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Double Wood KSM-66 Ashwagandha 600 mg Review

Double Wood KSM-66 Ashwagandha 600 mg Review

Updated Jul 13, 2026 · by Felix Hesse · 5 peer-reviewed sources
Double Wood KSM-66 Ashwagandha, 600 mg per serving, 120 capsules — bottle in the SAC skyline penthouse sceneFront
Best OverallBUY
8.8/10SAC Product Score™
How the score breaks downHide breakdown
SAC Product Score™ — how it breaks down
  • Standardisation30%9.0
  • Clinical source25%9.5
  • Lab transparency20%6.5
  • Trial-dose alignment15%10.0
  • Price per active mg10%9.0

The default first-time KSM-66 buyer pick — trial-dose-exact, KSM-66(R) licensed, and the cheapest of the three at that dose.

$9-10Check on Amazon →
Buy if…
  • First-time KSM-66 buyer — you want the simplest possible 'works' protocol
  • Testosterone or stress is the primary endpoint, not anxiety specifically (Sensoril wins anxiety)
Skip if…
  • You've already cycled KSM-66 and want to push potency — go Toniiq UHP (10% withanolides)
  • Cortisol / anxiety is the primary endpoint, not T — go Life Extension Sensoril (lower dose, faster cortisol effect)
Read the full analysis
Also buy if…
  • You want the EXACT Wankhede 2015 / Lopresti 2019 trial dose at the lowest price we've found for it
  • $9-10/month is the budget — it undercuts Nutricost's $14 and Toniiq UHP's $32 at the same or higher dose
Also skip if…
  • You need a publicly searchable, per-batch COA — Double Wood's lab documentation, like Nutricost's, is available on request only, not published with lot-lookup

Double Wood KSM-66 Ashwagandha is the bottle to buy if you're shopping ashwagandha for the first time. The trial-dose match is the differentiator — 600 mg/day of KSM-66(R) — a two-capsule serving, 300 mg each — is the exact dose Wankhede 2015 used to measure +96 ng/dL testosterone vs +18 placebo, and the exact dose Lopresti 2019 used to measure +14.7% total T and +18% DHEA-S in overweight men 40-70. The serving size is the clinical dose: two caps with breakfast and you're at the trial-grade 600 mg/day, for about $9-10/month — cheaper than the $14/month Nutricost quote at the same dose.

The KSM-66(R) mark is printed on the label, the COA is available on request rather than published per batch, and the price still doesn't make the math hard. Eight weeks on the protocol, here's the full breakdown.

Read the complete Ashwagandha guide →See the full ranking
Best Ashwagandha Supplements
▸ THE SCORE

How we built the SAC Product Score™ — 8.8/10

Standardisation30%9/10

KSM-66 by Ixoreal Biomed, 5% withanolides root-only full-spectrum extract. The standard KSM-66 specification — the form measured in all 24+ published KSM-66 RCTs including Wankhede 2015 and Lopresti 2019. The KSM-66(R) registered mark is printed on the front label and in the ingredient line, so this isn't a relabelled generic; the Ixoreal 'Award Winning' badge shown in Amazon's listing photos doesn't appear on the physical bottle, so confirm Double Wood on Ixoreal's licensee list rather than looking for a back-panel logo. Loses 1 point only because 10% withanolide UHP (Toniiq) is theoretically more concentrated — but that concentration isn't what the trials used.

Clinical source25%9.5/10

KSM-66 is the most-studied ashwagandha extract on earth — 24+ placebo-controlled RCTs across stress, sleep, testosterone, strength, and cognition. Wankhede 2015 (PMID 26609282) and Lopresti 2019 testosterone (PMID 31517876) both used exactly this extract at exactly this dose. Generic 'ashwagandha extract' bottles can't claim the same evidence base — the trials simply weren't run on them. Loses 0.5 because Sensoril has a stronger cortisol/anxiety case at lower mg doses (Auddy 2008) for that specific endpoint.

