The latest medical research on Nutrition

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Vitamin B-12 malabsorption and renal function are critical considerations in studies of folate and vitamin B-12 interactions in cognitive performance: NHANES 2011-2014.

J Clin Nutrition

Cognitive health is a public health concern among older adults. Dietary supplement (SUP) use is common and concerns have been raised about high folic acid intake among those with vitamin B-12 deficiency and exacerbation of poor cognitive performance (PCP).

We evaluated SUP use, usual folic acid intake, and blood folate and vitamin B-12 concentrations in relation to cognitive performance.

We used NHANES 2011-2014 data on adults aged ≥60 y (n = 2867) and estimated total usual folic acid intake from diet and supplements, vitamin B-12 intake from SUPs, blood folates, vitamin B-12 concentrations, vitamin B-12 insufficiency (≤258 pmol/L), high folate (serum folate ≥59 nmol/L or RBC folate ≥1609 nmol/L), and PCP (<34 on the Digit Symbol Substitution Test). We assessed folate distributions adjusted for multiple variables, including renal function.

Compared with persons without PCP, adults with PCP were less likely to use supplements containing folic acid (mean ± SEE: 34.4% ± 2.4%) or vitamin B-12 (mean ± SEE: 47.5% ± 1.6%). Among vitamin B-12-insufficient adults, 18.0% ± 1.6% (mean ± SEE) reported taking a vitamin B-12 supplement. Among participants with high folate and insufficient vitamin B-12 concentrations, 34.3% ± 11.5% (mean ± SEE) reported taking vitamin B-12-containing supplements. Persons with high folate and normal vitamin B-12 concentrations had lower odds of PCP [aOR (adjusted odds ratio): 0.61; 95% CI: 0.45, 0.83] than persons with normal folate and vitamin B-12. Persons with high folate and normal methylmalonic acid (MMA) had lower odds of PCP (OR: 0.56; 95% CI: 0.40, 0.78) than those with normal folate and MMA concentrations. After adjustment for renal function, elevated risk of PCP was attenuated among persons with high folate and MMA. Concurrent high folate and insufficient vitamin B-12 concentrations were not associated with PCP.

Differential associations between vitamin B-12 and MMA highlight the need to consider renal function in studies of high folate and low vitamin B-12 status. Consumption of vitamin B-12 supplements concurrent with low vitamin B-12 status may indicate vitamin B-12 malabsorption.

A Classification System for Defining and Estimating Dietary Intake of Live Microbes in US Adults and Children.

Journal of Nutrition

Consuming live microbes in foods may benefit human health. Live microbe estimates have not previously been associated with individual foods in dietary databases.

We aimed to estimate intake of live microbes in US children (aged 2-18 y) and adults (≥19 y) (n = 74,466; 51.2% female).

Using cross-sectional data from the NHANES (2001-2018), experts assigned foods an estimated level of live microbes per gram [low (Lo), <104 CFU/g; medium (Med), 104-107 CFU/g; or high (Hi), >107 CFU/g]. Probiotic dietary supplements were also assessed. The mean intake of each live microbe category and the percentages of subjects who ate from each live microbe category were determined. Nutrients from foods with live microbes were also determined using the population ratio method. Because the Hi category comprised primarily fermented dairy foods, we also looked at aggregated data for Med or Hi (MedHi), which included an expanded range of live microbe-containing foods, including fruits and vegetables.

Our analysis showed that 52%, 20%, and 59% of children/adolescents, and 61%, 26%, and 67% of adults, consumed Med, Hi, or MedHi foods, respectively. Per capita intake of Med, Hi, and MedHi foods was 69, 16, and 85 g/d for children/adolescents, and 106, 21, and 127 g/d for adults, respectively. The proportion of subjects who consumed live microbes and overall per capita intake increased significantly over the 9 cycles/18-y study period (0.9-3.1 g/d per cycle in children across categories and 1.4 g/d per cycle in adults for the Med category).

This study indicated that children, adolescents, and adults in the United States steadily increased their consumption of foods with live microbes between the earliest (2001-2002) and latest (2017-2018) survey cycles. Additional research is needed to determine the relations between exposure to live microbes in foods and specific health outcomes or biomarkers.

