Interactions on record — worth a quick check against your medications. Based on 2 of 4 ingredients. Check your meds →
Dietary supplement

Rice Fiber First Ingredients & Drug Interactions

by Greens First

Rice Fiber First label
See full label image
Other (e.g. Tea Bag) Category: Other Combinations
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Rice Fiber First against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Rice Fiber First is a dietary supplement by Greens First with 4 active ingredients. Its ingredients are commonly taken for diarrhea relief, constipation and digestive health, cholesterol support.Based on those ingredients, 23 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Apple Pectin. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Rice Fiber First by Greens First

Ask about any prescription or over-the-counter medication and we check it for interactions with Rice Fiber First by Greens First — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Rice Fiber First by Greens First

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Partial disclosure
Ingredient Transparency · database check
Partial

Most active ingredients list an amount, but at least one is hidden in a blend or missing.

Why this rating?
  • The label discloses an exact amount for 3 of its 4 active ingredients.
  • “R.F. Proprietary Blend” is a proprietary blend — the label gives one combined amount (4,800 mg) without saying how much of each component you get.

Rice Fiber First contains four active ingredients: Apple Pectin, stabilized Rice Bran derivative, Methylcellulose, and an ingredient called RiceFiberRx. These work together as a fiber supplement — pectin and rice bran are soluble and insoluble fibers that add bulk and support digestive function.

Methylcellulose is a thickening agent that also adds fiber. The product also contains inactive ingredients (Calcium Carbonate, Stearic Acid, and Magnesium Stearate) as binders and fillers.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: digestive health, cholesterol and glucose support.
  • We looked for evidence on: Dyslipidemia, Hypercholesterolemia, Diabetes, Impaired glucose tolerance (Prediabetes), Diarrhea, Irritable bowel syndrome (IBS) — and 4 related terms.
  • The strongest evidence on file: Pectin is rated "Possibly Effective" for Hypercholesterolemia (Natural Medicines).
  • Also on file: Rice Bran is rated "Possibly Effective" for Dyslipidemia.
  • Also on file: Pectin is rated "Insufficient Reliable Evidence To Rate" for Diarrhea, Irritable bowel syndrome (IBS), Impaired glucose tolerance (Prediabetes).

Apple Pectin is rated possibly effective for high cholesterol (hypercholesterolemia), though the evidence isn't robust. For prediabetes (impaired glucose tolerance) and radiation exposure, there isn't enough reliable evidence to know if pectin works.

Stabilized rice bran is also rated possibly effective for high cholesterol and related blood lipid problems (dyslipidemia). For colorectal cancer prevention, the evidence suggests it's probably not effective.

We don't have effectiveness ratings for Methylcellulose or RiceFiberRx in our data.

The evidence, ingredient by ingredient Pectin Rice Bran

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 2 of the 2 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 2 of 2.
  • General safety write-ups exist for 2 of 2.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Apple Pectin is generally well tolerated from food and typical supplement amounts. The most common side effects are mild — diarrhea, gas, loose stools, and gentle cramps.

Allergic reactions, including anaphylaxis, are rare but possible in people sensitive to pectin. Stabilized rice bran is also generally well tolerated but can cause abdominal discomfort, gas, and unpredictable bowel habits when you first increase your fiber intake.

Rare serious allergic reactions are possible. If you have a known pectin or rice allergy, avoid this product.

Side effects, ingredient by ingredient Pectin Rice Bran

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 1 of the 2 matched ingredients can interact with medications — Pectin.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: heart-rhythm medications.
  • For scale: 23 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Check with your pharmacist before taking this product if you use digoxin (Lanoxin) for your heart, lovastatin (Mevacor) for cholesterol, or tetracycline antibiotics — pectin may lower how much of these medications your body absorbs and make them less effective. We couldn't verify interaction data for Methylcellulose and RiceFiberRx, so it's worth discussing those ingredients with us if you take any regular medications.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glancePartially disclosed formula with some supporting evidence for its stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

This fiber supplement may help with cholesterol management if the pectin and rice bran components deliver their effect — but the evidence is modest. It's a reasonable option for general digestive fiber if you don't take digoxin, lovastatin, or tetracycline antibiotics.

