5.1.2. Monitoring Weight Changes

Measuring weight can be confronting for patients and given that the BMI is not always an accurate measurement of weight, it is important to discuss weight measurements with patients to ensure they are comfortable. Monitoring changes in weight over time, (i.e., monthly) can be a useful indication of under- or overnutrition. It can also be useful in identifying serious illnesses associated with sudden and unplanned weight loss, such as cancer [142] and inflammatory bowel disease [143]. The BMI or a waist circumference can help to identify changes in weight over time. However, as previously stated, the BMI must be used with caution. A visual assessment or asking a patient if their clothes are tighter or looser can be less confronting and still obtain the same information. Dietary strategies for pain management are likely to result in improvements in overall health and potentially weight loss. For a successful and sustained nutrition-related change, focusing on pain is more likely to resonate with a patient, compared to weight loss [144]. Patients are more likely to feel validated and motivated which will assist with behavior changes [144,145].

## 5.1.3. Identifying Other Comorbidities

Several studies have shown that people experiencing chronic pain also have multiple comorbidities [45,146]. Many of these comorbidities can be influenced by nutrition, such as cardiovascular disease (CVD), diabetes, and depression [147–149]. Recent studies have found that people with musculoskeletal pain were twice as likely to have CVD than those without [150], people with diabetes were 1.4 times more likely to report lower back pain and 1.2 times more likely to report neck pain [102], and people with depression were three times more likely to experience non-neuropathic pain and six times more likely to experience neuropathic pain [151]. Globally, a poor diet is the top modifiable risk factor for morbidity [152]. Chronic pain and chronic health conditions share a relationship with inflammation, oxidative stress and a poor diet quality [153]. As such, many of the nutrition recommendations in Table 2 may not only improve pain experiences but may also improve the severity and impact of other chronic health conditions [53]. A referral to a dietitian should also be considered so a detailed and tailored assessment and relevant advice can be provided.


**Table 2.** Nutrition recommendations for people experiencing chronic pain.

\* Glycemic index is a ranking system for carbohydrate foods and is based on the speed of digestion and impact on the blood glucose levels over a period of time. Glucose has a GI of 100 and this is the reference used for other foods. Carbohydrates that breakdown quickly and lead to a sharp increase in blood glucose levels are high GI foods. Carbohydrates that breakdown slowly and lead to a gradual and sustained increase of the blood glucose levels are low GI foods.

#### 5.1.4. Identifying Abnormal Biochemistry Results

As outlined in Section 3.2, there are several micronutrient deficiencies that are commonly associated with chronic pain, such as the B-group vitamins and Vitamin D [56,79,82,157]. These can be identified through routine pathology tests. Dietitians can also identify these deficiencies through comprehensive dietary assessment methods. While it is unclear what the

exact relationship is between chronic pain and micronutrient deficiencies, evidence suggests that some vitamins, especially the B-group vitamins, play a role in maintaining the health of the nervous system and pain-signaling pathways [121,158]. Additionally, this paper also outlines several underlying mechanisms associated with chronic pain, including a disrupted lipid and glucose metabolism. Abnormal serum lipids, glucose, and insulin can be used to identify issues with metabolism that may be present and contributing to pain experiences in people with pain [94].

#### 5.1.5. Identifying Gastrointestinal Complaints

Gastrointestinal complaints are common in people experiencing chronic pain. A recent systematic review found that people with irritable bowel syndrome were 1.8 times more likely to have fibromyalgia and that 50% of those with fibromyalgia had a least one functional gastrointestinal disorder [159]. Functional gastrointestinal disorders (FGIDs) comprise a variety of chronic and recurrent gastrointestinal symptoms that cannot be explained by structure or biochemical abnormalities [160]. While the exact nature of FGIDs is still unclear, it has been linked with an altered gut-brain communication and a hypersensitivity of the enteric nervous system [161]. People experiencing chronic pain should be screened for symptoms associated with FGIDs, such as abdominal pain, dysphagia, dyspepsia, diarrhea, constipation, and bloating [161]. There are several strategies (e.g., medication, exercise, cognitive behavior therapy, and nutritional strategies) that are used to manage symptoms using an interdisciplinary approach. From a nutrition perspective, there are a variety of options. These include a diet that is low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs), modifying the fiber intake, or restricting certain foods, such as caffeine, alcohol, spicy foods, and foods high in fat [162,163]. Given the variety in dietary strategies, it is important to refer patients to a dietitian to ensure a comprehensive dietary assessment is undertaken before trialing these strategies. Some of these dietary strategies can result in an inadequate nutrient intake. For example, a low FODMAP diet is an elimination diet and removing foods and food groups from the diet leads to a nutritional inadequacy [164]. Thus, it is vital that dietitians work with patients to ensure they can meet their nutritional needs while trialing these strategies.

#### 5.1.6. Assessing the Dietary Intake

A poor dietary intake is another risk factor for chronic pain. Many people experiencing pain are likely to have a limited intake of the core nutrient-rich foods and an excessive intake of energy-dense nutrient-poor foods [82,83]. Health professionals can measure the dietary intake by assessing the diet quality. Diet quality can be defined as a varied nutritious diet, which provides individuals with adequate amounts of essential nutrients needed to support overall health and wellbeing [165]. Optimizing the diet quality will address several risk factors in one strategy. Diet quality can be measured using a diet quality index or diet score such as the Diet Quality Index-International [166], the Healthy Eating Index [167] or the Dietary Inflammatory Index [168]. Some can be automatically calculated, such as the Australian Recommended Food Score (ARFS), which can be determined by completing an online questionnaire called the Healthy Eating Quiz [169]. Every country also has a set of dietary guidelines and health professionals can compare a patient's intake against these guidelines to determine areas for improvement. However, as acknowledged in Philpott (2019), chronic pain services would significantly benefit from including dietitians and their skills in the assessment, medication, and support of diets specific to chronic pain [170]. Dietitians can conduct detailed and tailored dietary assessments which provide more insight into a patient's dietary intake and can identify more areas for improvement.
