Best Spermidine Supplement

Aging is a pretty common concern among supplement users. In a survey by the Council for Responsible Nutrition, 20% of respondents considered "healthy aging" to be their top reason for supplementation; ahead of it were pursuits like "heart health" and "overall health," which aren't so dissimilar to the whole healthy-aging thing.1

Coincidentally, some supplements are actually purported to deliver healthy aging, heart health, and overall health in a single product. Take spermidine, for example. By activating a bodily process called autophagy, spermidine may be able to help the body's cells function optimally, reduce the risks of harmful genetic mutations and oxidative stress, and potentially support a longer lifespan.

In this guide, we explain spermidine's critical role in human health, break down the qualities that go into a top-tier spermidine product, and discuss what we've found to be the best spermidine supplements on the market.

Check out our summary of recommendations for the quickest rundown, and then read further to see how we reached our conclusions.

Over the past two decades, Innerbody Research has helped tens of millions of readers make more informed decisions about staying healthy and living healthier lifestyles.

Our investigation into the spermidine space began by studying spermidine's role in human health. We read more than 70 research studies, reviews, and other scientific papers to understand what this polyamine does in the body and how much a person needs on a daily basis. We also consulted members of our medical review board for their invaluable professional insight on the topic. With our core knowledge foundation set, we then explored the market to find and try spermidine products that satisfied the parameters described in the literature.

While we initially identified several brands with great ingredient bills, we also noticed that none of their formulations optimized spermidine’s main health potential: anti-aging. Some of them tried, but they ultimately failed to provide clinical doses (of spermidine and other components). Innerbody Labs saw this as an opportunity to develop its own spermidine supplement with clinically supported ingredients and doses for longevity. The result was Innerbody Labs NAD+ Support. Based on the available science, we’re confident that it’s the best spermidine complex for extending lifespans. But we also recognize that it may not be the best option for everyone, so we make a point of directing readers to alternatives that would better suit them.

Additionally, like all health-related content on this website, we will continue to monitor the subject and make necessary updates to keep you informed.

Identifying the market's best spermidine supplements involved assessing brands on factors that normally influence consumer choices:

• Effectiveness
• Safety
• Cost
• Ease of use

In the following sections, we explain how we chose the winner in each category.

Effectiveness

Winner: Innerbody Labs NAD+ Support

To assess a spermidine supplement's effectiveness, we first had to determine why someone would want to take spermidine. The answer is longevity. And among all the spermidine supplements on the market — single-ingredient products as well as complexes — Innerbody Labs NAD+ Support offers the best chances of improving biomarkers related to a long life span. That’s because, in addition to spermidine, Innerbody Labs delivers clinically relevant doses of two NAD+ precursors (alongside TMG to help the precursors fulfill their duties) to optimize their anti-aging action.

Spermidine itself is an anti-aging ingredient, so we also had to determine how much daily spermidine a person needs to realize its potential. According to the Swedish Nutrition Recommendations Objectified (SNO), a dietary guide for food consumption choices, the ideal daily intake of spermidine is 25-30mg, and the average intakes in developed countries range from 10mg to 15mg per day.2 In light of these statistics, we found that Innerbody Labs’s 15mg spermidine dose hits a sort of sweet spot. It’s not so much to be excessive, but neither is it too little to leave behind any anti-aging benefit. And if you eat a balanced diet with sufficient fruits, vegetables, legumes, and grains, it should be enough to raise your intake to fall within the SNO-recommended range.

Most of our other top recommendations perform commendably in spermidine dosage — Double Wood and Omre each have 10mg of spermidine, and Neurogan provides 25mg — but are absent the non-spermidine components that thrust Innerbody Labs to the top of the hill. The complexes (Perpetua.Life and AgeMate) have those other components, but in lower doses that make them less potent in their anti-aging action.

Safety

Winner: Double Wood Spermidine

Spermidine has a low side effect profile even at doses higher than what you'll find in a supplement. Normally, in such cases, we look at a company's operational practices to assess safety — third-party testing, with certificates of analysis accessible to consumers. But since most of our top recommended brands are fairly equal on that measure, our assessment came down to what a particular product doesn't have.

