GLOBAL SHIPPING | USA SHIPS FREE OVER $75

items 75 add $5 more for FREE shipping
Free Gift
InfiniWell Physicians Also Recommend

Ready to get started?

0 Items

Loading

Your orders,

  • My Order

    Liquid error (snippets/cart_drawer line 696): Array 'customer.orders' is not paginateable.
BPC-157 RAPID PRO - 500MCG

$159.95

BPC-157 Probiotic | ABC

$149.95

PTD-DBM

$69.95

DUO

$59.95

Methylated B-Complex dietary supplement: 90 vegetarian capsules for energy & metabolism support.
Supplement facts label showing detailed vitamin B-complex content per serving, including percentages of daily value.
Methylated B-Complex supplement bottle, 90 capsules, showing a comprehensive blend of active B vitamins.
90 vegetarian capsules of B-complex dietary supplement in clear bottle, next to glass; light background.
Methylated B-Complex dietary supplement: 90 vegetarian capsules for energy & metabolism support.
Supplement facts label showing detailed vitamin B-complex content per serving, including percentages of daily value.
Methylated B-Complex supplement bottle, 90 capsules, showing a comprehensive blend of active B vitamins.
90 vegetarian capsules of B-complex dietary supplement in clear bottle, next to glass; light background.

METHYLATED B-COMPLEX

High Potency, Comprehensive B-Complex*

$29.95
4.9
Rated 4.9 out of 5 stars
441 Reviews
View Ingredients & Nutrition Facts
Qty
  • Supports Healthy Methylation & Carbohydrate Metabolism
  • Promotes Nervous System, Immune & Adrenal Health
  • Supports Neurotransmitter Production For A Positive Mood
  • Protects Against Stress-Induced Nutrient Depletion

Active Ingredients: Thiamine (Vitamin B1), Riboflavin (Vitamin B2), Niacin, Vitamin B6, Folate, Vitamin B12, Biotin, Pantothenic Acid, Choline Bitartrate, Inositol

Other Ingredients: Hydroxypropyl Methycellulose, Magnesium Stearate, Silicon Dioxide, Vegetable Capsule (Hypromellose)

HOW

Take 1 capsule daily or as directed by your healthcare practitioner.

WHEN

Daily

DOSE

1 Capsule

  • Benefits

    • Supports Healthy Methylation & Carbohydrate Metabolism
    • Promotes Nervous System, Immune & Adrenal Health
    • Supports Neurotransmitter Production For A Positive Mood
    • Protects Against Stress-Induced Nutrient Depletion
  • Ingredients

    Active Ingredients: Thiamine (Vitamin B1), Riboflavin (Vitamin B2), Niacin, Vitamin B6, Folate, Vitamin B12, Biotin, Pantothenic Acid, Choline Bitartrate, Inositol

    Other Ingredients: Hydroxypropyl Methycellulose, Magnesium Stearate, Silicon Dioxide, Vegetable Capsule (Hypromellose)

  • How To Use

    HOW

    Take 1 capsule daily or as directed by your healthcare practitioner.

    WHEN

    Daily

    DOSE

    1 Capsule

or set up interest-free payments with Shop Pay Delivery every 30 Days. Cancel anytime.

METHYLATED B-COMPLEX

Subscribe & Save
  • Subscribe $25.46 $29.95
  • One-Time $29.95

Formulation

Vitamin B1

  • Found In 
  • Lean Pork Chops, Salmon
  • Source 
  • Thiamine HCl 
  • Benefits 
  • Brain, Heart, Immune Function, Eye Health, Metabolism 
  • Science 
  • 19,782 published articles

Vitamin B2

  • Found In
  • Lean Beef, Dairy Products
  • Source
  • Riboflavin HCl
  • Benefits
  • Energy Production, Fat, Carb Metabolism
  • Science
  • 21,401 published articles

Niacin

  • Found In
  • Red Meat, Poultry, Fish
  • Source
  • Niacinamide
  • Benefits
  • Cholesterol, Blood Pressure, Metabolism, Skin Health
  • Science
  • 14,556 
  • published articles

Vitamin B6

  • Found In
  • Avocados, Chick Peas, Spinach, Eggs
  • Source
  • Pyridoxyl-5-Phosphate
  • Benefits
  • Brain, Energy, Heart Health
  • Science
  • 22,042 published articles

