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Fn Life Science

IMMUNE FUNCTION

IMMUNE FUNCTION

  • Supports Natural Killer (NK) Cells
  • Fuel for Immune Readiness
  • Essential Nutrients Magnesium & Vitamin C
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1-Monthly subscription

30 ServingsSAVE 15%

$49.99$42.49
$1.42 per serving
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3-Monthly subscription

90 ServingsSAVE 25%

$149.97$112.48
$1.25 per serving
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One Time Purchase

No commitment, full price

30 Servings

$49.99
$1.67 per serving
60-day money back guarantee Free shipping on all orders

Advanced Immune & NK Cell Support

Boost your body’s natural defense system with IMMUNE FUNCTION, a powerful blend of immune-boosting nutrients to enhance natural killer (NK) cell activity, and support overall immunity. This advanced formula contains potent compounds like vitamin C, IP6 and Inositol, L-Lysine, D3, K2, Zinc, Magnesium, and the citrus bioflavonoid. By reinforcing your body’s natural defense mechanisms, IMMUNE FUNCTION helps you stay resilient, energized, and ready to take on any challenge.*

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REAL USERS

REALRESULTS

"I'm 80 and living with Parkinson's, and the medications left me dealing with chronic, debilitating constipation. Nothing helped—prescriptions, Miralax, Metamucil—all gave inconsistent or extreme results. Then I found Gut Function. It worked immediately to restore my regularity, and three months later, it's still my go-to. It's been a true relief and a major improvement in my daily life. Highly recommended."

L

Larry R.

Verified

"I've been taking NAD+ Function, and the flush effect has been a game-changer for me. During the flush, I notice a real difference in how my body feels and moves, and it gives me strength and confidence I didn't have before. Adding L-Arginine and the other support ingredients including tart cherry, alongside nicotinic acid makes this formula even better and tastes great. I'm truly impressed with how much better I feel using this combination."

S

Sean K.

Verified

"A remarkable improvement in my digestive balance and bathroom routine. It has made a real, meaningful difference in my everyday life. I was resorting to anti-diarrheal meds probably twice a week and constantly worrying about what I could eat. Now, I only need that kind of medicine maybe once every 6-8 weeks, and don't have to worry so much about when and what I eat. Gut Function has really helped to stabilize things for me."

F

Fr. Mike

Verified

"I've been pooping nearly all my life and these are some of the best ones yet! But seriously, I've had IBS-like symptoms most of my life. Gut Function has settled that down and has just made things more normal."

N

Nick T.

Verified

"I have been using Gut Function for over 6 months and have noticed great results. As a cancer patient, I use it primarily for detoxification binding and supporting gut microbiome health. I have found that it helps keep my digestion more regular. Knowing that it also supports my body while I'm going through treatment gives me extra peace of mind. I appreciate that it's clean, gentle, and easy to take consistently. Overall, it has become a staple in my daily routine, and I feel it has made a positive difference in my overall well-being."

G

Gina B.

Verified

"I worked with D. Penberthy to get myself to 'On-Ramp' myself up to 1,000 mg of plain IR nicotinic acid [NAD+ Function]. Like the literature says, I've found increased effects with 1000 mg of Vitamin C [in Immune Function]. The combination is the best thing I've taken."

C

Charlotte H.

Verified

"I started using the Immune Function formula because I wanted extra support for my health. Adding it to my routine gave me a real sense of confidence and control in my recovery journey. The fact that it includes IP6+ Inositol and L-lysine along with other nutrients that boost my natural immunity and supports my natural killer cells makes it simple and convenient. I feel better knowing I'm giving my body the support it needs."

D

Daniel A.

Verified

"I've been using NAD+ Function for a while now and really like it. I love how thoughtfully the formula is put together. Steady energy, blood flow — I feel reinvigorated. Understanding the flush is a game changer. It lets me know it's working, and I've noticed I don't have the mid day crash. I also feel more clear-headed and focused. Pairing it with my healthy diet has made a noticeable difference."

