At a glance

What is documented, and what stays open

Swipe sideways on mobile. All rows reflect the named sources as they read on August 27, 2026; companies and pages change, so use the sources at the end to re-check anything before relying on it.

Part 1

The company, on paper

Start with the question the search box actually asks: who is Nathan & Sons? The answer sits in the US Patent and Trademark Office's public TSDR database. The UNDERBRUSH trademark, serial number 98793988, is owned by NATHAN & SONS LLC, a limited liability company organized in Wyoming, with an owner address at 1912 Capitol Ave, Ste 500 in Cheyenne. The application was filed October 10, 2024, and the mark was registered on the Principal Register on July 1, 2025, as US registration 7850981. The filing declares first use of the mark on April 1, 2023. A second application, serial 99024763, filed January 31, 2025, seeks to register the combined mark NATHAN & SONS UNDERBRUSH REMINERALIZING GUM and names Nathan Malonson as the applicant; it was still pending as of the date this review was written. That is a real company with real intellectual property, and it answers the most basic version of the legitimacy question immediately: this is not an anonymous storefront.

The company's own press release, distributed via EIN Presswire on May 12, 2025, fills in the founding story. It describes founder Nathan Mal as a former executive chef who developed the gum after a personal dental issue made him question conventional gum ingredients, and states the brand grew "without external funding." The release is datelined Placerville, California. Modern Retail, a retail trade publication, adds the timeline: the company was founded in 2022, first went viral with a TikTok video posted over Thanksgiving weekend 2023, hard-launched in January 2024, and, per the company, "surpassed $30 million in sales" in 2024. Whatever you conclude about anything else in this review, the growth is documented by a named trade outlet, and it is the honest explanation for why so many people are typing this company's name into a search box.

One company, one flagship product

A point of frequent confusion worth settling early: Nathan & Sons and Underbrush are the same operation. Nathan & Sons is the company; Underbrush Remineralizing Gum is its flagship product, and the pending combined trademark stitches the two names into one. The company also sells Uprising Energy Gum, a Pearl Powder Tooth Scrub and a Pearl Serum, but the remineralizing gum is the product the advertising, the press and the search volume are about. This article reviews the company: its paperwork, its disclosure practice, its policies and its record. If what you want is a product-level comparison of the gum itself, ingredient by ingredient, we keep that in a separate piece: Minvelle vs Underbrush covers the gum head to head, and this page will not duplicate it.

The paper trail: three location signals, presented neutrally

Where is Nathan & Sons? The public record gives three different signals, and it is worth being precise about what each one is. The USPTO filings give the Cheyenne, Wyoming suite; that address is a commercial registered-agent office of the kind thousands of unrelated companies use as their legal address, so it tells you where the LLC is organized, not where anyone works. The press release is datelined Placerville, California, a town in the Sierra foothills, which is the company's own public statement of where its story is set. And the domain nathanandsons.com was created on June 21, 2023 through GoDaddy with a WHOIS privacy service, Domains By Proxy, shielding the registrant's details, which is a default setting rather than a suspicious one. None of these three signals contradicts the others, and none is unusual on its own; Wyoming LLCs, privacy-shielded domains and a founder working from wherever the founder lives are all standard furniture of American e-commerce. The neutral summary is simply that the company's public paper trail points at a legal address, a press dateline and a shielded registration rather than at a published operating address, and a buyer who wants to know where the seller physically sits will not find that on the pages we checked.

One more record worth naming because its absence is informative in the other direction: no Better Business Bureau profile exists for Nathan & Sons as of the date we searched. That is neutral, not damning. BBB profiles are often created in response to complaint volume, and a company can lack one for entirely unremarkable reasons. We state it because a review that checks a database should say so when the database comes back empty, and because it is a genuine point of contrast with some other brands in this category, whose third-party records we have covered elsewhere using the same documents-only method.

