Performance Lab Flex Review: Does it work?

The ultimate roundup of reviews for the joint supplement Performance Lab Flex
summarising the pros and cons, overall rating and the best discounts and offers.

performance lab flex joint supplement product

Disclaimer & disclosure: With any supplement we recommend consulting with your doctor or pharmacist before use. Ideally, we would all source our nutrition needs from a well-balanced real whole-food diet but, where this isn’t possible, high-quality supplements can provide an ‘insurance policy’ to ensure we maintain optimum nutrient levels. We may receive a referral commission from carefully curated brands we link to but always strive to provide fair and evidence-based discussion around any products we feature.

Reviews Roundup Summary

We found a lot of positivity surrounding Performance Lab Flex. There is a clear consensus amongst the many articles reviewing it that it’s a very high quality product. The formulation is based on science, with a lot of thought having gone into making it accessible to everyone – using all natural vegan-friendly ingredients, in a form that maximises absorption and is easy to swallow.

Overall average review rating
4.55 out of 5

Given that Performance Lab Flex comes with a full money back guarantee, we feel it’s definitely one to try.

Review Roundup Details

What is Performance Lab Flex?

Performance Lab Flex is a joint supplement that provides an easy-on-the-stomach blend of ‘ultramodern’ joint nutrients designed to soothe and protect achy joints, whilst helping joint lubrication, cartilage renewal and promote long-term joint health and flexibility.

performance lab flex knee joint benefits

What causes joint pain?

Joint pain can affect just one joint or many joints and is usually due to injury or arthritis. According to NHS UK, whilst osteoarthritis (which typically develops over time in later life) can affect one or many joints, other causes will mostly affect either one or many joints.

Common causes where the pain is in just one joint are cited as:

  • Knee pain, which is very common due to the continual demands placed upon knee joints.
  • Inflammation of the lining of the knee, often signalled by a sudden recurrence of pain following an injury to the knee.
  • Gout (or pseudo-gout), which is a form of arthritis and typically manifests itself in the big toe before moving to another joint.
  • Bleeding in the joint space, due to an injury like a ligament tear or bone fracture (medically known as haemarthrosis).
  • Cartilage damage behind the knee cap, thought to be due to overuse (medically known as chondromalacia patellae).

Common causes where the pain is in multiple joints are cited as:

  • The lesser known psoriasis arthritis, that actually affects 1 in 5 people.
  • The more commonly known rheumatoid arthritis.
  • Arthritis caused by a viral infection.

The different forms of arthritis are generally associated with swelling, pain and stiffness of the joints and a full medical run down can be found here. There are many other causes of knee pain, such as lupus and scleroderma, and it is essential to seek professional medical advice with any undiagnosed ongoing joint pain.

What makes Performance Lab Flex different to other joint supplements?

performance lab flex open bottle with capsulesWith Performance Lab Flex, the reviews we examined praised a joint supplement that covers all the bases of what the science suggests to date, harnessing the development of innovative combinations of ingredients to increase absorption and interaction with biological processes. So to coin a phrase, ‘the whole is greater than the sum of its parts’.

As we’ll discuss further on, whilst the ingredients generally used in bone joint supplements are safe, the effectiveness of the individual ingredients tend to show differing degrees of promise in the treatment and pain management of conditions such as rheumatoid arthritis, osteoarthritis and osteoporosis, and so research is ongoing.

Let’s be very clear, this is no miracle cure for joint pain, no supplement is (although one or two reviews did claim amazing results when taking it), but Performance Lab have designed their supplement to be used “regularly and consistently to support smooth, comfortable movement and protect against long-term bone-grinding damage”, thereby improving physical performance and prolonging an active lifestyle.

Who makes Performance Lab Flex?

Performance Lab supplements are made by UK-based Opti-Nutra Ltd. Opti-Nutra® have a mantra to “uphold the highest nutritional supplement formulation standards in the world” by using:

  • nutrients backed by scientific evidence,
  • best-in-class nutrient forms that improve potency, efficacy, safety and tolerability
  • and novel nutrient combinations to unlock superior performance.

We particularly like their focus on producing products that are 100% vegan, allergen-free with natural, GMO-free ingredients (meaning they are not genetically modified). They also place an emphasis on purity, quality and consistency, so you always know exactly what you are getting with every batch, a must-have for any high-quality supplementation regime.

What are the ingredients?

Performance Lab Flex is built around what Opti-Nutra® call “the most evidence-backed joint stack known to science” – Glucosamine, Chondroitin and MSM. Full details of the published ingredients are as follows:

performance lab flex ingredients

Let’s take a closer look at the key ingredients…

All the reviews we looked at were unanimous that Glucosamine is the single most important ingredient to look for in a joint supplement, citing its naturally high concentrations in joint cartilage, ligaments, tendons and fluid that surrounds the joints. It’s a non-essential amino acid within the cell tissue that helps cushion and lubricate joints.

