Alpha Lipoic Acid

2,628 Reviews Scanned

In order to provide you with accurate and valuable pieces of information and reviews, we have conducted in-depth research for the best alpha lipoic acid of 2024. In addition, you will find our top picks and highest-reviewed products in the section below.
# Preview Product Rating
1 Nutricost Alpha Lipoic Acid 600mg Per Serving, 240 Capsules - Gluten Free, Vegetarian Capsules, Soy... Nutricost Alpha Lipoic Acid 600mg Per Serving, 240 Capsules - Gluten Free, Vegetarian Capsules,... No ratings yet
2 Sundown Alpha Lipoic Acid 600mg, Supports Antioxidant Health, Dietary Supplement, 60 Capsules Sundown Alpha Lipoic Acid 600mg, Supports Antioxidant Health, Dietary Supplement, 60 Capsules No ratings yet
3 Horbaach Alpha Lipoic Acid 600mg | 240 Capsules | with Biotin Optimizer | Non-GMO and Gluten Free... Horbaach Alpha Lipoic Acid 600mg | 240 Capsules | with Biotin Optimizer | Non-GMO and Gluten Free... No ratings yet
4 Doctor's Best Alpha-Lipoic Acid 600, Helps Support Glucose Metabolism and Regenerate Antioxidants*... Doctor's Best Alpha-Lipoic Acid 600, Helps Support Glucose Metabolism and Regenerate...
5 IMMUNOVITES Stabilized R-Alpha Lipoic Acid ((True)) 600mg per Serving [[High Potency & up to 40x... IMMUNOVITES Stabilized R-Alpha Lipoic Acid ((True)) 600mg per Serving [[High Potency & up to 40x... No ratings yet
6 Superior Labs Alpha Lipoic Acid - Pure Non-GMO ALA 600mg (4 Month Supply) 120 Servings - Zero... Superior Labs Alpha Lipoic Acid - Pure Non-GMO ALA 600mg (4 Month Supply) 120 Servings - Zero... No ratings yet
7 THORNE Alpha-Lipoic Acid - 300 mg - Supplement Liver Detox, Antioxidant Support, Nerve Health and... THORNE Alpha-Lipoic Acid - 300 mg - Supplement Liver Detox, Antioxidant Support, Nerve Health and... No ratings yet
8 NOW Supplements, Alpha Lipoic Acid 600 mg with Grape Seed Extract & Bioperine®, Extra Strength, 120... NOW Supplements, Alpha Lipoic Acid 600 mg with Grape Seed Extract & Bioperine®, Extra Strength,... No ratings yet
9 Simply Natures Pure Alpha Lipoic Acid 600mg 120 Veggie Capsules, Non-GMO Thioctic Acid 4 Month... Simply Natures Pure Alpha Lipoic Acid 600mg 120 Veggie Capsules, Non-GMO Thioctic Acid 4 Month... No ratings yet
10 BULKSUPPLEMENTS.COM Alpha Lipoic Acid Capsules - ALA Supplement, Alpha Lipoic Acid 600mg - ALA... BULKSUPPLEMENTS.COM Alpha Lipoic Acid Capsules - ALA Supplement, Alpha Lipoic Acid 600mg - ALA...
11 Pure Encapsulations Alpha Lipoic Acid 600 mg - ALA Supplement for Liver Support, Antioxidants, Nerve... Pure Encapsulations Alpha Lipoic Acid 600 mg - ALA Supplement for Liver Support, Antioxidants,...
12 NOW Supplements, Alpha Lipoic Acid 250 mg, Supports Glutathione Production*, Free Radical... NOW Supplements, Alpha Lipoic Acid 250 mg, Supports Glutathione Production*, Free Radical... No ratings yet
13 Toniiq 1000mg Ultra High Strength Alpha Lipoic Acid Capsules - Highly Purified 99%+ USP Standard -... Toniiq 1000mg Ultra High Strength Alpha Lipoic Acid Capsules - Highly Purified 99%+ USP Standard... No ratings yet
14 NatureBell Alpha Lipoic Acid 600mg Per Serving with Vitamin B1 Complex | 4 in 1 - [R-ALA | S-ALA |... NatureBell Alpha Lipoic Acid 600mg Per Serving with Vitamin B1 Complex | 4 in 1 - [R-ALA | S-ALA... No ratings yet
15 Best Naturals Alpha Liopic Acid 600 mg 120 Count - ALA Alpha Lipoic Acid Powerful Antioxidant Best Naturals Alpha Liopic Acid 600 mg 120 Count - ALA Alpha Lipoic Acid Powerful Antioxidant
16 Source Naturals Alpha Lipoic Acid, Time Released Antioxidant Protection* - 120 Time Release Tablets Source Naturals Alpha Lipoic Acid, Time Released Antioxidant Protection* - 120 Time Release Tablets No ratings yet
17 Alpha Lipoic Acid 1,000mg, 180 Veggie Capsules – 50/50 R-ALA & S-ALA for Max Bioavailability –... Alpha Lipoic Acid 1,000mg, 180 Veggie Capsules – 50/50 R-ALA & S-ALA for Max Bioavailability... No ratings yet
18 Jarrow Formulas Alpha Lipoic Sustain With Biotin, Dietary Supplement for Antioxidant, Cellular... Jarrow Formulas Alpha Lipoic Sustain With Biotin, Dietary Supplement for Antioxidant, Cellular... No ratings yet
19 Carlyle Alpha Lipoic Acid 600mg | Plus Biotin Optimizer | 90 Capsules | Non-GMO & Gluten Free... Carlyle Alpha Lipoic Acid 600mg | Plus Biotin Optimizer | 90 Capsules | Non-GMO & Gluten Free...
20 Puritan's Pride Alpha Lipoic Acid Softgel 300mg, Supports Antioxidant Health, 120 ct Puritan's Pride Alpha Lipoic Acid Softgel 300mg, Supports Antioxidant Health, 120 ct No ratings yet