Part 2

What the product pages disclose, and what they don't

Here is the product as its own page presents it, captured August 27, 2026. Underbrush Remineralizing Gum is a chicle-base gum sold in four flavors, Mastic Mint, Berry, Cinna-Mastic and Tropic Twist, plus a Variety Pack, in two-, four- and eight-pack tiers. The entry two-pack shows a sale price of $29.99, with variant prices we observed running from $20.99 to $79.99 across flavors and tiers, and subscription pricing below one-time pricing. The usage instructions read: "Chew 1-2 pieces after meals for at least 30 minutes or as long as you'd like," and the page's own FAQ adds that "One pack should last for one week. A four-pack is approximately a 30-day supply if you chew 2 pieces per day." One number the page never states: how many pieces are in a pack. A shopper can learn how long a pack should last but not how many pieces that promise is built on, which makes per-piece price comparisons impossible from the official page alone.

The ingredients are published in a collapsible "Ingredients List" section on the product page, names only, with a separate list per flavor. The mint-family list names: xylitol, a chicle gum base (chicle, candelilla wax, citric acid), erythritol, mastic gum, spruce gum, acacia gum, mint flavor, myrrh gum, hydroxyapatite (nano and micro), calcium carbonate, calcium bentonite clay, magnesium carbonate, zinc gluconate and a terpene blend (menthone, carvone, cineol); the berry-family list swaps in fruit powders and stevia extract. The page adds that "The complete, current ingredient declaration is printed on the packaging." No quantities are given for any ingredient, in any flavor. The free-from claims, verbatim: "NO Gluten, Sugar, Aspartame, Sucralose" and "Contains ZERO Plastics, PFAS, parabens," plus "Made in USA with globally sourced ingredients." As a formula on paper, we will say plainly what we also said about other natural-base competitors: a chicle, mastic, spruce and myrrh chew base is a genuinely characterful materials choice, and xylitol plus erythritol is exactly the sweetener pairing our own gum uses. Whoever wrote this recipe knows the category.

The three numbers you cannot find

Now the disclosure audit, which is the core of this review. Hydroxyapatite is the headline active ingredient, the one in the product's name, the one the research tradition behind "remineralizing" rests on. That research treats two variables as load-bearing: how much of the mineral reaches the tooth, and at what particle size. On the Nathan & Sons pages we checked, three numbers are missing. First, no milligram amount of hydroxyapatite per piece appears anywhere: not on the product page, not in the FAQ, not in the reference sections. Second, no particle-size figure appears; the page describes the ingredient as included "in nano and micro particle sizes," a phrase that names two categories without giving a single nanometer measurement. Third, no certificate of analysis, the standard lab document that would verify identity and content, is published anywhere we looked. The ingredient list tells you the mineral is present. Nothing on the site tells you how much, how small, or on whose measurement.

Why this matters is not pedantry. The clinical literature on hydroxyapatite oral care is a literature about amounts and sizes; a study of a gum delivering a defined dose says nothing about a gum delivering an undefined one. A buyer comparing brands on disclosure can see the pattern across the whole category in our hydroxyapatite gum database, which tracks exactly these fields, brand by brand: dose published, size published, certificate published. Most brands fail at least one of those tests. The reason this review dwells on it here is that this particular brand runs the largest claims in the category off the smallest set of published numbers, and, as the next section shows, its own content team appears to know it.

Their own comparison page concedes the point

This is the single most striking document we found, and it is Nathan & Sons' own. The company publishes a comparison article on its blog, "Underbrush Hydroxyapatite Gum vs Competitors: 2026 US Guide," which ends in a "Quick decision helper" table matching buyer needs to brands. The row for clean-label, plastic-free buyers names Underbrush as the best fit, reasonably. But the row for the need "Concentration transparency" names a different brand entirely: "Best fit: Enamio," a competitor the same article describes as "emphasizing pharmaceutical-grade manufacturing standards and high active concentration." Read that again with the previous section in mind. The company's own editorial content, on its own domain, tells shoppers that if they want to know how much active ingredient is in their gum, the best fit is a competitor. It does this while its own product page publishes no concentration at all. We add no characterization to that; the company's table speaks in its own voice, and it says the transparency category belongs to someone else.

