Description
Intra-Workout Amino Acids, Built as One Complete Formula
Hard sessions burn more than carbohydrate. As the minutes add up, your body starts drawing on its own amino acid pool, and muscle protein is part of that pool. intrAMINO x¹² is the answer in capsule form: intra-workout amino acids you take while you train, so repair begins before the session ends.
The name tells you what is inside. X¹² stands for twelve active ingredients working as one system: all nine essential amino acids (EAAs) your body cannot make, including the three BCAAs in a 2:1:1 ratio from AjiPure®, plus glycine for connective tissue, pyridoxal 5′-phosphate, the active form of vitamin B6, and Bioperine® black pepper extract.
It is an anticatabolic amino acid formula, which simply means it works against muscle breakdown. BCAAs give the signal and the fuel, the full EAA profile gives muscle everything it needs to rebuild, and vitamin B6 contributes to normal protein and glycogen metabolism. Because it is a capsule, it adds nothing to your bottle: no sweetness, no flavour, no change to the carbohydrate mix you already trust.
- 12 active ingredients
- 9 / 9 essential amino acids
- 2:1:1 AjiPure® BCAA ratio
- 5,725 mg amino acids per daily dose
- 200 vegan capsules
Protect
2,000 mg of BCAAs supply working muscle with the amino acids it burns first, so less of your own muscle protein is broken down as the session goes on.
Sustain
Isoleucine and valine feed energy production, while a high BCAA-to-tryptophan ratio helps keep mental fatigue at bay when the effort gets long.
Rebuild
Leucine switches on muscle protein synthesis and the other eight EAAs give it the materials. Glycine, lysine and threonine cover tendons, ligaments and cartilage.
For Wellbeing and Healthy Ageing: the Amino Acids Your Body Cannot Make
You do not need a race number to need amino acids. Nine of them are essential: your body cannot make them, so every one has to arrive through food or supplementation, every single day. They are the raw material for muscle, collagen, enzymes, hormones and the brain’s chemical messengers.
That need does not shrink with age. Muscle mass begins to decline gradually from around 40, and with the years muscle responds less readily to the protein we eat, so the quality and completeness of your amino acid intake start to matter more. intrAMINO x¹² is an essential amino acids supplement that delivers all nine in free form, ready to absorb without digestion, together with glycine for collagen and active vitamin B6.
Stay strong as you age
Leucine triggers muscle protein synthesis and the full EAA profile supplies it. Keeping muscle is one of the most valuable things you can do for mobility, metabolism and independence.
Plant-based and flexitarian diets
Lysine, methionine and leucine are the amino acids most often short in vegan and vegetarian eating. x¹² tops up all three in a 100% vegan capsule.
Skin, joints and connective tissue
Glycine makes up a third of collagen. Lysine cross-links it, threonine completes it. Together they supply the building blocks for skin, tendons and cartilage.
Mood, focus and sleep chemistry
Phenylalanine is the starting point for dopamine and noradrenaline, tryptophan for serotonin and melatonin. Vitamin B6 contributes to normal psychological function.
Everyday energy
Vitamin B6 contributes to normal energy-yielding metabolism and to the reduction of tiredness and fatigue, while methionine and lysine feed the body’s own creatine and carnitine production.
Immune support
Antibodies and immune cells are built from amino acids. Vitamin B6 contributes to the normal function of the immune system.
How to use it for wellbeing: the daily dose stays the same. Take 5 capsules at the start of your walk, gym class, yoga session or active part of the day, and 5 capsules after you activity.
Intra-Workout Amino Acids for Your Sport
intrAMINO x¹² was designed first as amino acids for endurance athletes, and it carries over to every sport where sessions are long or hard. The protocol never changes: 5 capsules as you start, 5 capsules at halfway. Here is what intrAMINO x¹² does for yours.
Fitness and Strength Training
Build while you lift
Lifting creates the stimulus, amino acids supply the response. Leucine switches on muscle protein synthesis and the other eight EAAs give it something to build with, so repair starts while you are still under the bar rather than an hour later. It is the ideal partner for fasted morning sessions, long high-volume workouts and cutting phases, when protecting lean mass matters most.
How to use it: 5 capsules with your first warm-up set, 5 capsules midway through the session.
Cycling
Hours in the saddle without paying for them in muscle
Three, four, five hours on the bike. Carbohydrate keeps the pedals turning, but BCAA oxidation climbs steadily as glycogen falls, and your legs pay for it the next day. As amino acids for cycling go, capsules have one big advantage: they fit in a jersey pocket and add nothing to your bottle, so the carbohydrate concentration you have dialled in stays exactly as it is. Valine and the high BCAA-to-tryptophan ratio help you stay sharp when the final climb arrives.
