Effect of vitamin D supplementation on testosterone levels in men.
In a one-year randomized controlled trial, vitamin D supplementation significantly increased total, bioactive, and free testosterone in vitamin D-deficient men.
Natural Testosterone Pioneer: Christopher Walker | Founder of Monthlees | Duke Neuroscience | Former Co-Founder of UMZU | Learn more about the formulator
30 daily testosterone supplement sachets -
Testosterone support with clinical potency
Designed to target low testosterone, micronutrient deficiencies, stress, and sleep. With 16x active dosage than your average "booster" & 30+ clinically proven ingredients.
30-Day Results Guarantee
30 Day Money Back Guarantee
Free Shipping Every Month (PLUS+ Members)
Best Seller
Testosterone I/O Foundation Stack
The Testosterone Foundation Stack is designed to be taken daily as the baseline input layer for the Testosterone I/O system. These daily essentials support hormone balance, stress resilience, cellular energy, testosterone production, & overall vitality.
NOTHING ELSE COMPARES.
$79.00
$129.00
Members Save
Just $2.63/day - 1 simple daily pack
Increase Total T up to 35% in as little as 30 days*
Increase Free T ~25–60% in as little as 30 days*
Cancel Anytime. No Commitments.
*Human clinical studies on key nutrients in the Foundation formula report testosterone increases ranging from ~10% to over 30%, with free testosterone often rising even more due to reductions in SHBG. When deficiencies are corrected simultaneously, improvements in the 15–35% range for total testosterone are biologically plausible within the first month. Free US shipping credits for all Monthlees Plus+ members.
30-Day Money Back Guarantee
Everything you need to overcome low T. Nothing you don't.
Built on biology
Most “testosterone boosters” chase symptoms. Foundation supports the inputs your body actually needs to produce testosterone, manage stress, and maintain hormonal balance.
Clinically-Dosed Essentials
Every ingredient is included at evidence-based levels used in human research — not “label dressing.” That means real doses of the nutrients most men are missing.
All-In-One Solution
Foundation supplies the daily raw materials that support:
• hormone production
• stress resilience
• cellular energy
• metabolic health
Nothing You Don't Need
No proprietary blends. No trendy herbs with weak evidence. No unnecessary fillers.
Just the core nutrients most directly connected to testosterone health.
Because better systems beat bigger stacks.
Why the Testosterone I/O Foundation works so well: Low T isn't a testosterone deficiency. You're just low in the micronutrients needed to support testosterone production.
Most Men Are Missing The Basics
Modern diets are low in magnesium, boron, and trace minerals — nutrients involved in hormone production. When these are missing, the body simply can't run the system properly.
Testosterone Is Built On Micronutrients
Hormones don't appear out of nowhere. They depend on specific vitamins, minerals, and metabolic cofactors that support the body's natural production pathways.
All-In-One Daily Smart Stack Sachet
Instead of juggling multiple supplements, everything comes organized into one daily smart stack sachet. No guesswork. No stacking. Just take the pack.
Consistency = Effortless
Hormonal health responds to daily inputs over time, not occasional supplements. The daily pack makes consistency effortless.
Contains no:
Dairy
Gluten
Preservatives
Fish
Wheat
Peanuts
Soy
Sesame
Artificial Flavors
Animal Products
Artificial Colors
GMOs
Shellfish
Tree Nuts
Eggs
Why “Testosterone Boosters” Completely Fail
Most products promise to “boost testosterone” with herbs or proprietary blends. But testosterone production doesn’t work that way. It depends on something much deeper: micronutrient foundations.
Your Body Needs The Right Micronutrient Inputs Every Single Day
Testosterone production is influenced by a network of systems — including nutrient status, stress response, metabolism, and mineral balance.
When those systems aren’t supported, no single ingredient can solve the problem.
HEAD-TO-HEAD
Same problem. Very different "solutions."
Not all testosterone supplements are built the same. Here’s what you’re actually getting for your money — compared side by side.
Comparison
What matters most
Winner
Testosterone I/O Foundation
ALL-IN-ONE SOLUTION
1 pack - $2.63/day
Precision-Targeted. Clinical Potency.
Typical Men's Multi
Generic & Underdosed
1 pill/day
Broad nutrient coverage, but drastically underdosed and non-specific for supporting testosterone and hormonal health. Typically use poorly bioavailable forms of each ingredient for cost-cutting.
Test Booster
Single-Pathway Formula
2–4 capsules/day - $49-$99/mo.
Often centered on herbal extracts or temporary stimulation rather than full-system hormone support.
DIY Stack
Multiple Bottles
30+ Bottles - $403/mo.
You could buy all of the ingredients in the Foundation stack individually. Flexible but hard to maintain, expensive, & a shopping nightmare.
Coverage
What are you actually getting?
