Reishi for Cats

What the newer cat study tells us, how to compare mushroom preparations, and where reishi belongs in healthy-aging nutrition.

By La Petite Labs Editorial 14 min read

As Seen On

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Hollywood Elixir® Senior Cat Supplement

Contains 25 mg Reishi Mushroom

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Contents

Reishi is a mushroom whose polysaccharides and other compounds are studied for effects on immune activity. That makes it an ingredient of interest when caring for an aging cat, but “immune support” can cover very different claims. A newer controlled study in cats tested reishi within a blend of three mushroom extracts and colostrum. Its findings give us useful feline evidence—and a specific preparation to understand.

Reishi preparations differ in how they are made and what they contain. Research needs to be read with the tested preparation and outcome in view; it does not supply a universal dose for every product. Hollywood Elixir contains a declared reishi extract and separate yeast beta-glucan within its complete 17-active NAD+ longevity nutritional system. Understand the full formula, preparation and serving together.

Reishi is a name for the mushroom, not a complete specification

Also known as lingzhi, reishi commonly appears in supplement research under the name Ganoderma lucidum. It contains several groups of compounds, including polysaccharides and triterpenes. Researchers study these for different biological actions. 8

A product can draw on that mushroom in different ways. Whole mushroom material, an extracted preparation and a blend containing several species do not become equivalent because each label includes “reishi.” The name tells you where to begin; the preparation tells you more about what is actually being supplied.

Woman kneeling with two long-haired tabby cats while holding a Hollywood Elixir box beside a food bowl

Immune signalling means cells responding to information

Immune cells detect signals and change what they do in response. Researchers can study those changes by measuring the substances cells release or how they respond to a later challenge. In a canine laboratory experiment, a beta-glucan from the organism Euglena altered later responses in cultured immune cells, alongside changes in their metabolism. 3

That work helps explain the interest in this ingredient category. It was not a study of feeding reishi to cats. Nor does a stronger measured response automatically mean a healthier animal: the type of response, its timing and the animal’s condition all matter.

Woman exercising beside a tabby cat, with a Hollywood Elixir box and food bowl on a small table

The recent cat trial tested a complete mushroom blend

A 2026 randomized, blinded, placebo-controlled trial involved 20 healthy adult cats. For 12 weeks, the active group received 900 mg daily of a preparation combining turkey tail, red reishi and lion’s mane water extracts with bovine colostrum. The experiment therefore tested a blend, rather than reishi alone. 1

Orange-and-white cat reaching toward a woman holding a Hollywood Elixir box while sitting in a chair

What changed in the cats

The blend produced modest changes in gut microbial and metabolite measures and lower serum triglycerides. Fecal characteristics did not improve, and no adverse health effects were observed. 1 These findings indicate biological activity in the tested setting; they do not establish fewer infections, a calming effect or longer life.

Gray-haired man holding a Hollywood Elixir box while two cats rest beside him in an armchair

The dog study adds a different piece of evidence

A 2024 feeding study used 40 adult beagles and a reishi preparation declared to contain at least 70% beta-glucans. After vaccination, the highest-amount group showed a greater rise from baseline in a rabies-specific antibody measure than controls. Several other immune findings were trends rather than clear treatment effects. 2

That is a reason to keep investigating the preparation. It is not a cat dosing study or proof of disease protection. Our reishi guide for dogs follows the canine evidence in its own context.

Reishi is a mushroom studied for immune-related compounds. In cats, the research so far concerns blends rather than reishi on its own.

Reishi’s place in Hollywood Elixir

Hollywood Elixir is a complete 17-active NAD+ longevity nutritional system for dogs and cats. Reishi sits beside a separately declared yeast beta-glucan ingredient, with NAD precursors, mitochondrial ingredients, antioxidants and the wider formula bringing other cellular roles into the same preparation. 4

Each full 2.5 g sachet contains 25 mg of reishi powder extract standardized to 35% total polysaccharides, plus 50 mg of beta-1,3/1,6-D-glucan powder from Saccharomyces cerevisiae. 5 These are two distinct ingredients within the system. The product’s purpose extends beyond a mushroom blend: it brings several aspects of healthy-aging nutrition into one addition to food.

Tabby cat looking up at a Hollywood Elixir sachet held above it, with the product box on a small table

Why energy conversion and cellular protection belong in the picture

Cells need usable energy to do their work. NAD accepts electrons during nutrient metabolism; its reduced form, NADH, passes electrons into mitochondrial reactions in which CoQ also participates. This transfer helps establish the conditions used to make ATP, the cell’s energy currency. 6 13

Cells also have reactions for dealing with reactive molecules. Glutathione-dependent enzymes help remove peroxides. 7 Energy conversion and this form of protection are different jobs, which is why a broader nutritional design includes more than an immune-associated ingredient.