How to use it: 5 capsules as you roll out, 5 capsules at the halfway point or the café stop.
Running
Protection for muscles, tendons and gut
Running adds something cycling does not: impact. Every stride is an eccentric load on muscle fibres and on the tendons and cartilage around them, so amino acids for running need to cover more than muscle. x¹² does, with EAAs and BCAAs for muscle and glycine, lysine and threonine as collagen building blocks. Threonine also feeds the gut’s protective mucus layer, and a capsule adds no extra sweetness or fluid to a stomach that is already working hard.
How to use it: 5 capsules at the start line or first kilometre, 5 capsules at half distance.
Swimming
Made for early starts and double sessions
Swim training means high volume, often twice a day and often before breakfast. That leaves long windows around training with no protein on board. intrAMINO x¹² closes the gap without a meal sitting in your stomach, and glycine and lysine supply collagen building blocks for hard-working shoulders. There is nothing to mix on poolside: the tub lives in your kit bag.
How to use it: 5 capsules before the warm-up, 5 capsules between main sets.
HYROX and CrossFit
Strength under endurance fatigue
Running into sleds, wall balls into burpees: functional fitness asks muscle to produce force while it is already tired and acidic. Histidine supplies the essential half of carnosine, muscle’s own acid buffer. BCAAs feed the work and help hold off central fatigue, and phenylalanine is the raw material for the dopamine and adrenaline that keep you driving through the last station.
How to use it: 5 capsules in the warm-up, 5 capsules at the midpoint of the race or between the strength block and the WOD.
Tennis
Sharp in the third set
A match has no clock. It might take 70 minutes or three hours, and it is decided by repeated sprints and split-second decisions made under fatigue. BCAAs help keep the mind fresh as the match lengthens, phenylalanine supports focus and reaction, and the collagen amino acids look after shoulders, elbows and knees. Capsules are quick to take at a changeover and easy on the stomach.
How to use it: 5 capsules in the warm-up, 5 capsules at a changeover mid-match.
How to Use intrAMINO x¹² and What Is in Every Dose
| Ingredient | Per 10 capsules |
|---|---|
| L-Glycine | 1,250 mg |
| L-Leucine AjiPure® | 1,000 mg |
| L-Lysine | 750 mg |
| L-Isoleucine AjiPure® | 500 mg |
| L-Valine AjiPure® | 500 mg |
| L-Histidine | 375 mg |
| L-Threonine | 375 mg |
| L-Phenylalanine | 375 mg |
| L-Methionine | 375 mg |
| L-Tryptophan | 225 mg |
| Pyridoxal 5′-phosphate | 14.7 mg |
| of which vitamin B6 | 10 mg (714%*) |
| Black pepper extract Bioperine® | 10 mg |
*NRV: Nutrient Reference Value. Each daily dose provides 5,725 mg of amino acids, of which 4,475 mg are essential amino acids and 2,000 mg are BCAAs (2:1:1). Net weight: 147.6 g. 200 vegetable capsules.
Ingredients: L-Glycine, Capsule (Glazing agent (hydroxypropylmethylcellulose)), L-Leucine AjiPure®, L-Lysine, L-Isoleucine AjiPure®, L-Valine AjiPure®, L-Histidine, L-Threonine, L-Phenylalanine, L-Methionine, L-Tryptophan, Bulking agent (microcrystalline cellulose), Anti-caking agents (magnesium salts of fatty acids, silicon dioxide), Pyridoxal 5′-phosphate (Vitamin B6), Black pepper extract (Piper nigrum L. fruit) Bioperine®.
Allergen information: May contain traces of gluten, milk, egg, soy, celery, nuts, sulphur dioxide and sulphites, fish, molluscs and crustaceans.
Inside the Formula: 12 Active Ingredients, Each With a Job
Nothing in intrAMINO x¹² is there to fill space. Below, every ingredient is explained three ways: in plain language, in scientific detail, and in terms of what it adds to the other eleven.
01 / 12: 1,250 mg per daily dose
Glycine The Collagen Builder That Calms the System
What is glycine?
Glycine is the smallest amino acid in your body and one of the busiest. It makes up roughly a third of collagen, the protein that holds tendons, ligaments, cartilage and skin together. Your body makes some glycine itself, but probably not enough to cover everything it is used for, which is why it leads the formula at the highest dose.
The science of glycine
Collagen is built on a repeating three-amino-acid pattern in which every third position is glycine. Only glycine is small enough to sit at the centre of the triple helix, so without it the fibre cannot form. Metabolic studies estimate that the body’s own production falls several grams a day short of total demand, which is why glycine is described as conditionally essential.