If you do take any of those or any other prescription medication, check with us first using the tool on this page. Start with a small dose to let your digestive system adjust.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 2 of 4 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jul 25, 2024.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Rice Fiber First, straight from the product label.

Brand Greens First
Barcode (UPC) 826106247794
Net contents 180 Caplet(s)
Market status On market
Date entered into DSLD Jul 25, 2024
DSLD ID 312790
Product type Other Combinations
Supplement form Other (e.g. Tea Bag)
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Rice Fiber First by Greens First, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
3 Caplet(s)
Maximum serving Sizes:
3 Caplet(s)
Servings per container
60
UPC/BARCODE
826106247794
IngredientAmount% DV
Methylcellulose686 mg--
Apple Pectin418 mg--
R.F. Proprietary Blend4800 mg--
RiceFiberRx3696 mg--
stabilized Rice Bran derivative0 NP--

Other ingredients: Calcium Carbonate, Stearic Acid, Magnesium Stearate

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Formula

Rice Fiber First Stabilized Rice Bran Caplets contain a proprietary, bio-medical food blend of a highly nutritious insoluble dietary fiber (pre-digested stabilized rice bran derivative) and soluble fiber (apple pectin). The proper combination of these fibers taken daily helps to support: Healthy weight management Bowel regularity Gastro-Intestinal & bowel health Normal cholesterol levels Normal glucose levels Normal lipid levels Because Rice Fiber First Stabilized Rice Bran Caplets contain pre-digested, water soluble fractions of stabilized rice bran, this fiber does not cause bloating or gas by producing methane or carbon dioxide in the gastrointestinal track. Rice Fiber First Stabilized Rice Bran Caplets contain a superior quality nutritional fiber contain over 100 antioxidants; Gamma Oryzanol; Polyphenols; Alpha Lipoic Acid, Ferulic Acid; CoQ10; Inositol Hexaphosphate (IP6); Beta Sitosterol and other Phytosterols; Vitamin E including tocopherols and tocotrienols; minerals and trace minerals.

Antioxidant rich, nutritional fiber Stabilized rice bran caplets Rice Fiber First 180 caplets/ 885 mg fiber per caplet

Suggested/Recommended/Usage/Directions

Eating right just got easier-try the Greens First Wellness Shake! The Greens First Wellness Shake is made by mixing Greens First (Original or Berry) together with either flavor of Greens First Boost (Chocolate or Vanilla). It's the perfect nutritious and delicious "instant breakfast" or an anytime "energy booster" and part of the Alkalize Now Program.

Directions for use: Take three caplets twice a day with 8 ounces (or more) of water, or as directed by your healthcare professional. Mix & match to make the wellness shake

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

Formulation

Helps support: Gastro-Intestinal & bowel health Normal glucose levels Normal cholesterol & lipid levels A Dietary Supplement for regularity, cleansing & healthy weight management

FDA Statement of Identity

A Dietary Supplement for regularity, cleansing & healthy weight management

Brand IP Statement(s)

Ceautamed Worldwide, LLC All Rights Reserved

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Rice Fiber First by Greens First label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Rice Fiber First label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Rice Fiber First by Greens First

These are the 4 active ingredients this product is made of. Select any to open its full monograph.

Serving size3 Caplet(s) Dosage formOther (e.g. Tea Bag) Servings per container60 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

R.F. Proprietary Blend

4800 mg per serving

Other (inactive) ingredients: Calcium Carbonate, Stearic Acid, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

Rice Fiber First by Greens First Drug Interactions

Want to check YOUR meds against Rice Fiber First?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
23Drugs
23 Moderate

Ingredients driving the most interactions

Apple Pectin 23

Individual Drug Interactions

The ingredients in Rice Fiber First interact with 23 drugs. Click any drug to see the details.

