Transparent Labs Bulk Black is the high-stimulant version of one of the best-selling, most clinically respected pre-workouts on the market — taking the foundational Bulk formula and adding more caffeine, Vitamin D3, elevated B vitamins, and a more comprehensive micronutrient profile to produce a harder-hitting formula for experienced users who want more from their pre-workout. Every ingredient is listed at its exact dose with no proprietary blends. No artificial sweeteners. No artificial colors. No artificial flavors. Sweetened with stevia and colored naturally with beet root powder. 30 servings.†
Full Supplement Facts — Transparent Labs Bulk Black (Per 1 Scoop Serving)
- Citrulline Malate 2:1 — 8,000mg
- Beta-Alanine — 4,000mg
- Betaine Anhydrous (BetaPure) — 2,500mg
- Taurine — 1,300mg
- L-Tyrosine — 1,000mg
- AlphaSize Alpha-GPC (50%) — 300mg
- Caffeine Anhydrous (PurCaf Organic) — 275mg
- L-Theanine — 200mg
- Theobromine — 50mg
- AstraGin — 50mg
- Infinergy DiCaffeine Malate — 30mg (~22mg additional caffeine)
- Total Caffeine — approximately 297mg
- Vitamin D3 — 75mcg | Vitamin B6 — 5mg | Vitamin B12 (Methylcobalamin) — 250mcg
- Zinc — 10mg | Boron (Boron Citrate) — 3mg
- Sodium — 150mg | Potassium — 100mg
- No artificial sweeteners, flavors, or colors. Stevia sweetened. Third-party tested.
- 30 servings per container
- California Prop 65 Warning applies — see label
What's Inside Transparent Labs Bulk Black
Nitric Oxide and Pump Matrix
- Citrulline Malate 2:1 — 8,000mg — at 8g, this is one of the highest citrulline malate doses in any mainstream pre-workout. The 2:1 ratio means the compound is two parts citrulline to one part malic acid by weight, providing 5.33g of active L-citrulline per serving. Citrulline converts to arginine in the kidneys far more efficiently than supplemental arginine itself, driving sustained nitric oxide production without the arginine absorption limitations. Research has confirmed citrulline malate improves strength, aerobic performance, and muscle endurance. At 8g, Bulk Black meets or exceeds every clinically studied dose. Malic acid also plays a direct role in the Krebs cycle — it is an intermediary in cellular energy production, contributing independently to exercise performance.†
Endurance and Performance Matrix
- Beta-Alanine — 4,000mg — 4g is the full clinical dose supported in research for maximizing muscle carnosine saturation. Carnosine is the primary intramuscular buffer that counteracts the buildup of hydrogen ions during high-intensity work — the accumulation responsible for the burning sensation that causes muscles to fatigue during intense sets. At 4g daily, research shows significant increases in muscle carnosine levels within 2-4 weeks, meaningfully extending time to fatigue and improving work capacity across high-intensity exercise modalities. Some users experience a harmless tingling sensation (paresthesia) from beta-alanine — this is normal and diminishes with consistent use.†
- Betaine Anhydrous (BetaPure) — 2,500mg — BetaPure is a premium, third-party verified betaine source that guarantees purity and potency above generic trimethylglycine. At 2,500mg — the dose used in the most-cited research studies — betaine has been shown over 6 weeks to significantly improve bench press volume and support body composition. Betaine functions as an osmolyte that draws water into muscle cells (supporting cellular hydration and intramuscular volume), a methyl donor that supports homocysteine metabolism and cardiovascular health, and an endogenous creatine precursor that supports phosphocreatine availability.†
- Taurine — 1,300mg — taurine is a versatile ergogenic ingredient that contributes to four separate performance mechanisms in a single compound: osmolyte activity supporting cellular hydration, calcium signaling optimization for improved muscle contractions, antioxidant protection against exercise-induced oxidative stress, and nootropic activity that complements caffeine without adding stimulant load. The combination of taurine and caffeine produces a distinctly smoother, more focused energy experience than caffeine alone.†
Focus and Energy Matrix
- Caffeine Anhydrous (PurCaf Organic) — 275mg + Infinergy DiCaffeine Malate — 30mg — approximately 297mg total caffeine from two sources. PurCaf is organic caffeine derived from green coffee beans (Coffea arabica) rather than synthetic caffeine anhydrous — the distinction matters for individuals who prefer clean-sourced stimulants. The immediate 275mg onset delivers the acute energy and performance benefits caffeine is known for — reduced perceived exertion, improved strength output, enhanced fat oxidation, and greater training drive. The 30mg of Infinergy (di-caffeine malate, a sustained-release form) extends the tail end of caffeine's effect, smoothing the dropoff and reducing post-workout energy crash without requiring a second dose.†
