Serum 25(OH)D and Cognition: A Narrative Review of Current Evidence.

The effect of low serum 25(OH)D on cognitive function is difficult to determine owing to the many factors that can influence these relationships (e.g., measurements, study design, and obesity). The primary purpose of this review was to synthesize the current evidence on the association between serum 25(OH)D and cognition giving special consideration to specific influential factors. A search was conducted in PubMed for studies published between 2010 and 2018 using terms related to serum 25(OH)D and cognition. Only studies that used liquid chromatography tandem-mass spectrometry (LC-MS) were included, since this is considered the 'gold standard method', to measure serum 25(OH)D. Of the 70 articles evaluated, 13 met all inclusion criteria for this review. The majority of the observational and longitudinal studies demonstrate a significant association between low serum 25(OH)D and compromised cognition. However, two randomized controlled trials showed inconsistent results on the impact of vitamin D supplementation on cognitive function. The varied methodologies for ascertaining cognition and the inclusion or exclusion of confounding variables (e.g., obesity, sunlight exposure) in the statistical analyses make drawing conclusions on the association between serum 25(OH)D and cognitive functioning inherently difficult. Despite the known higher occurrence of serum 25(OH) deficiency among minority populations, the majority of studies were conducted in with White participants. In order to more clearly discern the relationship between serum 25(OH)D and cognitive functioning, future studies should target more diverse study populations and utilize comprehensive measures to reliably capture cognition, as well as important known determinants of serum 25(OH)D.

Intensive medical nutrition therapy: methods to improve nutrition provision in the critical care setting.

Patients requiring mechanical ventilation in an intensive care unit commonly fail to attain enteral nutrition (EN) infusion goals. We conducted a cohort study to quantify and compare the percentage of energy and protein received between standard care (n=24) and intensive medical nutrition therapy (MNT) (n=25) participants; to assess the percentage of energy and protein received varied by nutritional status, and to identify barriers to EN provision. Intensive MNT entailed providing energy at 150% of estimated needs, using only 2.0 kcal/cc enteral formula and 24-hour infusions. Estimated energy and protein needs were calculated using 30 kcal/kg and 1.2 g protein/kg actual or obesity-adjusted admission body weight. Subjective global assessment was completed to ascertain admission intensive care unit nutritional status. Descriptive statistics and survival analyses were conducted to examine time until attaining 100% of feeding targets. Patients had similar estimated energy and protein needs, and 51% were admitted with both respiratory failure and classified as normally nourished (n=25/49). Intensive MNT recipients achieved a greater percentage of daily estimated energy and protein needs than standard care recipients (1,198±493 vs 475±480 kcal, respectively, P<0.0001; and 53±25 vs 29±32 g, respectively, P=0.007) despite longer intensive care unit stays. Cox proportional hazards models showed that intensive MNT patients were 6.5 (95% confidence interval 2.1 to 29.0) and 3.6 (95% confidence interval 1.2 to 15.9) times more likely to achieve 100% of estimated energy and protein needs, respectively, controlling for confounders. Malnourished patients (n=13) received significantly less energy (P=0.003) and protein (P=0.004) compared with normally nourished (n=11) patients receiving standard care. Nutritional status did not affect feeding intakes in the intensive MNT group. Clinical management, lack of physician orders, and gastrointestinal issues involving ileus, gastrointestinal hemorrhage, and EN delivery were the most frequent clinical impediments to EN provision. It was concluded that intensive MNT could achieve higher volumes of EN infusion, regardless of nutritional status. Future studies are needed to advance this methodology and to assess its influence on outcomes.

Adequacy of oral intake in critically ill patients 1 week after extubation.

Hospital malnutrition is associated with increased morbidity and mortality, particularly among patients admitted to intensive care units (ICUs). The purpose of this observational study (August to November 2007) was to examine the adequacy of oral intake and to identify predictors of oral intake after ICU patients were removed from invasive mechanical ventilation. Patients aged > or = 18 years who required mechanical ventilation for at least 24 hours, advanced to an oral diet postextubation, and did not require supplemental enteral or parenteral nutrition were included. The first 7 days of oral intake after extubation were assessed via modified multiple-pass 24-hour recall and the numbers of days on therapeutic diets and reasons for decreased intake were collected. Oral intake <75% of daily requirements was considered inadequate. Descriptive statistics, chi2, Student t tests, and logistic regression analyses were conducted. Of the 64 patients who met eligibility criteria, 50 were included. Of these 50 patients, 54% were women and intubated for 5.2 days, with a mean age of 59.1 years, body mass index of 28.7, and Acute Physiology and Chronic Health Evaluation II score of 21.9. Subjective Global Assessment determined 44% were malnourished upon admission to the ICU. The average daily energy and protein intake failed to exceed 50% of daily requirements on all 7 days for the entire population. The majority of patients who consumed <75% of daily requirements were prescribed a therapeutic diet and/or identified "no appetite" and nausea/vomiting as the barriers to eating. Although more research is needed, these data call into question the use of restrictive oral diets and suggest that alternative medical nutrition therapies are needed to optimize nutrient intake in this unique patient population.