Factors that Moderate the Effect of Nitrate Ingestion On Exercise Performance in Adults: A Systematic Review With Meta-Analyses and Meta-Regressions.

Advances in Nutrition

To identify how variables such as exercise condition, supplementation strategy, participant characteristics and demographics, and practices that co...

Infant and child formula shortages: now is the time to prevent recurrences.

J Clin Nutrition

An acute shortage of infant formulas in the United States occurred in early 2022, exacerbating a longer-standing less severe shortage over the last...

Urinary Potassium Excretion and Mortality Risk in Community-Dwelling Individuals with and without obesity.

J Clin Nutrition

Potassium intake has been shown to be inversely associated with blood pressure and premature mortality. Previous studies suggested that the association between potassium intake and blood pressure is modified by obesity, but whether obesity similarly influences the association between potassium intake and mortality is unclear.

To investigate whether potassium intake, reflected by 24-hour urinary excretion, is associated with all-cause mortality, and to explore potential effect modification by obesity.

We performed a prospective cohort study in community-dwelling individuals. The association between urinary potassium excretion and all-cause mortality was investigated by multivariable Cox regression. We performed multiplicative interaction analysis and subgroup analyses according to BMI and waist circumference.

In 8,533 individuals (50% male) mean age was 50 ± 13 years, mean urinary potassium excretion was 71±21 mmol/24 hrs, median BMI was 25.6 (IQR 23.1-28.4) kg/m2 and mean waist circumference was 89±13 cm. During follow-up of 18.4 [IQR 13.5-18.8] years, 1,663 participants died. Low urinary potassium excretion (1st vs. 3rd sex-specific quintile) was associated with an increased mortality risk (fully adjusted HR 1.38 [95% CI 1.18, 1.61], P < 0.001, irrespective of body dimensions (Range of HR for all body dimensions 1.36 to 1.70, all P < 0.05). High urinary potassium excretion (5th vs. 3rd quintile) was associated with increased mortality risk in participants with obesity (BMI ≥30 kg/m2; HR 1.52 [1.00, 2.30]), but not in participants without obesity (BMI <25 kg/m2; HR 0.89 [0.62, 1.26]) (P-interaction = 0.001).

Low potassium intake was associated with increased mortality risk in community-dwelling individuals. In individuals with obesity, high potassium intake was also associated with increased mortality risk.

Arginine catabolism metabolites and atrial fibrillation or heart failure risk: two case-control studies within the PREDIMED trial.

J Clin Nutrition

Arginine-derived metabolites are involved in oxidative and inflammatory processes related with endothelial function and cardiovascular risk.

To prospectively examine the associations of arginine catabolism metabolites with the risk of atrial fibrillation (AF) or heart failure (HF), and to evaluate the potential modification of these associations through Mediterranean diet (MedDiet) interventions in a large primary prevention trial.

Two nested matched case-control studies were designed within the PREDIMED trial. Five hundred and nine incident cases and 547 matched controls for the AF case-control study, and 326 cases and 402 matched controls for the HF case-control study participants were selected using incidence density sampling. Fasting blood samples were collected at baseline and arginine catabolism metabolites were measured using liquid chromatography tandem mass spectrometry. Multivariable conditional logistic regression models were applied to test the associations between the metabolites and incident AF or HF. Interactions between metabolites and intervention groups (MedDiet groups vs control group) were analyzed with the likelihood ratio test.

Inverse associations with incident AF were observed for arginine [OR per 1 SD (95% CI): 0.83 (0.73, 0.94)]) and homoarginine [0.87 (0.76, 0.98)], whereas positive associations were found for the asymmetric dimethylarginine/symmetric dimethylarginine ratio (ADMA/SDMA) [1.15 (1.01, 1.31)] and citrulline [1.19 (1.01, 1.39)]. For HF, inverse associations were found for arginine [0.82 (0.69, 0.97)] and homoarginine [0.81 (0.68, 0.96)], and positive associations for the ADMA/SDMA ratio [1.19 (1.02, 1.41)], N1-acetylspermidine [1.34 (1.12, 1.60)], and diacetylspermine [1.20 (1.02, 1.41)]. In the stratified analysis according to the dietary intervention, the lower HF risk associated with arginine was restricted to participants in the MedDiet groups (p for interaction 0.044).