Structure is only part of the story. Glycine is one of the three amino acids in glutathione, the cell’s main antioxidant, and one of the three precursors of creatine. It combines with succinyl-CoA in the first step of haem synthesis, a reaction that depends on vitamin B6. In the brainstem and spinal cord it acts as an inhibitory neurotransmitter, which is the basis of its calming reputation.
Formula synergy: glycine in intrAMINO x¹²
Training loads connective tissue as much as it loads muscle. The nine EAAs rebuild the contractile protein; glycine supplies the raw material for the collagen around it, working with lysine and threonine. It also pairs with methionine for creatine and glutathione, and with P5P for haem. Leading an intra-workout formula with glycine is unusual, and it is deliberate.
Glycine health benefits
- Provides the main building block of collagen for skin, joints and bones
- Supports the body’s production of glutathione, its master antioxidant
- Supports calm and restful sleep as an inhibitory neurotransmitter
- Helps maintain skin elasticity through collagen renewal
- Feeds the body’s own creatine production for cellular energy
- Contributes to haem production for healthy red blood cells
- Supports bile acid formation for normal fat digestion
Glycine sport benefits
- Reinforces tendons, ligaments and cartilage under training load
- Fuels natural creatine synthesis for high-intensity efforts
- Supports glutathione defences against exercise-induced oxidative stress
- Supports haemoglobin production for oxygen delivery
- Aids overnight recovery through better sleep quality
- Helps look after joints during high-mileage training blocks
- Gentle on the stomach, even in the middle of a session
02 / 12: 1,000 mg per daily dose
L-Leucine AjiPure® The Switch That Turns Muscle Building On
What is leucine?
Leucine is the most important of the three branched-chain amino acids (BCAAs). Think of it as the ignition key: when leucine rises in your blood, muscle cells read it as a sign that building materials have arrived and switch on repair. The leucine in x¹² is AjiPure®, made by fermentation from plant sources by Ajinomoto, the Japanese pioneer of amino acid production, to an exceptionally high purity.
The science of leucine
Inside the muscle cell, leucine is detected by a sensor protein called Sestrin2. When leucine binds, Sestrin2 releases its brake on the mTORC1 complex, which then activates p70S6 kinase and 4E-BP1 and starts the translation of new muscle protein. This is why researchers speak of a leucine threshold: the amount of leucine in a meal or supplement strongly influences how much muscle protein synthesis it stimulates.
Leucine is also one of the few amino acids that muscle burns directly. Most amino acids are processed in the liver, but BCAAs are broken down mainly in skeletal muscle, and leucine oxidation rises several-fold during sustained exercise. The first step of that breakdown, transamination by the BCAT enzyme, depends on vitamin B6.
Formula synergy: leucine in intrAMINO x¹²
Leucine leads the 2:1:1 BCAA ratio, the classic and most widely studied ratio in sports nutrition. But a signal alone builds nothing: if leucine switches on protein synthesis and the other essential amino acids are missing, the process stalls. That is the whole logic of x¹². Leucine turns the key, and the other eight EAAs in the capsule are the materials already waiting on site.
Leucine health benefits
- Stimulates muscle protein synthesis at any age
- Helps preserve lean muscle mass as we get older
- Supports muscle maintenance during weight loss
- Helps maintain strength and mobility in later life
- Supports a healthy metabolism by protecting metabolically active muscle
- Supports healthy body composition
- Tops up plant-based diets, which are naturally lower in leucine
Leucine sport benefits
- Triggers the mTOR pathway that drives muscle repair
- Reduces muscle protein breakdown during long sessions
- Speeds up recovery between training days
- Helps reduce post-exercise muscle soreness
- Provides a direct fuel for working muscle
- Protects lean mass in heavy training blocks and weight cuts
- Supports strength and power adaptations
03 / 12: 750 mg per daily dose
L-Lysine The Collagen and Carnitine Connector
What is lysine?
Lysine is an essential amino acid that is often the lowest one in cereal-heavy and plant-based diets. Your body needs it to build strong collagen, to make carnitine, the shuttle that carries fat into your cells’ power stations to be burned, and to absorb and hold on to calcium.
The science of lysine
In collagen, lysine residues are converted to hydroxylysine and then linked to one another by the enzyme lysyl oxidase. These cross-links are what give collagen fibres their tensile strength. Without enough lysine, collagen is made but not properly reinforced.
Lysine is also the carbon backbone of carnitine. Protein-bound lysine is methylated three times, using methyl groups that come from methionine, and released as trimethyllysine, which is converted to carnitine in a four-step pathway that also requires vitamin B6, vitamin C, niacin and iron. Human studies additionally report that lysine improves intestinal calcium absorption and reduces its loss in urine.
Formula synergy: lysine in intrAMINO x¹²
x¹² carries three of the things the carnitine pathway asks for in one capsule: lysine as the backbone, methionine as the methyl donor and P5P as a cofactor. On the structural side lysine teams up with glycine and threonine for collagen. It sits third in the formula by dose because it is the amino acid plant-based athletes are most likely to be short of.
