Dietary Spices in the Prevention of Rheumatoid Arthritis: Past, Present, and Future.

Spices, defined by the US Food and Drug Administration as aromatic vegetable substances, in the whole, broken, or ground form, whose significant function in food is seasoning rather than nutrition, are an integral part of any Indian cuisine and are added to impart tastes, flavor, and color to the curries. In addition to their use in cooking, spices are also known to possess medicinal benefits and have been used in the various traditional and folk systems of medicine to treat ailments. Scientific studies carried out in the past have shown conclusively that most of the commonly used Indian spices and some of their phytochemicals possess antioxidant, free radical scavenging, anti-inflammatory, antibacterial, and antiviral effects; modulate detoxification enzymes, stimulate the immune system, reduce inflammation, and modulate steroid metabolism; and have antimutagenic, gastroprotective, and anticarcinogenic effects. Studies carried out during the past two decades have shown that commonly used Indian spices, such as fenugreek (. Trigonella foenum-graecum L., family Fabaceae), coriander (. Coriandrum sativum L., family Apiaceae), ginger (. Zingiber officinale Roscoe, family Zingiberaceae), turmeric (. Curcuma longa L., family Zingiberaceae), and their phytochemicals 6-shogaol (present in ginger), curcumin (present in turmeric), eugenol (present in clove Syzygium aromaticum L., family Myrtaceae), and thymoquinone (present in black cumin Nigella sativa L., family Ranunculaceae), possess beneficial effects in amelioration of rheumatoid arthritis in preclinical studies. Of these, ginger, turmeric and the oil of Nigella sativa have been shown also to possess beneficial effects in humans. For the first time, this chapter summarizes the findings from both preclinical and clinical studies with these spices and phytochemicals in rheumatoid arthritis, and also emphasizes the mechanisms of action responsible for the observed effects of each of the spices/phytochemicals.