How The Body Digests Nutrients

This article is to help people to attain a deeper understanding of how their body digests the specific nutrients they intake on a daily basis and where those nutrients can be sourced. Although this information is widely available, it is rare to find it on health and fitness websites as most just work on the assumption that the general public know what the nutrients are. In many cases that is probably true, but knowledge is power and understanding what you are putting into your body is the best way to encourage yourself to manage it correctly.

How The Body Digests Nutrients – Carbohydrates

Carbohydrates are an essential part of any balanced diet. It is the form of nutrient most easily broken down by the human body; it’s the body’s preferred energy source. A balanced diet includes a variety of different carbohydrates that are classified by their chemical structure and properties. The three types of Carbohydrates are:

– Monosaccharide and Disaccharide which are both simple sugars (Glucose and Sucrose)
– Polysaccharide which are complex carbohydrates (Bread, Pasta and Rice)

Mono and Di are both quickly absorbed into the bloodstream. Poly are slowly absorbed into the bloodstream resulting in a slower energy release.

The digestion of carbohydrates occurs when the salivary enzyme ‘amylase’ begins breaking the larger carbohydrate molecules into smaller, easier to handle molecules. A minor amount of break down happens in the stomach due to a lack of specific enzymes. However, digestion increases speed once again in the small intestine where carbohydrate specific enzymes break down the molecules to an absorbable size. The liver is the final stopping point at which the last of the molecules are broken down and absorbed.

How The Body Digests Nutrients – Fats

Fat is an essential nutrient in a balanced diet that is required for a huge number of important bodily functions. The key with fats is ensuring you are consuming the correct types of fats for your health and bodily function without over consumption of incorrect fats resulting in a greater risk of chronic diseases such as coronary heart disease and diabetes. The three types of fats are:

– Saturated (meat fat, egg yolk, dairy, palm oil, coconut oil)
– Monounsaturated (almond oil, olive oil, rapeseed oil, avocados, seeds)
– Polyunsaturated (vegetable oils, fish oils, sardines, mackerel)

Fat represents the body’s largest store of potential energy. It insulates the body and is essential in Protein absorption. The digestion of fat occurs in the stomach, predominantly though, the breakdown occurs in the small intestines. Bile, produced by the liver, is released by the Gall bladder into the small intestine. Enzymes are then released from the small intestine and the pancreas which finalise the digestion of the fats. The fatty acids left over are then packaged into lipoproteins so they can be transported into the bloods.

How The Body Digest Nutrients – Protein

Protein is the predominant building block for many of the tissues within your body. It has functional and structural roles within the human body and can be used as a powerful food source. Proteins can be found in two forms:

– Complete Animal Proteins (eggs, milk, meat, poultry, fish, soya)
– Incomplete Plant Proteins (legumes, seeds, nuts, whole grains)

There are risks to excessive protein consumptions such as kidney failure, dehydration, increases in body fat as excess protein is converted into fats.

The digestion of protein begins with breakdown in the stomach whereby gastric acid unravels and untangles the Protein molecules enabling breakdown to finish in the small intestine by specific enzymes such as pepsin and rennin.

None of the three macro nutrients are absorbed directly across the mucosal membrane of the stomach. IN fact, almost all of the nutrient absorption occurs in the small intestine. Only water, alcohol and other substances such as aspirin are rapidly absorbed through the stomach lining.

There are six vital nutrient classes essential for human survival. They are:

– Carbohydrates
– Fats
– Proteins
– Vitamins
– Minerals
– Water

Achieving a balanced intake of each of these will increase your chances of good health, improved bodily functions and better performance.

How The Body Digests Nutrients – Recommendations For Nutrient Intake:

Protein – 0.75g/kg of bodyweight (1.2-1.5g/kg for strength and endurance athletes)
Fat – 95g for men, 70g for women
Carbohydrates – 1g provides 4kcal of energy. 50-60% of total energy intake should come from carbohydrates.

The key to nutrition is to ensure you are eating a good balance of nutrients, avoiding processed, sweetened and pre-cooked food as often as possible and focusing predominantly on foods in their most natural, organic and fresh state. Remember you are what you eat, your food is your fuel.

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