8 Low Caffeine Pre-Workouts That Are Still VERY Effective

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When it comes to pre-workout supplements, you might find yourself wondering if more equals better. In the case of caffeine content, I’ve found that a little less goes a whole lot further. You get fewer jitters and avoid the post-workout crash. 

Below, I’m sharing my experience testing eight low-caffeine pre-workouts, which still provide incredible benefits while minimizing the adverse side effects of the “high stim” products.

In a Hurry? Here’s The Top Pick!

• Transparent Labs Stim-Free Pre-Workout takes the top spot with 0mg of caffeine per serving while providing clinical doses of all the key ingredients to support strength, stamina, pump, and mental focus. 

• Many pre-workouts that use little to no caffeine tend to either have low doses of all ingredients (as with C4 Original or Optimum Nutrition Gold Standard Pre) or focus solely on muscle pump. Transparent Labs provides a well-rounded formula to improve ALL aspects of training.

• Transparent Labs Stim-Free only costs $1.66 per serving, making it a great value for its benefits. Other clinically dosed, low-stimulant products like Pump Serum and Pre-Kaged Stim Free cost anywhere from $2.75 to $3.10 per serving. 

Why Trust My Recommendation? 

I have been a supplement store manager for over ten years, allowing me to test dozens of pre-workout products and provide insight into industry trends and consumer behaviors. I am a Certified Strength and Conditioning Specialist and Certified Nutrition Coach who has personally tried and tested every pre-workout on this list. 

How To Define “Low Caffeine” In Pre-Workout

What constitutes “low caffeine” can vary from individual to individual. Someone who typically drinks coffee and/or energy drinks throughout their day will have a different caffeine threshold than someone who never does. 

For the purposes of this article, I have defined a low-caffeine pre-workout to be one that is 200mg of caffeine or less. 

The first reason is that the FDA recommends a safe upper limit of 400mg of caffeine daily. 

That is to say, it is the FDA’s belief that if you consume 400mg of caffeine per day or less, you are unlikely to experience any negative long-term side effects. 

The 200mg I have suggested as “low caffeine” is 50% below the limit set by the FDA. 

Also, in my evaluation of more than 50 pre-workout supplements available on the market, I’ve found that the caffeine levels vary from 0 to 425mg per serving, with most products falling between 200 and 325mg. 

I chose 200mg or less to be on the bottom end of this trend. 

Key Criteria: How I Ranked The Pre-Workouts

In my experience evaluating pre-workout supplements, I have found that low-caffeine products tend to have two significant problems.

First, products that are low in caffeine tend to be low in all ingredient doses, resulting in products that provide little overall benefit. 

The second issue is that low-caffeine products, especially those that are caffeine-free, tend to focus predominantly on ingredients for increasing pump and don’t include many ingredients for strength, stamina, or mental focus. 

As such, I have based my evaluations on the following criteria:

• Caffeine Content: Contains 200mg of caffeine or less per serving.

• High-Quality Ingredients: High-quality ingredients, like patented or trademarked ones, have a stronger body of clinical evidence proving their effectiveness. Products that use these high-quality ingredients are more likely to deliver their advertised benefits.  

• Clinical dosing: As mentioned, many products with low caffeine also tend to have low doses of all other ingredients, meaning you won’t see the desired benefits. I assessed these pre-workouts based on whether they had clinical doses of their key ingredients and honestly highlighted any drawbacks of any products.

• Cost per serving: I recognize that many people have different supplement budgets. I have included pre-workouts that cover the low to higher-cost per-serving spectrum to help you choose the best product. 

• Taste And Mixability: Pre-workouts are only effective if you actually drink them. I have done my best to choose products that have the best of both worlds regarding being high-quality products that still taste good and mix well. 

Best Low-Caffeine Pre-Workouts

• Best Overall: Transparent Labs Stim-Free (0mg caffeine)
• Runner Up: XWerks Ignite (150mg caffeine)
• Best for Endurance: 4Gauge (150mg caffeine)
• Most complete formula: Transparent Labs Bulk (200mg caffeine)
• Best for mental focus and mood: Bucked Up (200mg caffeine)
• Best for Fat Loss: Transparent Labs Lean (180mg caffeine)
• Best for Strength: MyPro The Pre-Workout (150mg caffeine)
• Best for Pump: Pump Serum (0mg caffeine)

1. Transparent Labs Stim-Free (0mg caffeine)

Overall rating: 4.5/5

I have been obsessed with this pre-workout since I got my hands on it in early 2023. 