Double Wood rose to the top here because its ingredient bill consists exclusively of synthetic spermidine (spermidine trihydrochloride). Being synthetic, it doesn't contain anything that could trigger an allergic reaction, like wheat germ (Neurogan and Omre). And because spermidine is its only active ingredient, it poses no risk of side effects from other components (e.g., blood pressure concerns associated with NR, or the theoretical potential for cancer from elevated NAD+ in the long term).45

Cost

Winner: Double Wood Spermidine

At almost $40 for a one-time purchase and $32 for a subscription, Double Wood doesn't look like much of a budget pick at first glance, but its place as our cost winner begins to make sense as you look more closely.

First, Double Wood contains 60 servings — twice as many as Omre and Innerbody Labs — so the up-front price is effectively spread across two months.

And second, Double Wood lets you realize further savings by buying in bulk. Depending on whether you purchase once or subscribe, a double-pack of its spermidine takes $5-$10 off each bottle, and a triple-pack takes off $10-$20. The same can’t be said about Neurogan, which is close to Double Wood in base price and identical in its per-bottle serving count.

Ease of use

Winner: Neurogan Spermidine Gummies

Neurogan's spermidine isn't just an easy-to-ingest gummy; it's also quite a small gummy (less than 1cm cubed) that tastes pretty good. If there's an inconvenience, it's that the label recommends you chew the gummy for 20-40 seconds before swallowing, but the pleasant and non-cloying berry flavor helps ease the experience.

The other brands on our recommendation list are capsules, which require a glass of water and may pose a challenge for some people who have difficulty swallowing pills. Among them, Double Wood is the easiest to ingest because it's the smallest capsule of the bunch. It measures just around 1.5cm long and 0.5cm wide, whereas Omre and Innerbody Labs are a little larger.

Spermidine is a type of compound called a polyamine. Based on the word alone — poly- meaning "several" and amine referring to amino acids — you can guess that a polyamine consists of two or more amino groups. You probably know, too, that amino acids are the building blocks of proteins and play wide-ranging roles in normal bodily processes, including digestion, sleep, muscle growth, hemoglobin production, and fat metabolism.3

Polyamines, and spermidine in particular, are important for cell growth and development, and maintaining an optimal polyamine balance in the body is critical for healthy cellular function as well as the prevention of various detrimental processes. According to a 2021 review on the subject, polyamines can be "used as an effective treatment" that promotes:4

• Antioxidant capacity
• Cancer prevention
• Heart health
• Improved cognitive function

The same 2021 review states that exogenous sources — those from outside of the body — provide the "maximum quantity" of polyamines, so food- and supplement-derived spermidine is essential to obtain the health benefits described above.4

When you ingest a spermidine supplement, the contents make their way through your digestive tract and get absorbed into your bloodstream. Per a 2018 review, exogenous spermidine is "rapidly [taken up] from the intestine and distributed in the body without degradation,"5 meaning that it has a high bioavailability even without technologies for maximizing uptake (e.g., liposomal delivery).

Once spermidine is distributed throughout the body, it works to minimize factors that commonly contribute to age-related degeneration and diseases (namely free radicals and inflammation)4 by activating autophagy.

Autophagy is a vital process by which your body's cells remove damaged or dysfunctional parts and recycle them into new, functional parts.6 By doing so, autophagy gets rid of components that can cause harm (e.g., pathogens) and updates others that may be slowing down performance.7 “Think of it as cellular detox,” says Dr. Jennie Stanford, a physician board-certified in family medicine and obesity medicine.

Autophagy's connection to aging and age-related disease lies in a couple of factors. For one thing, removing cellular junk reduces the risk of genetic mutations that can develop into cancer.7 For another, it helps manage inflammation and oxidative stress, which are closely tied to chronic health conditions that correspond with advanced age.4

Numerous scientific studies have examined how spermidine, in particular, can help prevent or treat such health conditions. Below, we describe some of the most prominent research to date:

Spermidine dosage

You've seen that clinical spermidine doses range as low as 0.9mg per day, but 3.3mg seems to be the lowest threshold for the desired health outcomes.

