Turmeric has been in the spotlight as of late, especially with respect to its anti-inflammatory properties. Because I have been adding turmeric to my dogs’ food and to my own smoothies to help with general inflammation postworkouts, I thought I would write a Nutritionist’s View column on this bright yellow spice. Turmeric has been around for centuries; however, it has become extremely popular over the last several years.
WHAT IS TURMERIC?
Turmeric, a member of the ginger family, is “a bright yellow aromatic powder obtained from the rhizome of a plant of the ginger family, used for flavoring and coloring in Asian cooking and formerly as a fabric dye” (1,2). The compound called curcumin or curcumin longa linn is what gives turmeric its yellow color. Curcumin is the main curcuminoid of turmeric (2), and it is what gives turmeric its anti-inflammatory properties.
WHAT IS OSTEOARTHRITIS?
Osteoarthritis is sometimes called degenerative joint disease or degenerative arthritis (3). Osteoarthritis is the most common chronic disorder of the joints, with approximately 27 million individuals affected in the United States (3). Although osteoarthritis can affect any joint in the body, it most frequently affects the knees, hips, lower back, and neck (3). Osteoarthritis is the result of cartilage breaking down within the joints, resulting in inflammation, pain, and decreased mobility and physical function (3).
Anyone can contract osteoarthritis; however, it usually occurs in individuals ages 65 years and older. The main causes of osteoarthritis include genetic predisposition, weak muscles around the joints, previous injury to the joint, obesity, and increasing age (3).
EFFECTS OF TURMERIC ON OSTEOARTHRITIS
There have been a number of studies where turmeric was used to research its effects on diabetes mellitus, depression, cancer, inflammation, and osteoarthritis. Murugan et al. (4) studied the effects of turmeric on osteoarthritis in mice. They induced osteoarthritis in mice with injections of a chemical called monosodium iodoacetate in the right knee. Monosodium iodoacetate causes cartilage breakdown that is similar to the pathological changes of human osteoarthritis. They reported that turmeric significantly decreased the variance between left and right leg weight distribution. They reported that turmeric resulted in a balance between breakdown and building up of joint cartilage. Would this same effect occur in humans?
Haroyan et al. (5) conducted a randomized, double-blind, placebo-controlled study on the effects of curcumin (the compound within turmeric) on osteoarthritis. The curcuminoid complex extract they used was from turmeric rhizome. They also assessed its effect in combination with boswellic acid extract, which is from the Indian frankincense root. They chose to include boswellic acid in this study because it has been shown to reduce inflammation in osteoarthritis as well.
Haroyan et al. (5) began the study with 201 participants who were between the ages of 40 and 70 years (average age was approximately 56 years). Although the researchers included both men and women, the majority (approximately 90%) of participants were women. Participants were randomized into one of three groups: 1) one group took capsules that contained 333 mg of curcuminoids; 2) another group took capsules that contained 350 mg of curcuminoids and 150 mg of boswellic acid; and 3) a placebo group. Each group took their respective capsules three times per day. The researchers used the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), which is a validated and commonly used questionnaire to assess the state of pain, stiffness, and physical function in individuals with osteoarthritis, as one of their outcome measures.
After the 12-week trial, Haroyan et al. (5) reported that the groups who took the curcuminoid or curcuminoid plus boswellic acid supplements had significantly decreased pain from osteoarthritis, with improved physical function (e.g., fast-paced walking test). However, the curcuminoid plus boswellic acid showed a slightly better improvement than curcuminoid alone. The researchers concluded that the combination of curcuminoid and boswellic acid may have resulted in synergistic effects of these compounds on the inflammation resulting from osteoarthritis (5).
Although these represent just two studies on the effect of turmeric on osteoarthritis, the results are promising. Nonetheless, more research needs to be conducted to ascertain consistent results.
HOW TURMERIC MAY REDUCE INFLAMMATION
The mechanism of how turmeric (curcumin) may reduce inflammation has not been clearly defined. Cao et al. (6) studied the effects of curcumin on cartilage formation (also known as chondrogenesis) in mesenchymal stem cells. Mesenchymal stem cells are used as germ cells in cartilage tissue engineering. They reported that curcumin worked to maintain cartilage balance.
Li et al. (7) reported that curcumin suppresses inflammatory pathways through its actions on a particular signaling enzyme in the joints. These researchers strongly recommend that curcumin should be researched as a preventative treatment of osteoarthritis in humans and companion animals.
Murugan et al. (4) reported that turmeric upregulates the type II collagen gene. This could be another mechanism on how turmeric helps reduce inflammation.
The aforementioned research represents three possible mechanisms of how curcumin can help to reduce inflammation in osteoarthritis. More research in this area needs to be conducted to define the exact mechanism, however.
Turmeric is a spice that can have significant benefits on reducing inflammation resulting from osteoarthritis. Although much of the research has shown positive results, more research needs to be conducted to ascertain consistent results. Nonetheless, turmeric can easily be added to smoothies and meals.
Turmeric is considered safe when taken by mouth (8). However, some adverse effects from consuming turmeric have been observed and may include nausea, diarrhea, increased risk of bleeding, increased menstrual cycle flow in women, increased liver function tests, decreased blood pressure, and increased gallbladder contractions (9).
4. Murugan S, Bethapudi B, Purusothaman D, Raja P, Velusami CC. Antiarthritic effect of polar extract of Curcuma longa on monosodium iodoacetate induced osteoarthritis in rats. Antiinflamm Antiallergy Agents Med Chem
. 2018. [Epub ahead of print]
5. Haroyan A, Mukuchyan V, Mkrtchyan N, et al. Efficacy and safety of curcumin and its combination with boswellic acid in osteoarthritis: a comparative, randomized, double-blind, placebo-controlled study. BMC Complement Altern Med
6. Cao Z, Dou C, Dong S. Curcumin inhibits chondrocyte hypertrophy of mesenchymal stem cells through IHH and notch signaling pathways. Chem Pharm Bull (Tokyo)
7. Li X, Feng K, Li J, et al. Curcumin inhibits apoptosis of chondrocytes through activation ERK1/2 signaling pathways induced autophagy. Nutrients