Osteoarthritis is the most common version of arthritis and affects millions of people around the world, including about 30 million people in the United States alone. The condition is characterized by the slow breaking of the cartilage, which acts as a buffer between the joints. As cartilage degenerates, the joints can become swollen, stiff and painful and the condition tends to worsen over time. Osteoarthritis can affect any joint in the body, but it is found more often in the knees, hips, hands and spine. Traditionally, osteoarthritis is referred to as a condition of wear – in other words, the joints that are used more often or more heavily are more likely to suffer a constant disruption of the cartilage, eventually leading to osteoarthritis. There are some known risk factors for osteoarthritis – for example, more commonly it affects older people and women are more likely to develop it than men. Likewise, previous injuries to the joints and bone deformities also increase the chances of developing the condition. Another known risk factor for osteoarthritis is obesity. This is partly due to the excessive stress exerted on the joints when carrying more weight around, but the connection between excess weight and osteoarthritis can go a little deeper.
A team of researchers from Queensland University of Technology and the University of Southern Queensland, both in Australia, recently studied a connection between dietary fat and the onset of osteoarthritis. The group was led by professors Yin Xiao and Lindsay Brown. This recently published study follows the previous work of Prof. Xiao, who discovered that antioxidants and anti-cholesterol drugs (statins) can slow down the progression of joint damage attributed to fatty acids found in foods such as palm oil and butter. In this research project, Prof. Xiao has specifically studied the effects of a diet rich in saturated fatty acids and simple sugars on osteoarthritis. These dietary components reflect the nutritional elements commonly found in junk food: high fats and carbohydrates. The study shows that osteoarthritis may have less to do with the general use of our joints and more to do with what we eat regularly. According to their results, a diet containing 20% saturated fat and simple carbohydrates produced osteoarthritic changes in the knee.
A year before, the team of prof. Xiao discovered a link between leptin, a hormone involved in obesity and some cellular degeneration in cartilage cells (chondrocytes). Leptin was found to be highly expressed in human osteoarthritis (Huang Z et al., 2016). The researchers sought to explore the possible effects and mechanisms of leptin on apoptosis (cell death) and the autophagy of chondrocytes during the onset of osteoarthritis. The expression of the enzyme Lysyl oxidase-like 3 (LOXL3) in the cartilaginous tissues and the concentration of leptin in the synovial joint fluid (SF), was measured in samples of 45 patients with osteoarthritis and 25 healthy donors. The LOXL3 protein was positively regulated in patients with osteoarthritis, which was positively correlated with the concentration of leptin in the synovial fluid. Therefore if leptin increases LOXL3 in cartilage cells, promoting inflammation, this means that there must be some connection between fat metabolism and cartilage health. The deposits of saturated fatty acids in the cartilage change its metabolism and weaken the cartilage, making it more prone to damage. This, in turn, would lead to osteoarthritis pain from the loss of the shock-absorbing effect of cartilage. Long-term use of animal fats, butter and palm oil seemed to weaken the cartilage of the mice that fed on them.
However, when they replaced meat fat with lauric acid – a saturated fat commonly found in coconut oil – the opposite effect was observed: Lauric acid seemed to be beneficial. When the researchers replaced the fat of meat in the diet with lauric acid, they found signs of decreased deterioration of cartilage and metabolic syndrome. The researchers conclude that the replacement of traditional diets containing lauric acid derived from coconut with palmitic acid derived from palm oil or stearic acid derived from animal fat has the potential to worsen the development of both the metabolic syndrome and osteoarthritis. Although the results will need to be replicated, this could be another reason to avoid a high fat and high carbohydrate diet. This also confirms other team results about the beneficial effect of coconut oil on metabolic profiles (de Munter W et al., 2016 Datta P et al., 2017 Larrañaga-Vera A et al., 2017). However, since obesity has shown a clear connection with the state of the intestinal microbiota, some teams of researchers have already explored this hypothesis in animal laboratory models. with good preliminary data (Collins H et al., 2015; Shang Q et al., 2016).
So it’s not just the cold or the humidity. It seems that osteoarthritis also finds one of its roots in the wrong way to seat at the table.
- edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
Letteratura scientifica
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