Lysine health benefits
- Essential for collagen formation in skin, bones and connective tissue
- Supports calcium absorption and retention for strong bones
- Provides the backbone of carnitine, used to turn fat into energy
- Supports the production of antibodies, enzymes and hormones
- Fills the most common amino acid gap in plant-based diets
- Supports healthy skin and hair structure
- Supports normal tissue repair
Lysine sport benefits
- Strengthens tendons and ligaments through collagen cross-linking
- Supports carnitine production for fat burning in long efforts
- Supports bone strength in high-impact sports
- Contributes to muscle protein repair as an essential amino acid
- Helps vegan and vegetarian athletes meet their lysine needs
- Supports connective tissue recovery after heavy loading
- Supports immune resilience through heavy training blocks
04 / 12: 500 mg per daily dose
L-Isoleucine AjiPure® The Energy BCAA That Gets Fuel Into Muscle
What is isoleucine?
Isoleucine is the second of the three BCAAs. Its speciality is energy: it helps muscle take up and use glucose, and your body can turn it into fuel by two different routes. If leucine is the builder, isoleucine is the one keeping the lights on.
The science of isoleucine
In muscle cell and animal studies, isoleucine increases glucose uptake into muscle through a pathway that does not depend on insulin, and human trials report a lower blood glucose response when it is taken alongside carbohydrate. In practical terms, it helps move the sugar you take in to the place where it is burned.
Isoleucine is both glucogenic and ketogenic. Its carbon skeleton is split into acetyl-CoA, which enters the Krebs cycle directly, and propionyl-CoA, which is converted to succinyl-CoA and tops up the cycle’s own intermediates. Like leucine, it is broken down mainly in skeletal muscle, starting with a B6-dependent step.
Formula synergy: isoleucine in intrAMINO x¹²
In the 2:1:1 ratio leucine gives the signal while isoleucine and valine supply the fuel. Isoleucine is the reason x¹² pairs so well with a carbohydrate drink: the carbohydrate provides glucose and isoleucine helps your muscles use it. AjiPure® quality again, for purity you can rely on mid-session.
Isoleucine health benefits
- Supports normal glucose uptake by muscle cells
- Contributes to steady energy levels through the day
- Supports muscle maintenance as we age
- Supports the body’s natural immune defences
- Required to build body proteins and enzymes
- Supports recovery from physical stress
Isoleucine sport benefits
- Helps working muscle take up glucose during exercise
- Provides a direct fuel for muscle in prolonged efforts
- Feeds the Krebs cycle to sustain energy production
- Reduces muscle breakdown as part of the BCAA trio
- Supports endurance in the late stages of long sessions
- Speeds up post-exercise recovery
- Complements your carbohydrate fuelling strategy
05 / 12: 500 mg per daily dose
L-Valine AjiPure® The Fatigue Fighter
What is valine?
Valine is the third BCAA. It is a muscle fuel like the other two, but it has a second job that endurance athletes care about: it competes with tryptophan for entry into the brain. More BCAAs in the blood means less tryptophan crossing over, and that is one of the main explanations for why BCAAs help you feel less mentally drained late in a long effort.
The science of valine
BCAAs and tryptophan cross the blood-brain barrier on the same transporter, LAT1. During prolonged exercise plasma BCAAs fall as muscle burns them, while free tryptophan rises because fatty acids displace it from albumin. The ratio of free tryptophan to BCAAs climbs, more tryptophan enters the brain and serotonin synthesis increases. This is the central fatigue hypothesis.
Supplying BCAAs during exercise keeps that ratio down, and trials have reported lower ratings of perceived exertion and mental fatigue at the same workload. Metabolically, valine is glucogenic: it is converted to succinyl-CoA, replenishing the Krebs cycle and supporting glucose production late in endurance work.
Formula synergy: valine in intrAMINO x¹²
Valine completes the 2:1:1 ratio and is the reason the BCAAs sit at 2,000 mg while tryptophan is held at 225 mg, roughly nine to one. You get a complete EAA profile for protein synthesis without giving up the anti-fatigue advantage of BCAAs during the session itself.
Valine health benefits
- Supports muscle maintenance and tissue repair
- Contributes to energy production as a glucogenic amino acid
- Supports mental stamina on demanding days
- Supports a healthy nitrogen balance in the body
- Supports normal growth and repair of body proteins
- Works with leucine and isoleucine to preserve lean mass with age
Valine sport benefits
- Helps delay central (mental) fatigue in long sessions
- Lowers perceived effort at the same pace
- Serves as a fuel source for working muscle
- Supports blood glucose late in endurance efforts
- Helps reduce markers of muscle damage after hard training
- Supports focus and decision-making under fatigue
- Completes the 2:1:1 BCAA ratio
06 / 12: 375 mg per daily dose
L-Histidine The Raw Material of Your Acid Buffer
What is histidine?