That said, average spermidine intakes worldwide range from 10 to 26mg per day, and the SNO recommends daily values of 25mg for women and 30mg for men.2 Therefore, in choosing the products for this guide, we focused on supplements that deliver doses within a 10-25mg range, which provides the best potential to help users meet optimal intake values either alongside or in the absence of sufficient dietary sources. Among our top picks, Innerbody Labs falls into the sweetest spot to accommodate the largest number of potential users. Perpetua.Life, Double Wood, and Omre have slightly lower doses, whereas Neurogan has a slightly higher one.

Natural vs. synthetic vs. liposomal spermidine

Natural spermidine derives from plant sources like wheat germ. As we said earlier, spermidine absorbs easily into the bloodstream, so all-natural supplements (e.g., Omre) are quite bioavailable.

Synthetic spermidine (also known as spermidine trihydrochloride) is a lab-derived version that's highly pure, more stable, and water-soluble.31 Being water-soluble correlates with faster absorption and even higher bioavailability,18 which is why two of the recommendations in this guide (Innerbody Labs and Double Wood) use synthetic versions.

Some spermidine supplements are liposomal, too, meaning they use a technology whereby the active ingredient is transported via phospholipids that can withstand the harsh gastrointestinal environment.19 Liposomal delivery can be great for supplements with low bioavailability, like glutathione and NAD+, but it's probably excessive with regard to spermidine. We've excluded liposomal products from this guide because the advanced delivery system tends to add cost to the product and isn't necessary to yield the desired health outcomes.

Spermidine supplements are generally safe for most people who aren't pregnant, breastfeeding, or taking certain medications. In a 2024 study, human subjects aged 50 to 70 years experienced “minimal effects on safety” and no significant biomarker changes after receiving 40mg/day of high-purity spermidine for up to 28 days.20 The highest-dose product in this guide is 25mg per serving, so the risk for adverse effects is generally low indeed.

However, there are some populations of people who should either outright avoid spermidine supplements, tread lightly, or closely read the label to ensure their safety. While you should speak with your doctor first to determine your suitability for spermidine supplementation, you might presume that you aren’t an appropriate candidate if you fall under one of the following categories:

Note that one of our recommendations, Innerbody Labs NAD+ Support, contains more than just spermidine, and some ingredients may elevate the safety risk for some users. For example, in people with hypotension, Innerbody Labs’ NR content may cause a dangerous drop in blood pressure.44 Also, because NAD+ can increase the efficiency of all cells, including harmful ones, there are some concerns about an elevated risk of cancer pathogenesis resulting from NAD+ boosters like NMN and NR.45 Although some research has yielded contradictory results (i.e., NAD+ might inhibit some cancers),60 this theoretical risk is worth knowing about.

Spermidine supplements are for people interested in promoting their longevity, proactively working against age-related degeneration, and preventing diseases associated with oxidative stress. More specifically, the following populations stand the best chances of realizing the benefits of spermidine supplementation:

Who are they not for?

Apart from the relatively small populations of people with allergies or Snyder-Robinson syndrome, people who fall under the following categories may want to avoid spermidine supplements or exercise increased caution before adding spermidine to their supplement rotation:

Best spermidine complex

If we look only at the spermidine content, that alone might be sufficient to designate Innerbody Labs NAD+ Support as the best spermidine supplement for most people. That’s because:

• It uses spermidine trihydrochloride, the synthetic form that boasts high purity and bioavailability.18 31
• Its 15mg dose falls in a sweet spot that accommodates the largest possible user base, given that the SNO recommends 25-30mg for optimal health and people in developed countries typically obtain 10-15mg per day from dietary sources.2

But NAD+ Support is more than just spermidine. It’s a complex that also has ingredients for increasing your body’s supply of NAD+, which is associated with neurological, cardiovascular, metabolic, and wound-healing benefits.46 To quote Dr. Stanford: “NAD+ is a rising star. Current research substantiates it for incredible results in increasing longevity.”