SaleBestseller No. 1
Nutricost Alpha Lipoic Acid 600mg Per Serving, 240 Capsules - Gluten Free, Vegetarian Capsules, Soy...
  • Alpha Lipoic Acid - 240 Capsules Per Bottle; 120-240 Servings Per Bottle
  • 600mg of Potent, High Quality Alpha Lipoic Acid Per Serving (300mg Capsules)
  • Vegetarian Capsules. Always Over a Year Remaining Before Expiration (See bottom of bottle)
  • Non-GMO, Gluten Free, Soy Free, Vegetarian Friendly, And 3rd Party Tested
  • Made In a GMP Compliant, FDA Registered Facility
SaleBestseller No. 2
Sundown Alpha Lipoic Acid 600mg, Supports Antioxidant Health, Dietary Supplement, 60 Capsules
  • Each serving contains 600mg of Alpha Lipoic Acid to help turn glucose into cellular energy (2)
  • SUPPORTS ANTIOXIDANT HEALTH (2): Alpha Lipoic Acid is an antioxidant that helps fight free radicals (2); free radicals can cause oxidative stress that...
  • A ONE-PER-DAY ALPHA LIPOIC ACID SUPPLEMENT: One Alpha Lipoic Acid 600mg capsule daily helps to support antioxidant health
  • THIRD-PARTY TESTED: Sundown products are always third-party tested for safety and quality; we are a proudly American company that sources ingredients...
  • CLEAN (1) VITAMINS: All Sundown vitamins are Non-GMO and free of gluten; wheat; dairy; lactose and artificial flavors
SaleBestseller No. 3
Horbaach Alpha Lipoic Acid 600mg | 240 Capsules | with Biotin Optimizer | Non-GMO and Gluten Free...
  • ALPHA LIPOIC ACID: Premium form of ALA, a compound commonly known as the "universal antioxidant"
  • SCIENTIFIC FORMULA: 600 mg of ALA plus 999 mcg of Biotin per serving in quick-release capsules
  • EXPERTLY CRAFTED: Our professional formula is backed by our commitment to purity and potency
  • HORBAACH MANUFACTURERS: Laboratory Tested, Trusted Ingredients, Superior Quality, 100% Guaranteed!
  • NATURALLY FREE OF: Gluten, Wheat, Yeast, Lactose, Artificial Flavor, Artificial Color & Non-GMO
SaleBestseller No. 4
Doctor's Best Alpha-Lipoic Acid 600, Helps Support Glucose Metabolism and Regenerate Antioxidants*...
  • DOCTOR’S BEST ALPHA-LIPOIC ACID (ALA) - plays an important role in the production of cellular energy in the body. ALA is naturally occurring and...
  • SUPPORT YOUR BODY WITH ANTIOXIDANTS – ALA is a powerful antioxidant and supports the regeneration of antioxidants. Alpha lipoid acid also appears to...
  • SUPPORTS THE BODY’S DEFENSE AGAINST FREE RADICALS - recycles antioxidants such as Vitamin C and Vitamin E that have the ability to quench a wide...
  • FREE RADICALS FOR OVERALL WELL-BEING – free-radical fighting antioxidant ALA produces energy through ALA supplementation. Supports healthy aging,...
  • During the summer months products may arrive warm but Amazon stores and ships products in accordance with manufacturers' recommendations, when...
Bestseller No. 5
IMMUNOVITES Stabilized R-Alpha Lipoic Acid ((True)) 600mg per Serving [[High Potency & up to 40x...
  • POWERFUL ANTIOXIDANT: Alpha Lipoic Acid(ALA) the universal anti-oxidant is vital to your health, but sometimes your body doesn't have enough. It...
  • STABILIZED & HIGH POTENCY: R-ALA the High Potency supplement when not formulated correctly can be useless. Once R-ALA is connected to Sodium(Na), it...
  • HIGH ABSORPTION: Stabilized R-Alpha Lipoic Acid has been shown to have 40x more absorption to help produce desirable biological actions and bind to...
  • CONTAINS NO S-ALPHA LIPOIC ACID: Typical ALA products are a combination of both R and S versions of ALA, meaning 50% of the product is spent on an...