Hollywood Elixir supplies NR tartrate and niacin, ingredients used in NAD production, alongside CoQ10, reduced glutathione, other antioxidants and its reishi/yeast ingredients within the full formula. 4 That is a biological rationale for the combination, not proof that the sachet raises a cat’s NAD or reproduces a laboratory result. The NAD+ guide for cats explains the energy side in more detail.

See how cells make, use and recycle NAD+ in our NADome and NADomics guide.

Hand gently petting an orange-and-white cat beside a food bowl and Hollywood Elixir box

“Powder” and “extract” answer different questions

A powder is a physical form. An extract describes a preparation process. After constituents are extracted, the material can be dried into a powder—so those two words can accurately appear on the same label. Hollywood Elixir’s current specification identifies its reishi as a powder extract. 5

This matters when comparing amounts. A large scoop of whole mushroom powder and a smaller quantity of an extract may represent different materials. Milligrams tell you their mass; they do not make the preparations interchangeable or establish which one best matches a recommendation.

Man holding a Hollywood Elixir box beside a black cat, an orange tabby and a food bowl

Read total polysaccharides and beta-glucans as different declarations

Beta-glucans belong to the broader polysaccharide category. A total-polysaccharide percentage therefore does not tell you how much of that total is beta-glucan. The distinction is visible in the research and current ingredient declarations. 2 5

Hollywood Elixir’s reishi specification is 35% total polysaccharides. Multiplying its 25 mg full-sachet amount by 35% gives 8.75 mg on that declared basis; it does not produce an 8.75 mg beta-glucan claim. The yeast beta-glucan has its own separate entry. Keep both lines intact when comparing formulas.

Compare the preparation before the headline percentage

Useful details include the named mushroom, the material used, the extraction description and what the stated percentage measures. “Fruiting body” identifies different source material from “mycelium,” but neither phrase alone supplies a complete comparison. A percentage is more useful when its meaning is clear.

Use the Hollywood Elixir ingredient guide to inspect the preparation actually declared. Where a manufacturer has not disclosed a detail, leave it unanswered until confirmed. Borrowing another brand’s process description can make two unlike products appear deceptively similar.

An extract can be a powder. Compare how the ingredient was prepared, as well as how much is in the serving.

Silver tabby sitting beside a food bowl and a Hollywood Elixir box held in a person's hand

DVM Voice: Clinical Vignette of a Common Pattern in Senior Cat Aging

Case provided by JoAnna Pendergrass, DVM

Sasha, a 12-year-old cat, was brought in after her owner noticed increased thirst and urination, lethargy, vomiting, and a generally unkempt appearance. Examination showed weight loss, elevated blood pressure, and reduced vitality.

Diagnostic testing revealed elevated kidney markers, poorly concentrated urine, and protein loss in the urine — findings consistent with chronic kidney disease, one of the most common chronic conditions in senior cats.

Her care required a kidney-focused diet, blood pressure management, targeted supplementation, medication support, and regular monitoring — a necessary plan, but one started after clinical signs were already visible.

Clinical takeaway: Sasha’s case reflects why senior-cat wellness should begin before obvious decline. Earlier monitoring, body-condition tracking, hydration awareness, antioxidant support, and daily cellular resilience may help support quality of life as cats age.

Single-case vignette. Not generalizable. Veterinary diagnosis and monitoring are essential for increased thirst, urination, vomiting, lethargy, weight loss, or suspected kidney disease.

Explore Hollywood Elixir Research →
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A study amount is not a serving instruction

Research quantities describe study preparations. A different product needs its own instructions.

The same care applies to a supplement panel: a full-sachet declaration describes that quantity of product, while the current cat directions determine the serving. Follow the instructions for the exact preparation and any individual plan from the treating clinic. Increasing a mixed formula to obtain more reishi also increases every other ingredient in it.

Woman leaning toward a fluffy orange cat beside a Hollywood Elixir box and green food bowl

A manufactured extract does not automatically need brewing

Owners sometimes encounter “hot-water extraction” and wonder whether they should add boiling water before feeding a powder. Those are separate steps. Extraction describes how an ingredient was made; the finished product’s directions describe how it should be used.

Hollywood Elixir is a prepared powder for mixing with food. 4 Follow its current instructions rather than adding a home extraction step. If a particular preparation’s directions are unclear, check them before changing how it is served. The useful outcome is a consistent portion that the cat will eat.

