Horse Fuel Ingredients: All 6, and What the Research Says
Horse Fuel lists six ingredients: vitamin D3 at 84 mcg, boron at 7 mg, and four herbs at 100 mcg each. Vitamin D3 and boron land close to real research doses. The four herbs sit near 1/2,500 to 1/35,000 of the amounts studies used. The label also prints fenugreek's Latin name under the tribulus terrestris line, a printing error.
What are the 6 ingredients in Horse Fuel?
Six ingredients, six printed amounts. Here is what each one is, before we check the amount against the science.
Every ingredient in Horse Fuel gets its own printed amount. That is a plus: many men's gummies hide their ingredients inside a single "blend" number, so no one can check any one dose. Horse Fuel does not do that. Here is the label order, word for word from the Supplement Facts panel:
- Vitamin D3 (cholecalciferol)
- Boron (boron glycinate)
- Fenugreek Seed Extract 10:1 (Trigonella foenum-graecum L.)
- Maca Root Extract 10:1 (Lepidium meyenii Walp.)
- Tribulus Terrestris Extract 10:1 (printed as Trigonella foenum-graecum L. (label error))
- Horny Goat Weed Extract 10:1 (Epimedium brevicornum Maxim.)
Two of the six, vitamin D3 and boron, sit at doses that match real nutrition science. The other four are herbal extracts, each listed at exactly 100 mcg. That is a tiny number, and the rest of this page checks it against the research.
Explore each Horse Fuel ingredient
Tap through all six. Each panel shows the research dose, the human evidence level and a safety note, sourced below.
Vitamin D3
cholecalciferol · vitamin
The sunshine vitamin. This is the one ingredient in Horse Fuel dosed well above the daily need. This label's 84 mcg (3,360 IU, 420% DV) dose is well above the RDA but under NIH ODS's adult Tolerable Upper Intake Level of 100 mcg (4,000 IU)/day.
- In one gummy
- 84 mcg (3,360 IU), 420% DV
- Dose used in research
- RDA 600-800 IU
- Safety note
- NIH ODS sets the adult Tolerable Upper Intake Level for vitamin D at 4,000 IU (100 mcg)/day.
- Sources
- Martineau et al., 2017
Boron
boron glycinate · trace mineral
A trace mineral. 7 mg is close to the 10 mg used in a small hormone study and under the 20 mg adult upper limit. Only small, short-duration human trials (e.g., Naghii 2011, n=8) have examined boron's hormonal effects; results are promising but preliminary and not yet confirmed in larger trials.
- In one gummy
- 7 mg
- Dose used in research
- 10 mg/day studied short-term for hormonal effects
- Safety note
- Boron is generally well tolerated at typical supplemental doses, but NIH ODS sets a Tolerable Upper Intake Level of 20 mg/day for adults from all sources combined.
- Sources
- Naghii et al., 2011
Fenugreek Seed Extract 10:1
Trigonella foenum-graecum L. · seed
A seed extract studied for men's hormones at 250-600 mg a day. A meta-analysis of 4 small RCTs found fenugreek extract raised total testosterone versus placebo.
- In one gummy
- 100 mcg
- Dose used in research
- 250-600 mg/day of standardized fenugreek seed extract in the pooled RCTs showing a testosterone effect
- Safety note
- MSKCC reports fenugreek may potentiate warfarin and increase bleeding risk, and has been linked to a case of serotonin syndrome when combined with the SSRI sertraline.
- Sources
- Mansoori et al., 2020
Maca Root Extract 10:1
Lepidium meyenii Walp. · root
A Peruvian root studied at 1.5-3.5 grams a day of dried root. Systematic reviews find only limited, low-quality trial evidence for sexual function and libido benefits.
- In one gummy
- 100 mcg
- Dose used in research
- 1.5-3.5 g/day of dried maca root powder, typically for 6-12 weeks
- Safety note
- Maca root has limited long-term human safety data.
- Sources
- Shin et al., 2010 · Lee et al., 2023
Tribulus Terrestris Extract 10:1
printed as Trigonella foenum-graecum L. (label error) · plant
A traditional herb studied at 400-750 mg a day. The label prints fenugreek's Latin name under it. A 2025 systematic review found Tribulus improved erectile function in some trials at 400-750 mg/day but had little consistent effect on testosterone.
- In one gummy
- 100 mcg
- Dose used in research
- 400-750 mg/day of standardized extract for 1-3 months in the reviewed trials
- Safety note
- LiverTox rates Tribulus terrestris an unlikely cause of liver injury at typical doses, and the one severe case (jaundice and kidney dysfunction in a bodybuilder) was judged more likely caused by undisclosed anabolic steroid use rather than Tribulus itself.
- Sources
- Vilar et al., 2025
Horny Goat Weed Extract 10:1
Epimedium brevicornum Maxim. · leaf
A traditional herb with mostly animal research. No human efficacy dose is set. No controlled human efficacy trials of Epimedium or icariin for sexual function were found; erectile benefits are shown only in rat studies.
- In one gummy
- 100 mcg
- Dose used in research
- no established human efficacy dose
- Safety note
- LiverTox rates horny goat weed an unlikely cause of liver injury, but a 2025 case report documented severe muscle spasms and markedly elevated creatine kinase and creatinine in a man who took an unregulated online Epimedium supplement.
- Sources
- Brown et al., 2019 · Shindel et al., 2010
Horse Fuel dosage vs. research dosage: an honest look
Horse Fuel prints every amount, so we can put each one next to the doses used in studies.