Transparent Labs Stim-Free is the highest quality, most complete caffeine-free pre-workout I have ever encountered. 

Transparent Labs Stim-Free contains clinical doses of citrulline, beta-alanine, betaine, taurine, and elevATP ®, which are all ingredients with research backing them as being effective for increasing nitric oxide production, endurance, strength, and energy. 

Despite not having any caffeine, I felt like I had the strength and stamina to push through all of my regular workouts, and I enjoyed the fact that there were no side effects like jitteriness or insomnia. 

Transparent Labs uses high-quality, patented ingredients in their formulas and avoids using any artificial flavors or colors. 

Their products are third-party tested and Informed Choice certified, making them a suitable option for any tested athletes. 

You can purchase the Stim-Free pre-workout for $1.66, which is a remarkable value for the doses of ingredients that it provides. 

Learn more in my detailed review of Transparent Labs Stim-Free.

Highlights

• Caffeine-Free
• Third party tested and Informed Choice Certified
• No artificial flavors or colors

Drawbacks

• Doesn’t provide a significant mental focus boost

2. XWerks Ignite (150mg caffeine)

Overall rating: 4/5 

When I first saw the XWerks Ignite formula, I was underwhelmed and wasn’t expecting much. From a technical standpoint, some key ingredients in Ignite are underdosed, including citrulline and beta-alanine, two key ingredients for increasing nitric oxide production and endurance. 

Despite this, I had incredible results when I tested XWerks Ignite. I set a personal best in my 5-mile run time and felt I could have kept running forever. I felt the same kind of stamina when I hit the weight floor for my strength days. 

I also noticed a mood-boosting energy from this pre-workout, which I found made up for any shortcomings since I had the enthusiasm to push through workouts, even with minimal ingredients for supporting strength. 

Ignite contains 150mg of caffeine per serving, equal to approximately 1 medium cup of commercial coffee. Notably, with this product, even though it has caffeine, I didn’t experience any jitteriness or anxiety, and I did not experience a post-workout crash. 

XWerks Ignite costs around $1.63 per serving, which is almost exactly what I calculated the average cost of pre-workout to be when assessing more than 50 commercially available products. 

Ignite has four flavors: Green Apple, Watermelon, Blue Raspberry, and Orange. 

Learn more in my detailed review of XWerks Ignite.

Highlights

• 150mg of caffeine
• Blend of nootropics to boost mood and mental focus
• Great taste

Drawbacks

• Does not provide significant pump
• Uses synthetic sweeteners and flavors

3. 4Gauge (150mg caffeine)

Overall rating: 4/5 

4Gauge pre-workout might be interchangeable for the runner-up spot with XWerks Ignite, depending on your preferences. 

Where XWerks supports mental focus, 4Gauge prioritizes endurance, pump, and recovery. To be transparent, when I tested 4Gauge personally, I didn’t notice a significant muscle pump despite the product having a clinical 6g dose of citrulline per serving, but that could have been due to personal factors and not the product itself. 

One great thing about 4Gauge is their commitment to natural ingredients. They don’t use any artificial flavors or colors in their products, and they add food-based ingredients like beetroot powder and coconut water to boost athletic performance. 

4Gauge has 150mg of caffeine, enough to provide good energy but not so much that you would experience negative side effects like jitteriness or anxiety. 

This formula is best suited for HIIT and cardio-based exercise and does not contain any beta-alanine, making it suitable for people who don’t like the “tingly feeling” they sometimes get from pre-workouts. 

Learn more in my detailed review of 4Gauge.

Highlights

• 150mg caffeine
• Great hydration and endurance formula
• No artificial flavors, colors, or sweeteners

Drawbacks

• Does not contain many ingredients for strength or mental focus
• Has the aftertaste of beets

4. Transparent Labs Bulk (200mg caffeine)

Overall rating: 4.5/5

This product could have held the top spot on this list, but because it contains 200mg of caffeine, the upper end of the low-caffeine threshold, I further bumped it in favor of options with less caffeine. 

The formula of Transparent Labs Bulk is very similar to the Transparent Labs Stim-Free formula. They contain the same clinical doses of the key performance-enhancing ingredients, including citrulline, beta-alanine, betaine, and taurine. 

Transparent Labs Bulk does not contain elevATP® (a caffeine-free energy source) and instead sees the addition of 200mg of caffeine and Alpha-GPC, Theanine, and Theobromine to boost energy and mental focus. 