Histidine is the essential amino acid your muscles use to make carnosine, the natural buffer that soaks up the acid behind the burn of hard efforts. It is also the starting point for histamine, which regulates blood flow, digestion and alertness, and it sits at the heart of haemoglobin, the protein that carries oxygen.
The science of histidine
Carnosine is a dipeptide of beta-alanine and histidine, assembled in skeletal muscle by carnosine synthase. The buffering comes from histidine’s imidazole ring, whose pKa of about 6.8 is almost perfectly placed to absorb hydrogen ions as muscle pH drops. Beta-alanine normally limits the rate of carnosine synthesis, but histidine is the half that can only come from the diet, and weeks of beta-alanine loading have been shown to lower histidine levels in blood and muscle.
Histidine is converted to histamine by histidine decarboxylase, a vitamin B6-dependent enzyme. In haemoglobin, a histidine residue holds the iron atom of each haem group in place, and other histidine residues give the molecule much of its capacity to buffer carbon dioxide and acid.
Formula synergy: histidine in intrAMINO x¹²
Most amino acid formulas stop at BCAAs. x¹²includes histidine because muscle protein cannot be built without it and because athletes who use beta-alanine are drawing on their histidine pool. The P5P in the formula is the cofactor for its conversion to histamine, the messenger that widens blood vessels in muscle after exercise.
Histidine health benefits
- Precursor of carnosine, a protective antioxidant dipeptide in muscle and brain
- Needed to make histamine for normal digestion and alertness
- Supports haemoglobin structure and oxygen transport
- Binds zinc and copper for transport around the body
- Supports the body’s antioxidant defences
- Supports the skin’s natural barrier and moisture factors
- Essential for growth and repair of all tissues
Histidine sport benefits
- Supplies the essential half of carnosine, muscle’s own acid buffer
- Helps delay the burn in high-intensity efforts
- Supports buffering capacity in sprints, climbs and intervals
- Backs up your histidine pool if you supplement beta-alanine
- Supports oxygen transport through haemoglobin
- Supports blood flow to muscle during recovery
- Contributes to muscle protein repair as an essential amino acid
07 / 12: 375 mg per daily dose
L-Threonine The Gut and Connective Tissue Protector
What is threonine?
Threonine is an essential amino acid that your gut claims first. It is a major component of mucins, the proteins that form the protective mucus layer lining your intestines. It is also found in collagen, elastin and tooth enamel, and in the antibodies of your immune system.
The science of threonine
The intestine retains a large share of dietary threonine on its first pass, mostly to make mucins. The protein core of a mucin is unusually rich in threonine, serine and proline, and the threonine and serine residues carry the sugar chains that turn the protein into a gel. When threonine is short, mucin production is one of the first things to fall.
Threonine also matters at the level of cell signalling. Many of the enzymes that control muscle adaptation, including mTOR and AMPK, are serine/threonine kinases: they pass messages by attaching phosphate groups to threonine residues on other proteins. Surplus threonine is broken down by a vitamin B6-dependent enzyme to feed the Krebs cycle.
Formula synergy: threonine in intrAMINO x¹²
Endurance exercise diverts blood away from the gut and asks it to handle large amounts of carbohydrate at the same time. Threonine supplies the gut lining with the amino acid it uses most. Alongside glycine and lysine it also completes the connective tissue trio in the formula.
Threonine health benefits
- Supports the gut’s protective mucus barrier
- A building block of collagen and elastin for skin and connective tissue
- Supports immune function as a key component of antibodies
- Supports healthy digestion
- Contributes to the proteins of tooth enamel
- Supports normal fat metabolism in the liver
- Needed to maintain the body’s protein balance
Threonine sport benefits
- Helps maintain the gut barrier under race-day stress
- Supports the gut lining when high-carbohydrate fuelling puts it to work
- Builds collagen and elastin in tendons and ligaments
- Supports immune defences during heavy training
- Essential for muscle protein synthesis
- Supports connective tissue recovery
08 / 12: 375 mg per daily dose
L-Phenylalanine The Drive and Focus Precursor
What is phenylalanine?
Phenylalanine is where your body’s get-up-and-go chemistry begins. It is converted into tyrosine, and tyrosine into dopamine, noradrenaline and adrenaline, the messengers of motivation, focus and readiness. Tyrosine is also needed to make thyroid hormones and the pigment melanin.
