13. PROTEINS Flashcards
This module covers: • Thestructure,functions, dietary sources and factors affecting the bioavailability of protein and amino acids. • The primary role of amino acids in metabolic and physiological processes.
1
Q
How many different proteins are synthesised by each human cell?
A
It is estimated that a typical human cell is required to synthesise approx. 10,000 different proteins.
2
Q
What is a potential pitfall of high protein diets, despite being prized for weight loss, increasing satiety and muscle mass gains?
A
High ANIMAL PROTEIN diets create acidity in the body, increase the risk of various diseases and are associated with a shortened life expectancy.
3
Q
What percentage of body weight does protein account for?
A
About 17%
4
Q
Proteins are organic compounds, containing which four elements?
A
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
4
Q
Which one of the four elements contained in proteins distinguish it from carbohydrates and fats?
A
Nitrogen
5
Q
What are the basic building blocks of proteins and what does each one contain?
A
Amino acids, each one containing:
* An amino group – NH2
* A carboxylic acid group – COOH
* A unique side group (R-group) which differentiates amino acids from each other.
5
Q
There are approximately 1000 amino acids in nature. How many of these are in the human body and required to make up all the different proteins?
A
20
5
Q
What is another word for ‘polypeptide’?
A
Protein
5
Q
Why is the 3D ‘primary structure’ that a protein folds into so important?
A
This 3D structure is closely linked to the function of the protein so that it functions like a lock and key.
6
Q
There are approximately 1000 amino acids in nature. How many of these are in the human body and required to make up all the different proteins?
A
20
6
Q
TRUE OR FALSE:
All amino acids are used as protein building blocks
A
FALSE.
There are hundreds of ‘non-protein’ or ‘non-proteinogenic amino acids’ that aren’t encoded for in the genetic code, but may have other uses.
6
Q
Which amino acids are required for the synthesis of glutathione?
A
cysteine, glutamic acid and glycine
7
Q
How many amino acids are classed as ‘essential’ and what does this mean?
A
There are 9 amino acids that are termed ‘essential’ since humans cannot synthesise them either at all or in sufficient quantities, so they must be supplied in the diet.
8
Q
Explain what a complete protein is and provide THREE examples of foods that fit this category.
A
Food that contains all nine essential amino acids are termed ‘complete proteins’.
- Vegan foods that are complete proteins includes quinoa,
buckwheat, pumpkin seeds, chia seeds, hemp seeds, tempeh.
- Animal foods: meat, poultry, fish, eggs and dairy (except butter).
9
Q
Name all the essential amino acids
A
- Phenylalanine
- Valine
- Threonine
- Tryptophan
- Isoleucine
- Methionine
- Histidine
- Leucine
- Lysine
Mnemonic: PVT TIM HiLL
10
Q
What does “conditionally essential” mean in terms of protein, and why is histidine sometimes considered as falling into this category?
A
‘Conditionally essential’ amino acids can be synthesised in the body, but become essential under certain circumstances such as acute disease / burns.
Histidine is not synthesised in adults, but can be produced by intestinal bacteria, although unclear if enough. The absence of histidine also does not impair protein synthesis, making it seemingly non-essential.
11
Q
What causes proteins to be ‘denatured’ and how does this affect their function?
A
- Exposure to heat, variations of pH, alcohol and heavy metals such as aluminium.
- When proteins are denatured, they lose their 3D structure and hence their function. The structure effectively unravels.
12
Q
TRUE OR FALSE:
Denaturation and proteolysis change the primary structure of amino acids.
A
FALSE.
Denaturing does not change the primary structure (the amino acid sequence) – proteolysis does that, but denaturation facilitates the process of proteolysis by making proteins more accessible to be worked on by proteolytic enzymes such as pepsin.
13
Q
At which pH is pepsin optimally active?
A
2
14
Q
RECAP:
Name 5 of the many functions proteins have in the body.
A
- Structure of body tissues, e.g. Collagen.
- Movement e.g. Actin and myosin fibres (in muscles).
- Carrier molecules, e.g. Haemoglobin.
- Storage molecule, e.g. Ferritin (iron).
- Fluid balance in the blood, e.g. Albumin.
- Enzymes (for reactions in the body).
- Hormones (e.g. Insulin) and cell membranes.
- Immune function, e.g. Antibodies.
- Clotting mechanisms, e.g. clotting factors.
- Alternative energy source.