Like Stim-Free, Bulk does not use any artificial flavors, colors, or preservatives in its formula and is third-party tested for quality and label accuracy.

The only potential downside to Transparent Labs Bulk is that the large scoop size requires quite a bit of water (around 12oz or about 350ml) to mix well. This isn’t an issue that is exclusive to this pre-workout but rather is common among most clinically-dosed pre-workouts. 

Bulk costs $1.66 per serving, making it one of the best value pre-workouts on the market.

Learn more in my detailed review of Transparent Labs Bulk.

Highlights

• 200mg of caffeine
• The most comprehensive blend of clinically dosed ingredients
• No artificial flavors or colors
• Third-party tested and Informed Choice Certified

Drawbacks

• Requires lots of water to mix
• Is on the higher end of the low-caffeine spectrum and may be too much for some users

5. Bucked Up (200mg caffeine)

Overall rating: 3.5/5

In the same way that I was surprised by how good I felt while taking XWerks Ignite, I was blown away by how good I felt taking Bucked Up. 

Bucked Up contains a clinical dose (6g) of citrulline malate for increasing nitric oxide production, but all of the other ingredients used in the formula either fall short of clinical dose standards or don’t have enough evidence behind them to have an established dose. 

After testing dozens of different pre-workout supplements during my career, Bucked Up still stands out in my top 5 for its euphoric energy. When taking Bucked Up, I felt incredibly excited to be working out and wanted to squeeze the most out of every single rep, often staying at the gym past my usual workout time because I wanted to keep going. 

My reason for rating this below Ignite, which also is a mood-boosting pre-workout, is that it contains 200mg of caffeine per serving, and since I am specifically rating low caffeine pre-workouts, I gave higher list spots to those that had a lower caffeine content. 

Bucked Up does use artificial sweeteners and flavors, but they’ve removed artificial food dyes and use natural options like beta carotene, beetroot powder, and blue spirulina to color their pre-workout. 

Bucked Up costs around $1.66 per serving, a good value for individuals who want to feel increased energy and motivation from their pre-workout. 

Those who want to prioritize strength and athletic performance might opt for Transparent Labs Bulk instead. 

Learn more in my detailed review of Bucked Up.

Highlights

• 200mg of caffeine
• Blend of adaptogens and nootropics provides a euphoric feeling
• More than 20 flavors available
• Great for individuals who want to feel motivated to go to the gym

Drawbacks

• Fails to meet clinical doses of some key performance ingredients
• High end of the low-caffeine spectrum may be too high for some individuals

6. Transparent Labs Lean (180mg caffeine)

Overall rating: 4/5 

Transparent Labs Lean is the third Transparent Labs pre-workout on this list. 

Lean contains a few cross-over ingredients to Bulk and Stim-Free, like citrulline, beta-alanine, and betaine. The key difference is that only citrulline meets clinical dose standards, while the other two ingredients contain lower doses falling just shy of what has been proven effective in clinical research. 

Notable additions to Lean include acetyl l-carnitine, choline, and chromium. These ingredients can contribute to improved mood, memory, and fat breakdown. 

When I tested Lean, I appreciated the clean energy that the 180mg of caffeine provided, and I felt like I had good mental focus with no jitteriness or crash afterward. 

I also noticed that I sweat A LOT more than I did with other pre-workouts (likely due to the carnitine). 

While I believe that Bulk and Stim-Free are preferable options to maximize strength, power, and muscular endurance, I think Lean is a fantastic option for cardio sessions or individuals who want to increase fat loss. 

Lean has the same benefits mentioned with Bulk and Stim-Free, including no artificial flavors or colors and publicly disclosed third-party testing results. 

The cost per serving is $1.66, and Lean is available in 9 delicious flavors.

Learn more in my detailed review of Transparent Labs Lean.

Highlights

• 180 mg of caffeine
• Third party tested
• No artificial flavors or colors
• Contains additional ingredients to support fat loss

Drawbacks

• Not very effective for pump or strength
• Misses clinical doses for a few key ingredients

7. MyPRO The Pre-Workout (150mg caffeine)

Overall rating: 3/5 

The Pre-Workout by MyPRO is very similar in formula to Transparent Labs Bulk, but MyPro has slightly lower doses of all ingredients. 