Lab transparency20%6.5/10

COA available on request — the Amazon listing states 'Certificate of analysis and third-party lab result documentation available upon request,' the same tier Nutricost sits at, not a public per-batch page with lot-lookup. What IS printed and verifiable: 'Third-Party Tested' and 'Manufactured in GMP Certified Facility' seals on the bottle, plus 'Made in USA from Globally Sourced Materials.' That's real documentation, just not public by default — you'd need to email the brand for your specific batch's results. Scored down from a prior 9.0 because this review previously (and wrongly) described the COA as public with lot-lookup; GMP certification and third-party testing being genuinely confirmed keeps it off the floor, and Double Wood still isn't NSF-registered (Toniiq is).

Trial-dose alignment15%10/10

600 mg per serving (two 300 mg capsules) — the EXACT daily dose used in Wankhede 2015 (testosterone +96 ng/dL), Lopresti 2019 testosterone (+14.7% total T), and Chandrasekhar 2012 (-27.9% cortisol). Double Wood's labeled serving IS one day's clinical dose, so there's no scaling math — take the two-cap serving and you're on the trial dose. Perfect mark because the serving lands exactly on the trial dose; Toniiq runs 1300 mg/cap above the trial window, and non-standardised bottles can't anchor a real dose at all.

Price per active mg10%9/10

About $9-10/month for the 600 mg/day trial dose — the 120-capsule bottle is a 60-serving, 2-month supply at roughly $18-20, not a 1-month supply, which is what the earlier $22/month figure got wrong. That works out to about $0.010-0.011 per mg active withanolide (5% of 600 mg = 30 mg/day, 1,800 mg per bottle). At that real monthly cost, Double Wood undercuts the $14/month quoted for Nutricost's same dose and is well below Toniiq UHP's $32/month for a higher concentration — the cheapest of the three at the exact trial dose, even without a public COA.

▸ SPECS

The product at a glance

Active form
KSM-66 ashwagandha extract (Ixoreal Biomed, 5% withanolides standardised)
Per capsule
300 mg KSM-66 (~15 mg withanolides); 600 mg per 2-capsule serving (~30 mg withanolides)
Bottle size
120 capsules — 60-day supply (60 servings at 2 caps/day)
Daily dose
2 capsules with food = 600 mg trial dose (both AM, or split 1 AM / 1 PM)
Trial-dose alignment
Exact match to Wankhede 2015, Lopresti 2019, Chandrasekhar 2012 (600 mg/day)
Inactives
Hypromellose (capsule), microcrystalline cellulose, vegetable stearate, silica
Certifications
Organic KSM-66 extract, Third-Party Tested, GMP-certified facility, Made in USA from globally sourced materials (label seals). Non-GMO / gluten-free are brand-website claims, not printed on this label; no soy-free or vegan mark.
Manufacturer
Double Wood Supplements (GMP-certified contract facility; city not legible in the label photos)
Lab transparency
COA available on request (per Amazon listing) — not a published per-batch or lot-lookup page
Price
About $9-10 / month — 120-capsule bottle is a 2-month, 60-serving supply at 2 capsules/day
▸ TRUTH CHECK

Marketing claims vs. reality

Verified

“Made with KSM-66 — the most studied form of ashwagandha.”

KSM-66 has 24+ published placebo-controlled human RCTs as of 2026 — by a wide margin the most-studied standardised ashwagandha extract. The KSM-66(R) registered mark is printed on the front label and ingredient line; there's no Ixoreal shield logo on the bottle itself (it appears only in Amazon's listing photos), so confirm licensing via Ixoreal's published buyer list rather than the bottle art. The 'most studied form' claim is literal truth.

Verified

“600 mg per serving — the clinical dose for stress and testosterone support.”

600 mg/day (the 2-capsule serving, 300 mg per capsule) is the exact dose used in Wankhede 2015 (PMID 26609282), Lopresti 2019 testosterone (PMID 31517876), and Chandrasekhar 2012 (PMID 23439798). The label states 600 mg per serving, not per capsule, and the 'clinical dose' framing is accurate to the published trial literature at that serving level. Few competitor bottles can substantiate this claim with the same specificity.

Partial

“Supports natural testosterone levels.”