  • SUPPLEMENT FACTS BOXES: With so many Alpha Lipoic Acid to choose from, always confirm the Supplement Facts box on the label states "STABILIZED (Na)...
Bestseller No. 6
Superior Labs Alpha Lipoic Acid - Pure Non-GMO ALA 600mg (4 Month Supply) 120 Servings - Zero...
  • A POWERFUL ANTI-AGING ANTIOXIDANT – Our bodies need ALA to produce energy but only excess ALA - which can only be achieved through supplementation -...
  • HEALTHY NERVE FUNCTION, TINGLING HAND, FEET, LIMBS - Each serving contains powerful 600mg of pure ALA in a vegetable capsule for superior absorption....
  • ABSOLUTE PURITY - ZERO SYNTHETIC ADDITIVES, FILLERS, HEAVY METALS, ADULTERANTS - You will never see unnecessary additives such as stearates, dioxides,...
  • UNQUESTIONABLE QUALITY - ALL PRODUCTS PRODUCED IN 3rd PARTY CERTIFIED NSF CERTIFIED FACILITIES - Few are and can pass the stringent standards of NSF....
  • DON’T ASK US, ASK OUR CUSTOMERS – We are among the highest rated brands online and have serve thousands of satisfied customers with our high...
Bestseller No. 7
THORNE Alpha-Lipoic Acid - 300 mg - Supplement Liver Detox, Antioxidant Support, Nerve Health and...
  • Has important nerve protective effects
  • Supports liver health
  • Helps maintain mental sharpness
  • Thorne products contain ingredients from the purest sources worldwide. Flavors, colors, preservatives, and sweeteners are derived from natural...
  • Thorne's commitment to integrity and science-backed products has helped us earn the trust of thousTrusted: Thorne is trusted by 45,000 health...
Bestseller No. 8
NOW Supplements, Alpha Lipoic Acid 600 mg with Grape Seed Extract & Bioperine®, Extra Strength, 120...
  • CERTIFICATIONS/CLASSIFICATIONS: Kosher, Dairy Free, Egg Free, Made without Gluten, Nut Free, Soy Free, Vegan/Vegetarian
  • Product Note: Exposure to heat or sunlight may lead to melting/damage of product. Hence customers are expected to be available during the product...
  • GMP Quality Assured: NPA A-rated GMP certification means that every aspect of the NOW manufacturing process has been examined, including our...
  • Packaged in the USA by a family owned and operated company since 1968
Bestseller No. 9
Simply Natures Pure Alpha Lipoic Acid 600mg 120 Veggie Capsules, Non-GMO Thioctic Acid 4 Month...
  • WHY Buy our Alpha Lipoic Acid? We use the highest grade R-Lipoic Acid ensuring maximum benefit to YOU!
  • HOW does it help YOU? ALA is an antioxidant that is made by the body. But sometimes it needs a boost!
  • WHAT else is in Simply Nature's Pure ALA? ZERO fillers, ZERO binders and ZERO artifical ingredients!
  • WHERE is Simply Nature's Pure Alpha Lipoic Acid Made? Right Here in the USA!
Bestseller No. 10
BULKSUPPLEMENTS.COM Alpha Lipoic Acid Capsules - ALA Supplement, Alpha Lipoic Acid 600mg - ALA...
  • Elevate Your General Health and Well-being: Tailored to support your overall health, our Alpha Lipoic Acid capsules, in Alpha Lipoic Acid 600mg, is...
  • Versatility for all Lifestyles: Whether you're an athlete, a sprinter, or someone simply looking to stay healthy, our ALA supplement, in ALA capsules,...
  • Optimized Servings: With 2 capsules per serving, our Alpha Lipoic Acid 600mg capsules are structured to provide both ease of use and the ability to...
  • Transparent and Trustworthy: Experience the confidence that comes with choosing a supplement that not only meets rigorous third-party testing but also...
  • Commitment to Excellence: Produced in a facility compliant with strict cGMP standards, our Alpha-Lipoic Acid supplement, in ALA capsules, stands as a...
Bestseller No. 11
Pure Encapsulations Alpha Lipoic Acid 600 mg - ALA Supplement for Liver Support, Antioxidants, Nerve...
