Evaluation of an 8-Week Vegan Diet on Plasma Trimethylamine-N-Oxide and Postchallenge Glucose in Adults with Dysglycemia or Obesity

ABSTRACT Background Trimethylamine N-oxide (TMAO), a metabolite generated by the gut in response (in part) to meat consumption, is linked to poor cardiometabolic health. Objectives We investigate the effect of an 8-week vegan diet, followed by a 4-week period of unrestricted diet, on glucose tolerance and plasma TMAO in human omnivores with obesity or dysglycemia. Methods This interventional single-group prospective trial involved 23 regular meat eaters with dysglycemia [glycated hemoglobin ≥ 5.7% and ≤8% (39–64 mmol/mol)], or obesity (ΒΜΙ ≥ 30 kg/m2) aged 57.8 ± 10.0 years. Participants [14 men (60.9%) and 9 women (39.1%)] were supported in following a vegan diet for 8 weeks, followed by 4 weeks of unrestricted diet. The primary outcomes (plasma TMAO and glucose) were assessed at baseline, during the vegan diet (weeks 1 and 8), and after the unrestricted diet period (week 12). TMAO was assessed after fasting and glucose was measured as a time-averaged total AUC using a 180-minute oral-glucose-tolerance test. Generalized estimating equation models with an exchangeable correlation structure were used to assess changes from baseline, adjusting for age, sex, ethnicity, and weight. Results TMAO levels (marginal mean) were reduced after weeks 1 and 8 of a vegan diet compared to baseline, from 10.7 (97.5% CI, 6.61–17.3) μmol/L to 5.66 (97.5% CI, 4.56–7.02) μmol/L and 6.38 (97.5% CI, 5.25–7.74) μmol/L, respectively; however, levels rebounded at week 12 after resumption of an unrestricted diet (17.5 μmol/L; 97.5% CI, 7.98–38.4). Postprandial glucose levels (marginal means) were reduced after weeks 1 and 8 compared to baseline, from 8.07 (97.5% CI, 7.24–8.90) mmol/L to 7.14 (97.5% CI, 6.30–7.98) mmol/L and 7.34 (97.5% CI, 6.63–8.04) mmol/L, respectively. Results for glucose and TMAO were independent of weight loss. Improvements in the lipid profile and markers of renal function were observed at week 8. Conclusions These findings suggest that a vegan diet is an effective strategy for improving glucose tolerance and reducing plasma TMAO in individuals with dysglycemia or obesity. This study was registered at clinicaltrials.gov as NCT03315988.

Cow's milk exclusion in young children: Parents motives, sources of information and perception of their child's eating behaviours

Research has assessed the diets of young children that follow a diet that excludes cow's milk. However, there is insufficient information about why parents decide to exclude cow's milk, where they obtain nutritional information, and their child's eating behaviours. This is important as the prevalence of cow's milk allergy is increasingly common in children, alongside a growing preference for plant-based diets. The purpose of this research was firstly to explore why parents exclude cow's milk from their child's diets and if this is due to recommendations from a health care professional. Secondly, to understand where parents source information to enable them to provide a healthy diet for their child. Finally, to explore parent's opinions of their child's eating behaviours.Thirty parents of children aged 1–3 years who exclude cow's milk and 20 parents of children who did not follow a restricted diet completed an online questionnaire. The questionnaire comprised of three blocks of questions. The first asked about the parents, the second pertained to the child. If they excluded cow's milk they were asked why they made this decision and who advised them. Parents were also asked where they source nutrition information for their child. The final block of questions consisted of the Child Eating Behaviour Questionnaire.Parents reported excluding cow's milk due to cow's milk allergy (60%), lactose or milk intolerance (10%), suspected allergy or intolerance (27%) or personal choice (3%). When asked “Who advised you to remove cow's milk from your child's diet?” the majority responded that it was their own decision (35%), followed by GP advice (24%). The most common sources of nutrition information for parents of children that exclude cow's milk came from parenting webpages (21%), and social media (19%), whilst those on an unrestricted diet obtained information from health visitors (24%) and parenting webpages (19%). There were no differences in eating behaviours between children that excluded cow's milk and children that did not except for satiety responsiveness (p = 0.014), which was greater in the cow's milk exclusion group.This preliminary data indicates that many parents exclude cow's milk from their child's diets based on their own advice. Where parents of children on an unrestricted diet sourced nutrition information from their health visitor, few parents of children who exclude cow's milk used this source of support (7%).

The Benefit of Large Neutral Amino Acid Supplementation to a Liberalized Phenylalanine-Restricted Diet in Adult Phenylketonuria Patients: Evidence from Adult Pah-Enu2 Mice

Many phenylketonuria (PKU) patients cannot adhere to the severe dietary restrictions as advised by the European PKU guidelines, which can be accompanied by aggravated neuropsychological impairments that, at least in part, have been attributed to brain monoaminergic neurotransmitter deficiencies. Supplementation of large neutral amino acids (LNAA) to an unrestricted diet has previously been shown to effectively improve brain monoamines in PKU mice of various ages. To determine the additive value of LNAA supplementation to a liberalized phenylalanine-restricted diet, brain and plasma monoamine and amino acid concentrations in 10 to 16-month-old adult C57Bl/6 PKU mice on a less severe phenylalanine-restricted diet with LNAA supplementation were compared to those on a non-supplemented severe or less severe phenylalanine-restricted diet. LNAA supplementation to a less severe phenylalanine-restricted diet was found to improve both brain monoamine and phenylalanine concentrations. Compared to a severe phenylalanine-restricted diet, it was equally effective to restore brain norepinephrine and serotonin even though being less effective to reduce brain phenylalanine concentrations. These results in adult PKU mice support the idea that LNAA supplementation may enhance the effect of a less severe phenylalanine-restricted diet and suggest that cerebral outcome of PKU patients treated with a less severe phenylalanine-restricted diet may be helped by additional LNAA treatment.

Effect of Consumption of Cocoa-Derived Products on Uric Acid Crystallization in Urine of Healthy Volunteers

The purpose of this study was to determine the effects of consumption of different cocoa-derived products on uric acid crystallization in urine of 20 healthy volunteers. Participants were requested to select the specific diet that they wished to follow during the 12 h prior to collection of urine. The only restriction was that the diet could not include any product with cocoa, coffee, or caffeine. On the first day, each volunteer followed their selected diet, and an overnight 12 h urine sample was collected as the baseline urine. After seven days on an unrestricted diet, each volunteer repeated the same diet with 20 g of milk chocolate, chocolate powder, or dark chocolate during breakfast and another 20 g during dinner. Overnight 12 h urine samples were then collected. Urine volume, pH, oxalate, creatinine, uric acid, theobromine, and a uric acid crystallization test were determined for each sample. The results for all 20 patients show that uric acid crystallization was significantly lower following the consumption of chocolate powder or dark chocolate relative to baseline or following the consumption of milk chocolate. The results indicated that increased concentrations of urinary theobromine reduced the risk of uric acid crystallization.