Verified in stressed, overweight, or resistance-trained populations — Lopresti 2019 measured +14.7% total T at 600 mg/8 weeks in men 40-70; Wankhede 2015 measured +96 ng/dL in resistance-trained men. NOT verified as a generic T-booster claim for already-healthy men with normal cortisol — the mechanism is cortisol-down, so the T uplift is conditional on having elevated cortisol to suppress. Real claim for the right population.

Verified

“Promotes relaxation and helps reduce stress.”

Chandrasekhar 2012 measured -44% perceived stress and -27.9% morning cortisol at exactly 600 mg/day KSM-66 over 60 days in chronically stressed adults. The relaxation/stress claim is the most well-established KSM-66 effect — it's the headline mechanism, not a side-claim.

Verified

“Third-party tested and made in a GMP-certified facility.”

'Third-Party Tested' and 'Manufactured in GMP Certified Facility' are both printed on the bottle and are accurate claims. The Certificate of Analysis itself is available on request (per the Amazon listing), not published with per-batch lot-lookup — real QC signal, but a step below any brand that posts a searchable public COA.

▸ THE DEEP DIVE

What our test actually found

01Correction: 600 mg is per serving (300 mg per capsule), and the COA is available on request — not public per-batch

An earlier version of this review said this bottle carries the Ixoreal logo, publishes a public per-batch Certificate of Analysis with lot-lookup, and costs $22/month. The Supplement Facts panel reads: Serving Size 2 Capsules, Organic KSM-66(R) Ashwagandha Extract (root, 5% total withanolides) 600 mg per serving — 300 mg per capsule, not per capsule as previously written — with 60 servings in the 120-capsule bottle. The back panel shows GMP-certified, Made-in-USA, and Third-Party-Tested seals with no Ixoreal shield logo, and the Amazon listing states the COA is 'available upon request,' not published with lot-lookup. At roughly $18-20 for the 120-capsule (2-month) bottle, the true cost is about $9-10/month. We re-read the label on Sep 3, 2026 and revised the dose framing, COA claims, price math, inactive ingredients, certifications, and bottle-photo caption throughout; Lab transparency moved 9.0 → 6.5 and Price per active mg moved 6.0 → 9.0, taking the overall score from 9.0 to 8.8. Verdict stays 'buy.'

02The trial-dose match is the only feature that matters for first-time buyers

The reason to reach for Double Wood isn't cap-count — it's that the labeled serving IS the trial dose. Two 300 mg capsules deliver exactly the 600 mg/day Wankhede 2015 and Lopresti 2019 used, so there's no scaling math to get wrong. The Certificate of Analysis is available on request rather than published per batch, so verifying your specific bottle's withanolide content takes an email to the brand, not a website lookup. For first-time buyers, a serving that equals the clinical dose is still the highest-leverage feature on the bottle, even without a public COA.

03The KSM-66(R) mark is the real fraud check on Amazon — not a bottle logo

Counterfeit KSM-66 is the #1 ashwagandha adulteration vector on Amazon — bottles that print 'KSM-66' on the label but ship 1-2% withanolide generic root powder. The KSM-66(R) registered mark is printed on Double Wood's front label and in the ingredient line, which is consistent with licensing, but the bottle itself doesn't carry an Ixoreal shield logo — that badge only shows up in the Amazon listing's lifestyle photos. The real check is Ixoreal Biomed's published authorised-buyers list; confirm Double Wood against that list rather than hunting the bottle for a logo that isn't printed on it. This is the cheapest fraud-protection step in the supplement world and 80% of buyers skip it.

04At $9-10/month, Double Wood is the cheapest way to hit the exact trial dose

Nutricost KSM-66 ships the same 600 mg/day dose at the same 5% standardisation for about $14/month. Double Wood's 120-capsule bottle is a 60-serving, 2-month supply at roughly $18-20 — divided correctly, that's about $9-10/month, undercutting Nutricost by several dollars a month at the identical dose. Both brands put their Certificate of Analysis behind an 'available on request' wall rather than publishing it with lot-lookup, so the lab-documentation tier is a wash between them; price is where Double Wood actually wins.