Comprehensive
30+ vitamins/minerals + ashwagandha + boron + selenium + K2 (MK-4 & MK-7)
Broad
Basic multivitamin coverage
Narrow
Usually only a few testosterone-oriented ingredients
Variable
Depends on how many products you buy
Form Quality
Ingredient forms and bioavailability
Premium
Includes Albion® minerals, methylfolate, methylcobalamin, K2
Mixed
Often mixed-quality forms
Mixed
May prioritize a few actives over broad form quality
Custom
Can be strong, but only if selected carefully
Daily Simplicity
How easy is it to stay consistent?
1 packet/day
Grab-and-go smart stack
Simple
Usually 1 bottle, but less specialized
Moderate
Often multiple capsules daily
Harder
Multiple bottles, refills, and routine complexity
Meet the Testosterone I/O Foundation Stack
A daily protocol designed to support the systems behind male vitality. FOUNDATION delivers a precision stack of potent & completely bioavailable micronutrients designed to support energy metabolism, stress balance, & hormonal health.
Each daily sachet contains 30+ foundational micronutrients — making it simple to support the systems your body relies on... every single day.
Best Seller
Testosterone I/O Foundation Stack
The Testosterone Foundation Stack is designed to be taken daily as the baseline input layer for the Testosterone I/O system. These daily essentials support hormone balance, stress resilience, cellular energy, testosterone production, & overall vitality.
NOTHING ELSE COMPARES.
$79.00
$129.00
Members Save
Just $2.63/day - 1 simple daily pack
Increase Total T up to 35% in as little as 30 days*
Increase Free T ~25–60% in as little as 30 days*
Cancel Anytime. No Commitments.
*Human clinical studies on key nutrients in the Foundation formula report testosterone increases ranging from ~10% to over 30%, with free testosterone often rising even more due to reductions in SHBG. When deficiencies are corrected simultaneously, improvements in the 15–35% range for total testosterone are biologically plausible within the first month. Free US shipping credits for all Monthlees Plus+ members.
30-Day Money Back Guarantee
THE FOUNDATION FORMULA
31 Ingredients. One Foundational System.
Every daily Foundation pack is organized around the biological systems testosterone depends on—from mineral balance and hormone cofactors to stress regulation, methylation, and metabolic support.
Vitamin A
Retinyl Acetate
600 mcg RAE
67%
Vitamin E
d-Alpha Tocopherol Succinate
33.5 mg
223%
Iodine
Potassium Iodide
200 mcg
133%
Zinc
Albion® Zinc Bisglycinate Chelate
30 mg
273%
Selenium
L-Selenomethionine
200 mcg
364%
Copper
Albion® Copper Bisglycinate Chelate
2 mg
222%
Manganese
Albion® Manganese Bisglycinate Chelate
4 mg
174%
Molybdenum
Albion® Molybdenum Glycinate Chelate
250 mcg
556%
Potassium
Potassium Chloride
100 mg
2%
Silica
Horsetail (Equisetum arvense) Whole Herb
100 mcg
†
Boron
Boron Glycinate
10 mg
†
Boron
Boron Citrate
200 mcg
†
Zinc
Albion® Zinc Bisglycinate Chelate
30 mg
273%
Magnesium
Magnesium Glycinate
133 mg
32%
Selenium
L-Selenomethionine
200 mcg
364%
Vitamin A
Retinyl Acetate
600 mcg RAE
67%
Vitamin K2
Menaquinone-4 (MK-4)
1000 mcg
†
Vitamin K2
Menaquinone-7 (MK-7)
100 mcg
†
Vitamin D3
Cholecalciferol
125 mcg
625%
Vitamin K2
Menaquinone-4 (MK-4)
1000 mcg
†
Vitamin K2
Menaquinone-7 (MK-7)
100 mcg
†
Vitamin A
Retinyl Acetate
600 mcg RAE
67%
Zinc
Albion® Zinc Bisglycinate Chelate
30 mg
273%
Iodine
Potassium Iodide
200 mcg
133%
Organic Ashwagandha Root
Withania somnifera
380 mg
†
Ashwagandha Extract
Withania somnifera root, standardized to 1.5% withanolides
95 mg
†
Magnesium
Magnesium Glycinate
133 mg
32%
Vitamin B6
Pyridoxine Hydrochloride
20 mg
1176%
Pantothenic Acid
d-Calcium Pantothenate
100 mg
2000%
Inositol
—
40 mg
†
Magnesium
Magnesium Glycinate
133 mg
32%
Potassium
Potassium Chloride
100 mg
2%
Chromium
Chromium Polynicotinate
200 mcg
571%
Vanadium
Bisglycinatooxovanadium (BGOV)
150 mcg
†
Inositol
—
40 mg
†
Choline
Choline Bitartrate
25 mg
5%
Riboflavin
—
17 mg
1308%
Niacin
Niacinamide
200 mg NE
1250%
Pantothenic Acid
d-Calcium Pantothenate
100 mg
2000%
Thiamin
Thiamine HCl
15 mg
1250%
Riboflavin
—
17 mg
1308%
Niacin
Niacinamide
200 mg NE
1250%
Vitamin B6
Pyridoxine Hydrochloride
20 mg
1176%
Folate
Metafolin® + calcium L-5-methyltetrahydrofolate
680 mcg DFE
170%
Vitamin B12
Methylcobalamin
6 mcg
250%
Biotin
D-Biotin
300 mcg
1000%
Pantothenic Acid
d-Calcium Pantothenate
100 mg
2000%
Choline
Choline Bitartrate
25 mg
5%
PABA
para-Aminobenzoic Acid
25 mg
†
Evidence-based ingredients
The science behind the ingredients
Foundation was built by selecting ingredients associated with hormone health, metabolic function, stress physiology, and cellular energy. Use this section to showcase the clinical rationale and featured research behind your formula.
