Almost a third of adults report some type of joint pain. Yes, Boomers are getting older. But, they don’t just don’t sit still and ache; they stay active by taking care of their joints with functional foods and beverages that keep them moving.
Although exercise is essential for keeping joints healthy, strenuous exercise can lead to wear and tear on the cartilage within joints -- resulting in inflammation, pain, stiffness and decreased range of motion.
Functional foods and beverages formulated for joint health can help build the cartilage matrix, reduce cartilage breakdown and decrease pain, stiffness and inflammation, helping consumers stay active.
Glucosamine and chondroitin sulfate still lead the joint-health ingredient category, but research is showing omega-3 fatty acids; vitamins C, E and K; carotenoids; collagen; and botanicals could also help ease pain, especially by strengthening bone and renewing cartilage.
Glucosamine and chondroitin sulfate are the most extensively studied ingredients for both osteoarthritis (characterized by the breakdown of cartilage and subchondral bone) and joint pain in today’s more active adults. Glucosamine, synthesized by cartilage cells, is a naturally occurring amino sugar found in meat, fish and poultry. It’s used as a building block of the cartilage matrix. Chondroitin sulfate is the predominant proteoglycan, a type of glycosylated protein (a protein with a glycosaminoglycan chain attached), present in cartilage.
There are three main forms of glucosamine currently in use as an ingredient in health products: glucosamine sulfate, glucosamine hydrochloride and N-acetyl-glucosamine. Studies show both glucosamine in sulfate and hydrochloride forms help rebuild the cartilage matrix and decrease activity of hyalurondiase, an enzyme that damages tissue.
In addition, sulfate is a source of the essential mineral sulfur, used to stabilize the connective tissue matrix within cartilage. Glucosamine HCl has 99% purity, whereas glucosamine sulfate has 74% purity (therefore, greater amounts of glucosamine sulfate might be necessary to achieve a reduction in symptoms and improve aspects of joint health). In contrast to glucosamine HCl and sulfate, little research has been done on N-acetyl-glucosamine.
Following an initial surge of popularity, glucosamine/chondroitin came under scrutiny when the level of its efficacy drew some questions. The National Institutes of Health (NIH)-sponsored, multi-center Glucosamine/chondroitin Arthritis Intervention Trial (GAIT) was the largest randomized, controlled trial to examine the efficacy of glucosamine sulfate, glucosamine HCl and chondroitin sulfate. GAIT compared five treatment regimens in more than 1,500 patients with osteoarthritis of the knee. Subject groups received 1,500mg glucosamine HCl; 1,200mg chondroitin sulfate; 1,500mg glucosamine HCl, plus 1,200mg chondroitin sulfate; the prescription drug celecoxib; or a placebo.
After 24 weeks, the patients with moderate-to-severe osteoarthritis who were taking glucosamine HCl plus chondroitin sulfate experienced significant improvement, compared to placebo, determined based on results of a Western Ontario and McMaster Osteoarthritis (WOMAC) score. (WOMAC is a set of standardized questions that assess pain, stiffness and physical functioning in patients with hip and knee osteoarthritis.)
No significant improvement was noted in any of the other treatment groups or in those with only mild osteoarthritis.
In an ancillary study with a subset of participants from the original GAIT trail, researchers examined the effect on loss of joint space width in patients with knee osteoarthritis over a two-year period of glucosamine and chondroitin sulfate alone or in combination, as well as with celecoxib or placebo. None of the treatments resulted in clinically significant differences in joint space loss compared to placebo. However, many individuals with osteoarthritis experience little or no loss in joint space width, making this measure of questionable use when it is the only outcome measure studied.
Few studies have examined glucosamine supplementation in healthy individuals. In one randomized, double-blind, placebo-controlled trial, men with a history of acute sports-related knee injury received either 1.5g of glucosamine or placebo for 18 days. Glucosamine supplementation resulted in a significant improvement in knee flexion and extension but no change in pain and swelling.
Two placebo-controlled studies found 1.5g and 3g of glucosamine decreased collagen breakdown without affecting collagen synthesis in male soccer players and bicyclists. However, the effect of glucosamine on cartilage breakdown disappeared after study subjects stopped taking it.
Taken together, these studies suggest glucosamine could protect cartilage in otherwise healthy individuals without osteoarthritis by decreasing collagen breakdown.
Glucosamine is often harvested from the shells of shellfish, though there are no reports of allergic reactions, possibly because shellfish allergies stem from the protein (meat) of the shellfish, not the shells. Glucosamine increases bleeding time and is therefore contraindicated for people who take prescription blood thinners.
Combining glucosamine with chondroitin sulfate may decrease glucosamine absorption. And, though glucosamine alone or glucosamine plus chondroitin sulfate may improve certain aspects of joint health, neither have been shown to provide immediate relief from painful, stiff joints.
Oiling the Joints
The long-chain omega-3 fatty acids found in fish, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have modest anti-inflammatory effects in the body. In addition, in culture models using osteoarthritic cartilage cells treated to mimic arthritis-induced cartilage degradation, omega-3 fatty acids decreased cartilage breakdown and inflammation.