Part 3

The claims, next to the record

The homepage headline, in the site's own capitals: "THE WORLD'S FIRST REMINERALIZING CHEWING GUM." A company blog post repeats it in prose, stating that "Nathan and Sons proudly stands as the world's first and best remineralizing gum." Set one public date next to that claim. The company's own trademark filing declares first use of the UNDERBRUSH mark on April 1, 2023. A randomized controlled trial of a hydroxyapatite chewing gum in orthodontic patients, by Porciani and colleagues, was published in 2014 and is indexed on PubMed under PMID 25122980, nine years before that declared first-use date, and remineralizing gum research more broadly predates it by more than that. Both dates are in public databases. We report them side by side and leave the arithmetic to the reader.

The product page's meta description, the text the company writes for search engines, lists "What our customers report in just 3 weeks," including "Cleaner Mouth Than Ever Before," "Fresher Breath," "Better Gum Health," "Natural Teeth Whitening" and "Less Sensitivity." The page body carries claims including "Fights Bacteria Growth," "Better At Removing Plaque" and "Helps Prevents Tartar Formation." Further down, the same page carries the standard disclaimer, quoted verbatim: "this product is not intended to diagnose, treat, cure, or prevent any disease. These statements have not been evaluated by the U.S. Food and Drug Administration." Both passages are the company's own text on the same page. The customer-report framing attributes the benefit list to what customers say rather than to what the product does, which is a careful construction; the disclaimer then formally withdraws any disease claim. A shopper deciding how much weight the benefit list deserves should read it with both texts in view, and should notice that the list describes reports, not measurements.

We ran their citations through PubMed. Here is what resolved.

Unlike some competitors, Nathan & Sons does cite research: the product page carries numbered reference sections, one per ingredient, with roughly 39 linked citations in the format of author, title, journal, year. That is the right instinct, and we want to be fair about the result of checking it. On August 27, 2026 we took eight of those citations and resolved each one against PubMed and CrossRef, the public indexes of the biomedical literature. Three resolved cleanly to exactly the papers named. Five did not. The table shows each case; the remaining citations, roughly 31, were not checked, so this is a spot-check and not an audit of the full list.

Swipe sideways on mobile. Spot-check run on August 27, 2026 against PubMed and CrossRef: 8 of roughly 39 citations checked, 3 clean, 5 with author or link mismatches. The rest were not checked.

What does a five-of-eight mismatch rate mean? We will not speculate about how the errors happened; wrong author attributions and malformed links can come from sloppy manual work or from automated drafting, and the reader's guess is as good as ours. What can be said factually: reference sections exist to let readers verify claims, and a reference that names the wrong authors or points at the wrong paper cannot be verified as written; a reader who trusted the section's look without resolving the links would come away more confident than the links justify; and the underlying ingredients do have real literature, which makes the errors unnecessary. The fix costs one afternoon with a research librarian's care: resolve every citation, correct the author names, repair the links. Each corrected line would improve this review on the spot.

Part 4

The reviews, and the refund policy

The independent review record for a company this size is surprisingly thin, which is itself worth knowing. The Trustpilot profile for nathanandsons.com showed, on August 27, 2026, a score of 2.7 out of 5 from 14 reviews, with 57% of them one-star and 29% five-star. Fourteen reviews is a very small sample for a brand reporting eight-figure sales, and we would caution against reading a stable satisfaction rate into it in either direction; a handful of new reviews could move that score substantially. What the existing reviews contain is still reportable: one one-star reviewer in May 2026 described a subscription cancellation process they called "tricky" and wrote of "hidden costs behind what seems like a deal." That is one consumer's account, quoted from a public profile, and we present it as exactly that. For a wider unfiltered picture of what actual users say about the product itself, our roundup of real user discussions of Underbrush collects the recurring praise and complaints in one place.