- L-Tyrosine — 1,000mg — tyrosine is the amino acid precursor to dopamine, norepinephrine, and adrenaline. During high-stress physical demand, catecholamine depletion is a real performance limiter — supplemental tyrosine replenishes the substrate needed for continued neurotransmitter synthesis under training load. Research shows tyrosine supplementation improves cognitive flexibility and performance in demanding, cognitively stressful situations — directly applicable to the mental demands of a hard training session.†
- AlphaSize Alpha-GPC (50%) — 300mg — AlphaSize is a patented, pharmaceutical-grade form of Alpha-GPC that guarantees 50% active Alpha-GPC content. This is the most bioavailable choline precursor available and the form used in the published performance research on Alpha-GPC. It crosses the blood-brain barrier efficiently, raising acetylcholine levels for improved mind-muscle connection, mental focus, and reaction time. Alpha-GPC has also been shown in research to acutely increase growth hormone secretion, supporting fat oxidation and reducing muscle catabolism during and after training.†
- L-Theanine — 200mg — at 200mg alongside approximately 297mg of caffeine, the caffeine-to-theanine ratio here is approximately 1.5:1. Theanine produces alpha-wave relaxation in the brain without sedation, smoothing out the anxious or jittery edge that high caffeine doses can produce in sensitive individuals while preserving alertness, focus, and the performance benefits of caffeine. The combination is one of the most well-researched nootropic pairings in the supplement category.†
- Theobromine — 50mg — the primary alkaloid found in cocoa beans and a structural relative of caffeine. Theobromine is a milder, longer-lasting stimulant that contributes to mood elevation, prolonged energy, and cardiovascular tone. It complements caffeine's acute energizing effects with a sustained mood and motivation component that contributes to the clean, crash-free energy profile Transparent Labs is known for.†
Testosterone and Micronutrient Support
- Vitamin D3 — 75mcg (3,000 IU) — Vitamin D3 is a steroid hormone precursor that plays a direct role in testosterone biosynthesis. Low Vitamin D status is strongly associated with lower testosterone levels, and supplementation in deficient individuals has been shown to significantly support testosterone levels. Transparent Labs includes Vitamin D3 in Bulk Black specifically for its hormonal and performance support relevance — most people who train primarily indoors are deficient.†
- Zinc (Zinc Citrate) — 10mg — zinc is an essential cofactor for testosterone production enzymes and is depleted through sweat during intense exercise. Athletes and regular gym-goers are at particular risk for zinc depletion, making supplementation directly relevant to maintaining healthy testosterone levels in an active population.†
- Boron (Boron Citrate) — 3mg — boron is a trace mineral shown in clinical research to support free testosterone levels by reducing sex-hormone binding globulin (SHBG) — the protein that binds testosterone in the bloodstream making it unavailable to tissues. Lower SHBG means more bioavailable free testosterone.†
- Vitamin B6 — 5mg | Vitamin B12 (Methylcobalamin) — 250mcg — active B vitamins serving as coenzymes for energy metabolism, neurotransmitter synthesis, and red blood cell production. Methylcobalamin is the bioactive form of B12 that doesn't require conversion before use.†
- AstraGin — 50mg — patented absorption enhancer (Astragalus membranaceus and Panax notoginseng) that improves intestinal uptake of amino acids and other active compounds throughout the formula. Consistent with Transparent Labs' attention to bioavailability, not just raw doses.†
- Sodium — 150mg | Potassium — 100mg — electrolyte support for hydration and muscle function during training. A practical addition that separates Bulk Black from pre-workouts that ignore the hydration component of performance.†
Frequently Asked Questions About Transparent Labs Bulk Black
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What is the difference between Bulk and Bulk Black?
The original Transparent Labs Bulk is a mid-to-high stimulant pre-workout with approximately 200mg of caffeine per serving. Bulk Black is the higher-stimulant version with approximately 297mg total caffeine, additional Vitamin D3, higher B12, and a slightly different micronutrient profile. Both share the same core pump and performance formula — 8g citrulline malate, 4g beta-alanine, 2.5g betaine, AlphaSize Alpha-GPC, AstraGin, and the full testosterone support matrix. Bulk Black is the choice for experienced stimulant users who find standard Bulk's caffeine level insufficient and want the hardest-hitting version of the formula. Both are fully clean labels with no artificial sweeteners, colors, or flavors.† -
Why does Transparent Labs not include creatine in Bulk Black?
This is a deliberate formulation decision based on research. Research indicates caffeine and creatine may have conflicting er