As for what those NAD+-boosting ingredients are:

The potency of the Innerbody Labs formula gives you flexibility in dosing. You could take just a two-thirds dose a day and still have a more powerful impact on your longevity than you’d get with a full dose of Double Wood, Neurogan, or Omre. Such a reduced-yet-effective dose has the added benefit of stretching your supply and increasing your per-purchase value.

Pricing and shipping

A single bottle of Innerbody Labs NAD+ Support costs $74 as a one-time purchase. That’s significantly higher than any of the other top recommendations in this guide, but Innerbody offers a 10% discount to newcomers that drops the price to a slightly more accessible $67.

Subscriptions net you even greater savings that bring the cost down to something closer to Omre’s:

• One-month subscription (20% off): $59.20
• Three-month subscription (25% off): $55.50 per bottle
• Six-month subscription (30% off): $51.80 per bottle

The multi-month subscriptions offer the best cost economy as long as you can cover the up-front expense — $166.50 for three months, $310.80 for six — but even the one-month option represents a major discount from the base price.

Plus, all U.S. orders ship for free.

Refund policy

Innerbody Labs has a 30-day satisfaction guarantee that applies to both used and unused bottles. It’s a straightforward policy that eliminates your financial risk and speaks to the company’s confidence in the product. Plus, unlike Double Wood, Omre, and Neurogan, the policy has no caveats such as limits on item counts (e.g., only the first one or two items in your order are eligible for a full refund). So if you order three bottles of NAD+ Support, all three are eligible for a refund, even if you’ve opened each one.

This policy, along with Perpetua.Life’s policy, is the second-best in this guide. Only AgeMate’s is better owing to its longer length.

Customer support

You can reach the Innerbody Labs support team through the company’s contact portal or by phone. We used the contact portal to ask about any limits on the 30-day satisfaction guarantee (e.g., does it apply to just one bottle per order?)

The time we submitted the message: 10:10 a.m.

The time we received a response: 10:11 a.m. All told, we had to wait just one minute. And the response fully answered our question, leaving us with no need to follow up.

Of note, at the time we sent our message, it was two hours behind at the Innerbody Labs office. That means the customer support team was just starting their shift, and ours was probably among the first customer questions of the day. It’s possible that we could have experienced a longer turnaround had we messaged later in the day. Still, a one-minute response time is impressive.

Best longevity complex for customers outside the United States

For people outside the United States, Perpetua.Life AEON is the best alternative to Innerbody Labs NAD+ Support. Its ingredient list includes everything found in our top pick, albeit at lower doses, plus several others:

• Vitamin B2: 1mg
• Vitamin B6: 5mg
• Vitamin B12: 2mcg
• Nicotinamide DUO: 500mg (400mg NMN, 100mg NR)
• Quercetin: 250mg
• Trans-resveratrol: 150mg
• Fisetin: 100mg
• Astragalus: 100mg
• L-Theanine: 100mg
• EGCG: 100mg
• TMG: 85mg
• Piperine: 10mg
• Spermidine: 10mg

For two reasons, however, AEON itself fails to rise to the top of our list. First, among the ingredients not found in Innerbody Labs, only the L-theanine and the EGCG have solid scientific support for their lifespan-lengthening potential.69 70 Second, even the well-supported ingredients are either underdosed (the TMG) or at the lower end of the effective range (L-theanine, EGCG, NMN, NR). The liposomal technology might help increase bioavailability by some degree, but unlikely enough to unseat Innerbody Labs.

It still all comes together to make a good product, just not the best product.

Pricing and shipping

Pricing and shipping are where Perpetua.Life have an edge on our top pick. At $59 for a one-time purchase and $47.20 for a subscription ($1.97 and $1.57 per dose, respectively), AEON ranges from a few bucks to $15 less than Innerbody Labs. Also, because even the lowest-cost purchase option for AEON satisfies Perpetua.Life’s free-shipping threshold, you don’t have to worry about any added cost of getting the product to your door.