  • Antioxidant Supplement: Provides nutritional support for metabolic processes with alpha lipoic acid, an antioxidant that helps support cells against...
  • Nerve Support Supplement: Alpha lipoic acid supports nerve health, maintains healthy nerve function, and supports the nervous system
  • Supports Carbohydrate Metabolism: Alpha lipoic acid supports healthy carbohydrate uptake and helps to maintain healthy carbohydrate utilization*
  • ALA Supplement: Our supplements are made with only premium ingredients sourced from trusted suppliers and guided by our nutritional experts, then...
  • Pure Difference: What we leave out matters, too; Pure Encapsulations products are FREE FROM common allergens, artificial or unnecessary ingredients,...
SaleBestseller No. 12
NOW Supplements, Alpha Lipoic Acid 250 mg, Supports Glutathione Production*, Free Radical...
  • SUPPORTS GLUTATHIONE PRODUCTION*: Alpha lipoic acid (ALA) is naturally produced in the human body in very small amounts, but is also available through...
  • TAKE 1 CAPSULE DAILY: ALA is unique because it supports the body's free radical scavenging systems and can function in both water and fat...
  • NON-GMO: ALA can also recycle the antioxidant vitamins C and E, thereby extending their activities.*
  • GMP Quality Assured: NPA A-rated GMP certification means that every aspect of the NOW manufacturing process has been examined, including our...
  • Packaged in the USA by a family owned and operated company since 1968.
SaleBestseller No. 13
Toniiq 1000mg Ultra High Strength Alpha Lipoic Acid Capsules - Highly Purified 99%+ USP Standard -...
  • The Highly Purified Form of Alpha Lipoic Acid - Toniiq 1000mg per serving Alpha Lipoic Acid contains an unprecedented purity level of 99%+ (other...
  • Bioavailable - Alpha-Lipoic Acid has amazing health benefits, but purity and absorption have always been a major challenge; something most other alpha...
  • Setting a New Standard for Purity - To ensure that you are getting the highest-quality product, each batch is tested for quality and purity both...
  • Quality, First, and Foremost - Toniiq products are produced in a GMP-certified and NSF-approved state-of-the-art manufacturing facility right here in...
  • Each Batch is Individually Tested - We test each batch both ourselves and through a third-party independent laboratory to ensure our ingredients...
Bestseller No. 14
NatureBell Alpha Lipoic Acid 600mg Per Serving with Vitamin B1 Complex | 4 in 1 - [R-ALA | S-ALA |...
  • Efficiently absorbed ALA capsules 600mg with the special Myelinctin formula. A high bioavailable 4-in-1 water and fat soluble combination that...
  • Myelinctin is a special synergistic compound that contains two top grade forms of lipoic acid and b vitamins. The addition of thiamine and...
  • Taking an ALA supplement may replenish natural levels over time and can be used to support super antioxidant properties for energy production, nervous...
  • Authentic non-GMO ALA formula. Contains pure ingredients free of wheat, soy, dairy, gluten, eggs, fish, shellfish, peanuts, and tree nuts. All...
Bestseller No. 15
Best Naturals Alpha Liopic Acid 600 mg 120 Count - ALA Alpha Lipoic Acid Powerful Antioxidant
  • 3rd Party Lab Tested for Purity & Quality
  • 600 mg of Alpha Lipoic Acid per Capsule - 120 Capsules per Bottle.
  • Non-GMO & Gluten Free.
  • Proudly Made in USA, GMP Compliant, FDA Registered Facility.
  • No Artificial Color, Flavor or Sweetener, No Preservatives, No Sugar, No Milk, No Corn, No Soy, No Egg, No Lactose, No Gluten, No Wheat, No Yeast, No...