The science of phenylalanine
The pathway runs in clear steps. Phenylalanine hydroxylase in the liver converts phenylalanine to tyrosine. Tyrosine hydroxylase, the rate-limiting enzyme, produces L-DOPA, and aromatic L-amino acid decarboxylase, which depends on vitamin B6, turns L-DOPA into dopamine. Dopamine is then converted to noradrenaline and, with a methyl group donated by methionine, to adrenaline.
During long or stressful efforts, catecholamine turnover in the brain rises and precursor availability can become the limiting factor. Studies of tyrosine under cold, heat and cognitive stress report better preserved working memory and attention, which is why this pathway interests endurance and team-sport athletes alike. Phenylalanine also stimulates the satiety hormone CCK.
Formula synergy: phenylalanine in intrAMINO x¹²
Late in a session the limiter is often the mind, not the muscle. Phenylalanine supplies the first link in the chain that keeps drive and concentration up, P5P is the cofactor for the step that produces dopamine, and methionine provides the methyl group for adrenaline. Three ingredients, one pathway.
Phenylalanine health benefits
- Precursor of dopamine, noradrenaline and adrenaline
- Supports motivation, alertness and mental drive
- Supports focus and working memory under stress
- Provides the tyrosine needed to make thyroid hormones
- Supports melanin production for skin and hair pigmentation
- Supports appetite regulation through satiety signalling
- Supports a balanced, positive mood
Phenylalanine sport benefits
- Supports mental drive and motivation in hard sessions
- Sharpens focus and reaction time under fatigue
- Feeds the adrenaline response for high-intensity efforts
- Supports decision-making in the late stages of competition
- Supports resilience to heat, cold and physical stress
- Essential for muscle protein synthesis
09 / 12: 375 mg per daily dose
L-Methionine The Methyl Donor Behind Creatine and Carnitine
What is methionine?
Methionine is the sulphur-containing essential amino acid, and every protein your body makes begins with it. It is also turned into SAMe, the body’s universal methyl donor, which is needed to make creatine, carnitine and adrenaline. And it provides the sulphur for cysteine, glutathione and taurine.
The science of methionine
Methionine reacts with ATP to form S-adenosylmethionine (SAMe), which donates methyl groups in more than a hundred reactions. Creatine synthesis alone consumes roughly 40% of them. Methionine is also the initiator amino acid of translation: the ribosome cannot begin a new protein chain without it.
After donating its methyl group, SAMe becomes homocysteine. Homocysteine is either recycled back to methionine or sent down the transsulfuration pathway, where two vitamin B6-dependent enzymes, cystathionine beta-synthase and cystathionine gamma-lyase, convert it to cysteine. Cysteine is then used to make glutathione and taurine.
Formula synergy: methionine in intrAMINO x¹²
Methionine is the hub of the formula’s synergy. With glycine it feeds creatine synthesis. With lysine it feeds carnitine synthesis. With glycine and P5P it feeds glutathione. And because P5P drives the pathway that processes homocysteine, the formula supplies the methyl donor and the cofactor that completes its cycle. It is also the limiting amino acid in legumes, so it matters for plant-based athletes.
Methionine health benefits
- Starts the synthesis of every protein in the body
- Produces SAMe, the universal methyl donor for DNA, hormones and neurotransmitters
- Provides the sulphur for glutathione antioxidant defences
- Supports healthy hair, skin and nails through sulphur-rich keratin
- Supports liver function and normal fat metabolism
- Precursor of cysteine and taurine
- Fills the amino acid gap in legume-based diets
Methionine sport benefits
- Supplies methyl groups for natural creatine synthesis
- Supports carnitine production for fat burning
- Supports glutathione recovery after the oxidative stress of training
- Initiates muscle protein synthesis
- Supports taurine production for muscle function
- Supports the synthesis of adrenaline for intense efforts
- Provides sulphur for cartilage and connective tissue
10 / 12: 225 mg per daily dose
L-Tryptophan The Serotonin and Recovery Amino Acid
What is tryptophan?
Tryptophan is the least abundant essential amino acid in food and the only raw material your body has for serotonin, the messenger of mood and wellbeing, and from it melatonin, the hormone that sets your sleep rhythm. Your body also converts tryptophan into vitamin B3 and NAD+, the molecule at the centre of cellular energy production.
The science of tryptophan
Tryptophan hydroxylase converts tryptophan to 5-HTP, and the vitamin B6-dependent enzyme aromatic L-amino acid decarboxylase converts 5-HTP to serotonin. In the pineal gland serotonin is then turned into melatonin. Most tryptophan, however, follows the kynurenine pathway towards NAD+, at a rate of roughly 60 mg of tryptophan for every 1 mg of niacin equivalent.
Exercise changes how this pathway behaves. Trained muscle increases its content of kynurenine aminotransferases, B6-dependent enzymes that convert kynurenine into kynurenic acid, a form that cannot cross into the brain. This is one of the mechanisms proposed to link regular endurance training with greater resilience to stress.