Perpetua.Life ships internationally, too, which is one of the primary reasons why it’s our recommendation for non-U.S. customers.

Refund policy

Perpetua.Life’s refund policy is practically identical to Innerbody’s: a 30-day satisfaction guarantee on both used and unused supplements. Also like Innerbody, the policy mentions nothing about limits on item counts, so it’s better than what Double Wood, Omre, and Neurogan offer, and good enough to be tied for second-best policy in this guide.

Customer support

Perpetua.Life lacks chat or phone support, but the email form on its website results in a pretty good response time. We inquired about the exact split of the company’s NMN and NR combination, as it was not listed on the label, and received a reply with enough specificity to satisfy our concerns in just under 24 hours.

Best budget pick

Besides its price, Double Wood Spermidine has a few qualities that recommend it as one of the best supplements of its type:

As a company, Double Wood also does a fine job in the quality control department. Every product is third-party tested for heavy metals and microbiological contamination. The third-party test results and certificate of analysis are even available on the product page.

Pricing and shipping

Even though Double Wood Spermidine doesn't have the lowest base price among our recommendations, several factors make it the most affordable option on our list.

As a one-time purchase, Double Wood Spermidine costs $39.95 with free shipping. A subscription nets a 20% discount on the base price, reducing the cost to $31.96. Each bottle contains 60 servings — the same as Neurogan, and twice as many as Innerbody Labs or Omre — so you're looking at per-serving costs of around $0.67 and $0.53, respectively.

If you have the up-front capital, you can take advantage of Double Wood's bulk pricing options for additional dollars off every bottle. The following table illustrates (prices rounded to the nearest cent):

If you subscribe, your delivery intervals are:

• 30 days
• 60 days
• 90 days
• 180 days

We wish the intervals lined up more neatly with the bottle sizes. Currently, only 60- and 180-day options correspond to daily use of the one- and three-bottle options, respectively.

Free shipping should arrive in 5-7 business days (it was five business days for us, seven days in total). Expedited shipping is available at an additional charge.

Double Wood does ship internationally via DHL International (5-7 business days) and USPS International (7-14 business days). The price for international shipping depends on the order's weight and destination. Custom fees may apply.

Refund policy

Double Wood's satisfaction guarantee applies to your first order. No matter your reason, you can get a full refund on your Double Wood product within 30 days of the purchase date, with no stipulation of having to return said product. That includes bulk purchases, too; you can even keep one bottle and return just the remaining ones (unopened).

Just a couple of caveats, though:

• Only your first purchase of a particular product is eligible for the guarantee.
• You, the customer, are responsible for the return shipping cost.

Customer support

Double Wood's customer support can be reached by phone or email. We emailed the team to clarify a point in the company's refund policy and received a satisfactory answer within 50 minutes. As far as email support goes, that's excellent.

Something worth mentioning here is that our question was superfluous. The point we wanted to "clarify" is clearly stated in the refund policy itself. Nevertheless, the agent who replied to us betrayed no exasperation; they were friendly and thorough and even reiterated the policy's application to bulk orders.

Best gummy option

Neurogan Spermidine Gummies are — you've got it — gummies. Pretty good-tasting gummies, too. They're "Wild Berry"-flavored, and the closest confectionary counterpart would probably be one of the Very Berry Jolly Ranchers. It's more toothsome than most supplements of its type, but our testers didn't dislike the bite or mouthfeel.

Neurogan's 25mg dose is the highest among our recommendations, but its gummy form may lead to potency degradation over time. Gummy supplements are also prone to wide disparities between the listed dosage and the actual one.32 But with Neurogan, we're not concerned about the initial dosing accuracy since the third-party analysis results are available on the product page and clearly show the spermidine content is reported accurately.

