The Importance of Protein
Dr. Alison Adams
Proteins are much more complex molecules than either fats or carbohydrates. They consist of chains of amino acids folded into 3 dimensional structures that are integral to their function. The amino acids are like letters in an alphabet that are used to create different words (proteins).All amino acids contain a nitrogen-containing amine group (NH2), a carboxylic acid group (COOH) and a side-chain that varies between different amino acids.
Protein makes up most of the body weight after water. Dietary proteins are broken down by the various processes in the digestive system into their component amino acids which are absorbed in the small intestine. From here the nutrients are routed directly to the liver in the portal vein where the liver then apportions them to tasks such as repair and detoxification.
There are 20 amino acids employed in the body of which 8 are considered essential because they have to be consumed in the diet and cannot be synthesised by the body. This is because humans are missing certain enzymes possessed by other organisms that are able to synthesise these essential amino acids.
The amino acids absorbed are then sequenced by the body in the cells according to the genetic coding in the nucleus. Segments of DNA ‘unzip’ and are copied and then this messenger RNA (mRNA) is transported out of the nucleus to cell organelles called ribosomes where the genetic code is read and used to slot available amino acids in sequence to make proteins. The proteins either then spontaneously fold as a result of their inherent properties or are folded by other molecules.
Proteins can be folded into globular or fibrous forms. The globular proteins are soluble and many are enzymes, whereas fibrous proteins are often structural, such as collagen, the major component of connective tissue, or keratin, the protein component of hair and nails.Membrane proteins often serve as receptors or provide channels for molecules to pass through the cell membrane.
Proteins are not entirely rigid molecules and can shift between several related structures while they perform their functions. These changes are initiated by binding to the active site of an enzyme. All enzymes are highly specific for substrate molecules with which they are geometrically and electrically compatible. In some diseases such as Alzheimer’s disease proteins fail to fold correctly producing characteristic amyloid plaques.
Sources of protein
Although these terms have fallen from favour somewhat, first class proteins are classified as foods that offer a complete mix of the 20 amino acids humans require. First class proteins include animal products such as meat, fish, eggs and dairy produce.
Second class proteins contain only some of the amino acids required, but combining these protein sources can often result in a full range of amino acids. Combining wheat with beans (eg: baked beans on toast) or rice and kidney beans (eg: vegetarian chilli) produces the full complement of amino acids required by humans.
Proteins can be obtained from most foods to some greater or lesser extent. Fruits such as apples, bananas, grapes, pears and pineapples contain up to 5% protein; whilst grapefruit, various types of melon, oranges, papayas, peaches, strawberries and tangerines contain slightly more at between 5 and 10%.
Tomato, technically a fruit, contains more protein than other fruits at19% protein and most vegetables contain between 17 and 30% protein, although mushrooms, spinach and watercress all score more highly.
Nuts and seeds contain 9 to 18% protein, most grains contain somewhere between 14 and 19% protein and beans are a rich vegetable source with most beans offering between 20 and 40% protein with kidney and soy beans the most protein-dense at 58% of dry weight.
Meal replacement powders, liver cleansing formulas, whey and other protein powders will also contain a blend of amino acids required for detoxification and tissue maintenance.
Whilst consuming protein is essential and certainly critically important when trying to detoxify and rebuild tissue, excess protein intake can result in acidity which can promote inflammation. Most grains are acid forming, as are most dairy products, red meat, shell fish, salmon and turkey.
However, this can be countered with plenty of fruit and vegetables which are alkalising (with the exception of cranberries) and consumption of white fish,chicken, cottage cheese, whey protein, yoghurt, almonds, tofu, most nuts and seeds (except cashews, Brazil nuts, peanuts, pecans, tahini and walnuts) which are all either alkalising or minimally acid-forming.
Proteins and liver detoxification
Proteins are also required for detoxification of toxins and hormones in the liver. The liver processes all molecules through a two-phase system in which the substances are first made water soluble in a process known as Phase I detoxification or hydrolysis.This phase can result in some substances temporarily being rendered more toxic. Some of the products of Phase I detoxification are then excreted in the urine, but most arefurther processed through a second phase – Phase II or conjugation.
In this phase the liver combines the products of Phase I detoxification with a variety of polypeptides or amino acids and the resulting substances are then passed in the bile to be excreted in the faeces. Amino acids required for Phase II detoxification include the components of glutathione which are glycine, cysteine and glutamic acid, along with methionine, taurine, glutamine and aspartic acid.If the body lacks any of the amino acids or polypeptides required then Phase II detoxification will necessarily be limited and the toxic by-products of Phase I will be stored throughout the body producing the symptoms of fatigue, aching and poor function familiar to FRS sufferers.
Functions of proteins
Proteins have many diverse and important functions in the human body including:
Messengers Some hormones such as insulin are proteins as are some neurotransmitters and these can transmit a signal from the cell in which they were synthesised to dock on to receptors in other cells and produce some sort of effect.
Cell receptors are found on the cell membrane and act tobind a signalling molecule and induce a biochemical response in the cell.
Transmembrane proteinsCell membranes are studded with proteins which act as channels through the cell membrane allowing the passage of specific substances.
Antibodies or immunoglobulinsareprotein components of the adaptive immune system which bind foreign proteins targeting them for destruction. They can be free or anchored to the cell membranes of plasma cells.
Transport proteinsbind specific small molecules and transport them to other locations in the body. An example of which would be haemoglobin which is able to uptake oxygen in areas of high concentration (the lungs) and to release it in areas of low concentration (the tissues).
Structural proteinsThese give shape and rigidity to tissues and are often fibrous proteins. Examples include actin and myosin in muscles, tubulin in nervous tissue, collagen and elastin in connective tissues, and keratin which is found in hair and nails. Protein is also an important component of cell organelles such as mitochondria.
Enzymes There are many dozens of digestive and metabolic enzymes responsible for governing every aspect of structure and function throughout the body. If there are insufficient amino acids to create all the enzymes required, then this necessarily has a deleterious effect on all bodily processes.
Plasma proteins such as albumin, factor VIII and thrombin which all serve different and important functions in the blood.
An energy source Proteins can be used to create the glucose required to fuel all bodily processes. However, the nitrogen residues must be removed and this leaves ammonia which is converted to urea in the liver and then removed by the kidneys in the urine.
Symptoms of protein deficiency include:
- Oedema ie: water retention under the skin, most commonly affecting the legs, feet, and ankles.
- Weight loss
- Thinning of hair, development of brittle hair, or hair loss
- Ridging of finger- and/or toe-nails
- Reduced pigmentation of the hair and skin which becomes pale and burns easily
- Skin rashes, dry or flaky skin
- Weakness and lethargy
- Muscle soreness, weakness and/or cramps
- Slow wound healing and spontaneous bruising
- The development of ulcers
- Difficulty sleeping
- Nausea and/or stomach pain
- The development of gallstones
- Heart problems
- Organ failure and ultimately, death.
So a sufficient intake of high quality protein is important to rebuild and detoxify the body during The Natural Recovery Plan. However, excessive intake of protein can be counterproductive too resulting in worsening of immune conditions such as allergies and autoimmune diseases.