Amount in one gummyRange used in research or daily need
- Vitamin D384 mcg15-20 mcg daily need; 100 mcg upper limit
- Boron7 mg10 mg study; 20 mg upper limit
- Fenugreek Seed100 mcg250 mg to 600 mg
- Maca Root100 mcg1,500 mg to 3,500 mg
- Tribulus Terrestris100 mcg400 mg to 750 mg
- Horny Goat Weed100 mcgNo human dose established
Log scale: each step is 10 times the last. A 100 mcg dot sitting under a 250-600 mg band means the gummy holds about 1/2,500 to 1/6,000 of the studied amount.
| Ingredient | In one gummy | Dose used in research or daily need | Evidence |
|---|---|---|---|
| Vitamin D3 | 84 mcg (3,360 IU), 420% DV | RDA 600-800 IU | Moderate |
| Boron | 7 mg | 10 mg/day studied short-term for hormonal effects | Weak |
| Fenugreek Seed Extract 10:1 | 100 mcg | 250-600 mg/day of standardized fenugreek seed extract in the pooled RCTs showing a testosterone effect | Moderate |
| Maca Root Extract 10:1 | 100 mcg | 1.5-3.5 g/day of dried maca root powder, typically for 6-12 weeks | Limited |
| Tribulus Terrestris Extract 10:1 | 100 mcg | 400-750 mg/day of standardized extract for 1-3 months in the reviewed trials | Limited |
| Horny Goat Weed Extract 10:1 | 100 mcg | no established human efficacy dose | Weak |
100 mcg is 0.1 mg. Fenugreek was studied at 250-600 mg of extract a day, so one gummy holds about 1/2,500 of the low end. Maca studies used 1,500-3,500 mg of dried root, roughly 15,000 to 35,000 times more than the 100 mcg here. Even counting the 10:1 extract ratio, 100 mcg matches only about 1 mg of raw herb.
The two real doses: vitamin D3 at 84 mcg (3,360 IU) sits above the adult daily need of 15-20 mcg and under the 100 mcg upper limit (National Institutes of Health, 2024). Boron at 7 mg sits close to the 10 mg a small one-week trial used (Naghii et al., 2011), and under the 20 mg adult upper limit (National Institutes of Health, 2024).
The four small doses: fenugreek, maca, tribulus and horny goat weed, all at 100 mcg. None of them is dosed anywhere near the amount its own research used (Mansoori et al., 2020; Vilar et al., 2025). More on how the doses stack up against other products: how Horse Fuel works.
The tribulus line has a labeling error
The Tribulus Terrestris Extract line on the Supplement Facts panel prints Trigonella foenum-graecum L. underneath it. That is fenugreek's Latin name, and it is printed a second time, word for word, under the fenugreek line just above it. Tribulus terrestris has its own, different Latin name. This looks like a copy-paste printing error, and Vitalifes has not confirmed which plant is actually in that part of the gummy.
What we know
The ingredient is named Tribulus Terrestris Extract 10:1 at 100 mcg. The Latin name under it is wrong.
What we do not know
Whether the gummy contains tribulus terrestris, a second dose of fenugreek, or some mix of the two.
The boron line also carries an asterisk with no printed key anywhere on the panel in the product photos. Full line-by-line read: Horse Fuel Supplement Facts.
What the Horse Fuel label does not tell you
The label prints every active amount, but a few things stay off the panel. Here is what the photographed Supplement Facts and directions panels do not show.
- Other ingredients (gummy base, sweetener, colors, flavors) are not visible on the photographed panels
- What the * next to boron refers to (no key is printed)
- The correct Latin name for Tribulus terrestris (the label repeats fenugreek's)
- Extract standardization beyond the 10:1 ratio
- Third-party lab results (lot HOR-26/HO-6232 and CoA HOR-6232-26-HO are draft references, not lab proof)
- GMP certificate number and facility name
- Verified customer reviews (seller-supplied figures could not be checked against orders)
More on what the label does and does not say: Horse Fuel side effects.
Ingredients: common questions
What are the 6 ingredients in Horse Fuel?
Vitamin D3 (84 mcg), boron (7 mg), and fenugreek, maca, tribulus terrestris and horny goat weed extracts, each at 100 mcg.
Which Horse Fuel ingredient is dosed the strongest?
Vitamin D3. Its 84 mcg is 420% of the Daily Value, above the 15-20 mcg adult need and under the 100 mcg adult upper limit.
Are the four herbs in Horse Fuel dosed at research levels?
No. Each is 100 mcg (0.1 mg), while studies used 250 mg to 3,500 mg a day, thousands of times more.
What is the tribulus terrestris labeling error?
The label prints fenugreek's Latin name, Trigonella foenum-graecum L., under the tribulus terrestris line. It has not been confirmed which plant is actually inside.
Is 7 mg of boron a safe amount?
Yes, it sits under the 20 mg adult upper limit and near the 10 mg used in a small one-week study.
What does 10:1 extract mean on the label?
The extract is concentrated 10 times from the raw plant, so 100 mcg of extract is roughly equal to 1 mg of raw herb.
Does Horse Fuel list other ingredients like the gummy base?
No. The gummy base, sweetener, colors and flavors are not visible on the photographed panels.
Where can I see the full research dose for each ingredient?
In the table on this page, or in more detail on the Horse Fuel Supplement Facts page.
Keep reading
How does Horse Fuel work?
The same six ingredients, grouped by what they are meant to do in the body.
Read →Horse Fuel Supplement Facts, line by line
A full word-for-word read of both label panels, front to back.
Read →Horse Fuel side effects and interactions
What to watch for with boron, the herbs and vitamin D3.
Read →Order Horse Fuel from the authorized retailer
30 gummies per bottle, 1 a day. Packs of 3 or 6 bottles run from $10.92 a bottle on the listing, with 30-day returns. Questions first? Call +1 (302) 200-3480.