Folate

  • Found In
  • Spinach, Turnips
  • Source
  • 5-Methyltetrahydrofolic Acid
  • Benefits
  • Brain, Heart Health, Red Blood Cell Formation
  • Science
  • 69,828 published articles

Vitamin B12

  • Found In
  • Organ Meats, Clams
  • Source
  • Methylcobalamin
  • Benefits
  • Brain, Mood, Heart, Eye, Red Blood Cell Support
  • Science
  • 36,493 published articles

Biotin

  • Found In
  • Egg Yolks, Legumes
  • Source
  • Vitamin H
  • Benefits
  • Hair, Skin, Nails and Brain Health
  • Science
  • 36,292 published articles

Pantothenic Acid (Vitamin B5)

  • Found In
  • Organ Meats, Beef
  • Source
  • D-Calcium Pantothenate
  • Benefits
  • Energy, Metabolism of Fats and Carbs, Cholesterol
  • Science
  • 4,224 published articles

Choline

  • Found In
  • Eggs, Liver, Broccol
  • Source
  • Choline Bitartrate
  • Benefits
  • Brain Health, Liver Function, Metabolism
  • Science
  • 87,118 published articles

Inositol

  • Found In
  • Citrus Fruits, Melons, Beans, Grains, Nuts
  • Source
  • Myo-Inositol
  • Benefits
  • Blood Sugar, Cholesterol, Blood Pressure, Ovarian Health
  • Science
  • 50,145 published articles
overview

High Potency, Balanced Comprehensive B-Complex*

  • METHYLATED B-COMPLEX

    This advanced B-complex formulation includes eight essential B vitamins along with choline, inositol, and biologically active folate as 5-MTHF for optimal methylation. Methylation is a critical biochemical process that converts homocysteine into methionine and cysteine, supporting cardiovascular and nervous system health.*

  • OVERVIEW

    B vitamins are essential for the body’s ability to convert food into cellular energy. These water-soluble vitamins are absorbed in the small intestine and metabolized in the liver into their active coenzyme forms. Acting as coenzymes in the Krebs cycle, they are vital for the production of adenosine triphosphate (ATP), the body’s primary energy currency. Moreover, B vitamins like folate, B6, and B12 play pivotal roles in methylation, a process crucial for converting homocysteine into methionine and cysteine. Methylation influences DNA repair, gene expression, and overall mental and physical health.*

  • FUNCTIONS OF EACH ESSENTIAL B VITAMIN

    Thiamine (Vitamin B1)


    Thiamine is a key cofactor in A TP production within the Krebs cycle and is required for metabolizing fats, proteins, and carbohydrates. Modern diets often lack sufficient thiamine due to the over-processing of grains. Research from randomized, double-blind, placebo-controlled trials indicates that high-dose thiamine supplementation may also support balanced blood sugar levels.1*


    Riboflavin (Vitamin B2)


    Riboflavin serves as a precursor for flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), critical for energy production and antioxidant activity. Riboflavin deficiency can lead to oxidative stress and impaired energy production. Studies suggest that maintaining optimal riboflavin levels can help promote healthy blood pressure, especially in genetically predisposed individuals.2*


    Niacin (Vitamin B3)


    Niacin, transformed into NAD and NADP in the body, is a cofactor in mitochondrial energy production. It supports oxidation-reduction reactions and promotes cardiovascular health, with substantial evidence demonstrating its role in maintaining healthy cholesterol levels.3*


    Vitamin B6


    With involvement in over 100 enzymatic reactions, B6 is vital for lipid metabolism, neurotransmitter production, immune function, and hormone regulation. Studies show that higher dietary intake of B6 supports cardiovascular health and enhances lymphocyte activity, promoting immune function in older adults.4,5*


    Folate (5-MTHF)


    Folate is indispensable for DNA synthesis, methylation, and mitochondrial energy metabolism. Unlike folic acid, which requires enzymatic conversion, 5-MTHF is bioactive and readily utilized by the body. This ensures better folate absorption, particularly in individuals with suboptimal enzyme activity. Folate also supports neural tube development during pregnancy and overall cellular function.*


    Vitamin B12


    Essential for fat and carbohydrate metabolism, protein synthesis, and mitochondrial energy regulation, B12 is primarily found in animal-based foods. This nutrient supports neurological health, mood, and energy production. V egan and vegetarian diets often lack adequate B12, making supplementation critical.6*