Name any 5 of the above
15
Q
Which protein provides building material for ligaments, tendons, blood vessel walls and dermis?
A
Collagen
16
Q
Which amino acids are components of:
a) Thyroid hormones
b) Epinephrine, norepinephrine, dopamine
c) Serotonin, melatonin
A
a) Tyrosine (+ iodine)
b) Tyrosine
c) Tryptophan
17
Q
Which proteins, found in blood and bodily fluids are used by the immune system to identify and neutralise foreign materials such as bacteria and viruses?
A
Immunoglobulins
IgG: abundant throughout the body
IgA: body secretions
IgE: allergies
IgM: first response
18
Q
Which proteins bind to the following to provide transport:
a) Calcium, zinc and vitamin B6
b) Iron
c) Copper
d) Oxygen
A
a) Albumin
b) Transferrin
c) Ceruloplasmin
d) Haemoglobin
19
Name two amino acids, which if contained in proteins make them good buffers, helping to keep the acid-base balance of body fluids such as the blood.
Histidine
Cysteine
20
What is ‘oncotic pressure’?
Proteins such as albumin attract water. This osmotic pressure from proteins in fluid is called ‘oncotic pressure’.
21
Name two possible protein-related causes of oedema
- Excessive protein losses due to kidney disease.
- Inadequate protein synthesis due to liver disease.
- Inadequate dietary intake of protein (malnutrition).
## Footnote
This explains the appearance of ascites (a distended, fluid-filled abdomen) in the world's poorest countries.
22
Name three glycoproteins in the body and give their functions.
* **Mucins** – found in mucus and saliva; provide a protective, lubricating barrier.
* **ABO blood (type) antigens.**
* **Hormones** – incl. Luteinising Hormone (LH), Follicle Stimulating Hormone (FSH) and Thyroid Stimulating Hormone (TSH)
* **Major Histocompatibility Complex** – cell surface receptors involved in adaptive immunity (e.g. antigen presentation).
* **Proteoglycans** (a subclass of glycoprotein) are bound to glycosaminoglycans (GAGs) and found in the extracellular matrix e.g. chondroitin sulphate, found in cartilage – shock absorbs.
23
What is 'deamination'?
For individual amino acids to be used as an energy source or to be stored as fat, they need to undergo ‘deamination’.
This involves the removal of the nitrogen-containing amino group from amino acids and occurs primarily in the liver.
24
What toxic substance forms during deamination and what process occurs that enable it to be safely excreted from the body?
During deamination, **ammonia** is formed which is very toxic. To convert the ammonia to a water-soluble compound, it must go through a series of transformation reactions in the liver known as the ‘urea cycle’ to ensure that it can be excreted by the kidneys.
The less toxic, water-soluble compound formed is ‘urea’, which is filtered out by the kidneys as part of urine
25
What is the end result of amino acids that have undergone 'deamination'?
Following deamination (the removal of the amine group), the remaining fragments of amino acids may be used to produce glucose or ketones. These can be used as energy or to become energy storage.
26
Explain what happens in the urea cycle.
- Ammonia formed by deamination needs to be converted to ‘urea’ to ensure its safe removal from the body. This involves the Urea Cycle, which takes place in hepatocytes (liver cells).
- The Urea Cycle is the sole endogenous source of the amino acids arginine and citrulline, plus ornithine (an important liver support and detox agent)
27
What metabolic state can impairments of the liver’s Urea Cycle lead to. List three possible symptoms thereof.
‘**Hyperammonemia**’.
Symptoms include:
- Chronic fatigue
- headache
- irritability
- nausea and diarrhoea
- poor concentration
- confusion
- intolerance of high protein foods.
28
What is the importance of ‘transamination’?
Transamination an important step in the synthesis of some non-essential amino acids. If a particular non-essential amino acid is not available, the body can make it from another.
29
Briefly outline how 'transamination' occurs
Transamination is an important step in the synthesis of some non-essential amino acids. If a particular non-essential amino acid is not available, the body can make it from another.
The amino group of an amino acid is transferred onto an enzyme. The enzyme then transfers the amino group on to a ketoacid, thus forming the new amino acid.
30
Which vitamin is a coenzyme for transamination? Name three food sources rich in this nutrient.
**Vitamin B6** which is abundant in:
* wholegrains
* green vegetables
* sunflower seeds
* pistachios
* walnuts
* bananas
* lentils
* avocados
* meat & fish.
31
What is the ‘amino acid pool’?