The Pre-Workout contains citrulline (4g), betaine (2.5g), creatine (2g), and beta-alanine (2g). These ingredients support nitric oxide production, strength, and muscular endurance. 

Alongside the 150mg of caffeine, The Pre-Workout also contains n-acetyl l-tyrosine and theacrine to boost mental focus and energy while reducing the likelihood of a post-workout crash. 

I find this pre-workout the best option for anybody new to pre-workout. It has a lower caffeine level to reduce the likelihood of jitteriness, anxiety, or insomnia. 

The lower doses of other ingredients also reduce the likelihood of experiencing other side effects commonly associated with pre-workout, like nausea and skin tingling. 

The Pre-Workout has a slightly lower cost per serving than the other products, coming in at around $1.50 per serving. The subscribe and save feature by MyPro allows you to save up to 40% off of your pre-workout, making this the absolute best cost-per-serving option.

Highlights

• 150 mg of caffeine
• Well-rounded formula for strength, endurance, and mental focus

Drawbacks

• Falls short on clinical doses of key ingredients for strength and pump
• Uses artificial flavors, sweeteners, and food dyes

8. Pump Serum (0mg caffeine)

Overall rating: 3/5 

Pump Serum is a massively dosed pre-workout, delivering more than 30 grams of performance and pump-enhancing ingredients per scoop. 

I felt like this was an important addition to the low-caffeine list since it is one of the highest-dosed caffeine-free options available on the market, and I did not experience any negative side effects like nausea when I tested it. (Some products I tested in the past that were dosed this high had negative side effects like upset stomach, bathroom trips, and headaches). 

This formula is completely stimulant-free, and the ingredients are all specifically chosen to boost nitric oxide production. 

Increased nitric oxide production can have a vasodilating effect, meaning more blood flow and oxygen delivery to the muscles, which can support athletic performance and recovery. 

However, most people take nitric oxide boosters for aesthetic muscle pump effects. 

Pump Serum had the most significant muscle pump effect of any pre-workout I tested (when a 2-scoop serving was taken). 

Despite advertising itself as a 1 or 2-scoop product, most ingredients only reach clinical dose standards when a 2-scoop serving is taken. This makes Pump Serum $2.75 per serving and may be out of budget for some individuals. 

I will be completely honest: I felt like this product had among the worst taste and mixability of any pre-workout I have tested, but it was worth it for the incredible pump effects.

Learn more in my detailed review of Pump Serum.

Highlights

• Caffeine-free
• No skin tingling or negative side effects
• The best option for people who want the best muscle pumps

Drawbacks

• Poor taste and mixability
• Does not provide energy or mental focus
• Expensive 

Products That Didn’t Make The Cut

• C4 Original: Meets the low-caffeine criteria but falls short on clinical dosing for nearly every other ingredient. 

• O.N. Gold Standard Pre: Meets low-caffeine criteria but fails to deliver significant doses of most ingredients. 

• Alani Nu Pre-Workout: Meets low-caffeine criteria and has reasonable doses of the ingredients it includes. The items on this list have more ingredients overall and are more well-rounded pre-workouts. Alani Nu is not a bad option, it just didn’t crack the Top 8. 

• Gorilla Mode Nitric: It delivered incredible pumps, but I found that TL Stim-Free and Pump Serum edged it out for caffeine-free options. Still a good option to try, but very expensive and doesn’t taste or mix well. 

• Swolverine Pre: A caffeine-free pre-workout that is great for beginners but was more expensive than Transparent Labs and didn’t provide as good of a benefit. 

• Legion Pulse Stim-Free: Another great, stim-free option. Clinically dosed, third-party tested, and high-quality ingredients. It didn’t make the cut because of its high cost per serving ($2.25) compared to Transparent Labs.

• Naked Energy: A high-quality formula with zero flavors, colors, or additives. It didn’t make the cut because its ingredients are too low dosed to provide a significant benefit.

Understanding Caffeine in Pre-Workout

Caffeine is naturally found in over 60 plants, including coffee beans and tea. It is a stimulant that speeds up the central nervous system, resulting in an increase in alertness and mood. 

When taken before exercise, caffeine can improve nearly every aspect of athletic performance. It can improve performance in high-intensity activities (HIIT), improve muscular endurance, strength, and power, and improve cardiovascular (aerobic) performance. 

Furthermore, caffeine is incredibly inexpensive to include in pre-workouts, adding to its appeal.

