Nutritional intervention in chronic pain: an innovative way of targeting central nervous system sensitization?

INTRODUCTION: Few treatment programs for chronic pain nowadays take a dietary pattern or adipose status into account. AREAS COVERED: An important role of neuroinflammation in chronic pain is now well established, at least in part due to increased central nervous system glial activation. Based on preclinical studies, it is postulated that the interaction between nutrition and central sensitization is mediated via bidirectional gut-brain interactions. This model of diet-induced neuroinflammation and consequent central sensitization generates a rationale for developing innovative treatments for patients with chronic pain. Methods: An umbrella approach to cover the authors' expert opinion within an evidence-based viewpoint. EXPERT OPINION: A low-saturated fat and low-added sugar dietary pattern potentially decreases oxidative stress, preventing Toll-like receptor activation and subsequent glial activation. A low-saturated fat and low-added sugar diet might also prevent afferent vagal nerve fibers sensing the pro-inflammatory mediators that come along with a high-(saturated) fat or energy-dense dietary pattern, thereby preventing them to signal peripheral inflammatory status to the brain. In addition, the gut microbiota produces polyamines, which hold the capacity to excite N-methyl-D-aspartate receptors, an essential component of the central nervous system sensitization. Hence, a diet reducing polyamine production by the gut microbiota requires exploration as a therapeutic target for cancer-related and non-cancer chronic pain.

The effect of a portion size intervention on French fries consumption, plate waste, satiety and compensatory caloric intake: an on-campus restaurant experiment.

BACKGROUND: One of the driving factors of dietary overconsumption throughout the last decennia is the increase of food portion sizes. Larger portions induce higher daily energy intake, so reducing portion size may reduce intake of excess calories. However, real-life studies about the effects of portion size reduction are lacking. Therefore, this study examined the effect of a French fries portion size reduction on French fries consumption, French fries plate waste, satiety and caloric intake during the subsequent afternoon among university students and employees in a Belgian on-campus restaurant setting. Moreover, this study evaluated consumers' perception about the portion size reduction. METHODS: The study took place over a two-time (i.e. baseline and intervention week) 4-day period (Tuesday-Friday) in the on-campus restaurant where ±1200 meals are served every day. French fries' portions were reduced by 20% by replacing the usual porcelain bowl served during the baseline week (±200 g) with smaller volume paper bags during the intervention week (±159 g) in a pre-post real-life experiment. French fries consumption and plate waste were measured in 2056 consumers at baseline and 2175 consumers at intervention. Additionally, interviews were conducted directly after lunch and again between 4 and 6 p.m. on the same day to assess satiety and caloric intake at pre and post in a small subsample of both French fries consumers (n = 19) and non-French fries consumers (n = 14). Post-intervention, the same subsample was interviewed about their perception of the portion size reduction (n = 28). RESULTS: Total French fries intake decreased by 9.1%, and total plate waste decreased by 66.4%. No differences were found in satiety or caloric intake between baseline and intervention week among the French fries' consumers. The majority (n = 24, 86%) of French fries consumers noticed the reduction in portion size during the intervention. Although most participants (n = 19, 68%) perceived the reduced portion size as sufficient, only a minority of participants (n = 9, 32%) indicated post-intervention that they would agree with a permanent implementation. CONCLUSIONS: Reducing portion size may lead to reduced caloric intake, without changing perceived levels of satiety.

Effect of vitamin D supplementation on non-skeletal disorders: a systematic review of meta-analyses and randomised trials.

Randomised trials reported up to Dec 31, 2012, did not confirm that vitamin D supplementation could protect from non-skeletal health conditions affecting adults, as was expected on the basis of data from observational studies. To examine whether the more recently published meta-analyses and trials would change past conclusions, we systematically reviewed meta-analyses of vitamin D supplementation and non-skeletal disorders published between Jan 1, 2013, and May 31, 2017, that included study participants of all ages, including pregnant women. We also searched for randomised trials not included in meta-analyses. We identified 87 meta-analyses, of which 52 were excluded because they contained less recent literature or were of suboptimal quality. We retrieved 202 articles on trials that were not included in meta-analyses. Recent meta-analyses reinforce the finding that 10-20 µg per day of vitamin D can reduce all-cause mortality and cancer mortality in middle-aged and older people. Although vitamin D doses were greater than those assessed in the past, we found no new evidence that supplementation could have an effect on most non-skeletal conditions, including cardiovascular disease, adiposity, glucose metabolism, mood disorders, muscular function, tuberculosis, and colorectal adenomas, or on maternal and perinatal conditions. New data on cancer outcomes were scarce. The compilation of results from 83 trials showed that vitamin D supplementation had no significant effect on biomarkers of systemic inflammation. The main new finding highlighted by this systematic review is that vitamin D supplementation might help to prevent common upper respiratory tract infections and asthma exacerbations. There remains little evidence to suggest that vitamin D supplementation has an effect on most conditions, including chronic inflammation, despite use of increased doses of vitamin D, strengthening the hypothesis that low vitamin D status is a consequence of ill health, rather than its cause. We further hypothesise that vitamin D supplementation could exert immunomodulatory effects that strengthen resistance to acute infections, which would reduce the risk of death in debilitated individuals. We identified many meta-analyses of suboptimal quality, which is of concern. Future systematic reviews on vitamin D should be based on data sharing so that data for participants with the same outcomes measured in the same way can be pooled to generate stronger evidence.

