a balance of the three macronutrients: complex carbohydrates, lean proteins and healthy fats.
Frequently Asked Questions
Excess energy in our body is stored as fat. So, ironically fat is the macronutrient that gives the most energy among three.
Carbohydrates and protein each contain 4 calories per gram, while fat contains 9 calories per gram.
As per recommendations, adults should aim to obtain approximately 45 to 65 percent of their daily calories from carbohydrates, 10 to 35 percent from protein, and 20 to 35 percent from fat.