Our results suggest that arginine catabolism metabolites could be involved in AF and HF. Interventions with the MedDiet may contribute to strengthen the inverse association between arginine and the risk of HF.This trial was registered at as ISRCTN35739639.

Effects of vitamin C supplementation on gout risk: results from the physicians' health study II trial.

J Clin Nutrition

Short-term randomized trials suggest that a 500 mg/day vitamin C supplement reduces serum urate, while observational studies show vitamin E is inversely associated with gout risk.

We evaluated the effect of supplemental vitamin C (pre-specified primary exposure) and vitamin E (pre-specified secondary exposure) on new diagnoses of gout.

We performed a post-hoc analysis of data from the Physicians' Health Study II (PHS II), a randomized, double-blind, placebo-controlled factorial trial of randomized vitamin C (500 mg/day) and vitamin E (400 IU every other day). The primary outcome was new gout diagnoses, self-reported at baseline and throughout the follow-up period of up to 10 years.

Among 14,641 randomized male physicians in our analysis, the mean age was 64 (SD, 9) years; 1% were Black and 6.5% had gout prior to randomization. The incidence rate of new gout diagnoses during follow-up was 8.0 per 1,000 person-years among those assigned vitamin C versus 9.1 per 1,000 person-years among those assigned placebo. The vitamin C assignment reduced new gout diagnoses by 12% (HR 0.88; 95% CI: 0.77, 0.99; P = 0.04). These effects were greatest among those with a BMI <25 kg/m2 (P-interaction = 0.01). Vitamin E was not associated with new gout diagnoses (HR: 1.05; 95% CI: 0.92, 1.19; P = 0.48).

Vitamin C modestly reduced the risk of new gout diagnoses among middle-aged male physicians. Additional research is needed to determine the effects of higher doses of vitamin C supplementation on serum urate and gout flares among adults with established gout. Identifier: NCT00270647.

Pre-pregnancy fat intake in relation to hypertensive disorders of pregnancy.

J Clin Nutrition

Many studies have linked intakes of fat and of specific fatty acids during pregnancy and preeclampsia, however the relation of intake before pregnancy with hypertensive disorders of pregnancy (HDP) is scant.

Evaluate intakes of major and specific types of fat before pregnancy with the risk of HDP: preeclampsia and gestational hypertension (GHTN).

We followed 11,535 women without chronic disease participating in the Nurses' Health Study-II from 1991 and 2009. Pre-pregnancy dietary fat was assessed by a food frequency questionnaire. Intakes of total, saturated, trans fatty acid (TFA), monounsaturated (MUFA), polyunsaturated (PUFA), and its subtypes (omega-3 and omega-6) were categorized into quintiles of intake. HDP were self-reported. The RR (95%CI) of HDP were estimated by log-binomial generalized estimating equation regression models with exchangeable correlation matrix to account for repeated pregnancies while adjusting for potential confounders.

During 19 years of follow-up, there were 495 cases of preeclampsia (2.9%) and 561 (3.3%) cases of GHTN in 16,892 singleton pregnancies. Mean (SD) age at pregnancy was 34.6 (3.9) years. Among major fat types, only pre-pregnancy TFA was related to higher risk of HDP (RR 1.32 [95%CI:1.05,1.66]), only for preeclampsia (RR 1.50, 95%CI:1.07,2.10) but not for GHTN (RR 1.21, 95%CI:0.87,1.70). Among specific types of PUFAs, intake of arachidonic acid was positively related with GHTN (RR 1.43 [95%CI:1.00,2.04]) but not preeclampsia (RR 1.08 [95%CI:0.75,1.57]). In analyses restricted to pregnancies one year after diet assessment, women in the highest intake of long-chain omega-3 fatty acids had 31% lower risk of HDP (95%CI: 3%,51%), which was driven by preeclampsia (RR 0.55 [95%CI:0.33,0.92]).

Pre-pregnancy intakes of total fat, saturated fat, and MUFA were unrelated to HDP, whereas TFA was positively related to HDP. These findings highlight the importance of ongoing efforts to eliminate TFA from the global food supply.