SaleBestseller No. 16
Source Naturals Alpha Lipoic Acid, Time Released Antioxidant Protection* - 120 Time Release Tablets
  • ULTIMATE PROTECTION. It is a critical component of an enzyme that generates acetyl coenzyme A, the start of the Krebs cycle that produces ATP in the...
  • SUPPORT YOUR BODY WITH ANTIOXIDANTS. It is a potent antioxidant and is active in both fat- and water-soluble regions of the cells. This makes ALA...
  • A HIGHLY EFFECTIVE ANTIOXIDANT. ALA scavenges and terminates free radicals. The quenching of free radicals is a highly important aspect of healthy...
  • OVER 40 YEARS OF TRUST. Source Naturals was created in 1982 by CEO Ira Goldberg to support each individual's potential to enjoy optimal health.
  • MANUFACTURED IN THE USA. Our facility is located in Scotts Valley California.
Bestseller No. 17
Alpha Lipoic Acid 1,000mg, 180 Veggie Capsules – 50/50 R-ALA & S-ALA for Max Bioavailability –...
  • Special Features – 2-in-1 alpha lipoic acid (ALA) vegetarian capsules, high bioavailable water & fat soluble forms, contains R-ALA & S-ALA to easily...
  • Benefits & Use – Due to ALA’s ability to be fat and water solubilized, this allows for ALA to reach a greater amount of antioxidant protection...
  • Dosage & Servings – 180 vegetable capsules per bottle with 3 veg capsules per serving, contains 500mg R-ALA with 500mg S-ALA per dose, up to a...
  • Purpose – As we age, the body’s natural production of ALA decreases and regular intake of Deal Supplement’s bioactive ALA may provide an optimal...
  • Quality Ensured – Non-GMO ingredients that are 3rd party lab tested and passed. Made without gluten, dairy, eggs, peanuts, soy, wheat, & yeast.
Bestseller No. 18
Jarrow Formulas Alpha Lipoic Sustain With Biotin, Dietary Supplement for Antioxidant, Cellular...
  • Antioxidant, Cellular Energy Production and Normal Glucose Metabolism Support Supplement: Contains one 120 count bottle of Jarrow Formulas Alpha...
  • Dietary supplement with 300 mg of Alpha Lipoic Acid, a cofactor in energy production involved in glucose fatty acid and amino acid metabolism
  • Each serving includes 330 mcg of Biotin, a cofactor necessary in the metabolism of fats and amino acids
  • Suggested Use: Adults, take one tablet one or two times a day with meals or as directed by your qualified healthcare professional
  • These statements have not been evaluated by the Food and Drug Administration; this product is not intended to diagnose, treat, cure, or prevent any...
SaleBestseller No. 19
Carlyle Alpha Lipoic Acid 600mg | Plus Biotin Optimizer | 90 Capsules | Non-GMO & Gluten Free...
  • ALPHA LIPOIC ACID: Premium form of ALA, commonly known as the "universal antioxidant"
  • ADVANCED FORMULA: 600 mg Alpha Lipoic Acid plus 999 mg Biotin per serving in quick release capsules
  • ROOTED IN WELLNESS: Carlyle provides premium, honest supplements in your pursuit to healthy living
  • CARLYLE MANUFACTURERS: Laboratory Tested, Trusted Ingredients, Superior Quality, 100% Guaranteed!
  • NATURALLY FREE OF: Gluten, Wheat, Yeast, Lactose, Soy, Artificial Flavor, Preservatives and Non-GMO
SaleBestseller No. 20
Puritan's Pride Alpha Lipoic Acid Softgel 300mg, Supports Antioxidant Health, 120 ct
  • Puritan's Pride products are made with the highest quality ingredients available.
  • Over 40 years in business and 19 million customers served with Puritan's Pride vitamins and supplements
  • Puritan's Pride Vitamins supports healthy immune function and promotes well-being.
  • Our vitamins helps promote healthier lives