EPA and DHA improve several symptoms associated with rheumatoid arthritis, including joint swelling and pain, duration of morning stiffness, global assessments of pain and disease activity, as well as the need for non-steroidal anti-inflammatory drugs. Also, in a meta-analysis of 17 randomized, controlled trials, taking 1.7-9.6g of omega-3s per day for three to four months reduced patient-reported joint pain intensity; minutes of morning stiffness; and number of painful and/or tender joints in adults with inflammatory joint pain from rheumatoid arthritis, inflammatory bowel disease or dysmenorrheal. EPA and DHA may also improve symptoms stemming from other causes of joint pain.
In a double-blind pilot study, 45 adults with at least three months of joint discomfort were randomized to receive either six capsules of 370mg EPA/DHA and 230mg standardized lemon verbena extract (14% w/w verbascoside) or placebo daily for six weeks and then three capsules daily for the next three weeks. After the nine-week period, those taking the EPA/DHA combined with lemon verbena extract showed significant improvements in pain and stiffness, as well as physical function as assessed by WOMAC and Lequesne’s scores. Lequesne is an index of severity of osteoarthritis of the hip.
Though there are no other published studies examining omega-3 supplementation in otherwise healthy adults with joint pain, a 2012 study published in the journal Osteoarthritis and Cartilage examined blood levels of omega-3 as PUFAs, EPA and DHA; total omega-6 PUFAs; and arachidonic acid. The researchers then compared those levels to total patellofemoral cartilage loss, tibiofemoral cartilage loss and inflammation of the synovial membrane.
The study found a significant inverse association between total plasma omega-3 PUFAs and DHA in particular and patella-femoral cartilage loss in a cohort of adults with osteoarthritis of the knee or at high risk of developing osteoarthritis of the knee.
While there was no significant relationship found between any of the other fatty acids and tibiofemoral cartilage loss or inflammation of the synovial membrane, subjects with higher plasma levels of the pro-inflammatory omega-6 fatty acid arachidonic acid tended to have higher levels of inflammation of the synovial membrane. And, though these results need to be interpreted with caution -- because they measured plasma fatty acid status at one point in time -- previous research supports a relationship between higher levels of arachidonic acid and inflammation of the synovial membrane.
Take Those Vitamins…and Minerals…and Collagen
Overproduction of reactive oxygen species (free radicals), combined with low levels of antioxidants, can damage a variety of structures within the body, including cellular lipids, proteins and DNA. Free radicals are produced by cells within joints and are thought to contribute to cumulative oxidative damage in osteoarthritic cartilage. A variety of studies have examined intake of various plants or constituents within plants and measures of joint health.
Vitamin C is essential for repairing and maintaining cartilage and bone; in vitro studies show beta-cryptoxanthin has an anabolic effect on bone formation, while reducing bone resorption. Additional support for vitamin C comes from the “Framingham Osteoarthritis Cohort Study,” which assessed usual dietary intake (by a food frequency questionnaire) in addition to knee health (by radiography) in 641 participants. Incidence of osteoarthritis was not associated with any nutrient.
In a cross-sectional study examining dietary antioxidant intake, assessed by a food frequency questionnaire, and knee structure 10 years after the dietary assessment in a cohort of 293 healthy, middle-aged adults without knee osteoarthritis, knee pain or knee injury, higher fruit consumption and higher vitamin C intake were associated with a decrease in measures involved in the pathogenesis of knee osteoarthritis.
In addition, the carotenoid class of vitamin A-like compounds, including lutein and zeaxanthin intake, were associated with a reduced risk of cartilage defects, and beta-cryptoxanthin intake was inversely associated with tibial plateau bone area, after adjusting for vitamin E intake. This study suggests vitamin C and fruit have positive effects on bone, while foods rich in lutein, zeaxanthin and beta-cryptoxanthin may also be important for joint health. However, it is important to keep in mind that dietary intake measures from 10 years prior might not be reflective of dietary intake by the time knee structure was examined.
While both of the aforementioned studies show certain carotenoids are beneficial for knee health and reducing osteoarthritis risk, the evidence on carotenoids is conflicting, at best. In a study examining carotenoid biomarkers in 200 adults with knee osteoarthritis and age, gender and race-matched controls without osteoarthritis, those with the highest blood levels of lutein and beta-cryptoxanthin were 70% less likely to have knee osteoarthritis than matched controls. However, adults with the highest levels of trans beta-carotene and zeaxanthin were more likely to have knee osteoarthritis.
Among many other nutrients associated with bone health, vitamin K is essential for bone and cartilage mineralization. And, the NIH-sponsored “Multicenter Osteoarthritis Study” (MOST), a longitudinal study of 3,026 adults who had or were at risk of having knee osteoarthritis, looked at plasma vitamin K (phylloquinone) concentration, as well as knee radiographs and MRIs.
