Thorne vs Doctor's Best Magnesium Glycinate (2026)
Buy Thorne. Its capsules are on NSF/ANSI 173, a testing list that checks what is in the capsule. Doctor’s Best is on no public testing list. Doctor’s Best costs less than half as much: $0.30 against $0.72 for 300 mg of magnesium at list price.
Price matters most? Buy Doctor’s Best. It is magnesium bound to amino acids too, with 200 mg in 2 tablets. Thorne costs 2.4 times as much for the same amount of magnesium, about $155 more a year at 300 mg a day. What the extra buys: an outside list that checks the capsule.
The numbers, side by side
| Thorne | Doctor’s Best | |
|---|---|---|
| Testing list | NSF/ANSI 173 | Not on the 5 lists we checked |
| Cost of 300 mg of magnesium | $0.72 | $0.30 |
| Best for | An outside check of what is in the capsule | The lowest price |
| Magnesium a serving | 120 mg in 1 capsule | 200 mg in 2 tablets |
| Form on the label | Magnesium glycinate | Magnesium lysinate glycinate chelate |
| Bottle | 90-serving bottle, $26.00 | 240 tablets, $23.99 |
| A year at 300 mg a day | $264 | $109 |
How each one is checked
Thorne’s capsules are on NSF/ANSI 173. NSF’s list names “Thorne Magnesium Glycinate, capsule, serving 4 capsules.” NSF checks that the product holds what the label says and has no unsafe levels of contaminants, and it retests from time to time. It is not a test for drugs banned in sport.
Doctor’s Best is on none of the 5 lists we searched (NSF/ANSI 173, NSF Certified for Sport, USP Verified, Informed Choice and Informed Sport, October 14, 2026). That does not mean it failed a test. Brands pay to join these programs, and many do not. It means no outside group lists it for you to check.
Drug-tested in sport? Neither product. Thorne’s Magnesium Bisglycinate powder is on NSF Certified for Sport (listing 1507934), which also screens for banned drugs. It is a different product from the $26 capsules. Every tested magnesium glycinate.
What the labels say
Both are chelates: magnesium bound to amino acids. Thorne’s label says magnesium glycinate. Doctor’s Best binds the magnesium to lysine and glycine (NIH label 322515). No study compares the two. Neither label lists magnesium oxide, the cheap form that the body absorbs less well (NIH).
Both labels allow more than the 350 mg daily limit for magnesium from pills; how many to take is below.
What the price gap costs you
At list price, 300 mg of magnesium costs $0.72 from Thorne and $0.30 from Doctor’s Best. Taken every day, that is about $264 against $109 a year. To check a price you see somewhere else, divide it by the mg in the bottle: Thorne’s holds 10,800 mg, Doctor’s Best’s 24,000 mg. What every glycinate costs.
How the two scored
Doctor’s Best scores 7.0 out of 10 and Thorne 6.5. Doctor’s Best wins on cost and on the amount in one serving; Thorne wins on testing. They rank 3rd and 5th of the 6 magnesium glycinates we score. Our score favors Doctor’s Best on price and dose. We name Thorne first only because an outside list checks it; if that does not matter to you, Doctor’s Best is the better buy. How we score.
Who should buy which
- You want one of these twoThorne
The one an outside list checks. 1 or 2 capsules (120 or 240 mg) a day keeps you under the limit. Check the price.
- You want glycinate for the least moneyDoctor’s Best
$0.30 for 300 mg at list price, in a 240-tablet bottle. Check the price.
- You want a tested glycinate for less than ThorneNature’s Truth
On NSF/ANSI 173, like Thorne, at $0.52 for 300 mg at list price. Check the price.
- You want our top glycinate pickRevive MD
On the Informed Sport list (every batch is tested for drugs banned in sport), $0.50 for 300 mg at list price (best magnesium glycinate). Check the price.
- You have kidney diseaseAsk your doctor first
If you have kidney disease, ask your doctor before you take magnesium. Weak kidneys cannot clear the extra, so it can build up (NIH).
Questions
Is Thorne or Doctor's Best magnesium glycinate better?
No study compares the two. Thorne is the one an outside list (NSF/ANSI 173) checks; Doctor’s Best is the one that costs less. Both bind magnesium to amino acids.
Why is Thorne magnesium more expensive than Doctor's Best?
Thorne’s bottle holds less magnesium for more money: $26.00 for 10,800 mg of magnesium (90 capsules) against $23.99 for 24,000 mg (240 tablets). Part of what you pay for is the NSF listing.
Is either one NSF Certified for Sport?
No. NSF Certified for Sport lists Thorne’s Magnesium Bisglycinate powder (1507934) and stick packs (1666128), which are different products from the capsules. If you are drug-tested, look up the exact product at nsfsport.com before you buy.
How many capsules or tablets should I take?
Keep magnesium from supplements at or under 350 mg a day (NIH). That is 2 Thorne capsules (240 mg) or up to 3 Doctor’s Best tablets (300 mg). Thorne’s label allows up to 4 capsules (480 mg) and Doctor’s Best’s says 2 tablets twice a day (400 mg); both are over the limit.
More: best magnesium glycinate · third-party tested glycinate · Nature Made vs Doctor’s Best · how much magnesium per day.
Sources
- NSF/ANSI 173 dietary supplement listings (info.nsf.org): “Thorne Magnesium Glycinate,” capsule, serving 4 capsules; no listings for Doctor’s Best. NSF Certified for Sport, USP Verified, Informed Choice and Informed Sport searched October 14, 2026.
- Labels: Thorne Magnesium Glycinate (120 mg per capsule, 1 to 4 a day) and Doctor’s Best, NIH label 322515 (200 mg per 2 tablets, magnesium lysinate glycinate chelate). Prices: each brand’s own list price, checked October 14, 2026. We quote no Amazon prices.
- NIH Office of Dietary Supplements. Magnesium fact sheet for health professionals (updated January 6, 2026).