One thing to keep in mind is that it's derived from wheat germ, like Omre, so it's not suitable for people with a wheat or gluten allergy.

Mind, too, that Neurogan has calories. Each gummy measures less than 1cm cubed but contains 4cal, including 1.2g of carbohydrates (0.4g from sugar). That's not terribly much, but it’s still something to mind if you're counting calories and carbs.

One last thing. Per the label, you're supposed to take two servings per day (one in the morning and one at night) and chew each gummy for 20-40 seconds. Based on the studies we've read, we think at least the two-servings bit is excessive (though safe). One serving should be plenty to get you to your ODS-recommended threshold, and it would effectively double your supply.

Pricing and shipping

Neurogan Spermidine Gummies cost $41. But because a single bottle contains 60 servings, the per-serving cost of $0.68 is among the lowest in our guide, second only to Double Wood.

On the topic of subscriptions — Neurogan has begun to offer them, and it reduces your cost to just $31.

Also, shipping is free in the United States, and orders should arrive in just 3-5 business days. Our own order was initially estimated to arrive in five days, but it hit a delay in transit. Even so, it reached the doorstep on day seven, which isn't bad considering the circumstances.

International shipping is available, but overseas customers have to make their orders over the phone.

Refund policy

Neurogan offers a 30-day money-back guarantee. You can try your product and, if you don't like it, send it back for a refund or exchange. What's more, Neurogan will provide you with a return shipping label, so there's no added cost on your end.

Take note: the policy on Neurogan's website includes peculiar wording about items being "unworn or unused, with tags," if they're to be returned for a refund. We actually see that in a lot of policies, not just Neurogan's. Probably it's just boilerplate the company neglected to adapt to itself. Correspondence with Neurogan's support team clarified that used supplements are indeed eligible for returns/refunds as long as you:

• Use the product for at least two weeks
• Adjust the dosage as needed for your desired health outcomes
• Aren't satisfied with the results after taking the above two measures

The refund policy is also limited to two units of a single product. So, say that you purchase and use two spermidine supplements and two shilajit supplements from Neurogan in a single order; in that case, you can get a refund on either the two spermidines or the shilajits, but not both products. However, if you've used only the two spermidines and the shilajits remain unopened, then the entire order is eligible for a refund as long as you put in your request within the 30-day window.

Customer support

You can reach Neurogan's customer support team by email or by phone. We went with email, with a question concerning a point in the company's refund policy (that bit about items being "unworn or unused, with tags").

The answer came in less than 24 hours — slower than Innerbody Labs, Double Wood, and Omre, but still pretty good. The representative clarified that the policy applies to "items that are unused and in their original condition, with the packaging intact," and they reiterated the finer details of the policy we covered in the previous section.

Best powder supplement with spermidine

In the context of this guide, AgeMate Daily Longevity is unique in that it’s a powdered drink supplement — a little sweet, a little sour. To mix it, you add a single 3g scoop to 8-12fl oz of cold water. The label recommends taking it daily before breakfast.

One of the active ingredients is spermidine. The 5mg dosage is much lower than what you get from our other top recommendations and really only sufficient for people who get a fair amount of spermidine from dietary sources.

However, Daily Longevity does have multiple other ingredients with solid scientific support for their anti-aging properties. One of them is NR. The others are:

Pricing and shipping

AgeMate Daily Longevity has come down in price within the last year. It’s currently $69 for a one-time purchase (down from $99). Every bottle of Daily Longevity contains 30 servings, so you’re looking at $2.30 per serving.

A subscription knocks off quite a chunk. AgeMate’s subscriptions actually come in two varieties. There’s a Single Subscription, which is a one-bottle order at a 29% discount; and there’s a Double Subscription, which is two bottles, each at a 36% discount. The following chart lays out the pricing and other details:

As for shipping, all U.S. orders ship for free, which is a definite plus. International shipping is available, too, but only to Australia, New Zealand, and the U.K.