Tabby cat licking its nose beside a food bowl and Hollywood Elixir box

Make room for the usual meal

A supplement routine succeeds only if the cat continues eating adequately. If adding a preparation causes food refusal, offer the familiar food without the addition while reviewing the approach. Persistent appetite loss merits prompt veterinary attention; it should not be dismissed as ordinary fussiness. 11

Introduce changes in a way that lets you observe acceptance and tolerability. Note appetite, stool and any vomiting, and keep the product name and serving available if a concerning change develops. Mushroom supplements can cause adverse reactions, and the whole formula needs to be considered. 9

Put liver warnings and medicines into the right context

Human references report liver injury associated with some reishi use and warn about potential interactions, including with blood-thinning and immune-suppressing medicines. 8 Those reports matter, but they do not establish a universal rule that every cat preparation becomes harmful after 30 days.

A cat with liver or kidney disease, an immune-mediated condition or ongoing medication needs an individual review before a mushroom supplement is added. 9 Bring the exact formula, amount and intended duration. That provides a useful basis for a decision; the word “natural” cannot supply one.

FIV or cancer requires a different kind of evidence

For a cat with FIV, cancer or another diagnosis, the proposed benefit needs to be specific to that condition. A broad claim about immune activity does not answer a treatment question.

For a cat receiving medical care, ask what the proposed addition is meant to achieve, whether the full preparation fits the treatment plan and how its use will be reassessed. Continue established care rather than interpreting supplement research as a reason to change medicines or monitoring.

Tabby cat sitting at a table with a food bowl and Hollywood Elixir box

An unidentified mushroom is an exposure question

If a cat eats an unknown mushroom, contact a veterinarian or animal poison service promptly. Some mushroom exposures can be dangerous, and identification can be difficult. Follow professional advice rather than waiting to see whether signs appear. 10

A labelled reishi preparation and an unidentified mushroom found outdoors are different situations. Evidence about one does not answer the other. This guide is for understanding a named supplement ingredient, not identifying mushrooms or deciding whether an unknown one is edible.

Woman cuddling a silver tabby and a cream-colored cat while holding a Hollywood Elixir box

Keep the purpose of the routine visible

For a healthy-aging addition, practical value includes the full nutritional design, the selected serving and whether it fits comfortably into feeding. A complete diet remains the foundation; an optional formula accompanies it. 12

Keep observations modest and useful: food intake, acceptance, new symptoms and questions for the next health review. A quiet afternoon cannot establish a calming effect, and a healthy month cannot prove stronger immunity. Cost is best compared at the actual serving and across the ingredients being supplied, rather than by the reishi number alone.

Consider reishi with the whole healthy-aging formula

Reishi research becomes more useful when the species, preparation and measured result stay together. Use the research to understand the ingredient, then the full label to understand the preparation you are considering.

Hollywood Elixir brings reishi into a broader 17-active NAD+ longevity system. Its combination of NAD-related nutrients, mitochondrial ingredients, antioxidants and immune-associated ingredients makes a complete cellular-nutrition routine practical in one food-mixed step. Explore the full formula and current cat serving to bring that wider approach to the usual meal.

Hollywood Elixir brings reishi into a complete formula built around energy production and cellular protection, in one addition to food.

Educational content only. This material is not a substitute for veterinary advice. Always consult your veterinarian about your cat’s specific needs. These statements have not been evaluated by the Food and Drug Administration. Products mentioned are not intended to diagnose, treat, cure, or prevent any disease.

Glossary

Reishi: a mushroom also called lingzhi, commonly named Ganoderma lucidum in supplement research.

Polysaccharides: carbohydrates made from linked sugar units; a broad category that includes beta-glucans.

Beta-glucans: a particular group of polysaccharides whose source and structure can differ.

Extract: a preparation made by drawing constituents from a source material; it may then be dried into a powder.

Standardization: a declared specification for a constituent or group of constituents.

Biomarker: a measured biological feature, such as an antibody concentration.

NAD: a coenzyme involved in cellular metabolism; NADH is its reduced form.

Related Reading

Aging & Senior Cat Guidance
• Cat Age Calculator: Cat Years to Human Years
• Cat Lifespan by Breed
• Lethargy in Cats
• Senior Cat Not Eating
• Cat Drinking A Lot
• Why Is My Senior Cat Withdrawn?

Healthy Aging Support
• NAD+ for Cats
• NMN for Cats
• Vitamins For Older Cats
• Senior Cat Food
• Longevity Drugs for Cats

References

Numbered references identify the sources used for specific claims. Read the study design, species and evidence boundaries alongside each finding.