When body proteins break down ('protein turnover'), they free amino acids to join the general circulation. These amino acids + diet-derived amino acids = the ‘amino acid pool’.
32
# TRUE OR FALSE:
Amino acids are readily stored in the body.
**FALSE**
Amino acids will be utilised or excreted – they are not stored. Essential amino acids generally have a longer half-life as they are more critical to the body in terms of supply.
## Footnote
(It is therefore important to have a regular supply of protein in the diet – particularly proteins containing the essential amino acids.)
33
Explain how chronic stress can increase the risk of osteoporosis
Stress causes protein losses in areas such as skeletal muscle, due to the catabolic actions of stress hormones (e.g. cortisol).
Chronic stress also impacts the framework of bones, as protein losses can also occur in the extracellular matrix (i.e. collagen).
34
Outline the process of muscle wasting that could occur from prolonged fasting or starvation
* When glucose and fatty acids supply is limited, cells are forced to use amino acids for energy production.
* Since amino acids are not stored, the only available source is from body component proteins such as those in lean tissue.
* These are then dismantled to be used for energy and in the long term cause tissue wasting.
35
List two life stages / circumstances during which higher protein diets or specific amino acids could be therapeutic.
* Pregnancy
* High performance athletes
* Injury recovery
36
# Discuss:
Animal sources provide more protein than plant sources.
Meat provides more protein than non-meat sources, but requires more energy to digest than plant sources. Heavy animal protein can accumulate in the intestinal wall, impairing absorption. In addition what is often added to meat dishes reduces its benefit. e.g., a hamburger with bacon and cheese brings with it high calories, trans-fats, heterocyclic amines and nitrosamines (cancer risk factors).
37
Name two anti-nutrients that could affect plant protein digestibility. What could be done to reduce their impact?
**Phytates and lectins.**
To support the digestibility of plant protein sources, consider soaking, sprouting and fermenting which can lower anti-nutrient factors.
38
Compare and contrast animal with plant protein
* Protein from animals are 'complete' sources whilst plant sources are generally lacking in one or two amino acids.
* Animal sources contain more protein but requires more energy to digest.
* Heavy animal protein can accumulate in the intestinal wall, impairing absorption whilst plant sources contain fibre that is beneficial for digestion.
* Animal protein sources often bring with it high calories, trans-fats, heterocyclic amines and nitrosamines whilst plant sources contain fibre, prebiotics, phytonutrients and other ‘qualities’ which can make them a superior choice for everyday healthy eating.
39
What advice can be given for optimising protein absorption?
* **Chew thoroughly and avoid drinking with meals.**
* **Support stomach acid levels:**
– Zinc and B6-rich foods (need for HCl production).
– Apple cider vinegar in a little water before meals.
– Bitter herbs and foods before meals (e.g. dandelion, rocket, watercress, artichoke, gentian, barberry bark, goldenseal). These also promote the release of pancreatic juice.
– Use betaine hydrochloride supplements with at least 600mg per capsule. Start with one when starting to eat, before increasing one capsule per meal up to a total of 5 max or until a feeling of warmth. If warm, cut one pill back.
40
List three fermentation products of protein that are detrimental to health. What effects do these have in the body?
Ammonia, amines, sulphides, and N-nitroso compounds.
They exert effects including systemic toxicity, nephrotoxicity and carcinogenesis.
41
What is a 'limiting' amino acid?
If an essential amino acid is in shorter supply than the amount needed to support protein synthesis, it is called a limiting amino acid.
42
Which vegan foods are 'complete proteins'?
Vegan foods that are complete proteins includes quinoa, buckwheat, pumpkin seeds, chia seeds, hemp seeds, tempeh.
43
Name the limiting amino acid in:
a) Beans
b) Nuts & seeds
c) Grains
d) Vegetables
e) Corn
a) Beans = Methionine
b) Nuts & seeds = Lysine
c) Grains = Lysine & threonine
d) Vegetables = Methionine
e) Corn = Tryptophan & lysine
44
How can all the essential amino acids be obtained on a plant-based diet?
Plant foods can be combined so that the limiting amino acid in one food is included in a food it is combined with e.g. vegetables and grains.
45
What are THREE adverse effects associated with long-term high
intake of animal protein?
- Methionine is an amino acid highly abundant in animal proteins and has an immune-stimulating effect on T cells, which if consumed in excess, is associated with over-reactive immune responses (autoimmunity and chronic inflammation). Excess methionine also increases homocysteine which is associated with atherosclerosis.