    Biotin


    Biotin is vital for the metabolism of fats, carbohydrates, and proteins, playing a key role in cellular processes and macromolecule synthesis. It is also associated with promoting healthy hair strength and growth6,7*


    Pantothenic Acid (Vitamin B5)


    Pantothenic acid and its active form, CoA, are essential for synthesizing fatty acids, phospholipids, amino acids, and steroid hormones. Approximately 95% of CoA resides in mitochondria, underscoring its role in energy production. Research highlights pantothenic acid’s ability to support tissue repair and regulate blood lipids.8,9,10*


    Choline Bitartrate


    Although not a B vitamin, choline is critical for forming cellular membranes and lipoproteins. It also synthesizes acetylcholine, a neurotransmitter vital for brain and muscle function. Choline supports cognitive health and cellular integrity.*

  • REFERENCES

    1. Alaei Shahmiri F, Soares MJ, Zhao Y, Sherriff J. Eur J Nutr. 2013 Oct;52(7):1821-4. Epub 2013 May 29.

    2. Wilson CP, Ward M, McNulty H, Strain JJ, Trouton TG,Horigan G, Purvis J, Scott JM. Am J Clin Nutr. 2012 Mar;95(3):766-72. Epub 2012 Jan 25.

    3. Mason CM, Doneen AL. J Cardiovasc Nurs. 2012 Jul-Aug;27(4):303-16.

    4. Rimm EB, Willett WC, Hu FB, et al. JAMA. 1998;279(5):359-364.

    5. Meydani SN, Ribaya-Mercado JD, Russell RM, Sahyoun N, Morrow FD, Gershoff SN. Am J Clin Nutr. 1991;53(5):1275-1280.

    6. Huskisson E, Maggini S, Ruf M. J Int Med Res. May-Jun 2007;35(3):277-289.

    7. Mock DM. Biotin. In: Ziegler E, Filer LJ, eds. Present Knowledge in Nutrition: International Life Sciences Institute; 1996:220-235.

    8. Plesofsky-Vig N. Pantothenic Acid. In: Ziegler E, Filer LJ,eds. Present Knowledge in Nutrition: International Life Sciences Institute.; 1996:236-244.

    9. Naruta E, Buko V. Exp Toxicol Pathol. 2001 Oct;53(5):393-8.

    10. Ellinger S, Stehle P. Curr Opin Clin Nutr Metab Care. 2009 Nov;12(6):588-95. Review.

Nutrition
Serving Size: 1 Capsule | Servings Per Container: 90
IngredientsAmount Per Serving
Vitamin B1 (as Thiamine HCL)
50 mg
Vitamin B2 (as Riboflavin)
50 mg
Niacin (as Niacinamide)
50 mg
Vitamin B6 (as Pyridoxine HCL)
50 mg
Folate (as 5-Methyltetrahydrofolic Acid)
680 mcg
Vitamin B12 (as Methylcobalamin)
500 mcg
Biotin
75 mcg
Pantothenic Acid (as D-Calcium Pantothenate)
50 mg
Choline (as Choline Bitartrate)
19 mg
Inositol50 mg

Other Ingredients: Hydroxypropyl Methycellulose, Magnesium Stearate, Silicon Dioxide, Vegetable Capsule (Hypromellose)

Practitioner Resources

Professional Information

People Requiring:

  • Cardiometabolic Protocols

  • Support for Heightened Energy Levels

  • Hormone Support

  • Mood & Neurological Support

  • Sleep & Stress Management

Your Peers Approve. See Why

4.9
Rated 4.9 out of 5 stars
Based on 441 reviews
Total 5 star reviews: 421 Total 4 star reviews: 17 Total 3 star reviews: 2 Total 2 star reviews: 0 Total 1 star reviews: 1
99%would recommend these products
Reviews Summary
Customers say this online shopping experience consistently meets their expectations. Many reviews mention the fast shipping and straightforward ordering process. The website receives praise for its user-friendly navigation and product variety. Common feedback includes satisfaction with order fulfillment and packaging quality. While most users express high satisfaction, some note varying experiences with delivery speed.
441 reviews
  • Mitch C.
    Verified Buyer
    16 hours ago
    Reviewing
    Infiniwell
    Rated 5 out of 5 stars
    Great Service

    Jury is still out of whether or not BPC-157 will help with my ailments, but Infiniwell has been awesome. There was initial mistake with my order and it was fixed IMMEDIATELY. This was rad considering I reached out to them in the off hours of the night. Good stuff.

