With age, the endogenous synthesis of hyaluronic acid for joints and other tissues physiologically tends to slow down, and it is precisely in this space that targeted nutrition and supplementation can offer support.
In this article we see what the most recent research really says on this double front – joints and dry eyes – which is still little talked about, and why, when it comes to oral intake, the molecular weight of the molecule makes a concrete difference.
What is hyaluronic acid and where does the body naturally produce it
Hyaluronic acid is a glycosaminoglycan, i.e. a long chain of sugars, present naturally in almost all connective tissues. The body synthesizes it autonomously through dedicated enzymes (hyaluronan synthase) and distributes it in very different districts:
As happens with collagen, the physiological availability of hyaluronic acid also tends to reduce with advancing age, with a possible impact on tissue hydration and joint and ocular comfort.
Hyaluronic acid for joints: how it works on synovial fluid
Hyaluronic acid is mainly responsible for the viscosity and elasticity of synovial fluid, the natural “lubricant” of the joints. It has been used in the clinical setting for joint infiltrations for years; more recent, and still in the consolidation phase, is research on its oral intake.
When we get up from a chair, climb stairs or lift a weight, synovial fluid allows the joint surfaces to slide with minimal friction and absorb the loads of movement. It is hyaluronic acid, thanks to its high molecular weight, that gives it this double
viscoelastic property.
With age, joint overload, intense sporting activity or in the presence of osteoarthritis, the concentration and average molecular weight of synovial hyaluronic acid tend to reduce: a phenomenon that researchers associate with a lower lubricating and shock-absorbing capacity of the joint.
Intra-articular infiltrations of hyaluronic acid (the so-called viscosupplementation) have long been widely used in the management of knee osteoarthritis, supported by numerous randomized trials.
The line of research on oral intake, however, is younger but growing rapidly: a systematic review published in 2024 on Mediterranean Journal of Rheumatology brought together the available studies on osteoarthritis and low back pain, with encouraging results on pain and joint function, while highlighting the need for larger and standardized trials.
One of the most recent data, in this sense, comes from a study published in December 2025 on Frontiers in Nutrition. After 12 weeks of oral intake of high molecular weight hyaluronic acid, WOMAC scores of pain, stiffness and functional difficulty improved significantly compared to placebo, without relevant adverse events or changes in blood and urine tests.
To confirm a promising picture, other trials have evaluated formulations containing hyaluronic acid in combination with other ingredients. A randomized double-blind trial conducted on people with mild knee osteoarthritis observed an improvement in symptoms after 8 weeks of oral low molecular weight hyaluronic acid in combination with glucosamine and chondroitin, while a trial published in Nutrients in 2023 evaluated a complex based on krill oil, astaxanthin and hyaluronic acid in people with mild osteoarthritis, with perceived benefits on joint comfort.
Hyaluronic acid and dry eyes: the link with ocular hydration
Hyaluronic acid is a natural component of the tear film and has been used for decades in the form of eye drops against dry eyes. Some preliminary studies suggest that oral intake, when combined with a topical treatment, can also promote dry eye comfort.
Dry eye syndrome is an increasingly widespread disorder, thanks to the prolonged use of screens – which reduces the frequency of blinking – as well as age, contact lenses, some medications and environmental factors such as air conditioning or heating.
Thanks to its high capacity to retain water molecules and its viscoelastic properties, hyaluronic acid contributes to the stability of the tear film and is today one of the most used ingredients in eye drops intended for the management of dry eyes, where it helps to keep the surface of the eye hydrated and lubricated.
Related to research on oral intake, a pilot randomized controlled study published in Journal of Ophthalmology compared, in people with dry eye, a group treated only with eye drops based on hyaluronic acid and a group that, in addition to the eye drops, also took hyaluronic acid orally (240 mg per day for 3 months): the group with oral supplementation showed additional improvements in some parameters of the ocular surface, such as the break-up time of the tear film. An interesting fact, which will require confirmation on larger cases before it can be generalized.
Oral use vs topical/filler use: the difference that (almost) no one explains
When talking about hyaluronic acid, there is often confusion between very different uses, which respond to different logics:
Precisely because of these characteristics, today there are supplements developed specifically for oral administration. Understanding this distinction helps to have correct expectations: an oral supplement can represent nutritional support over time, to be combined – not replaced – with any specific treatments indicated by the doctor, under his advice.