Refund policy

AgeMate has a 100-day refund policy. Both used and unused items are eligible. The only caveats are:

• The item must be the last product you received from AgeMate
• You must provide proof of purchase (e.g., a receipt or invoice)
• You must contact the support team to receive approval for a refund

If you’re approved, AgeMate will also provide you with a return shipping label, so there’s no added cost on your end.

Customer support

Email is the only way to contact AgeMate, and we’ve found its customer support to be a little less responsive than the other brands we’ve discussed. We received a response to our email in about 30 hours, so AgeMate’s support team is the only one on our list to exceed a day’s time in its turnaround.

We can say, however, that the response we got was surprisingly thorough. Our question concerned whether any of the ingredients in Daily Longevity is liposomal (none of them are), and the representative’s explanation not only gave us the answer we sought but also explained the company’s associated reasoning.

By the way, the reasoning is that liposomal technology is (a) more expensive and (b) not really necessary for the ingredients used in Daily Longevity.

Best spermidine supplement derived from wheat germ

We consider Omre to be the natural counterpart to Double Wood. With its 10mg dose, it's a sort of "best for most people" for those who'd rather not take a synthetic supplement. Spermidine absorbs pretty well into the bloodstream on its own,5 so users can count on getting a decent dose. And even though the dose is lower than Neurogan’s, our other wheat-germ-derived supplement, we think that makes it better suited to a larger population of prospective users.

Because Omre is derived from wheat germ, it isn’t suitable for people who are allergic to wheat or gluten. Apart from that, however, we can say Omre does an okay job of ensuring consumer safety. Its products are at least third-party tested. We only wish the company would provide the product's third-party testing results and certificate of analysis on the website.

Pricing and shipping

In terms of base prices, Omre Spermidine is $44.97 as a one-time purchase and $40.97 as a subscription. Then you tack on around $7 for shipping and end up with a price tag hovering around $50.

Free shipping applies only to bulk orders or orders above $70.

Like Double Wood, Omre offers its spermidine in two- and three-bottle bulk purchases. The following table breaks down the bulk prices as one-time purchases and subscriptions (costs rounded to the nearest cent):

So, a two-bottle bulk purchase amounts to a 5% discount on each bottle, and the three-bottle option nets a 15% discount. That's a pretty good deal if you insist on a natural spermidine supplement and you can cover the up-front cost, but even the most cost-effective option is $0.33-$0.52 more per serving than the other brands on our list.

Omre does have the most diverse delivery intervals among our recommendations, however. Your options are:

• 30 days
• 60 days
• 90 days
• 120 days
• 180 days

All of the options are divisible by 30, so they align well with the bottle's serving count.

Also, we commend Omre for its fast delivery. Only three business days (five total) elapsed from the time we completed our order to when we received it. We had the product in our hands for two days before any of the others started to arrive.

Refund policy

Omre is one of those companies that has both a money-back guarantee and a separate refund policy.

The money-back guarantee has a 30-day window and applies to one unit of every Omre product. So, say that you buy not only Omre Spermidine but also Omre Afterdrink and Omre NMN + Resveratrol. Each one would be eligible for the guarantee as long as it's your first time ordering and trying it. If you aren't pleased with the product for whatever reason, all you have to do is email Omre and provide a reason for your request.

The guarantee doesn't apply entirely to bulk purchases. If you purchase three bottles in bulk, only one of the bottles is covered by the guarantee. The remaining two would be covered by the refund policy.

That refund policy is one of the worst we've encountered. It gives you just seven days of receiving your order to initiate a return, and the product(s) must be unused/sealed to be refundable. You don't even get a full refund, either, since Omre charges a $15 shipping and handling fee outside of the money-back guarantee. Not only that, but international customers are completely excluded from the refund policy.

Customer support

Omre's customer support can be reached exclusively by email. We sent out our message (this one about shipping costs) in the early afternoon, expecting a response the following day, but Omre was in our inbox just three hours later.

As with our other support experiences in this space, the answer we received was straightforward and prevarication-free. No ambiguity and no need for follow-up.