3 Reasons to Avoid High Stim Pre-Workout

If you work out late in the evening

Even if you consider yourself someone well-adapted to caffeine, consuming high amounts of caffeine within the 5 hours before bed can still hurt your sleep. 

Research has shown that 400mg of caffeine taken 0, 3, and 6 hours before bedtime all significantly disrupt sleep. 

If this negative impact on sleep is experienced over multiple nights, it may harm daytime function. 

Possible side effects (jitteriness, heart palpitations, anxiety)

There are many documented negative side effects of high caffeine consumption (when used daily or in acute doses over 400mg daily). 

These side effects include jitteriness, nausea, elevated heart rate, heart palpitations, insomnia, and anxiety. 

If you want to consume other sources of caffeine throughout the day

Personally, I am unwilling to sacrifice my morning cup of coffee because it is a mood-boosting, ritualistic part of my day.

The FDA recommends a safe upper limit of 400mg of caffeine daily. If you enjoy consuming sources of caffeine aside from pre-workout, like coffee, tea, energy drinks, or sodas,, combining those drinks with pre-workouts could push you into potentially unsafe daily caffeine intakes. 

Are Pre-Workouts With Low Caffeine Still Effective?

Yes, pre-workouts that are low in caffeine are still effective. 

Other pre-workout ingredients can increase physical energy (e.g., Peak O2®, Peak ATP®), and stimulant-free nootropics can enhance mental focus and mood without adding more caffeine (e.g., DMAE, alpha-GPC.)

Ingredients like creatine, beta-alanine, citrulline, and betaine can all provide performance benefits, including increased strength, endurance, blood flow, and power.  

Which Ingredients Can Be Used As Alternatives To Caffeine For Increasing Energy?

• PeakO2 ®: A patented blend of adaptogenic mushrooms that help the body adapt to stress and increase power and endurance

• PeakATP ®: A patented form of  ATP Disodium, providing a source of literal energy to the body and acting as a signaling molecule to increase ATP (energy) production

• Carbohydrates: Carbs are used by the body during all of its energy systems and can be beneficial for enhancing athletic performance and recovery when consumed before, during, and after exercise

• Taurine: Plays a role in energy metabolism and can delay time to exhaustion 

Which Ingredients Can Be Used As Alternatives To Caffeine For Increasing Mental Focus?

• Agmatine: A chemical found in bacteria and plants that functions as a neurotransmitter in the brain

• Alpha-GPC: A precursor to acetylcholine (a chemical messenger in the brain). Research has linked acetylcholine to improved memory and cognitive function

• DMAE: affects neurotransmitters in the brain associated with memory and has neuroprotective properties. Supplementation may positively influence mood, memory, and mental focus

• Huperzine: Huperzine can increase acetylcholine levels in the brain, which can result in improved memory and cognitive function. 

• Nitrosigine ®: A patented ingredient designed to increase nitric oxide production in the body. THe latest research shows that it improves working memory and cognitive function in adults. 

How To Choose The Best Low Stimulant Pre-Workout

1. Pick your caffeine level

The first step in choosing the best low-caffeine pre-workout for yourself is determining how much caffeine you want per serving. 

For reference, one 8-oz cup of coffee brewed at home contains approximately 95mg.

2. Choose your additional benefits

Decide which benefits you want your pre-workout to offer you. 

Examples include energy, mental focus, strength, endurance, and muscle pump. After finding pre-workouts that fit your desired caffeine level, find options whose ingredients best match the benefits you hope to see from your pre-workout. 

For extra help, find my Supplement Ingredient Guide, which outlines more than 25 different pre-workout ingredients and what they do. 

3. Assess your budget

Once you have found some options that contain your ideal caffeine intake and ingredients, choose the option that best falls within your budget. 

The lowest range for clinically dosed, low-caffeine pre-workouts falls around $1.50-$1.75 per serving. Some options go as high as $2 to $3 per serving.

If all of the options you chose fall out of your price range, revert back to step 2, refine which benefits are most important to you, and filter out less important ones. Repeat as necessary. 

If you are still struggling to find a commercially available pre-workout that suits your desires and budget, consider a Do It Yourself pre-workout that allows you to save money on cost per serving and choose your desired ingredients. 

Frequently Asked Questions

What Pre-Workout Has The Least Amount of Caffeine?

There are many high-quality pre-workout supplements with zero caffeine, like Transparent Labs Stim-Free.

Of the caffeinated options, Naked Energy is among the lowest with 100mg of caffeine per scoop.