Vitamin K deficiency was associated with higher risk of knee osteoarthritis in one or both knees. In addition, the “Framingham Offspring Cohort” found low plasma phylloquinone concentration was associated with increased prevalence of osteoarthritis in the hand and knee. Although vitamin K deficiency is considered very rare, NHANES data suggests a significant portion of the adult population isn’t meeting adequate intake levels for vitamin K.
Recent studies have indicated that menaquinone, the K2 form of the vitamin, might be far more effective when it comes to bone and joint health. Studies over the past few years have proven menaquinone can be highly effective not only in preventing osteoporosis, but in enhancing vitamin D’s ability to generate new bone cells and modulate the interactions between vitamin D and calcium—especially as concerning mineralization and growth of blood vessels that feed new bone and joint tissues.
If collagen is a component of cartilage, does consuming collagen improve joint health? Previous research has supported the beneficial effects of collagen for decreasing pain in patients with osteoarthritis and rheumatoid arthritis.
More recent research suggests collagen can support joint health in those without arthritis. In a randomized, double-blind, placebo-controlled study in healthy volunteers with joint pain during activity, but no history of arthritis or joint pain at rest, researchers examined the effects of glycosylated undenatured type II collagen for joint support.
Study subjects who received 40mg of glycosylated undenatured type II collagen experienced a significant improvement in average knee extension, compared to placebo, at day 90 and at the end of the 120-day supplementation period. In addition, the supplementation group was able to exercise significantly longer on the stepmill after the 120-day period before experiencing joint discomfort. And, in two separate studies, 40mg of glycosylated undenatured type II collagen, taken daily, has been shown in two published, peer-reviewed studies to support joint health, according to researcher James Lugo, Ph.D.
The effect of foods, specific nutrients and plant compounds on cartilage and bone health is complex. Glucosamine, collagen, extract of boswellia and avocado-soybean unsaponifiables (ASUs) may improve various aspects of joint health when taken consistently over time. A diet comprised of foods rich in EPA, DHA, vitamins C, D and K, plus carotenoids, such as lutein and beta-cryptoxanthin, can help keep joints healthy, while possibly attenuating symptoms resulting from joint wear and tear.
Studies show boswellia extract, (derived from trees grown in the dry mountainous regions of India, Northern Africa and Middle East) helps decrease inflammatory markers and attenuate cartilage breakdown in a model of cartilage degradation. Two encouraging, in vitro studies of Boswellia frereana supported this. And, two published studies of boswellia in human subjects gave further evidentiary support. In a randomized, double-blind, placebo-controlled crossover study published in the journal Phytomedicine, Boswellia serrata extract, taken for 30 days, led to significant reductions in reported knee pain, increased knee flexion and increased walking distance in patients with osteoarthritis. However, radiological examination of the knee showed no changes after treatment.
The in vivo study on boswellia was a double-blind, randomized study which included 100 or 250mg B. serrata extract enriched with 30% 3-O-acetyl-11-keto-beta-boswellic acid (AKBA) or placebo for the treatment of knee osteoarthritis in 75 adults over a 90-day period. Both doses of B. serrata extract enriched with AKBA resulted in significant improvements in pain and physical function. And, significant improvements in pain and functional ability were noted after just seven days in the group taking 250mg of B. serrata extract enriched with AKBA.
In addition, both groups had a significant decrease in the cartilage degrading enzyme matrix metalloproteinase-3 in synovial fluid at the end of the study. Taken together, these results suggest 100 and 250mg of B. serrata extract enriched with AKBA can help reduce cartilage breakdown and improve knee functioning in patients with osteoarthritis.
In experiments conducted in vitro, ASUs reduce inflammatory markers within both osteoarthritic cartilage cells and the synovial membrane, while increasing type II collagen activity, which suggests ASU may repair and stimulate cartilage production.
And, in a prospective, double-blind, parallel-group, three-year trial, patients with symptomatic hip OA and low JSW were randomly assigned to receive either 300mg ASU or placebo. No significant differences were noted in JSW loss, although ASU significantly decreased the percentage of JSW deterioration compared to placebo. Another study found six months of ASU improved symptoms associated with knee and hip osteoarthritis compared to placebo. These studies suggest a potential role for ASU in patients with osteoarthritis.
Other botanical sources for joint health have been garnering attention of late. Given the effects of ginger on decreasing pain and inflammation associated with muscle damaging bouts of eccentric exercise, it seems like a plausible remedy for joint pain. So, too, has turmeric been subjected to scrutiny for its anti-inflammatory properties.
Even apple peels have been discovered to contain concentrated sources of phytochemical compounds, such as flavonoids and polyphenols, that, in some studies, have exhibited anti-inflammatory properties specifically beneficial to joint health.
The growth in ingredient science for healthy bones and joints is continuing to add to the ability of Americans to stay active. The technology that allows processors provide those ingredients in formats suitable for easy-to-enjoy foods and beverages makes it easy for consumers to take advantage of that ability.