The accuracy of methods for determining the internal length of a nasogastric tube in adult patients: A systematic review.

J Clin Nutrition

Blind insertion of nasogastric tubes is performed for several reasons: Nutrition and medication administration, gastric aspiration/decompression, and other, diagnostic reasons. Accidental intraesophageal and intestinal placement is common, and increases the risk of serious complications. Therefore, accurate determination of the internal length of the nasogastric tube prior to placement is considered a prerequisite for achieving correct gastric positioning.

To identify, assess and summarize the evidence on the accuracy of methods for determining the internal length of a nasogastric tube in adults.

Cochrane Library, EMBASE, PubMed, CINAHL, and Web of Science were searched up to January 31, 2022. Studies were eligible when reporting data on the accuracy of methods for determining internal nasogastric tube length in adults. Study selection, risk-of-bias assessment, and data extraction were performed independently by two investigators. Risk-of-bias was assessed using the Cochrane Risk-of-Bias Tool and the JBI Critical Appraisal Checklist for Cross Sectional Studies. A narrative synthesis of the results was then conducted.

Twelve papers were included in this review. All studies were observational, cross-sectional in nature, except for one RCT. Ten methods for determining the internal length of a nasogastric tube were described. Correctly positioned NG tubes ranged from 13% to 99%. Results showed that the nose-earlobe-xiphoid (NEX) distance + 10 cm (M = 59.9 - 60.7 cm) and (NEX x 0.38696) + 30.37 + 6 cm (M = 56.6 - 56.7 cm) could potentially result in accuracy as high as 97.4 and 99.0%, respectively.

Current data do not provide conclusive evidence of 100% accuracy in finding a correctly placed nasogastric tube when using a method for determining the internal length. Blind placement, using any of the documented methods, cannot be considered safe without additional verification of tube tip positioning. Furthermore, using any of these ten methods does not reduce the risk of pulmonary intubation. Systematic review registration: PROSPERO CRD42021243180.

Prenatal choline supplementation improves biomarkers of maternal docosahexaenoic acid status among pregnant participants consuming supplemental DHA: a randomized controlled trial.

J Clin Nutrition

Dietary methyl donors (e.g., choline) support the activity of the phosphatidylethanolamine N-methyltransferase (PEMT) pathway, which generates phosphatidylcholine (PC) molecules enriched in docosahexaenoic acid (DHA) that are exported from the liver and made available to extrahepatic tissues.

This study investigated the effect of prenatal choline supplementation on biomarkers of DHA status among pregnant participants consuming supplemental DHA.

Pregnant participants (N=30) were randomized to supplemental choline intakes of 550 mg/d (500 mg/d d0-choline + 50 mg/d deuterium labeled-choline [d9-choline]; intervention) or 25 mg/d (25 mg/d d9-choline; control) from gestational week (GW) 12-16 until delivery. All participants received a daily 200-mg DHA supplement and consumed self-selected diets. Fasting blood samples were obtained at baseline, GW 20-24, and GW 28-32; maternal/cord blood was obtained at Delivery. Mixed effects linear models were used to assess the impact of prenatal choline supplementation on maternal and newborn DHA status.

Choline supplementation (550 vs 25 mg/d) did not achieve a statistically significant intervention-x-time interaction for RBC PC-DHA (P=0.11); a significant interaction was observed for plasma PC-DHA and RBC total DHA, with choline supplementation yielding higher levels (+32-38% and +8-11%, respectively) at GW28-32 (P<0.05) and Delivery (P<0.005). A main effect of choline supplementation on plasma total DHA was also observed (P=0.018); its interaction with time was not significant (P=0.068). Compared with controls, the intervention group exhibited higher (P=0.007); main effect) plasma enrichment of d3-PC (d3-PC/total PC). Moreover, the ratio of d3-PC:d9-PC was higher (+50-67%, P<0.001) in the choline intervention arm (vs control) at GW 20-24, GW 28-32 and Delivery.

Prenatal choline supplementation improves hepatic DHA export and biomarkers of DHA status by bolstering methyl group supply for PEMT activity among pregnant participants consuming supplemental DHA Clinical Trial Registry: Synergy BetweenCholine and DHA; NCT03194659 (

Accelerometer-measured physical activity and sedentary time among children and their parents in the UK before and after COVID-19 lockdowns: a natural experiment.

