Pain and Diet

There are many topics on which we can advise chronic pain patients (CPP). We can teach them proper body mechanics, how to focus their minds away from pain, and, when necessary, what medications are most likely to provide them relief.

However, there is one question about which we are unable to provide very much information: is there any special diet that might reduce chronic pain? 

Over the years I have asked a number of nutritionists and dieticians if they were aware of any specific recommendations for CPP and none could provide any. The continuing paucity of information on the subject is reflected by the fact that a recent review on the subject in a leading pain journal is only 3 pages long.¹

Unless a patient has a vitamin deficiency such as thiamine deficiency that might be associated with a painful disorder; suffers from a disease such as diabetes that requires dietary restrictions; or is taking a medication the metabolism of which may be affected by certain foods (eg, grapefruit juice interferes with the metabolism of methadone thereby increasing the potency of the dose), we really have had no specific advice to offer CPP.

In general, we have advised CPP to follow the same healthy diet that we would recommend to anyone: maximize the amount of fruits, vegetables, and whole grain foods; minimize the amount of beef, dairy products, sugar, and salt; and use alcohol and caffeine in moderation.

Based on my experience, a more specific approach to diet is rarely discussed with CPP. No doubt it should be. Many of these patients report diminished appetite due to their pain but often gain weight, both because of inactivity and because they frequently spend much of their time at home with easy access to food. Some may snack on healthy vegetables or nuts but many eat high-calorie snack foods of limited nutritional value. I do try to highlight this to CPP, especially those with low back or lower extremity pain where weight gain may markedly exacerbate the pain and may also interfere with their active participation in physical therapy.

The recently published review describes 3 possible theories on relationships between food and pain that may help us provide dietary guidance to CPP. First, however, it is important to note 2 major factors that limit how clinically applicable these theories may be. There are only a scant number of studies to support any of the theories and most have used animal subjects. Also, 2 of the theories primarily focus on preventing inflammation, and inflammation is not always a factor in the etiology of chronic pain.

The first theory involves the ratio between omega-6 and omega-3 polyunsaturated fatty acids (PUFAs) in the diet. The typical American diet tends to be weighted toward higher intake of omega-6, which is in many vegetable oils and in meat from animals primarily raised on corn-based feed. The standard diet is less likely to contain omega-3–containing foods, especially fish. Several studies have indicated that intake of a higher ratio of omega-6:omega-3 PUFAs may predispose to inflammatory disorders, including osteoarthritis.

The second theory centers on the higher intake of polyamines (PA), which are found in high amounts in a variety of foods, including squid, oysters, garlic, broccoli, green peas, almonds, peanuts, oranges, and bananas. A number of these foods are known to have health benefits while, ironically, a number of low-PA–containing foods, such as bacon, white bread, butter, cream, and sugar, are generally discouraged in a healthy diet.² There are also many healthy foods, however, that are low in PA, including apples, yogurt, tomatoes, and salmon.

The theory posits that PA may be involved in the activation of N-methyl-D-aspartate (NMDA) receptors, which appear to play a role in the development of pain. Thus, a diet low in PA might theoretically provide the analgesic benefits of an NMDA receptor antagonist such as ketamine-and without the adverse effects.

Finally, there is some literature to suggest that the intake of certain flavonoid-containing foods, such as soy, green tea, citrus fruits, and dark chocolate, may provide analgesia via the anti-inflammatory and anti-oxidant effects attributed to these foods.

Although none of these theories is anywhere close to being proved, they do tend to support our overall general recommendations for a healthy diet. What is most important in treating CPP, however, is that health care providers do not overlook diet and do emphasize that eating right may have an impact not only on overall health but also on pain.

References:
1. Bell RF, Borzan J, Kalso E, et al. Food, pain, and drugs: does it matter what pain patients eat? Pain. 2012;153:1993-1996.
2. Cipolla BG, Havouis R, Moulinoux JP. Polyamine reduced diet (PRD) nutrition therapy in hormone refractory prostate cancer patients. Biomed Pharmacother. 2010;64:363-368.