Formula synergy: tryptophan in intrAMINO x¹²
Muscle protein synthesis stops at the first missing essential amino acid, so a formula without tryptophan is incomplete. x¹² includes it, but at the lowest dose in the formula by design: 225 mg against 2,000 mg of BCAAs keeps the BCAA-to-tryptophan ratio high during exercise, while still supplying what recovery and sleep chemistry need afterwards.
Tryptophan health benefits
- The sole precursor of serotonin, supporting mood and emotional balance
- Precursor of melatonin for a healthy sleep-wake rhythm
- Converted to vitamin B3 and NAD+ for cellular energy
- Supports appetite regulation
- Supports relaxation and resilience to stress
- Supports healthy sleep quality
- Essential for protein synthesis and often limited in the diet
Tryptophan sport benefits
- Completes the EAA profile so muscle protein synthesis is never held back
- Supports overnight recovery through the serotonin-melatonin pathway
- Contributes to NAD+ production for energy metabolism
- Supports mood and motivation through heavy training blocks
- Supports stress resilience through exercise-activated kynurenine metabolism
- Dosed low by design to keep the BCAA-to-tryptophan ratio high during exercise
11 / 12: 14.7 mg, providing 10 mg vitamin B6 (714% NRV) per daily dose
Pyridoxal 5′-Phosphate (Active Vitamin B6) The Coenzyme That Puts Amino Acids to Work
What is vitamin B6 (P5P)?
Pyridoxal 5′-phosphate, or P5P, is the active form of vitamin B6: the form your enzymes actually use. Vitamin B6 is the amino acid vitamin. Almost every reaction that converts, breaks down or builds something from an amino acid needs it, and so does the release of glucose from stored glycogen.
The science of vitamin B6 (P5P)
P5P is the coenzyme for more than 140 enzyme reactions, around 4% of all classified enzyme activities. In each one it forms a temporary bond with the amino acid and acts as an electron sink, making it possible to transfer amino groups (transaminases such as BCAT, ALT and AST), remove carboxyl groups (the decarboxylases that make dopamine, serotonin and histamine) or rearrange side chains (the transsulfuration enzymes).
Around 70 to 80% of the body’s vitamin B6 is found in muscle, bound to glycogen phosphorylase, the enzyme that releases glucose from glycogen. Common pyridoxine hydrochloride has to be converted in the liver before it can do any of this. x¹² supplies the vitamin directly in its coenzyme form.
Formula synergy: vitamin B6 (P5P) in intrAMINO x¹²
P5P is what turns ten amino acids into a system. It is the cofactor for the first step of BCAA metabolism, for the steps that lead from phenylalanine to dopamine, from tryptophan to serotonin and from histidine to histamine, for the methionine-to-cysteine route that feeds glutathione, and for building haem from glycine. Putting amino acids in a capsule is easy. Adding the coenzyme that processes them is what makes it a formula.
Vitamin B6 (P5P) health benefits
- Contributes to normal protein and glycogen metabolism
- Contributes to normal energy-yielding metabolism
- Contributes to normal functioning of the nervous system
- Contributes to normal psychological function
- Contributes to normal red blood cell formation
- Contributes to the normal function of the immune system
- Contributes to the reduction of tiredness and fatigue
- Contributes to the regulation of hormonal activity
Vitamin B6 (P5P) sport benefits
- Contributes to normal protein metabolism, so the amino acids you take are put to use
- Contributes to normal glycogen metabolism, the release of stored carbohydrate
- Contributes to normal energy-yielding metabolism during training
- Contributes to the reduction of tiredness and fatigue
- Contributes to normal red blood cell formation for oxygen transport
- Contributes to the normal function of the immune system in heavy training periods
- Contributes to normal functioning of the nervous system for coordination and control
12 / 12: 10 mg per daily dose
Bioperine® Black Pepper Extract The Absorption Amplifier
What is Bioperine®?
Bioperine® is a patented extract of black pepper fruit, standardised to at least 95% piperine, the compound that gives pepper its bite. The dose is tiny and its job is simple: to help your body absorb more of everything else in the capsule.
The science of Bioperine®
Piperine improves bioavailability in several ways. In intestinal cell studies it increases the uptake of amino acids, including leucine, isoleucine and valine, by acting on the brush border membrane and its transporters. It is also thought to increase blood flow and thermogenic activity in the gut wall and to slow some of the enzymes and efflux pumps that clear compounds before they reach the bloodstream.
In human studies run by its manufacturer, 5 mg of Bioperine® taken with a nutrient raised blood levels of that nutrient compared with taking it alone, and vitamin B6 was one of the nutrients tested. Each 5-capsule intake of x¹² delivers exactly 5 mg.