International Journal of Epidemiology

Restrictions due to the coronavirus disease 2019 (COVID-19) pandemic reduced physical activity provision for both children and their parents. Recent studies have reported decreases in physical activity levels during lockdown restrictions, but these were largely reliant on self-report methods, with data collected via unrepresentative self-report surveys. The post-pandemic impacts on children's activity levels remain unknown. A key question is how active children become once lockdown restrictions are lifted.

Active-6 is a repeated cross-sectional natural experiment. Accelerometer data from 1296 children aged 10-11 and their parents were collected in 50 schools in the Greater Bristol area, UK in March 2017-May 2018 (pre-COVID-19 comparator group), and compared to 393 children aged 10-11 and parents in 23 of the same schools, collected in May-December 2021. Mean minutes of accelerometer-measured moderate-to-vigorous physical activity (MVPA) were derived for weekdays and weekend and compared pre- and post-lockdown via linear multilevel models.

After adjusting for seasonality, accelerometer wear time and child/parent demographics, children's mean weekday and weekend MVPA were 7.7 min (95% CI: 3.5 to 11.9) and 6.9 min (95% CI: 0.9 to 12.9) lower in 2021 than in 2018, respectively, while sedentary time was higher by 25.4 min (95% CI: 15.8 to 35.0) and 14.0 min (95% CI: 1.5 to 26.5). There was no evidence that differences varied by child gender or household education. There was no significant difference in parents' MVPA or sedentary time, either on weekdays or weekends.

Children's MVPA was lower by 7-8 min/day in 2021 once restrictions were lifted than before the pandemic for all groups, on both weekdays and weekends. Previous research has shown that there is an undesirable age-related decline in children's physical activity. The 8-min difference reported here would be broadly comparable to the decline that would have previously been expected to occur over a three-year period. Parents' physical activity was similar to pre-pandemic levels. Our results suggest that despite easing of restrictions, children's activity levels have not returned to pre-pandemic levels. There is an urgent need to understand why these changes have occurred and how long they are maintained.

Serum Omega-3 Fatty Acids and Cognitive Domains in Community-Dwelling Older Adults From the Nuage Study: Exploring the Associations with Other Fatty Acids and Sex.

Journal of Nutrition

Omega-3 (n-3) polyunsaturated fatty acids (PUFAs) are suggested to play a role in the prevention of cognitive decline. The evidence may be inconsistent due to methodological issues including interrelations with other long-chain (14 or more carbons) fatty acids (LCFAs) and use of sex as a confounding factor rather than an effect modifier.

This study evaluated the association between serum n-3 PUFAs and performance across four cognitive domains, overall and by sex, while controlling for other LCFAs.

386 healthy older adults (77.4 ± 3.8 years; 53% females) from the Québec Longitudinal Study on Nutrition and Successful Aging underwent a cognitive evaluation and blood sampling. Verbal and non-verbal episodic memory, executive functioning, and processing speed were evaluated. Serum LCFA concentrations were measured by gas chromatography. LCFAs were grouped according to standard fatty acid classes and according to a factor analysis using principal component analysis (FA-PCA). Multivariate linear regression models were performed, including unadjusted and adjusted models for other LCFAs.

Higher n-3 PUFA concentrations were associated with better non-verbal memory and processing speed in fully adjusted models not including other LCFAs (betas of 0.21 and 0.19, respectively). The magnitude of these associations varied when other LCFAs were entered in the model (betas of 0.27 and 0.32, respectively) or when FA-PCA factors were considered (betas of 0.27 and 0.21, respectively). Associations with verbal episodic memory were limited to higher concentrations of eicosapentaenoic acid whereas there was no association between n-3 PUFAs and executive functioning. Higher n-3 PUFAs were associated with better verbal and non-verbal episodic memory in females, and with better executive functioning and processing speed in males.

These results suggest that other LCFAs should be considered when evaluating the association between n-3 PUFAs and cognitive performance in healthy older adults. Sex differences across cognitive domains warrant further investigation.