Why molecular weight matters when choosing an oral supplement
Not all hyaluronic acid supplements are the same. The molecular weight – the length of the chain, expressed in kilodaltons (kDa) or megadaltons (MDa) – influences the way in which the molecule behaves in the organism, its stability and, according to several studies, also the type of biological effect it can exert.
The literature has observed that low molecular weight hyaluronic acid and high molecular weight hyaluronic acid can behave differently in the body. It is a technical but crucial topic, because it helps to understand why two supplements with the same name on the label can, in theory, act differently.
High molecular weight hyaluronic acid appears to have physicochemical properties closer to those of physiological hyaluronic acid present in tissues.
The picture is not yet entirely univocal – some clinical trials have documented benefits even with low molecular weight formulations – but the most recent evidence, in particular the 2025 study mentioned in the previous paragraph, indicates an advantage of the high molecular weight in terms of the biological effect observed.
For this reason, when choosing a supplement, two technical aspects deserve attention:
- The molecular weight declared on the label, in kDa or MDa: high molecular weight formulations have longer chains and physical-chemical characteristics closer to those of hyaluronic acid naturally present in tissues.
- The form of intake: the liquid form, compared to capsules, may be more practical for those who have difficulty swallowing capsules or tablets or prefer modular dosages and a simpler intake method to include in the daily routine.
An example of a supplement that takes these parameters into account is HyalurOn® Plus by Nutrigea, a liquid supplement of high molecular weight Hyaluronic Acid (≥ 2.4 MDa), obtained through controlled bacterial fermentation – therefore of non-animal origin – with a concentration of 8 mg per ml. Being 100% vegan, it is also suitable for those who follow a plant-based diet.
Safety and tolerance: what to know before you start
Oral hyaluronic acid is generally considered well tolerated: the available clinical studies, conducted over periods ranging from a few weeks up to 12 months, have not reported serious adverse events, with at most a few isolated cases of mild gastrointestinal discomfort.
A practical aspect to know concerns the origin of the raw material: hyaluronic acid can be extracted from animal tissues (traditionally from roosters’ combs) or obtained through controlled bacterial fermentation, as in the case of vegan formulations; those with specific allergies or who wish to avoid animal raw materials should always check the source of the ingredient on the label.
As with any supplement, during pregnancy, breastfeeding, or in the presence of ongoing pathologies and pharmacological therapies, it is recommended to always seek the advice of your doctor before starting to take it.
Conclusions on hyaluronic acid for joints and eyes
Hyaluronic acid is much more than a skincare ingredient: it is a molecule physiologically present in the joints and eyes, two areas particularly exposed to the wear and tear of time, lifestyle and, in the case of the eyes, the prolonged use of digital devices. If you spend many hours in front of the screen, play sports or start to feel the first signs of aging on your joints, knowing this role can be useful to you.
Research on oral supplementation is still evolving, but the data available today suggests an interesting potential nutritional support, especially when moving towards high molecular weight and high purity formulations.
When choosing a supplement it is therefore worth considering not only the quantity of hyaluronic acid supplied, but also the quality of the raw material, the molecular weight and the consistency of intake: characteristics that can make the difference in a supplement designed to accompany the body’s well-being over time.
Frequently asked questions
Does oral hyaluronic acid work for joints?
A 2024 systematic review and some randomized clinical trials, including a trial published in 2025 on Frontiers in Nutritionsuggest a potential improvement in pain, stiffness and joint function after oral intake of hyaluronic acid.
How long before I notice a benefit on dry eyes?
In the available pilot study, improvements on the ocular surface were observed after approximately 3 months of continuous oral intake, in combination with a specific topical treatment for the eyes (which the doctor must prescribe). As with most nutritional supplements, consistency in intake represents an important element in evaluating their effects over time.
Is it different from hyaluronic acid used for wrinkles?
Yes. The hyaluronic acid of aesthetic fillers is injected, cross-linked and concentrated to give volume locally; that of oral supplements is instead taken orally, is absorbed and partly metabolised by the body through different mechanisms and is studied as a nutritional support, not as a local volumizing treatment.
These contents are for informational purposes, should not be understood as an indication of diagnosis and treatment of pathological states and are not intended to replace in any way the opinion of the Doctor. Supplements are not intended as substitutes for a varied and balanced diet and a healthy lifestyle. Read the warnings on the label.