Formula synergy: Bioperine® in intrAMINO x¹²
Absorption matters most when it is hardest. During exercise blood flow to the gut falls, yet that is exactly when x¹² is taken. Bioperine® is included to support uptake of the amino acids and of the P5P that processes them, at the same dose per intake that was used in the absorption studies.
Bioperine® health benefits
- Enhances the absorption of nutrients taken with it
- Shown in human studies to raise blood levels of vitamin B6
- Supports amino acid uptake across the gut wall
- Supports healthy digestion
- Provides natural antioxidant activity
- Supports thermogenesis
Bioperine® sport benefits
- Helps you get more from every capsule
- Supports amino acid uptake when gut blood flow drops during exercise
- Delivers 5 mg per intake, the dose used in absorption studies
- Supports BCAA uptake in the gut
- Supports absorption of the vitamin B6 that drives amino acid metabolism
- Natural, plant-derived and vegan
Intra-Workout Amino Acids: Your Questions Answered
What are intra-workout amino acids?
Intra-workout amino acids are amino acids taken during training rather than before or after it. The aim is to supply working muscle with essential amino acids and BCAAs at the moment it is burning them, so that less muscle protein is broken down and recovery starts sooner. intrAMINO x¹² provides all nine essential amino acids, including 2,000 mg of BCAAs, in capsule form.
When and how should I take intrAMINO x¹²?
Take 10 capsules daily: 5 capsules right at the beginning of your training session and 5 capsules halfway through, with water. One tub contains 200 capsules, which is 20 daily doses. Do not exceed the recommended daily dose.
What is the difference between EAAs and BCAAs?
The three BCAAs (leucine, isoleucine and valine) are a subset of the nine essential amino acids (EAAs). BCAAs signal and fuel, but muscle needs all nine EAAs to build new protein. intrAMINO x¹² is an EAA and BCAA supplement in one: the full EAA profile with the BCAAs in a 2:1:1 ratio.
Why capsules instead of an amino acid powder?
Free-form amino acids taste bitter, so powders rely on sweeteners, acids and flavourings. Capsules need none of them. They also keep your bottle free for carbohydrate and electrolytes, travel easily in a jersey pocket or kit bag, and give you an exact dose every time. That is why x¹² comes as EAA capsules rather than one more flavoured powder.
Can I take intrAMINO x¹² with carbohydrate drinks, gels or protein?
Yes. It is designed to sit alongside your carbohydrate fuelling during the session and a protein-rich meal or shake afterwards. Carbohydrate covers energy, intrAMINO x¹² covers amino acids, and neither changes how the other is mixed or dosed.
Can I take it if I do not train every day?
Yes. The essential amino acids are needed every day, with or without training. On lighter days keep the same daily dose of 10 capsules, taking 5 at the start of the most active part of your day and 5 halfway through it.
Is intrAMINO x¹² vegan and suitable for tested athletes?
Yes. intrAMINO x¹² comes as vegan amino acid capsules: the shell is plant-based (hydroxypropylmethylcellulose) and the AjiPure® amino acids are produced by fermentation. The formula contains only amino acids, vitamin B6 and black pepper extract, none of which appear on the WADA Prohibited List, and the tub carries the SCN Doping Free mark.
Who should not take intrAMINO x¹²?
It should not be consumed by pregnant women, by people taking antidepressants or by anyone with renal insufficiency. It contains L-phenylalanine, so it is not suitable for people with phenylketonuria (PKU). If you take prescription medication, speak to your doctor first, as black pepper extract can affect how some medicines are absorbed. Keep out of reach of young children.
Warnings and Storage
Warnings: Food supplements should not replace a varied and balanced diet and a healthy lifestyle. Do not exceed the stated recommended dose. Keep out of reach of young children. It should not be consumed by pregnant women or by individuals undergoing treatment with antidepressants or suffering from renal insufficiency.
Storage: Store in a cool, dry place out of reach of children. Store under 25°C and away from direct sunlight.
Vitamin B6 statements on this page are authorised nutrition and health claims. Other information describes the physiological roles of the ingredients and is provided for educational purposes. This product is a food supplement and is not intended to diagnose, treat, cure or prevent any disease.
Warnings: Discontinue use if you experience any allergy. A varied and balanced diet and a healthy lifestyle are important.
*This website is for your education and general health information only. The ideas, opinions and suggestions contained on this website are not to be used as a substitute for medical advice, diagnosis or treatment from your doctor for any health condition or problem. Users of this website should not rely on information provided on this website for their own health problems. Any questions regarding your own health should be addressed to your own physician. Please do not start or stop any medications without consulting with your doctor. We neither encourage you to do so, nor can we be held responsible for the fall out of failing to seek the counsel of a medical health practitioner.