1 of the 4 ingredients in Rice Fiber First interact with drugs. Each result below shows which ingredient is responsible. Apple Pectin

Each ingredient & the kinds of drugs it affects

For each ingredient in Rice Fiber First with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Apple Pectin3 drug types · 23 drugs

Digoxin (Lanoxin)

Theoretically, pectin might reduce the absorption of digoxin, potentially decreasing its effectiveness.
A small clinical study shows that taking digoxin with a kaolin-pectin suspension reduces the absorption of digoxin by about 62%. It is unclear if these effects are due to pectin, kaolin, or the combination.

Likelihood Possible Evidence B
Lovastatin (Mevacor)

Theoretically, pectin might reduce the absorption of lovastatin, potentially decreasing its effectiveness.
Case reports suggest that concomitant use of pectin and lovastatin might reduce the cholesterol-lowering effect of lovastatin, possibly due to reduced intestinal absorption of lovastatin.

Likelihood Possible Evidence D
Tetracycline Antibiotics

Theoretically, pectin might reduce the absorption of tetracycline antibiotics, potentially decreasing their effectiveness.
A small clinical study shows that taking tetracycline with bismuth subsalicylate in a kaolin-pectin suspension reduces the absorption of tetracycline by about 34%. It is unclear if these effects are due to pectin, kaolin, bismuth subsalicylate, or the combination.

Likelihood Possible Evidence B
Apple Pectin full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Rice Fiber First, from the product label.

Greens First

See all Greens First products
Name
Ceautamed Worldwide, LLC
City
Boca Raton
State
FL
ZipCode
33487
Phone Number
866-409-6262
Web Address
GreensFirst.com
Pharmacist Counseling Corner

Rice Fiber First by Greens First: Common Questions

Does Rice Fiber First by Greens First interact with any medications?
Yes. Based on its ingredients, Rice Fiber First has a known interaction with 23 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Rice Fiber First contains 4 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Will this give me side effects?
Most people tolerate the pectin and rice bran well. You might notice mild gas, loose stools, or slight cramping, especially when you first start — that usually settles as your gut adjusts. Allergic reactions are rare but possible if you're sensitive to pectin or rice.
Is this safe during pregnancy or breastfeeding?
Apple Pectin is rated likely or possibly safe in pregnancy and lactation, though concentrated supplement amounts haven't been studied as thoroughly as food amounts. Stabilized rice bran is likely safe in pregnancy. Because concentrated supplements are less well studied than food sources, talk with your doctor or pharmacist about whether this product is right for you during pregnancy or breastfeeding.
What is apple pectin and what does it do?
Pectin is a soluble fiber from apple skin and flesh that acts like a sponge in your digestive tract. It's possibly effective for lowering cholesterol, though the evidence isn't definitive. It also adds bulk and may support digestive function.
What is rice bran and why is it in here?
Rice bran is the nutrient-rich outer layer of rice grains. It contains both soluble and insoluble fiber and is possibly effective for managing cholesterol and blood lipids. Combined with pectin, it boosts the overall fiber content of this product.
Can I use this if I take multiple medications?
Not automatically — fiber supplements can interfere with absorption of some drugs. The checklist on this page lets you enter your medications to see if any conflict. Digoxin, lovastatin, and tetracycline antibiotics are the ones we know about; run all your prescriptions through to be sure.
How long does it take to work?
There's no timeline in our data for how quickly pectin or rice bran show an effect on cholesterol. General digestive changes — like softer stools or less constipation — often appear within a few days as your fiber intake rises.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Rice Fiber First label
Go deeper

The Full Monographs Behind Rice Fiber First’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Pectin

Interacts with 23 drugs

Pectin is a natural soluble fiber found in fruits like apples and citrus, and it is widely used in foods and as a fiber supplement. It may modestly help with cholesterol, blood sugar, and di...