- Unless organic, can contain chemical residues. Occurs either by direct oral or topical dosing of the animal (e.g. pesticides to control lice and fleas) or exposure to crop pesticides in feed. If eating meat, focus on organic, grass-fed sources.
- Heavy animal protein can accumulate in the intestinal wall, impairing absorption.
- Increases the risk of cancer. Polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs) produced during the high temperature cooking of meat are carcinogenic.
46
List four conditions associated with long-term high animal protein intake in humans.
* Osteoporosis
* Kidney disease
* Increased cancer risk
* Disorders of liver function
* Atherosclerosis
* Increased muscle soreness post-exercise
47
Outline the link between animal protein and cancer
- Both high and moderate animal protein intake increases cancer risk significantly, and is linked to cancer initiation and promotion.
- WHO (2015) classified red meat as a probable cause of cancer; processed meats (salted, cured, fermented, smoked) are deemed carcinogens.
- High intakes of red meat (especially processed) are strongly linked to several cancers. Polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs) produced during the high temperature cooking of meat
(e.g. frying, BBQ, high temp-roasting) are carcinogenic.
48
Discuss the effects of excess animal protein on the:
a) skeletal system
b) renal system
c) cardiovascular system
a) Due to the acidic burden of excess animal protein, it can draw calcium out of bones and increase the risk of osteoporosis.
b) The extra acidity from a high animal protein intake needs buffering by the kidneys which must also filter the increased urea generated.
c) It is associated with oxidation and inflammation in the endothelium.
49
What are the benefits of consuming plant-based protein?
Plant-based proteins contain health-supporting fibre, phytonutrients and prebiotics and lower levels of leucine than animal protein (which can increase the expression of the enzyme TOR).
It has been found to be protective against cancer, autoimmunity, diabetes mellitus and cardiovascular disease*.
| * research such as the China study
50
How does the protein content of human breast milk compare to the current protein requirement recommendation?
* Calories supplied from protein in human breast milk is about 6%.
* Current protein requirements suggest between 10-30% of calories.
51
What are the symptoms of physiological protein deficiency and at what level of intake does this manifest?
There are no physiological deficiency symptoms other than those of severe deficiency (growth failure, tissue wasting).
It is estimated that the risk of protein deficiency would start at values between 0.4-0.5 g/kg of body weight (e.g. 31.5g or below for a 70kg person).
52
What are the recommendations for protein intake in terms of:
a) General recommendation
b) Minimal physical activity
c) Moderate physical activity
d) Intense physical activity
a) 0.75g/kg
b) 1.0g/kg
c) 1.3g/kg
d) 1.6g/kg
53
How would you calculate the appropriate level of protein intake for an overweight client?
* Look up the healthy weight for a person of your client’s height.
* Use the midpoint of the healthy weight range to base your calculations.
* Multiply kg by 0.75 to get your RNI
54
What are the recommended protein intakes during pregnancy and lactation?
For pregnancy an additional 6g/day is recommended additional to general recommendation.
During lactation: an extra 11 g/day 0-6 months and 8 g/day 6+ months.
55
Name four groups of people in the developed world that are more likely to be affected by protein deficiency?
- **Children** whose diets are rich in highly refined / processed foods, high in sugar and soft drinks and low in high quality wholefoods.
- **Teenagers** dieting, or consuming only highly refined / processed foods / junk food, soft drinks, sweets etc.
- **Older people** whose immobility, dentition (poor chewing), digestive health (lower stomach acid and pancreatic juice levels), living situation etc. reduces their intake / digestion / absorption.
- **Anorexia nervosa** sufferers.
- **Recovering patients** such as post-surgery or trauma (i.e. for repair).
- **Homeless and disadvantaged people**, including those living in
substandard conditions in inner cities and rural areas.
- Those with **drug and alcohol addictions**.
- Those with **chronic digestive conditions** and chronic use of proton pump inhibitors (PPI). The lack of HCl impairs the digestion and subsequent absorption of proteins.
- **Chronic or active infections** deplete the body of proteins.
56
Amino acids are crucial for protein synthesis but also have many other functions. List three of these.
Individual amino acids also:
- Contribute to the synthesis of hormones and neurotransmitters.
- Act as neurotransmitters themselves e.g. glycine.
- Act as methyl donors e.g. methionine.
- Build bile acids for digestion (glycine and taurine).