What should you look for when purchasing the best alpha lipoic acid?

To purchase the right product, you need to research its qualities and flaws.

Diversity is highly important since it offers options for different budgets and lifestyles. Choosing the best alpha lipoic acid requires asking yourself the right questions to ensure the product is precisely what you need.

To make your money’s worth, you should thoroughly research the options you are presented with and ask the following questions:

  • How does buying alpha lipoic acid benefit me?
  • Is it worth the price?
  • Which alpha lipoic acid is the best option to go for in the nowadays market?
  • What features are essential when purchasing the alpha lipoic acid?
  • Which brand of the this is most trustworthy?
  • Which alpha lipoic acid has the best price/value ratio?

You are bound to have even more vitally important questions when purchasing the alpha lipoic acid. The best way to inform yourself about it is a meticulous exploration of internet resources and research for second opinions and customer reviews.

Various websites can hold pieces of information necessary for purchasing a top-notch product. Forums, reviews, and rating websites can all offer you the instrumental info needed to buy the best possible alpha lipoic acid. In order to get accurate information, you should explore trustworthy websites that have a history of providing customers with specific and genuine content.

Curee.org worked hard and conducted comprehensive research to get you the necessary information regarding the alpha lipoic acid.

It helps us to put together a high-quality buying guide that will provide you with pros and cons, features, and reasons the product is the right choice for you. To get the alpha lipoic acid that will suit your needs best, you should consider the following factors:

Advantages of the Brand

Every brand of alpha lipoic acid holds different values to it. Typically, each and every brand will have something unique that will attract your attention and make you consider their product as the leading option. The more unique the feature is, the more it will allure you to the product and its value.

Features

Each product has some value that separates it from the pack. Therefore, always ask yourself what features are relevant when purchasing the alpha lipoic acid? What is essential for this product to have?

Value of the product

This factor is crucial since it can tell you how much value you will get for your money’s worth when purchasing this.

Customer reviews

The second opinion always matters when you cannot decide on which product you should opt for. These reviews will paint you the picture of the alpha lipoic acid by real-world customers that had experience with the product and inform you on how well it served them.

Customer ratings


Customer ratings are similar to reviews but offer you a number or star rating of the alpha lipoic acid, which can tip the scales when you are unsure which product to choose.

Reliability

To get the alpha lipoic acid that will serve your purposes and pay off, you need to choose a reliable and durable one. High-quality product equals wise investment and peace of mind.

Beware off-brands

Purchasing the off-brand alpha lipoic acid is unwise. Always look for reliable brands that offer you the highest possible quality and are trusted and recognized as a legitimate option.

Curee.org always tends to bring its visitors accurate and valuable information that is relevant to the alpha lipoic acid. We always refresh and update our content since our priority is and has always been top-notch user experience.

If you have any questions or suggestions about our presentation of the this product, please let us know. You can contact us here, and if our article has made you interested in our work, you can find more about us and better realize our vision and what it represents.

FAQ:

Q: How much alpha lipoic acid should you take a day?

A: But alpha-lipoic acid is an unproven treatment, there is no established dose. Studies have used between 600-1,200 milligrams daily for diabetes and neuropathy; one review concluded that the evidence is convincing for the use of 600 milligrams daily for three weeks on symptoms of diabetic neuropathy.

Q: How does alpha lipoic acid help with weight loss?

A: Alpha lipoic acid may help reduce appetite, increase an individual’s energy, and stimulate the metabolism by regulating insulin levels. It can help prevent weight gain, but should not be relied upon as a sole source of weight loss support. It is still important to decrease caloric intake and increase physical activity.

Q: What is the best time of day to take alpha lipoic acid (ALA)?

A: There are specific times during the day that ALA is best taken. Due to the fact that ALA is an antioxidant it should be consumed as far away from the workout period as possible. This is because the metabolic damage that occurs during training is a key trigger for muscle growth.