How Long Does 200mg of Caffeine Last?

Typically, the effects of caffeine will be felt anywhere from 3-5 hours after ingestion.

The half-life of caffeine is around 5 hours. If you take 200mg of caffeine, half of that amount remains in your system 5 hours after ingestion. 

Are low-caffeine pre-workouts suitable for all types of workouts?

Low-caffeine pre-workouts are available in various formulas and can be suitable for all kinds of workouts, including strength, sprinting/power, endurance, or HIIT style workouts.

Transparent Labs Stim-Free provides the most well-rounded, caffeine-free formula. 

How to transition from a high-caffeine to a low-caffeine pre-workout?

While it is safe and reasonable to switch from a high-caffeine to a low-caffeine pre-workout immediately, you might prefer to do a gradual taper.

This can be done by slowly reducing the serving size of your current pre-workout until it matches the caffeine content of the one you want to take. 

Can they be used at any time of the day without affecting sleep?

Since the effects of caffeine can be felt for several hours after ingestion, even low-stimulant pre-workouts may affect sleep if taken too close to bedtime.

If you work out late in the evening and want to ensure your pre-workout does not disrupt your sleep, try a caffeine-free option like Transparent Labs Stim-Free.

References

Davis JK, Green JM. Caffeine and anaerobic performance: ergogenic value and mechanisms of action. Sports Med. 2009;39(10):813-32. doi: 10.2165/11317770-000000000-00000. PMID: 19757860.

Guest NS, VanDusseldorp TA, Nelson MT, Grgic J, Schoenfeld BJ, Jenkins NDM, Arent SM, Antonio J, Stout JR, Trexler ET, Smith-Ryan AE, Goldstein ER, Kalman DS, Campbell BI. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021 Jan 2;18(1):1. doi: 10.1186/s12970-020-00383-4. PMID: 33388079; PMCID: PMC7777221.

Drake C; Roehrs T; Shambroom J; Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med 2013;9(11):1195-1200.

de Souza JG, Del Coso J, Fonseca FS, Silva BVC, de Souza DB, da Silva Gianoni RL, Filip-Stachnik A, Serrão JC, Claudino JG. Risk or benefit? Side effects of caffeine supplementation in sport: a systematic review. Eur J Nutr. 2022 Dec;61(8):3823-3834. doi: 10.1007/s00394-022-02874-3. Epub 2022 Apr 5. PMID: 35380245.

Buford TW, Kreider RB, Stout JR, Greenwood M, Campbell B, Spano M, Ziegenfuss T, Lopez H, Landis J, Antonio J. International Society of Sports Nutrition position stand: creatine supplementation and exercise. J Int Soc Sports Nutr. 2007 Aug 30;4:6. doi: 10.1186/1550-2783-4-6. PMID: 17908288; PMCID: PMC2048496.

Bellinger PM. β-Alanine supplementation for athletic performance: an update. J Strength Cond Res. 2014 Jun;28(6):1751-70. doi: 10.1519/JSC.0000000000000327. PMID: 24276304.

Gough, L.A., Sparks, S.A., McNaughton, L.R. et al. A critical review of citrulline malate supplementation and exercise performance. Eur J Appl Physiol 121, 3283–3295 (2021). https://doi.org/10.1007/s00421-021-04774-6

Van Every, Derrick W. BS1; Plotkin, Daniel L. BS1; Delcastillo, Kenneth BS1; Cholewa, Jason PhD2; Schoenfeld, Brad J. PhD1. Betaine Supplementation: A Critical Review of Its Efficacy for Improving Muscle Strength, Power, and Body Composition. Strength and Conditioning Journal 43(4):p 53-61, August 2021. | DOI: 10.1519/SSC.0000000000000622

De Jesus Moreno Moreno M. Cognitive improvement in mild to moderate Alzheimer’s dementia after treatment with the acetylcholine precursor choline alfoscerate: a multicenter, double-blind, randomized, placebo-controlled trial. Clin Ther. 2003 Jan;25(1):178-93. doi: 10.1016/s0149-2918(03)90023-3. PMID: 12637119.

Liang, Yq., Tang, Xc. Comparative studies of huperzine A, donepezil, and rivastigmine on brain acetylcholine, dopamine, norepinephrine, and 5-hydroxytryptamine levels in freely-moving rats. Acta Pharmacol Sin 27, 1127–1136 (2006). https://doi.org/10.1111/j.1745-7254.2006.00411.x