  • CURTIS M.
    Verified Buyer
    22 hours ago
    Reviewing
    Infiniwell
    Rated 5 out of 5 stars
    Greatest

    Good customer service fast delivery

  • Jake G.
    Verified Buyer
    Yesterday
    Reviewing
    Infiniwell
    Rated 5 out of 5 stars
    Awesome

    great

  • Dennis S.
    Verified Buyer
    Yesterday
    Reviewing
    Infiniwell
    Rated 5 out of 5 stars
    Easy to do biz with

    Easy to do biz

  • Richard T.
    Verified Buyer
    Yesterday
    Reviewing
    Infiniwell
    Rated 5 out of 5 stars
    🏃‍♂️ **A Game-Changer for My Recovery**

    I originally started taking this for a knee injury, but to my surprise, I saw noticeable improvement in my calf injury within just one week. I hadn’t been able to run for two years — and now, in just one month, I’ve completed:

    - One 2-mile run

    - Two 3-mile runs

    - Two 5.45-mile runs

    The progress has been incredible. It’s not just about getting back on my feet — it’s about reclaiming something I thought I’d lost. This has truly been a transformative experience for me, and I wholeheartedly recommend giving it a try if you're dealing with similar setbacks.

FAQs

When fatigue, brain fog, or mood dips start showing up regularly, it’s easy to overlook something as basic as B vitamin intake. Micronutrients power hundreds of biochemical reactions linked to energy, brain function, and stress response, and many people aren't getting enough of the active forms their body can actually use.

InfiniWell’s Methylated B-Complex is a dietary supplement formulated with active coenzyme forms of eight essential B vitamins, including B12 (methylcobalamin) and folate (as L-5-MTHF). This advanced formula supports energy metabolism, nervous system balance, neurotransmitter production, and a healthy response to stress. It also helps replenish nutrients that are easily depleted by poor diet, overprocessed foods, or high-stress lifestyles.

It’s especially supportive for individuals with genetic traits—like methylenetetrahydrofolate reductase (MTHFR)—who may have trouble processing standard B vitamins.

  • What is methylation, and why is it important?

    Methylation is a vital biochemical process that affects nearly every system in the body. It helps regulate how your body functions by influencing:

    • Gene expression: Controls which genes are turned on or off
    • DNA repair: Helps fix damaged cells to maintain genetic stability
    • Neurotransmitter production: Supports the creation of mood-regulating brain chemicals like serotonin and dopamine
    • Detoxification: Assists in breaking down and removing harmful substances from the body
    • Cardiovascular health: Helps convert homocysteine into methionine, which may support heart and blood vessel health by reducing elevated homocysteine levels linked to cardiovascular problems
    Some people—especially those with genetic traits like the MTHFR gene mutation—may have trouble converting standard folic acid, a synthetic form of vitamin B9, into its usable form. InfiniWell’s formula includes activated methyl donors like L-5-MTHF, which your body can use right away to support methylation and the conversion of homocysteine into amino acids methionine and cysteine, both important for cardiovascular and neurological health.

  • What is a methylated B-vitamin complex?

    More commonly known as methylated B-complex, this B vitamin supplement contains active, bioavailable forms of B vitamins such as methylfolate (L-5-MTHF) and methylcobalamin (B12)—meaning the body can use them directly without needing to convert them. It supports methylation, a biochemical process that regulates gene expression, neurotransmitter synthesis, and cellular energy production.

    InfiniWell’s Methylated B-Complex formula uses these active forms to support better absorption and performance, especially in people with reduced methylation capacity.

  • What does methylated B-complex do?

    A methylated B-complex contributes to several essential functions that support everyday health:

    • Support energy production at the cellular level
    • Maintain a healthy nervous system and overall neurological health
    • Produce mood-regulating neurotransmitters for emotional balance and brain function
    • Support mental and cardiovascular health through proper methylation
    • Promote immune health and adrenal function
    • Replenish B vitamins commonly lost to dietary deficiencies, poor absorption, or high-stress lifestyles

  • How is InfiniWell’s Methylated B-Complex different from standard B-complex vitamins?

