Examining the Therapeutic Possibilities of Nutrition in Fibromyalgia
More than 2 decades after the World Health Organization recognized fibromyalgia (FM) as a clinical entity in the International Classification of Diseases,1 and despite updated diagnostic guidelines,2,3 its differential diagnosis and effective treatment remain poorly defined and challenging. Recognized as one of the most common chronic pain conditions, FM is estimated to affect between 3% and 6% of the world population and approximately 10 million people in the United States, disproportionately affecting more women than men.4
FM is characterized by chronic generalized pain and tenderness of unknown etiology, often accompanied by several associated symptoms including fatigue, sleep disturbance, headache, cognitive impairment, morning stiffness, depression, and gastrointestinal disorders.5-7 The significant overlap with several diseases, including chronic fatigue syndrome, migraine, irritable bowel syndrome, and temporomandibular joint disorder complicates FM differential diagnosis and optimal treatment. Despite these challenges, FM has been assigned its own diagnostic code — M79.7 — recognizing the syndrome for the first time as an official clinical diagnosis.8
Currently, there is no cure for FM. In the absence of a clear understanding of FM etiology and pathophysiology, effective and curative treatment has been elusive. The current treatment of FM is multifaceted in its approach, incorporating nonpharmacologic and pharmacologic options. The former approach includes physical exercise, cognitive behavioral therapy, and interventions to minimize triggers of FM, including sleep disorders such as sleep apnea, and mood problems such as stress, anxiety, panic disorder, and depression.9-11 Pharmacologic therapy is recommended when nonpharmacologic approaches fail to control the symptoms of FM adequately. In the United States, 3 drugs are approved by the US Food and Drug Administration for the treatment of fibromyalgia; 2 of these drugs, duloxetine (Cymbalta) and milnacipran (Savella), alter brain chemicals (serotonin and norepinephrine) to help control pain levels.9 Pregabalin (Lyrica) works by blocking overactive nerve cells involved in pain transmission. Other pharmacologic agents are used to manage other presenting symptoms such as sleep problems and depression. Despite the several pharmacologic treatment options available, no agent, or their combination, has demonstrated efficacy in treating all the symptoms of FM. The adverse effects associated with many of the pharmacologic agents, some warning against their use for the treatment of FM,12 call for improved understanding of FM etiology, pathophysiology, and the influences of personal habits and choices on FM symptoms, which may provide a new direction in FM treatment.
Among nonpharmacologic treatment approaches, nutrition is emerging as a promising tool for FM management. It has been proposed that deficiencies or imbalance in certain essential nutritional components may result in dysfunction of the pain inhibitory mechanisms, including fatigue and other FM symptoms. Indeed, deficiencies in certain amino acids, magnesium, selenium, and vitamins B and D are associated with increased muscle pain,5 and the benefits of specific diet and nutritional supplementation have been described in patients with FM.13
Recent efforts have attempted to improve understanding of the relationship between FM and nutrition; specifically, the relationship between metabolic state and muscle pain and the role of vitamins, metals, and antioxidants.5-7 For example, a diet rich in antioxidants, food that can increase nitric oxide level, and specific vitamins including vitamin B12/folic acid and creatine supplementation have been associated with improvement in FM symptoms.5 Specific nutritional deficiencies are also more commonly seen in individuals with FM, including deficiency in vitamin B and D, magnesium, iodine, iron, melatonin, selenium, and branched amino acids.5,6 In contrast, foods rich in histamine and heavy metals, including mercury, cadmium, and lead, exacerbate the symptoms of FM.5 It has been suggested that a diet rich in protein and vegetables may have a beneficial effect in reducing muscle pain, possibly because of higher concentrations of specific amino acids that provide energy for muscle function and strength and the increased antioxidant intake from vegetables.5,6
Not all amino acids are beneficial, however, because increased levels of homocysteine in the cerebrospinal ﬂuid are associated with FM-related musculoskeletal pain.5 A study in which individuals with FM and irritable bowel syndrome were challenged with a diet rich in glutamate found worsened FM symptoms compared with control participants who were not subjected to glutamate challenge.7 The results suggest that glutamate may play a role in FM symptoms in some patients. Studies have also examined the effects of physical exercise, body weight, and obesity in the development of or in exacerbating the symptoms of FM.5-7 A recent systematic review found that individuals with FM generally have a sedentary lifestyle, have higher body mass index, and are more likely to be overweight or obese.6 Furthermore, obese individuals show higher pain sensitivity, lower quality of life, and higher prevalence of fatigue. These symptoms have also been linked with reduced consumption of protein-rich foods and vegetables, poor sleep pattern, and depression.5,6
The link between nutrition and FM may provide a viable approach to explain individual variation in FM symptoms directly linked to personal nutritional habits and may present a potential approach to individualizing its management. When optimal levels of nutrition are achieved, FM pain levels are usually lowered.5 Currently, however, the research supporting dietary intake and FM is premature to categorically link cause and effect and allow the formulation of specific nutritional recommendations for FM management. However, based on the current evidence, there is a clear correlation between FM symptoms and healthy diet, physical exercise, and maintaining a healthy body weight. Among individuals with FM, providing guidance to improve dietary behavior, which may include supplementation to achieve an optimal nutritional status and interventions to maintain normal body weight, can contribute to improved control of FM symptoms.