B

Briana K.

Verified

"After struggling with my energy and side effects from other medications, I decided to try NAD+ Function as part of my routine. Over time, I noticed steady improvements in my labs, especially with overall balance. My energy and well-being also felt so much better. Later I added Immune Function, and I've been impressed with how much support it provides. Looking back, my health feels stronger now than it has in decades."

T

Tom W.

Verified

"I'm 73 and have dealt with gut issues most of my life—including after a sigmoid resection and a diagnosis of acid reflux. I was constantly bouncing between constipation and loose stools, relying on OTC meds that never really helped. Since taking Gut Function for the past six months, everything has changed. I'm finally regular, my acid reflux is under control, and I no longer need multiple medications. This product has truly brought me comfort and consistency for the first time in years. I highly recommend it."

M

Marilyn K.

Verified

"I've been dealing with gut issues and irregular digestion off and on for years. I've tried other microbiome products to no avail, but ever since I started taking Gut Function by Fn LIFE SCIENCE, everything's changed for the better! It's been a total game-changer—highly recommend it if you're looking to get your digestive health on track."

D

Dr. Matt L.

Verified

  • "I'm 80 and living with Parkinson's, and the medications left me dealing with chronic, debilitating constipation. Nothing helped—prescriptions, Miralax, Metamucil—all gave inconsistent or extreme results. Then I found Gut Function. It worked immediately to restore my regularity, and three months later, it's still my go-to. It's been a true relief and a major improvement in my daily life. Highly recommended."

    L

    Larry R.

    Verified

  • "I've been taking NAD+ Function, and the flush effect has been a game-changer for me. During the flush, I notice a real difference in how my body feels and moves, and it gives me strength and confidence I didn't have before. Adding L-Arginine and the other support ingredients including tart cherry, alongside nicotinic acid makes this formula even better and tastes great. I'm truly impressed with how much better I feel using this combination."

    S

    Sean K.

    Verified

  • "A remarkable improvement in my digestive balance and bathroom routine. It has made a real, meaningful difference in my everyday life. I was resorting to anti-diarrheal meds probably twice a week and constantly worrying about what I could eat. Now, I only need that kind of medicine maybe once every 6-8 weeks, and don't have to worry so much about when and what I eat. Gut Function has really helped to stabilize things for me."

    F

    Fr. Mike

    Verified

  • "I've been pooping nearly all my life and these are some of the best ones yet! But seriously, I've had IBS-like symptoms most of my life. Gut Function has settled that down and has just made things more normal."

    N

    Nick T.

    Verified

  • "I have been using Gut Function for over 6 months and have noticed great results. As a cancer patient, I use it primarily for detoxification binding and supporting gut microbiome health. I have found that it helps keep my digestion more regular. Knowing that it also supports my body while I'm going through treatment gives me extra peace of mind. I appreciate that it's clean, gentle, and easy to take consistently. Overall, it has become a staple in my daily routine, and I feel it has made a positive difference in my overall well-being."

    G

    Gina B.

    Verified

  • "I worked with D. Penberthy to get myself to 'On-Ramp' myself up to 1,000 mg of plain IR nicotinic acid [NAD+ Function]. Like the literature says, I've found increased effects with 1000 mg of Vitamin C [in Immune Function]. The combination is the best thing I've taken."

    C

    Charlotte H.

    Verified

  • "I started using the Immune Function formula because I wanted extra support for my health. Adding it to my routine gave me a real sense of confidence and control in my recovery journey. The fact that it includes IP6+ Inositol and L-lysine along with other nutrients that boost my natural immunity and supports my natural killer cells makes it simple and convenient. I feel better knowing I'm giving my body the support it needs."

    D

    Daniel A.

    Verified

  • "I've been using NAD+ Function for a while now and really like it. I love how thoughtfully the formula is put together. Steady energy, blood flow — I feel reinvigorated. Understanding the flush is a game changer. It lets me know it's working, and I've noticed I don't have the mid day crash. I also feel more clear-headed and focused. Pairing it with my healthy diet has made a noticeable difference."