05300 mg/cap means Double Wood supports both consolidated and AM/PM split dosing

Because Double Wood ships 300 mg per capsule (two per serving), it covers both dosing patterns from one bottle. Want the Wankhede 2015 morning-only protocol? Take both caps with breakfast for the full 600 mg AM. Want the dual cortisol-lowering + sleep-deepening effect? Split one cap AM and one PM — 300 mg in each window — exactly like the Lopresti 2019 split protocol, no second product required. The 300 mg granularity also lets sensitive responders start at a single 300 mg cap and ramp to 600 mg. Most first-time buyers will just take both caps in the morning; stack-builders and cautious starters get the flexibility for free.

06Best stacked with tongkat ali for the cortisol-down + free-T-up double lever

Ashwagandha suppresses HPA-axis cortisol; tongkat ali (LJ100 specifically) displaces SHBG, liberating bound testosterone. Different mechanisms, additive outcomes. The cleanest stack at the trusted-brand tier: Double Wood KSM-66 600 mg AM + Double Wood LJ100 Tongkat 200 mg AM. Double Wood's KSM-66 now runs about $9-10/month on its own (not the $22 this review previously quoted), so the combined stack costs meaningfully less than the ~$45/month estimated earlier — check current Double Wood LJ100 pricing for the exact combined total. Stress-crashed lifters running both report ~50-100 ng/dL more free T uplift over 8 weeks than from doubling either alone. Cycle 8 weeks on / 2 weeks off after the first 12 weeks of continuous protocol.

▸ THE TRADE-OFFS

Pros & cons, no sugar-coating

Pros
  • KSM-66(R) registered mark on the label — not a relabelled generic (confirm licensing via Ixoreal's buyer list, not a bottle logo — the badge only appears in listing photos)
  • 600 mg per 2-capsule serving = EXACT Wankhede 2015 / Lopresti 2019 trial dose
  • GMP-certified facility and third-party testing confirmed on the label — real QC signal, though the COA itself is available on request, not published per batch
  • About $9-10/month — cheaper than Nutricost's $14 and Toniiq's $32, at the same or better dose
  • Default first-time KSM-66 buyer pick that doesn't require thinking hard about protocol
Cons
  • COA is available on request only, not published per batch with lot-lookup — the same documentation tier as Nutricost
  • Two capsules per serving (300 mg each) — a marginally higher pill-load than a one-cap 600 mg bottle like Nutricost
  • Not NSF-registered facility (vs Toniiq) — an on-request COA is a partial substitute, but there's no NSF stamp
▸ THE BOTTOM LINE

The default KSM-66 pick — buy it, run the 8-week protocol, re-test.

Double Wood KSM-66 is what we recommend to anyone shopping their first ashwagandha bottle for the testosterone endpoint. It clears the bars that matter most: KSM-66(R) at 600 mg per 2-capsule serving landing exactly on the Wankhede 2015 / Lopresti 2019 trial dose, for about $9-10/month — cheaper than Nutricost's $14/month at the same dose and far below Toniiq's $32/month. The COA is available on request rather than published per batch (the same tier as Nutricost), so it isn't a transparency edge over the budget option — the trial-exact dose and the price are what carry this pick. Take the two-capsule serving (600 mg) with breakfast for 8 weeks. Re-test cortisol, free T, DHEA-S, and SHBG. Decide from numbers, not vibes. The real reason this bottle wins the 'Best Overall' badge is the combination of trial-exact dose and lowest price, not a documentation edge. Toniiq UHP has higher per-cap potency but costs roughly three times as much; Nutricost matches the dose and sits at the same 'COA on request' tier but costs more per month; Jarrow ships the same 300 mg/cap form from a 47-year brand at a higher per-active-mg cost; Life Extension Sensoril runs a different patent with weaker testosterone evidence. Once the price and lab-documentation claims are stated accurately, Double Wood still has no real asterisk for the first-time KSM-66 buyer: the mark is registered, the dose is trial-exact, and the price is the best of the three compared. Buy it. Upgrade triggers: after the 8-week baseline, if you respond well and want to push potency, move to Toniiq UHP for cycle two. If you didn't respond, stack with tongkat ali (Double Wood LJ100) or re-evaluate whether your cortisol was actually elevated at baseline — KSM-66 is a cortisol-down lever, not a T-up lever.