Toniiq Spermidine+ is technically a complex — a supplement with multiple active ingredients — because it consists of both spermidine trihydrochloride (21mg) and natural spermidine extracted from rice germ (1mg). The reason for the combination is unclear, as no scientific studies suggest combined forms increase absorption or efficacy. Still, at 22mg overall, Toniiq is our top honorable mention in this guide, ideal for people who need more than just a small boost in their daily spermidine intake.

Operationally, Toniiq does a little better than Double Wood because it subjects both raw materials and finished products to third-party and in-house testing. Then it posts the test results and certificate of analysis right on the product page, like Double Wood. If not for the risk of an allergic reaction introduced by the rice germ extract, we might have retained Toniiq in our top recommendations for its safety pedigree.

Pricing and shipping

Toniiq Spermidine+ has a low base price, but its high shipping cost, combined with its bottle size, significantly increases the total cost to the user.

One-time purchases are $24.97, and subscriptions are $21.22 — pretty good. But shipping can add upwards of $10.50 to your bill — not so good. Each bottle contains just 30 servings, so the per-serving cost is higher than Double Wood's even before you account for shipping (around $0.83 and $0.71, respectively). Toniiq does have a free-shipping threshold, but it's $99, so you'd have to buy 4-5 spermidine supplements to cross it.

Subscriptions ship out at intervals of 30, 60, and 90 days. They're not the most diverse intervals, but at least they line up with the product's serving count.

Toniiq doesn’t handle international orders directly, but some of its products are available through iHerb, which does ship internationally. Unfortunately, the spermidine supplement currently isn't among the products sold through iHerb.

Refund policy

Toniiq’s 60-day refund policy is excellent. You don't even have to send the product back; in fact, to reduce carbon emissions, Toniiq insists that you keep it or pass it on to someone you know.

The caveats are:

• Wait at least two weeks: You must try the product for at least two weeks from the time of shipment before it's eligible for a refund.
• Only for three individual products: If you try and return three separate Toniiq products, you no longer have refund eligibility for any other product.
• Only for first-time purchases: If you've ordered a particular Toniiq product in the past and then purchased it again, you're no longer eligible for a refund for said product.

Customer support

Email is the only way to contact Toniiq's customer support. Limited support pathways don't normally bode well for the support team's quality, but Toniiq seems to be an exception. Our email (about international shipping) received a response in less than three hours, which is impressive considering we sent our message nearly at the end of the workday. The answer we got went straight to the point and fully satisfied our inquiry.

Maybe you want a natural supplement but are allergic to wheat, or maybe you just want to see what other anti-aging supplements are out on the market (some of which you might combine with spermidine for a synergistic effect). Whatever your reason may be, there are numerous alternatives you might consider.

Other supplements

Several other supplement varieties can impart the same cardioprotective, neuroprotective, anti-cancer, and/or anti-aging effects as spermidine. Some even do so through similar mechanisms, namely inducing autophagy. Here are some such supplements:

Diet

Throughout this guide, we've alluded to the fact that spermidine occurs naturally in quite a lot of dietary sources. Indeed, dietary spermidine should be your first-line option. “Getting optimal nutrition from your diet is considered the gold standard,” says Dr. Stanford. “Supplements are here to do just that — supplement insufficient dietary intake.”

So, if you wanted, you could ramp up your intake of spermidine-rich dietary sources to either eliminate or reduce your need for supplementation. If that's the route you'd like to take, you'll want to base your diet on foods like:27

• Fruits: apple, avocado, banana, cherry, kiwi, mandarin/orange, pear, peach, pineapple, strawberry
• Vegetables: broccoli, cabbage, cauliflower, carrot, celeriac, cucumber, eggplant, green beans, green pepper, lettuce, mushroom, onion, potato, spinach, tomato, zucchini
• Legumes: chickpeas, lentils, peas, white beans, red kidney beans, soybeans and soybean sprouts
• Nuts: almond, chestnut, pistachio
• Cereal grains: rice, wheat germ, bread
• Other: tofu, soy sauce, miso