Whilst we’re generally quite positive about labs products, Performance Lab Flex falls foul of the fact that they try to keep their capsules small and their formulas to 2 capsule doses. Unfortunately for our Performance Lab Flex most joint supplements require relatively high volumes to be effective. With a complete dosage of 1000mg it’s not possible to get the ingredients that it does contain in their effective ranges.
For example, glucosamine in its sulfate form is usually dosed between 1000-3000mg and that’s just one of the ingredients in Performance Lab Flex, and whilst the version used in flex is equivalent to 750mg of glucosamine sulfate it’s still a bit too low to be in the ideal range. Unfortunately, this is a pretty consistent trend through the product. If we compare it to our number one rated joint supplement FlexAgain that uses a blend of ingredients that’s 4000mg.
There are a couple of positives for our Performance Lab Flex review and that’s the fact it does get a couple of ingredients right and doses Boswellia correctly so it will have some improvements to joint mobility and inflammation. And unlike a lot of it’s competitors it uses Phytodroitin so it is completely vegan . However, if we remove the dietary requirement issue, we can’t see any reason to recommend it over any of the other supplements on our best joint supplements list.
In short Performance Lab fall foul of their own selling point, and make a supplement that is going to benefit joint health, just less than pretty much all of it’s serious competition.
reviews of Performance Lab Flex are generally pretty positive, although we do
run into the issue that the product is only available on their website, meaning
that these reviews are curated. It’s remarkably difficult to find verified customer
reviews of Flex, so we can’t really say all too much here. Even trawling reddit
we only came up with reviews for some of the other performance lab products.
However, what we can say is that overall the company does have a decent reputation
for customer service, although we doubt that there would be many glowing
reviews of Performance Lab Flex as the product is middling and most of the same
benefits could be gained from a boswelic acid supplement.
The most commonly asked questions from Performance Lab Flex Reviews
Performance Lab Flex should be safe, although there can be some side effects as a result of glucosamine including:
Mild upset stomach, nausea, heartburn, diarrhea and constipation
And boswellia can cause stumulate the immune system so people with rheumatoid arthritis or other conditions should use with caution.
Whilst the ignredients themselves aren’t bad, in fact most of them do appear in the best joint supplements they’re all under dosed with the exception of boswellic acid.
Turmeric Extract (20% curcumin) 250 mg – Curcumin has been shown to reduce inflammation and improve joint mobility in people suffering from osteoarthritis, however the dosages were 500mg of pure curcumin not 20% curcuminoids. There is also some suggestion that curcumin may prevent the break down of bone in people with RA. 
Boswellia 100 mg – This one is all good, meta analysis of multiple studies show that Boswellia is effective for pain relief in sufferers of arthritis.  And 100mg is a good dosage, it’s not effective for more severe cases, the dose is a lot higher for more severe cases of joint pain.
Glucosamine 2KCl (vegan version) 500 mg – Glucosamine can be effective for reducing joint pain, it doesn’t seem to do much for the break down of joint tissue or overall joint health, but is a decent inclusion. Glucosamine 2KCL is purer than glucosamine sulfate, but less than HCL. This means that it’s around the same dose as 750mg of the more commonly used glucosamine sulfate. Whilst there are a couple of studies that suggest this could be within the minimum effective range, it is very much in the middle range. However, this is still better than a lot of competitors who use 500mg of glucosamine sulfate based on one study that showed positive results in such low doses, ignoring the many to the contrary. In short this is an “ok” addition to Performance Lab Flex, but it’s not ideal.
Phytodroitin (vegan chondroitin) 100mg – Phytodroitin is fine, all it really does is boost the efficacy of glucosamine. There was one study that backed it’s use individually, but that was at a dose of 800mg  and further studies have shown it to be ineffective without glucosamine.
MSM 100mg – This needs to be closer to 3000mg to be effective. It’s a good ingredient, but not really for combined supplements, although a lot of supplements do include it, which is most likely due to them not wanting to look like they’re missing an ingredient used in competitor products even if it’s not in an effective range.
real selling point for Performance Lab Flex is that it’s completely vegan, in
every other way it’s beaten out by competition. It’s the same price as FlexAgain, which contains the same ingredients in their none vegan version in
higher doses and with more effective ingredients on top of that.
Whilst it’s not a terrible joint health supplement, it’s not a particularly good one either. A disappointing supplement from Performance Lab, we generally expect better from their offering.
1 - https://protecnutra.com/2021/08/11/study-the-comparison-between-chondroitin-and-the-vegan-alternative-phytodroitin-%F0%9F%8C%B1
3 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7368679/
4 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4881293/