  1. Effects of a mushroom-based β-glucan blend on the gastrointestinal health and immune function of healthy adult cats. Evidence boundary: Randomized trial of a mushroom-and-colostrum blend in 20 healthy adult cats. It did not test reishi alone or Hollywood Elixir.↩ 1 · ↩ 2
  2. Functional properties of Ganoderma lucidum supplementation in canine nutrition. Evidence boundary: 2024 feeding study in 40 adult beagles using a specified reishi preparation. An antibody response is not a demonstration of disease prevention in cats.↩ 1 · ↩ 2
  3. β-Glucan-Induced Trained Immunity in Dogs. Evidence boundary: Canine immune-cell experiment, mainly using an Euglena-derived beta-glucan. This was laboratory work, not a feeding study of reishi.↩
  4. Hollywood Elixir current supplement facts. Evidence boundary: Current Hollywood Elixir ingredient declaration. Amounts refer to a full 2.5 g sachet; follow the current cat serving directions.↩ 1 · ↩ 2 · ↩ 3
  5. Hollywood Elixir current ingredient specifications. Evidence boundary: Hollywood Elixir ingredient specifications. Reishi total polysaccharides and the separate yeast beta-glucan are distinct declarations.↩ 1 · ↩ 2 · ↩ 3
  6. NADH:ubiquinone oxidoreductase oxidizes NADH and reduces CoQ. Evidence boundary: Curated account of normal mitochondrial electron transfer. It does not test the effect of oral Hollywood Elixir.↩
  7. Detoxification of Reactive Oxygen Species. Evidence boundary: Curated account of cellular reactions that handle reactive oxygen molecules. Normal biology does not establish a finished-product response.↩
  8. Reishi Mushroom. Evidence boundary: Human clinical reference, including reishi constituents, case reports and potential interactions. It does not establish a feline duration or dose threshold.↩ 1 · ↩ 2
  9. Medicinal Mushrooms. Evidence boundary: Veterinary guidance on administration, possible reactions and medical review of mushroom supplements. It is not a trial of Hollywood Elixir.↩ 1 · ↩ 2
  10. The Fungus Among Us: Mushroom Toxicosis. Evidence boundary: Poison-control guidance for mushroom exposure. Unknown wild mushrooms require a different response from comparing labelled supplements.↩
  11. Anorexia. Evidence boundary: Cornell guidance on reduced appetite in cats and the importance of adequate food intake.↩
  12. “Complete and Balanced” Pet Food. Evidence boundary: FDA explanation of complete-and-balanced food and its stated life-stage purpose.↩
  13. Niacin—Fact Sheet for Health Professionals. Evidence boundary: General B3 and NAD biochemistry. Human intake recommendations are not used as cat serving instructions.↩

FAQ

What is reishi used for in cat supplements?

Reishi supplies polysaccharides and other compounds studied for interactions with immune activity. The product’s preparation and the reason for using it should be clear before adding it to a cat’s routine.

Has reishi been studied in cats?

Yes. A controlled trial tested a reishi-containing blend in healthy adult cats; it did not isolate reishi’s contribution.

Is reishi powder different from an extract?

It can be. Powder describes physical form, while extract describes preparation. An extract may be dried into a powder, so check the full description rather than assuming every powder is whole mushroom material.

Does 35% polysaccharides mean 35% beta-glucans?

No. Beta-glucans are one group within the broader polysaccharide category. Hollywood Elixir’s reishi specification declares total polysaccharides; its yeast beta-glucan ingredient is listed separately.

How much reishi should a cat receive?

Use the directions for the exact product and any individual veterinary plan. The feline research amount describes a whole experimental blend, not a universal reishi dose. A full-sachet ingredient amount also needs to be distinguished from the selected cat serving.

Should I brew a reishi extract in hot water?

Follow the finished preparation’s instructions. A reference to hot-water extraction describes manufacturing and does not automatically require another heating step at home.

Is reishi safe for long-term use in every cat?

A limited study in healthy cats cannot establish that. Review the full product with the clinic when medical conditions or medicines are involved, and monitor tolerability. Human liver reports do not define a precise safe-duration rule for cats.

What does Hollywood Elixir add beyond reishi?

Its 17-active NAD+ longevity system includes NAD-related nutrients, mitochondrial ingredients, antioxidants, a separate yeast beta-glucan and the wider formula. It brings several connected nutritional roles into one prepared addition to food.

Orange-and-white cat beside a Hollywood Elixir box held in a person's hand

Discover LPL-01: How This Fits Into a Larger Feline Longevity System

Aging in cats unfolds quietly. It’s not driven by a single failure, but by gradual shifts across interconnected systems — cellular energy, oxidative balance, immune tone, and tissue integrity — each influencing the others over time.

This article explores one layer of that system. To understand what actually shapes long-term health, you need to step back and look at how these layers interact.

Start with the underlying science:

Keep exploring

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