    Unlike standard B-complex supplements that often use synthetic forms like folic acid or non-methylated B12, InfiniWell’s Methylated B-Complex delivers all eight essential B vitamins in a high-potency, balanced formula—along with choline, inositol, and biologically active folate (5-MTHF) for optimal methylation support.

    This advanced formulation includes:

    • 5-MTHF (methylated folate) and methylcobalamin (B12): To support methylation, an essential biochemical pathway that converts homocysteine into methionine and cysteine, amino acids that are important for cardiovascular and nervous system health
    • Vitamins B6 and B2: To help maintain energy production, support antioxidant function, and promote neurological health
    • Choline and inositol: To nourish nerve cells, support neurotransmitter production, and promote brain development and cognitive function

    Many standard formulas use folic acid, a synthetic form that requires enzymatic conversion before the body can use it. InfiniWell’s formula skips that step by using active coenzyme forms, which may be better absorbed, particularly in individuals with gene-related limitations like MTHFR variants.

    If you’re unsure whether a methylated B vitamin complex is right for you, it’s a good idea to talk to a health care professional, especially if you have known nutrient deficiencies, genetic variations, or are following a supplement regimen.

    This methyl B complex supports cardiovascular and mental health, nourishes the nervous system, and replenishes key nutrients, even in the face of oxidative stress or dietary deficiencies.

  • Is this supplement good for energy?

    Yes. B vitamins are essential co-factors in the body’s energy metabolism. They help convert carbohydrates, fats, and proteins into adenosine triphosphate (ATP), the molecule that stores and delivers energy at the cellular level.

    Methylated B vitamins make this process more efficient by skipping steps the body might struggle with due to genetic or enzyme limitations.

    InfiniWell’s formula supports steady, natural energy without relying on caffeine or stimulants.

  • How does this supplement support mental health and cognitive function?

    Methylated B vitamins help produce neurotransmitters like serotonin, dopamine, and norepinephrine—chemicals that regulate mood, focus, and emotional balance. They also support nervous system health and help maintain proper synaptic function.

    Low B vitamin levels may contribute to mental fatigue. InfiniWell's Methylated B-Complex helps rebuild your micronutrient reserve to support mood and focus over time.

  • How does this supplement support cellular energy and metabolic function?

    B vitamins are essential for energy metabolism. They help convert carbohydrates, fats, and proteins into ATP through the mitochondrial respiratory chain, the body’s primary system for generating energy at the cellular level. Low levels of B vitamins can disrupt energy generation, leaving you feeling sluggish or mentally foggy.

    InfiniWell’s formula includes coenzyme forms that help regulate mitochondrial enzymes (proteins that drive energy production in cells), activate nutrients like folate, and support nerve cell function. Nutrients like choline and B5 also support the metabolism of fatty acids, which your body uses for long-term fuel.

  • Who should consider using a methylated B-complex supplement?

    This supplement may be helpful for:

    Adults dealing with stress, irregular sleep, or gaps in their diet

    Ongoing stress, inconsistent sleep, and poor dietary habits can deplete B vitamin stores over time. A daily supplement can help replenish your micronutrient reserve and support mental clarity.

    Individuals experiencing low energy, brain fog, or mood changes

    These may signal low B vitamin levels. Methylated B vitamins support cellular energy, mood balance, and brain function—especially when diet, stress, or lifestyle create nutritional gaps.

    People with genetic variations (such as MTHFR)

    Certain gene variants may limit the body’s ability to convert standard folic acid into its usable form. A methylated B-complex provides nutrients in active forms the body can use right away.

    Those following vegan and vegetarian diets with limited B12 intake

    Since vitamin B12 is mainly found in animal products, people following vegan or vegetarian diets may benefit from supplementation to support energy and neurological health.

  • Is InfiniWell’s Methylated B-Complex safe for daily use?

    Yes—when taken as directed. InfiniWell’s formula is intended for regular use and contains no synthetic additives or folic acid. As always, consult your healthcare provider if you’re taking medications or managing a medical condition.

  • When should I take Methylated B-Complex?

    Take 1 capsule daily with or without food. For best results, take in the morning to support daytime energy and mood. If you’re taking other supplements or medications, ask your healthcare provider about the best timing.