They are also in agreement that Flex contains a generously high amount of glucosamine per serving for a joint supplement, with the added bonus that their unique glucosamine sulfate 2KCL formulation is sourced from vegan-friendly corn rather than the most commonly used shellfish.

When we turn our attention to research studies that have looked at the benefits of glucosamine, there are certainly those that report “significant” benefits for joint health. Not all studies found the same benefits when compared to placebos and some of the product reviews explained that part of the difficulty in assessing its individual effectiveness is that it’s often taken alongside other ingredients such as chrondroitin (more on that next).

Related research studies:

Chondroitin is another ingredient cited by most Flex product reviews as essential for a joint supplement, due to its important role in absorbing and retaining water molecules within cartilage. For this reason it’s often paired with glucosamine as a recognised combination that plays an important role in joint lubrication and shock absorption.

Many of the reviews point out the unique formulation developed by Opti-Nutra® (branded Mythocondro® Chondroitin Sulfate) is claimed to increase chondroitin bioavailability by 43% (a measure of the ability to be absorbed and used by the body).

Research studies on chondroitin appear to yield similar conclusions as for glucosamine (that we looked at above) which may partly be due to the fact that the two ingredients are often taken together.

Related research studies:

Commonly known as MSM, methylsulfonylmethane is an essential nutrient for the formation of chondroitin, glucosamine and collagen that in turn is essential in the formation and rebuilding of cartilage.

Many of the product reviews we reviewed felt the combination of MSM with its own unique formulation of chondroitin and glucosamine makes for an excellent joint supplementation stack for maintaining joint function. In particular, some note that a number of clinical trials have observed the reduction of knee pain and inflammation, suggesting it could be a good option for those specifically seeking a knee joint supplement.

The evidence appears to point more towards MSM in conjunction with other nutrients being more effective than using MSM in isolation, with early research showing promise for the slowing of joint degradation.

Related research studies:

In addition to its most well-known use in Indian cuisine, turmeric has gained widespread recognition over recent years for its reported powerful anti-inflammatory, anti-antioxidant and possible anti-cancer properties. It’s the plant pigament curcumin that gives turmeric its distinctive yellow colour that has been found to be the key nutrient that gives turmeric these benefits.

However, the amount of curcumin the body will absorb from general use in cooking is quite low, so many Flex product reviews pick up on the fact that Opti-Nutra’s own formulation – CurcuWIN® Curcumin – packs a relatively powerful dose, that is also designed to be up to 46 times more absorbable.

The benefits of turmeric appear to be widely validated amongst a range of research studies, with the clear potential to provide far reaching health benefits beyond joint health alone.

Related research studies:

Like turmeric, boswellia (more commonly known as Indian frankincense) has been reported to have powerful anti-inflammatory properties. The more comprehensive Flex product reviews cite boswellia as having been shown to reduce joint pain by reducing the ability of the enzyme known as 5-Lipoxygenase to damage and degrade cartilage over time.

They also like the way Opti-Nutra® have again developed their own formulation – AprèsFlex® Boswellia Serrata – to significantly increase body absorption, which is claimed to be 52% greater than standard boswellia. Combined together with CurcuWIN® Curcumin, they are generally considered an important pairing to help soothe and reduce joint pain.

Related research studies:

Strontium, a calcium-like trace mineral, is commonly featured in supplements for bone health and scientists continue to research its potential to treat thinning bone density (osteoporosis) and arthritis. Those with osteoporosis have been prescribed strontium ranelate to strengthen bone quality and reduce the risk of bone fractures.

This is the ingredient where we found the research garners the most mixed opinions and the jury appears to be out on the benefits of strontium in its various forms. So whilst Flex ticks the box for those looking for a bone supplement containing this popular ingredient we’ll continue to research it.

As with the other ingredients covered, Opti-Nutra® have developed their own formulation called NutriGenesis® Strontium. Interestingly, Performance Lab NutriGenesis® nutrients are lab grown, using a patented process that mirrors the way nutrients develop and grow in nature, with the aim of significantly increasing their absorption by the human body.

Related research studies:

What are the most cited pros and cons of Performance Lab Flex?

Performance Lab supplements are rapidly growing in popularity and with that popularity comes an ever growing number of published product reviews looking at the pros and cons of taking them. Amongst the vast majority of reviews we saw a clear consensus on a number of pros and cons of Performance Lab Flex:


Scientifically-proven ingredients / science backed nutrients.

High quality of ingredients.

Unique blend of ingredients for higher bioavailability and efficacy (especially curcumin from turmeric).

Vegan friendly.

A very ‘clean’ & pure product.



Only available via Performance Lab website.

Observed positive effects can take some weeks and months rather than immediate.

Those who really suffer with joint pain may need to take more than one serving per day.

We found these pros are frequently cited as being the reason for reviews going as far as saying they consider Performance Lab Flex to be the single best joint mobility and flexibility supplement on the market.

* Interestingly, whilst price was often cited as a negative for the product, the more comprehensive reviews tend to point out that with the relatively higher price for a joint supplement comes a significantly higher quality and efficacy of ingredients, that actually works out better value for money than many cheaper products.