Vitamin D status and ill health: a systematic review.

Low serum concentrations of 25-hydroxyvitamin D (25[OH]D) have been associated with many non-skeletal disorders. However, whether low 25(OH)D is the cause or result of ill health is not known. We did a systematic search of prospective and intervention studies that assessed the effect of 25(OH)D concentrations on non-skeletal health outcomes in individuals aged 18 years or older. We identified 290 prospective cohort studies (279 on disease occurrence or mortality, and 11 on cancer characteristics or survival), and 172 randomised trials of major health outcomes and of physiological parameters related to disease risk or inflammatory status. Investigators of most prospective studies reported moderate to strong inverse associations between 25(OH)D concentrations and cardiovascular diseases, serum lipid concentrations, inflammation, glucose metabolism disorders, weight gain, infectious diseases, multiple sclerosis, mood disorders, declining cognitive function, impaired physical functioning, and all-cause mortality. High 25(OH)D concentrations were not associated with a lower risk of cancer, except colorectal cancer. Results from intervention studies did not show an effect of vitamin D supplementation on disease occurrence, including colorectal cancer. In 34 intervention studies including 2805 individuals with mean 25(OH)D concentration lower than 50 nmol/L at baseline supplementation with 50 µg per day or more did not show better results. Supplementation in elderly people (mainly women) with 20 µg vitamin D per day seemed to slightly reduce all-cause mortality. The discrepancy between observational and intervention studies suggests that low 25(OH)D is a marker of ill health. Inflammatory processes involved in disease occurrence and clinical course would reduce 25(OH)D, which would explain why low vitamin D status is reported in a wide range of disorders. In elderly people, restoration of vitamin D deficits due to ageing and lifestyle changes induced by ill health could explain why low-dose supplementation leads to slight gains in survival.

A systematic review: influence of vitamin D supplementation on serum 25-hydroxyvitamin D concentration.

CONTEXT: Few studies in subjects over 50 yr of age have evaluated the influence of variable doses of vitamin D supplementation on serum 25-hydroxyvitamin D levels. OBJECTIVE: We performed a meta-analysis of changes in circulating 25-hydroxyvitamin D level associated with vitamin D supplementation in Caucasian subjects over 50 yr old. DATA SOURCES: We conducted a systematic search in literature databases and in references of past reviews. STUDY SELECTION: Randomized placebo or open-label trials that evaluated the influence of vitamin D supplementation on clinical outcomes were included in the study. DATA EXTRACTION: We reviewed trial characteristics and serum 25-hydroxyvitamin D concentrations at baseline and during the trial. DATA SYNTHESIS: Seventy-six trials published from 1984 to March 2011 included 6207 subjects allocated to 101 intervention groups that tested supplement doses ranging from 5 to 250 µg/d (median, 20 µg/d). For similar doses, trials could obtain increases in 25-hydroxyvitamin D three to four times lower than other trials. A meta-regression showed that in the absence of concomitant use of calcium supplements, the average increase in serum 25-hydroxyvitamin D concentrations was 0.78 ng/ml (1.95 nmol/liter) per microgram of vitamin D3 supplement per day. Compared to the vitamin D3, the vitamin D2 was associated with significantly lower increases (P = 0.03). Concomitant use of calcium supplementation and high 25-hydroxyvitamin D concentration at baseline was nonsignificantly associated with lower increases in 25-hydroxyvitamin D concentrations. CONCLUSIONS: Dietary recommendations and randomized trials on vitamin D supplementation should evaluate whether increases in circulating 25-hydroxyvitamin D levels match expectations--for instance, the average increases obtained by trials on vitamin D3 without concomitant calcium supplements.

Socioeconomic, health, and dietary determinants of multivitamin supplements use in Belgium.

OBJECTIVE: This study aimed at investigating the use of multivitamin supplements in relationship to dietary pattern, socio-economic conditions and some health indicators. METHODS: A cross-sectional design was used. Mailed questionnaires were sent to 5,000 Belgian military men. Use of multivitamins, frequency and food consumption were recorded during the past year, together with health (BMI, smoking, physical activity) and socioeconomic indicators (education, income). Dietary patterns were determined using the Mediterranean Diet Score (MDS). RESULTS: Use of multivitamin supplements was associated with healthy lifestyle characteristics, such as a higher physical activity level and non smoking. Moreover, it was found that on average more participants with a Flemish cultural background (19.8%) used supplements compared with participants with a French cultural background (9.3%). The MDS was related to multivitamin supplement use, with 34.9% of users having the highest score range. The socioeconomic indicators 'education' and 'income' were not related to vitamin supplement use. CONCLUSION: A low BMI, healthy diet, regular physical activity, non-smoking status and cultural background were associated with a higher intake of multivitamin supplements.