- Act as precursors for nitric oxide production e.g. Arginine.
- Help detoxify thousands of chemicals (i.e. phase 2 liver pathways).
- Act as precursors for the manufacture of endogenous antioxidants.
57
In which conditions are plasma or urine samples useful to explore amino acid insufficiencies / imbalances?
* Cardiovascular disease risk screen: higher levels of BCAAs (leucine, isoleucine, valine) and homocysteine, linked to heart disease→lower dietary intake.
* Chronic fatigue syndrome due to mitochondrial inefficiency
* Following long-term PPI use due to reduced amino acid absorption
| BCAA = Branched chain amino acid
58
Which amino acid is the most abundant in the human body?
Glutamine is the most abundant amino acid in the body, containing 60% of the total pool of free amino acids.
59
Under which conditions can glutamine become conditionally essential?
The body's glutamine synthesis becomes unable to meet higher requirements during acute stress, and hence it is considered conditionally essential. Stress states include injury (for wound healing) and infections (for supporting the immune response).
60
Discuss the interplay between Glutamine and the Intestinal Barrier
- Glutamine is the primary amino acid source for intestinal cells and helps to regulate tight junction integrity and enterocyte proliferation. Depletion results in decreased expression of tight junction proteins and increased intestinal permeability.
- Increased intestinal permeability causes include coeliac disease, IBD, candidiasis, alcohol, SIBO, food allergies / intolerances, chronic stress, nutrient deficiencies (e.g. glutamine, zinc), NSAIDs, chemotherapy.
- Intestinal permeability leads to the leakage of LPS into the blood, which can lead to various chronic diseases, e.g. autoimmunity.
| LPS = lipopolysaccharides (released from dying bacterial cell walls)
61
To address intestinal permeability, list THREE
a) glutamine-rich foods
b) nutrients
c) herbs
a) cabbage juice; spirulina; asparagus; broccoli; cod; salmon; bone broth.
b) N-acetyl glucosamine (in shellfish); Quercetin (apples, red onion, tomatoes, red peppers); Zinc (for rapid cell division and tight junction support);
Antioxidants (e.g. vitamin C, E and beta-carotene)
c) Turmeric, Marshmallow, Slippery Elm, Goldenseal, Myrrh.
62
Outline TWO important functions of glutamine in the body.
* **Immunity:** Supports lymphocyte and macrophage proliferation, and the production of cytokines by both lymphocytes and macrophages.
* **Neurotransmitter:** Glutamine is converted to glutamate (excitatory), before being converted to GABA (inhibitory). The conversion from glutamate to GABA requires vitamin B6, taurine and zinc. If this conversion is operating well, glutamine supplementation can have an anxiety-relieving, sleep supporting effect. An organic acids test can assist this understanding.
* **Hypoglycaemia:** Glutamine is a substrate for gluconeogenesis.
* **Muscle Recovery:** It is abundant in muscles and promotes faster exercise recovery. It reduces muscle breakdown.
63
What dosage of glutamine should be used suplementally?
Best to start low and gradually increase. 1-30g / day (ideally in mornings). Up to 30g/day can be used for HIV patients due to its intestinal, muscle, and immune-supporting functions.
64
Which drugs are known to interact with glutamine supplements?
**Anti-seizure medications**
e.g. phenobarbital, phenytoin, carbamazepine, primidone and valproic acid.
65
Which conditionally essential amino acid is formed from methionine and serine in the liver with co-factors of B6, B9 and B12 needed?
Cysteine
66
Which foods are direct sources of cysteine?
legumes, sunflower seeds, eggs, chicken
67
Cysteine is very important for detoxification and antioxidant support. For the synthesis of which molecule is it the rate-limiting amino acid?
Glutathione
68
Cysteine is needed for the formation of which two molecules?
Co-enzyme A
Taurine
69
Outline THREE functions of cysteine (and also its derivative, NAC)
* **Liver Detoxification / Antioxidant:** It is a building block of glutathione and plays a crucial role in the body’s antioxidant defences. It is crucial in liver drug metabolism (drugs deplete glutathione – cysteine regenerates it).
* **Reproductive Health:** It has been shown to increase sperm concentration (due to antioxidant properties) and positively impacts serum testosterone
* **Respiratory Health:** Expectorant properties (it breaks up mucus to aid easier elimination from the respiratory tract). Mainly due to the breakage of the disulphide bonds in mucoproteins.