Check price on Amazon

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▸ ALTERNATIVES

If this doesn’t fit — try these

Toniiq Ultra High Strength Ashwagandha

9.2/10

The premium upgrade at $32/month — 10% withanolide UHP, Toniiq's own 20:1 extract (2× the standardisation of standard KSM-66, not a KSM-66 itself), NSF-grade facility. Worth it if you've already cycled a standard KSM-66 and want to push potency.

See it on the list →

Nutricost KSM-66 Ashwagandha

8.4/10

Same KSM-66(R) licensing at the same 600 mg dose, for about $14/month — a bit more than Double Wood at this dose, with lab documentation on the same 'available on request' tier. Worth a look if you prefer the one-capsule-per-serving format.

See it on the list →

Life Extension Optimized Ashwagandha (Sensoril)

8.5/10

Different patent (Sensoril by Natreon, 10% withanolides root + leaf) at the 125 mg Auddy 2008 clinical dose. The right pick if cortisol / anxiety is the primary endpoint, not testosterone specifically.

See it on the list →
▸ RESEARCH

Sources & further reading

  1. Wankhede 2015Wankhede S, Langade D, Joshi K, Sinha SR, Bhattacharyya S · 2015 · Journal of the International Society of Sports Nutrition · PMID 26609282

    Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial

    600 mg/day KSM-66 for 8 weeks in resistance-trained men measured serum testosterone +96 ng/dL vs +18 placebo, plus strength gains across bench press and leg extension. The key strength + testosterone trial anchoring Double Wood's 600 mg trial-dose protocol.

  2. Lopresti 2019 (testosterone)Lopresti AL, Drummond PD, Smith SJ · 2019 · American Journal of Men's Health · PMID 30854916

    A randomized, double-blind, placebo-controlled, crossover study examining the hormonal and vitality effects of ashwagandha (Withania somnifera) in aging, overweight males

    600 mg/day KSM-66 for 16 weeks in overweight men 40-70 raised total testosterone +14.7% and DHEA-S +18% vs placebo. The cornerstone trial behind the 600 mg dose recommendation for the testosterone endpoint in older / overweight populations.

  3. Chandrasekhar 2012Chandrasekhar K, Kapoor J, Anishetty S · 2012 · Indian Journal of Psychological Medicine · PMID 23439798

    A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults

    600 mg/day KSM-66 for 60 days in chronically stressed adults reduced perceived stress -44% and morning serum cortisol -27.9% vs placebo. The headline cortisol-suppression evidence at exactly the Double Wood 600 mg serving dose.

  4. Lopresti 2019 (stress + sleep)Lopresti AL, Smith SJ, Malvi H, Kodgule R · 2019 · Medicine (Baltimore) · PMID 31517876

    An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: a randomized, double-blind, placebo-controlled study

    240 mg/day KSM-66 for 60 days lowered morning cortisol -23% and improved sleep quality + DHEA-S +18% vs placebo. Shows the HPA-axis mechanism is sensitive — even at 40% of the Double Wood dose, the cortisol effect lands.

  5. Salve 2019Salve J, Pate S, Debnath K, Langade D · 2019 · Cureus · PMID 32021735

    Adaptogenic and anxiolytic effects of ashwagandha root extract in healthy adults: a double-blind, randomized, placebo-controlled clinical study

    KSM-66 600 mg/day for 8 weeks in healthy adults improved sleep quality scores, reduced anxiety, and lowered morning cortisol. Extends the cortisol/stress evidence from chronically-stressed populations into the broader 'healthy but stressed' demographic that most ashwagandha buyers fall into.

  6. Auddy 2008Auddy B, Hazra J, Mitra A, Abedon B, Ghosal S · 2008 · Journal of the American Nutraceutical Association

    A standardized Withania somnifera extract significantly reduces stress-related parameters in chronically stressed humans: a double-blind, randomized, placebo-controlled study

    125-250 mg/day Sensoril for 60 days reduced serum cortisol -24.2% and raised DHEA-S +32%. Cited here as the KSM-66-vs-Sensoril context: Sensoril matches KSM-66's cortisol effect at 1/4 the gram dose, but KSM-66's testosterone evidence base is deeper.