    B

    Briana K.

    Verified

  • "After struggling with my energy and side effects from other medications, I decided to try NAD+ Function as part of my routine. Over time, I noticed steady improvements in my labs, especially with overall balance. My energy and well-being also felt so much better. Later I added Immune Function, and I've been impressed with how much support it provides. Looking back, my health feels stronger now than it has in decades."

    T

    Tom W.

    Verified

  • "I'm 73 and have dealt with gut issues most of my life—including after a sigmoid resection and a diagnosis of acid reflux. I was constantly bouncing between constipation and loose stools, relying on OTC meds that never really helped. Since taking Gut Function for the past six months, everything has changed. I'm finally regular, my acid reflux is under control, and I no longer need multiple medications. This product has truly brought me comfort and consistency for the first time in years. I highly recommend it."

    M

    Marilyn K.

    Verified

  • "I've been dealing with gut issues and irregular digestion off and on for years. I've tried other microbiome products to no avail, but ever since I started taking Gut Function by Fn LIFE SCIENCE, everything's changed for the better! It's been a total game-changer—highly recommend it if you're looking to get your digestive health on track."

    D

    Dr. Matt L.

    Verified

SCIENCE-DRIVEN FORMULATION

KEYINGREDIENTS

IP6 & INOSITAL

IP6 & INOSITAL

By regulating iron-dependent free radical production, inositol hexaphosphate (IP6) functions as a potent antioxidant with the ability to counteract numerous pathogenic processes. Beyond its antioxidant activity, IP6 has demonstrated effectiveness in modulating pathological calcification, a hallmark of conditions such as atherosclerotic cardiovascular disease, kidney stone formation, and cancer progression. IP6 can also reduce the diabetic biomarker HbA1c, supporting benefits for metabolic health.

L-LYSINE

L-LYSINE

Supports immune function by inhibiting viral replication and balancing arginine levels. Lysine is also critical for collagen synthesis and gut lining repair. L-Lysine cannot be produced in the body on its own. It plays a key role in protein synthesis, muscle development, and tissue repair, while also supporting immune function and healthy collagen formation. Because of its broad importance in human nutrition,

MAGNESSIUM

MAGNESSIUM

Magnesium (Mg²⁺) is an essential mineral that supports the brain, heart, and muscles by acting as a cofactor in over 300 enzymatic reactions. It plays a central role in energy metabolism, muscle and nerve function, and the regulation of blood glucose and blood pressure.

TESTED & STUDIED

THE RESULTSSPEAK

800%

NAD+ increase with Nicotinic Acid

100+

FDA clinical trials studied

92%

reported improved energy levels

BACKED BY EXPERTS

PROVEN BYSCIENCE

CELLULAR ENERGY

Fuels mitochondrial ATP production for sustained energy without stimulants.

DNA REPAIR

Activates PARP enzymes critical for repairing damaged DNA strands.

ANTI-AGING

Supports sirtuin activation — key regulators of aging and cellular health.

CARDIOVASCULAR

L-Arginine + Niacin synergy drives nitric oxide for vascular health.

QUESTIONS?

FREQUENTLYASKED

Yes, NAD+ Function pairs well with our GUT Function and Immune Function products. Consult your healthcare provider if you take prescription medications.

Most users report noticeable improvements in energy and mental clarity within 7-14 days. For optimal NAD+ elevation, consistent use for 30+ days is recommended.

Our formula uses immediate-release nicotinic acid which may cause a temporary warm flush. This is a normal, harmless response that typically decreases with regular use. It actually indicates the compound is working.

Nicotinic acid (niacin) is the most studied NAD+ precursor with over 100 FDA clinical trials. Studies show it raises NAD+ levels up to 800% — higher than NMN, NR, or even direct NAD+ IV infusions.