* **Insulin resistance:** Increases insulin sensitivity (useful in PCOS & diabetes).
70
Name two amino acids that can be therapeutically used in neurodegenerative diseases such as Alzheimer's and Parkinson's
NAC (Cysteine)
Tryptophan
71
Name three food sources high in methionine
* Animal foods: beef, eggs, chicken etc.
* Brazil nuts
* sunflower seeds
* beans
* whole grains (e.g. quinoa)
72
Although methionine is a major methyl donor for phase II liver detoxification, why can excess levels in the body be problematic?
* It can lead to raised homocysteine which damages the vascular endothelium and increases the risk of atherosclerosis and miscarriage.
* Excess methionine also increases acidity in the body.
73
Which amino acids and co-factors are necessary for the production of carnitine?
* Amino Acids: Methionine and Lysine
* Co-factors: Iron, vitamin C, B3, B6.
74
What is the main function of carnitine in the body?
Carnitine assists ATP synthesis from fatty acids: it facilitates the transport of long-chain fatty acids across the mitochondrial membrane so they can be oxidised to create ATP.
Its also removes potentially toxic metabolites out of mitochondria, and acts as an antioxidant.
75
List three therapeutic uses of carnitine
* Weight loss
* Heart failure
* Infertility – improves sperm count, motility; also reduces oxidative damage (highly concentrated in the testes).
* Fatigue and concentration
* Athletic performance
* ADHD (also shown to increase dopamine and acetylcholine production).
* Hyperthyroidism - acts as a peripheral thyroid hormone antagonist
76
If recommending carnitine supplementation, what drug interactions should one be mindful of?
* Anticoagulants (e.g. warfarin): Carnitine increases the blood-thinning effects.
* Thyroid-hormones: carnitine acts as a peripheral thyroid hormone antagonist, and thus high dose carnitine is contraindicated with hypothyroidism.
77
List two direct food sources of:
a) Carnitine
b) Creatine
c) Taurine
a) Nuts, seeds, avocado, asparagus, spinach, red meats, dairy.
b) Meat, fish and eggs.
c) Only in animal-sourced food (especially chicken / turkey thighs and fish). Also in breast milk.
78
What is the function of creatine in the body and how can it be used therapeutically?
It is a storage form of ATP.
It can be used in:
- Enhancing muscular performance (especially high intensity training)
- Heart failure and coronary artery disease (it is the first molecule to be depleted in cardiac ischaemia)
79
Which organ can be negatively affected by high levels of creatine?
High doses of creatine might affect renal function and combining creatine with nephrotoxic drugs (e.g. NSAIDs, some antibiotics) might have other harmful effects on kidney function.
80
Which amino acids could be used therapeutically to aid GIT repair for a client with IBD or intestinal permeability?
List three good food sources of each.
* **Glycine** [legumes, seaweed, spinach, kale, cauliflower, cabbage, banana, pumpkin, bone broth, meat, fish, eggs]
* **Glutamine** [cabbage juice, spirulina, asparagus, broccoli, cod, salmon]
81
Which amino acids are beneficial for liver support?
List two good food sources of each.
* **Glycine** [legumes, seaweed, spinach, kale, cauliflower, cabbage, banana, pumpkin, bone broth, meat, fish, eggs]
* **Cysteine** [ legumes, sunflower seeds, eggs, chicken]
* **Taurine** [chicken / turkey thighs and fish]
82
List two functions of glycine
* Collagen Synthesis
* Liver detox
* Neurotransmitters (inhibitory neurotransmitter in the CNS. Also reversibly converted to serine – used to form acetylcholine.)
83
Which foods are good sources of the conditionally essential amino acid taurine?
It is only found in animal-sourced food (especially chicken / turkey thighs and fish).
It is also in breast milk.
84
How does taurine impact muscle health?
Taurine is highly concentrated in muscles and plays an important role in contraction.
It is also important for heart health, with its muscle supporting, anti- inflammatory, blood pressure-lowering properties.
85
Name three functions of taurine in the body other than muscle health.
**Antioxidant**
- Protects mitochondria from ROS.
- Neutrophils contain high levels of taurine, which provides anti-inflammatory and antioxidant effects.
**Neurological**
- CNS neuromodulation – inhibitory neurotransmitter function (taurine is an agonist of GABA receptors in the CNS)
- Supports the development of the cerebellum (the “little brain”).
- Has neuroprotective functions.