31
Active ingredients
Human research
Supporting key ingredients
Multiple pathways
Hormones, metabolism, stress, and energy
Zinc supplementation and serum testosterone levels in healthy men.
Research has shown that zinc deficiency can reduce testosterone levels, and supplementation restored normal testosterone levels in deficient men.
Examining the effect of Withania somnifera supplementation on testosterone levels and reproductive health.
In a randomized controlled trial, men taking ashwagandha experienced significant increases in testosterone levels along with improvements in sperm quality and reproductive markers compared to placebo.
Short-term boron supplementation significantly affects testosterone levels.
This research found increases in free testosterone and reductions in inflammatory biomarkers after boron supplementation.
Myo-inositol supplementation and metabolic health outcomes.
Myo-inositol has been shown to support insulin sensitivity and metabolic signaling pathways that are closely connected to endocrine health.
Magnesium supplementation influences testosterone levels in athletes and sedentary subjects.
This study showed increased testosterone levels following magnesium supplementation, particularly with exercise.
Best Seller
Testosterone I/O Foundation Stack
The Testosterone Foundation Stack is designed to be taken daily as the baseline input layer for the Testosterone I/O system. These daily essentials support hormone balance, stress resilience, cellular energy, testosterone production, & overall vitality.
NOTHING ELSE COMPARES.
$79.00
$129.00
Members Save
Just $2.63/day - 1 simple daily pack
Increase Total T up to 35% in as little as 30 days*
Increase Free T ~25–60% in as little as 30 days*
Cancel Anytime. No Commitments.
*Human clinical studies on key nutrients in the Foundation formula report testosterone increases ranging from ~10% to over 30%, with free testosterone often rising even more due to reductions in SHBG. When deficiencies are corrected simultaneously, improvements in the 15–35% range for total testosterone are biologically plausible within the first month. Free US shipping credits for all Monthlees Plus+ members.
30-Day Money Back Guarantee
Why I Created Monthlees
When I was 19 years old, I was diagnosed with a brain tumor. That experience forced me to start asking deeper questions about how the human body actually works.
Over the next 18 months, I immersed myself in studying health, nutrition, and neuroscience — eventually earning my degree in Neuroscience from Duke University. Along the way, I discovered something powerful: the body is incredibly resilient & inherently self-healing when it’s given the right support.
Strategic nutrition and supplementation became a major part of my own health journey. And over the last two decades, I’ve devoted my life to helping millions of people around the world take a more proactive role in their health.
That experience completely changed how I thought about health — and ultimately shaped the way Monthlees was built.
I created Monthlees because I was tired of seeing people pay premium prices for supplements that were under-dosed, over-marketed, and difficult to trust.
My goal is simple: build the kind of brand I would want for myself and my family — with better ingredients, transparent formulas, meaningful dosages, and a business model built on long-term trust.
— Chris Walker, Founder of Monthlees
Discover more in our FAQ
Shoot our team an email & we’ll get back to you ASAP
How long does it take to process an order?
How long does it take to process an order?
Orders are typically processed within 1–2 business days. You will receive a confirmation email with tracking details once your order has been shipped. Please note that processing times may be slightly longer during high-demand periods or sales events.
Do you ship internationally?
Do you ship internationally?
Yes, we offer international shipping to most countries. Shipping rates and delivery times vary depending on the destination. Any applicable customs duties or taxes will be the responsibility of the recipient.
What is your return policy?
What is your return policy?
We accept returns within 30 days of delivery. To be eligible, items must be unused, in their original packaging, and accompanied by proof of purchase. If the item is faulty or damaged, we will cover the return shipping and provide a replacement or full refund.
What are your sizing options?
What are your sizing options?
This product does not require sizing. However, if you’re shopping for wearables or accessories on our store, detailed size charts are available on each product page to help you find the perfect fit.