What do users say about Performance Lab Flex?

Joint supplementation is a personal experience, so it’s helpful to hear what actual users of the product say about it. Here’s a selection of recent reviews:


I have been using this…
Review by Colin B. June 2022

I have been using this product for a few weeks. I suffer from knee pains after heavy training, running etc. I am sceptical of fast fix products but this one works for me. Since using Flex joint pain has reduced and recovery is a lot easier.


This stuff works!
Review by David S. on 15 Jan 2021

Tried various supplements from local health food stores. Saw the TV ads about another product. Did some research and decided on Flex instead for my better half. Wow! After a couple of weeks there was such a huge difference in the reduction of pain for her. I’m generally skeptical about product claims but this stuff really works!


Relieved the pain of hip impingement
Review by Elisha L. on 5 Jan 2021

I’ve been battling with hip impingement and arthritis for several years, and after various specialist consults been told double hip replacement is the only way forward. I researched supplements in desperate hope to get off the strong pain killers (and their side effects) and started taking Flex back in November. It took 4 weeks for any effect, but then suddenly I realised the pain was easing. 12 weeks on and I’m hardly taking any pain killers at all and comfortably able to walk 5 miles. I’ve even deferred on the steroid injections. I’m very happy and will continue with Flex for the foreseeable.


Review by Joseph J. on 7 Dec 2020

Been in so much pain while sleeping and just walking for over 10 years, My pain is gone. I sleep with no pain. I work out at least 5 days a week. One hour of cardio each day. M,W,F circuit lifting for 45-60 min after cardio. Two hours of singles on T and F night with an athletic 6’5” 50 year old I also do 45-60 minute stretch’s on T, Th morning before cardio. Iam 70, cut, 2 knee replacements, 2 spine surgeries, rotator cuff repaired 20 yrs ago. Fused spine from hip to shoulder blades. I WAS VERY SKEPTICAL. I tried everything. Thank you for FLEX!!


Clean, effective and vegan
Review by Mike W. on 24 Nov 2020

I wrecked the tendons and ligaments in my ankle in a car crash and I can honestly say Flex accelerated my recovery hugely. Astonished to find such a thing that is Vegan. I’m vegetarian – I’ve taken Omega-3 on and off for years – reluctantly putting up with the carageenean compromise because i like the results. These these are simply fantastic and will be a long-term purchase – the absolute best results and no carrageenan.


Reasonably priced, safe and effective
Review by Mark A. on 12 Nov 2020

I have arthritis in many joints but in one foot was particularly painful. I would take a NSAID for a week and the paid would diminish but a week later it would be back. I certainly didn’t want to take those indefinitely so searched for a supplement. After taking Flex for one week the pain had mostly subsided. Reasonably priced, safe and effective.


Now a believer…
Review by Edward F. on 10 Nov 2020

I was curious regarding Turmeric supplements. I searched online for reviews, found many positive opinions re: “Performance Lab Flex”. My daughter, a Nutritional Therapist, said the ingredients looked fine so I ordered Performance Lab Flex hoping for the best but, fully expecting another case of “snake oil”. To my surprise, the darn stuff worked! I used to have a shooting pain in my right hand middle finger when I went to grasp something…all gone. Hips are much improved and general joint pain is nearly gone. I’m now a believer! Thank you, I’ll be ordering more.

These reviews, and many more, are published on the Performance Lab website. For transparency purposes, it’s only fair to point out that whilst we trust the good people at Opti-Nutra®, we are unable to confirm if the published reviews provide a fully representative view across the whole user base.

What are the conclusions of Performance Lab Flex?

Overall average review rating
4.55 out of 5

Given what we’ve found across all the reviews we researched, we think Performance Lab Flex is certainly one to try. There is a clear consensus that it’s a very high quality product, based on science, with a lot of thought having gone into making it accessible to everyone – using all natural vegan-friendly ingredients, in a form that maximises absorption and is easy to swallow.

We are all individual beings though, with differing nutrient needs, and supplements that provide a positive outcome for one may not have the same effect for another. So, as with any supplement, you really have to try it to see if it’s suited for you personally.

And this is where it gets even better, because what we really like about Performance Lab products is that they offer a 30-day, money back, performance promise, so you can make your first purchase risk-free!

Where are the best prices and discounts for Performance Lab Flex?

As you may have seen in the pros and cons section above, Performance Lab Flex can only be purchased directly on the Performance Lab website. However, Performance Lab are growing a reputation for some pretty amazing deals, so if you decide to give Flex a try, make sure you check their website for the lowest prices and best offers.

Are there Performance Lab Flex discount codes available?

Whilst we didn’t find any genuine discount codes for Performance Lab Flex you can get a 10% discount on your first order by signing up to the Performance Lab newsletter. You may not see it straight away when you go on their website but browse a few pages and a popup should soon appear offering the extra 10% discount.