**Bile**
- Bile acid conjugation – end products of taurine conjugation are very soluble therefore flow better from the liver.
**Insulin**
- Shown to improve insulin resistance.
86
Which of the following amino acids could be used therapeutically in a client with both insomnia and hypertension:
a) Taurine
b) Glycine
c) Tryptophan
d) Theanine
a) Taurine
&
d) Theanine
87
How does taurine interact with blood pressure medications?
It may cause an additive effect
88
# TRUE OR FALSE:
Energy drinks are a good source of taurine and can be recommended to clients for muscle, neurological or antioxidant support
FALSE.
Whilst taurine is often added to energy drinks, they are NOT a good source of taurine, as they often contain refined sugars, caffeine, artificial sweeteners and other additives.
89
Name the only dietary source of the amino acid 'theanine'
Green tea.
90
Why could drinking green tea instead of coffee be a good choice for someone with anxiety, stress, low mood or the need to increase concentration?
**Green tea contains theanine**
- Theanine reduces the negative effects of caffeine naturally in green tea by having opposing effects (relaxing rather than stimulating).
91
Explain how theanine exerts positive effects on the neurological system
- After ingestion, theanine crosses the blood brain barrier and blocks glutamate receptors, whilst increasing GABA activity. GABA is inhibitory / calming.
- It increases alpha-brain waves producing a calming, mood- enhancing effect without drowsiness.
- It has been shown to increase serotonin and dopamine levels.
92
With which drugs can theanine negatively interact?
Theanine can lower blood pressure, so avoid using alongside anti-hypertensives or it may fall too low.
93
Name three good food sources of tyrosine.
Nuts, seeds, legumes, whole grains (e.g. quinoa, oats), fish, meat, poultry.
94
What are the main functions of tyrosine in the body and how can it be used therapeutically?
**Functions**
- Tyrosine is a precursor to the thyroid hormones, dopamine, epinephrine (adrenaline), norepinephrine (noradrenaline).
- It is also a precursor to melanin (the skin pigment).
**Therapeutic uses**
- Adrenal fatigue
- Hypothyroidism
- ADHD
- Depression
- Anxiety
- Cognition
95
What is the supplemental range for tyrosine and when is it contraindicated?
**Dosage:** 400-6000mg/day. Tyrosine seems to be safe when used in doses up to 150 mg/kg per day for up to 3 months.
**Contraindicated:**
- Overactive thyroid. Taking extra tyrosine might increase thyroxine levels, worsening cases of hyperthyroidism.
- Melanoma.
96
Name three good food sources of the amino acid tryptophan.
Brown rice, quinoa, pumpkin seeds, oats, bananas, turkey, fish, eggs.
97
What role does tryptophan play in endocrine health?
Tryptophan is used for serotonin and melatonin synthesis.
[It is assisted across the blood brain barrier by insulin. So if supplementing, consume with a carbohydrate-rich snack. This also explains why low serotonin levels cause carbohydrate cravings.]
98
Why is tryptophan important for energy metabolism?
Tryptophan is needed for ATP Synthesis since it is used to make vitamin B3, which is needed to form two coenzymes (NAD, NADP) involved in ATP production.
99
Name five therapeutic uses for tryptophan
* Depression
* Insomnia
* Stress and anxiety
* PMS
* Migraines
* Weight control (reducing cravings)
* Overcoming smoking addiction
* Fatigue
* Fibromyalgia
* Alzheimer’s and other neuro- degenerative diseases
100
What supplemental dosage and form of tryptophan can be recommended?
100-600mg tryptophan / day.
5HTP is usually preferred as it cannot be used for anything other than serotonin and melatonin production.
101
Name three foods containing phenylalanine
Avocado, brown rice, lentils, eggs, fish, meat, soy.
102
Into which other amino acid can phenylalanine be converted? How is it important for endocrine health?
It can be converted to tyrosine which is important for thyroid hormones, dopamine, adrenaline and noradrenaline.
103
For which skin condition could phenylalanine be used therapeutically?
Vitiligo.
It supports melanin production (via tyrosine pathway)
104
With which amino acid does lysine compete for absorption?
Arginine
105
For which viral condition can lysine be used therapeutically? Which foods rich in lysine can be used to this end?
Cold sores (*Herpes Simplex*).
Lysine dietary sources: quinoa, legumes, tempeh, chicken, eggs, dairy, fish, red meats.
106
Which nutrient can increase the efficacy of lysine?
Vitamin C