  • What are the ingredients in Methylated B-Complex?

    Active ingredients:

    • Thiamine (vitamin B1): Supports carbohydrate metabolism and nervous system function
    • Riboflavin (vitamin B2): Helps produce cellular energy and supports antioxidant activity
    • Niacin (vitamin B3): Aids in energy production and supports cardiovascular health
    • Vitamin B6 (as pyridoxal-5-phosphate): Supports mood, hormone balance, and immune function
    • Folate (as L-5-MTHF): Promotes methylation, DNA synthesis, and prenatal health
    • Vitamin B12 (as methylcobalamin): Supports red blood cell production, brain function, and energy metabolism
    • Biotin (vitamin B7): Aids in the metabolism of fats, carbs, and proteins; supports healthy hair and skin
    • Pantothenic acid (vitamin B5): Essential for hormone production and energy metabolism
    • Choline bitartrate: Supports brain development, nerve signaling, and liver function
    • Inositol: Helps regulate mood and supports nerve signaling and cell membrane health
    Other ingredients:

    • Hydroxypropyl methylcellulose: Used to create the plant-based capsule shell
    • Magnesium stearate: A flow agent that ensures even distribution of ingredients during manufacturing
    • Silicon dioxide: Prevents clumping and keeps the powder dry and stable
    • Vegetable capsule (hypromellose): A cellulose-based capsule

  • How does this formula support cardiovascular health?

    B vitamins support homocysteine metabolism, a process critical to cardiovascular function. Elevated homocysteine levels—often linked to genetic variations or poor methylation—may impact heart health. This formula includes activated B6, folate, and B12 to support normal homocysteine levels and cardiovascular wellness.

  • How can I get B vitamins through food?

    B vitamins are naturally abundant in many whole foods. You can find different B vitamins in:

    • Dark leafy vegetables like spinach, kale, and collard greens (rich in folate)
    • Whole grains and legumes (sources of thiamine, niacin, and pantothenic acid)
    • Eggs, dairy, poultry, and red meat (sources of B12, B6, and riboflavin)
    • Nuts, seeds, and avocados (contain biotin and B6)
    • Fish and other fatty protein sources (help supply B12 and support metabolism of fatty acids)
    That said, factors like stress, aging, restrictive diets, or poor absorption can make it harder to meet your daily needs through food alone. A methylated B-complex can help maintain consistent levels, especially if you're looking to support energy, mood, and long-term health.

  • What if I have dietary restrictions?

    InfiniWell’s Methylated B-Complex is suitable for most dietary lifestyles. It contains no dairy, gluten, soy, or artificial colors. It’s also a good choice for vegans and vegetarians who may need extra vitamin B12. If you have specific dietary needs or health concerns, check with your doctor or nutritionist before adding any supplement to your routine.

  • Glossary

    Key terms to know:

    • B complex methylated: A supplement containing B vitamins in their activated (methylated) forms, which the body can use without conversion. Often recommended for individuals with methylation-related genetic limitations.
    • Coenzyme forms: Biologically active versions of vitamins that the body can use immediately, without needing to convert them through enzymatic processes.
    • Energy metabolism: The body’s process of converting carbohydrates, fats, and proteins into cellular energy (ATP), primarily through the mitochondrial respiratory chain.
    • Genetic factors: Inherited traits that can affect how efficiently the body processes nutrients, including the ability to activate certain B vitamins.
    • Greater oxidative stress: A state in which the body’s antioxidant defenses are overwhelmed by free radicals, potentially increasing nutrient demands, especially for B vitamins that support mitochondrial and nervous system health.
    • Lipid metabolism: The process by which the body breaks down and uses fats for energy, hormone production, and cellular maintenance—supported in part by vitamins like B5 and choline.
    • Methylated B vitamins: Activated forms of B vitamins that don’t require enzymatic conversion. Common examples include methylcobalamin (B12) and L-5-MTHF (folate).
    • Methylation: A biochemical pathway that regulates gene activity, detoxification, neurotransmitter production, and cardiovascular health.
    • MTHFR gene mutation: A genetic variation that may impair the body's ability to convert folic acid to its usable form, making methylated folate more appropriate for some individuals. May be identified through genetic testing.
    • Neurotransmitters: Brain chemicals such as serotonin, dopamine, and norepinephrine that regulate mood, focus, and stress response.