The guarantee and the fine print, side by side

Here is the storefront's promise, from the product page's own meta description: "30-Day Satisfaction Guarantee | Fast Shipping + Easy Returns." And here is the refund policy on the same domain, same capture date: "For safety and hygiene reasons, consumable and oral-care products are final sale, including: Chewing gum (all flavors)," along with Pearl Powder, Pearl Serum, toothbrushes and "Any opened or used oral-care product." The policy offers a paid add-on at checkout, Package Protection, which covers a "Taste Guarantee" exchange path handled by the support team. On subscriptions, the policy states: "New subscriptions cannot be canceled within the first 10 days, giving you time to receive and try the product," after which they can be canceled, skipped or modified through the account portal. For orders shipped into the European Union, a 14-day cooling-off period applies to eligible items, with the consumable exclusions still applying unless covered by the protection add-on.

Both passages are Nathan & Sons' own text, and this review adds no adjective to either. A reader can hold them next to each other: a satisfaction guarantee headline written for the search results, and a policy page on which the product this company is famous for, chewing gum in all flavors, is listed as final sale. The practical consequence is not ambiguous, and it is the single most useful thing a buyer can take from this article: with this seller, the decisions that count are the ones made before checkout. Read the policy page itself before buying, know that the gum is final sale unless you bought the protection add-on, and know that a new subscription has a 10-day window in which the policy says it cannot be canceled at all. None of this is hidden; all of it is one click deeper than the banner.

In fairness

What is genuinely real about Nathan & Sons

A review built on documents owes the company the documents that favor it, and here they are substantial. The trademark is real: UNDERBRUSH sits on the USPTO's Principal Register, examined and granted, which is more intellectual-property substance than most brands in this category can show. The growth is documented by a named trade publication, not just by the company's own ads. The founding story, a chef formulating a gum after his own dental trouble and building the company without outside money, is consistent across the company's press release and the trade coverage. The product is real, arrives, and has a formula with genuine materials taste. The FDA disclaimer is present where it should be. And the ingredient list is published in plain text per flavor, which several competitors we have reviewed do not manage.

Then there is the counterfeit fight, which deserves its own paragraph because it is the most sympathetic documented fact about this company and it directly affects buyers. Modern Retail reports that more than 800 knock-off Underbrush brands appeared over two years, that the company has spent, in the founder's words, "over a million dollars excluding the ads and registration fees" fighting them, and that fake versions surfaced on Walmart Marketplace, eBay and even inside Amazon listings. The reporting describes customers "sending photos of pieces of metal or wood they found in it," referring to counterfeit gum. The company runs a dedicated "Scams & Knock-Offs" page for reporting fakes and has its support team flag taste and texture complaints as possible counterfeit cases. Take a moment with what that means practically: for this specific product, buying from an unofficial seller is not just a warranty risk, it is a documented physical-contamination risk. Whatever criticisms this review has recorded, on this point the company is plainly in the right, and the safest thing a buyer can do is exactly what the brand asks: buy only through its official channels.

Part 5

How Minvelle compares, on the one axis this article is about

We make a competing product, so let us keep this section narrow and honest. This is not a claim about whose gum is better; taste, chew feel and formula philosophy are personal, Underbrush's natural resin base is a genuinely nice piece of work, and a fair head-to-head of the products lives in our separate Underbrush comparison linked above. The comparison this article has earned is about one thing only: what a buyer can verify. Minvelle publishes its nano-hydroxyapatite dose per piece and its particle-size specification, publicly, where anyone can read them and hold us to them. Nathan & Sons, as of August 27, 2026, publishes neither. That is the entire comparison, and it is checkable in both directions: our numbers are on our pages, and the absence of theirs is on theirs.

The reason we keep making this point across every review in this series is that disclosure is the one axis a shopper can act on without a lab. You cannot taste a milligram figure or see a particle size, but you can check in thirty seconds whether a brand states them. The two-question test works on any hydroxyapatite product, ours included: what size, and how many milligrams per piece. Brands that answer in print are staking their name on numbers that can be checked and challenged; brands that do not answer are asking for trust without collateral. If you want to see how the whole shelf performs on that test, and how the gums actually chew when they arrive, our hands-on comparison of remineralizing gums runs the field through the same questions. Underbrush could join the disclosure column tomorrow with a single product-page edit, and we would report the change in this article's next update.

Questions, answered

The things people actually ask