Read the full Pectin monograph → Herb & supplement monograph

Rice Bran

Rice bran is the nutrient-rich outer layer of the rice grain and is a good source of fiber, healthy fats, and plant compounds. It is most studied for helping lower cholesterol, but for most...

Read the full Rice Bran monograph →
Sources

Sources & How We Checked

Rice Fiber First's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 18 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Pectin 11 references
  1. Jaakkola MS, et al. Asthma caused by occupational exposure to pectin. J Allergy Clin Immunol 1997;100:575-6. PubMed
  2. Westphal W, et al. [Exogenous allergic asthma following pectin exposure-a new occupational allergen]. Pneumologie 1990;44(Suppl 1):337-8.
  3. Baldwin JL, et al. Pectin-induced occupational asthma. Chest 1993;104:1936-7. PubMed
  4. Cohen AJ, Forse MS, Tarlo SM. Occupational asthma caused by pectin inhalation during the manufacture of jam. Chest 1993;103:309-11.
  5. Kraut A, et al. Christmas candy maker's asthma. IgG4-mediated pectin allergy. Chest 1992;102:1605-7. PubMed
  6. Richter WO, Jacob BG, Schwandt P. Interaction between fibre and lovastatin. Lancet 1991;338:706.
  7. Albert KS, Ayres JW, DiSanto AR, et al. Influence of kaolin-pectin suspension on digoxin bioavailability. J Pharm Sci 1978;67:1582-6. PubMed
  8. Albert KS, Welch RD, DeSante KA, et al. Decreased tetracycline bioavailability caused by a bismuth subsalicylate antidiarrheal mixture. J Pharm Sci 1979;68:586-8. PubMed
  9. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
  10. Federal Register April 17,2003. Anti-Diarrheal Products for over-the-counter human use; final monograph. Available at: http://www.fda.gov/OHRMS/DOCKETS/98fr/03-9380.pdf (Accessed 27 December 2004).
  11. Washio K, Nakamura M, Sato N, et al. Anaphylaxis in a pectin- and cashew nut-allergic child caused by a citrus bath. Allergol Int 2022;71(1):155-157. PubMed

See these in context on the Pectin monograph →

Rice Bran 7 references
  1. Covington TR, et al. Handbook of Nonprescription Drugs. 11th ed. Washington, DC: American Pharmaceutical Association, 1996.
  2. Fujiwaki T, Furusho K. The effects of rice bran broth bathing in patients with atopic dermatitis. Acta Paediatr Jpn 1992;34:505-10.
  3. Uenotsuchi T, Satoh E, Kiryu H, Yano Y. Pyemotes dermatitis caused by indirect contact with husk rice. Br J Dermatol 2000;143:680-2. DOI
  4. Satoh R, Tsuge I, Tokuda R, Teshima R. Analysis of the distribution of rice allergens in brown rice grains and of the allergenicity of products containing rice bran. Food Chem. 2019;276:761-767. PubMed
  5. Togashi Y, Inomata N, Suzuki A, Hakuta A, Aihara M. Pediatric case with rice bran allergy induced by epicutaneous sensitization in a family rice shop. Allergol Int. 2019;68(1):117-118. PubMed
  6. So WKW, Chan JYW, Law BMH, et al. Effects of a Rice Bran Dietary Intervention on the Composition of the Intestinal Microbiota of Adults with a High Risk of Colorectal Cancer: A Pilot Randomised-Controlled Trial. Nutrients 2021;13(2):526. PubMed
  7. Haneda Y, Kadowaki S, Furui M, Taketani T. A pediatric case of food-dependent exercise-induced anaphylaxis due to rice bran. Asia Pac Allergy 2021;11(1):e4. PubMed

See these in context on the Rice Bran monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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