Category Archives: Nutrition

Comparing Gastric Bypass Outcomes in Adolescents and Adults

Posted on by

Studies have shown that adults with obesity who were obese as adolescents have worse medical outcomes than persons who became obese in adulthood (Nat Rev Endocrinol 2018; 14: 183-8; NEJM 2011; 365; 1876-85). Thus, the question is whether earlier intervention would improve outcomes.

A recent study (TH Inge et al. NEJM 2019; 380: 2136-45, editorial TD Adams, pgs 2175-7) compares the 5-year outcomes of adolescents (n=161) and adults (n=396) who underwent Roux-en-Y gastric bypass (RYGB). The two prospectively enrolled cohorts were participants in two related but independent studies.

Key findings:

  • There was similar weight loss in both groups at the 5-year mark: -26% in adolescents and -29% in adults
  • Adolescents had greater remission in both type 2 diabetes (86% vs 53%) and in hypertension (68% and 41%).
  • Three adolescents (1.9%) and seven adults (1.8%) died in the 5-years after surgery.  Two of the adolescents deaths were consistent with overdose.
  • Reoperations were significantly higher in adolescents than adults (19 vs 10 reoperations per 500 person years). The authors comment that the reason for this finding is unclear, possibly related to recall bias or closer monitoring of the adolescents.
  • Nutrient deficiencies were common in adolescents at followup. After 2 years, 48% of adolescents had low ferritin compared with 29% of adults (98% of participants had normal ferritin prior to RYGB. The authors note that  this is likely related to adherence to vitamin/mineral supplementation (which is needed lifelong).

Limitations: observational study design

The associated commentary::

  • “Almost 6% of adolescents in the U.S. are severely obese and  bariatric surgery is now the only successful long-term management…Negative health outcomes of bariatric surgery reported in adolescents mirror those reported in adults — including, for example, potential for self-harm (including suicide) and increased risk of alcohol or drug abuse.”
  • “Adolescent patients may not have fully developed the capacity for decision making, especially about a procedure that will have lifetime consequences.”

My take: This study and commentary point out some clear health benefits for adolescents who undergo RYGB. Given the lifelong need for monitoring and adherence with medical treatment as well as some of the negative health outcomes, it is also clear how challenging it is to proceed with RYGB in teenage years.

Related blog posts:

Square in Toledo, Spain

 

NAFLD Outcomes After Bariatric Surgery

Posted on by

A recent systematic review and meta-analysis (Y Lee, et al. Clin Gastroenterol Hepatol 2019; 17: 1040-60) included 32 cohort studies with 3093 liver biopsy specimens from patients with nonalcoholic fatty liver disease (NAFLD).

Key findings:

  • Bariatric surgery resulted in a biopsy-confirmed resolution of steatosis in 66%, inflammation in 50%, ballooning degeneration in 76%, and fibrosis in 40%.
  • Bariatric surgery resulted in worsening features of NAFLD in 12%.
  • The authors note that Roux-en-Y Gastric Bypass (RYGB) “showed greater reduction of liver side effects and higher: resolution of NAFLD.”
  • Jejejnoileal bypass (JIB) and biliopancreatic diversion (BPD) “both have been associated with higher liver function morbidity.”
  • The overall GRADE quality of evidence was considered very low.

My take: Though better studies are needed, the majority of patients’ livers appear to benefit from bariatric surgery.

Related blog posts:

Rural Areas Main Driver for Increasing Obesity

Posted on by

Nature  569, 260–264 (2019) : Full Text: Rising rural body-mass index is the main driver of the global obesity epidemic in adults

From Abstract:

  • Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017.
  • We show that, contrary to the dominant paradigm, more than 55% of the global rise in mean BMI from 1985 to 2017—and more than 80% in some low- and middle-income regions—was due to increases in BMI in rural areas.
  •  In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women.

How Often Do Children with Obesity Have a Fatty Liver?

Posted on by

According to a recent study (EL Yu et al. J Pediatr 2019; 207: 64-70), about one-third of boys and one-fourth of girls with obesity have nonalcoholic fatty liver disease (NAFLD).

This study from San Diego with 408 children aged 9-17 years (mean 13.2 years) with obesity evaluated for NAFLD with laboratories (to exclude other etiologies) and with liver MRI proton density fat fraction (PDFF), with ≥5% considered the threshold for NAFLD.

Key findings:

  • Prevalence of NAFLD was 26% in this population, with 29.4% in males and 22.6% in females
  • The optimal cut offs of ALT for detecting NAFLD in this study were ≥30 U/L for females and ≥42 U/L for males. These are much lower than NASPGHAN guidelines which proposed ≥80 U/L or twice the ULN as thresholds for further investigation.  (The NASPGHAN recommendations are likely to have higher specificity in identifying children at greater risk for nonalcoholic steatohepatitis (NASH).)

Limitations:

  • 77% of this cohort were hispanic, thus prevalence may vary significantly in other populations.
  • MRI-PDFF -the exact cut off is unclear.  The authors note that if 3.5% were chosen, the NAFLD prevalence jumped to 49.3% (according to Table II –though the discussion stated 53.2%)

My take: Understanding the likelihood of NAFLD in children at risk is a helpful first step.  This study points to the growing use of non-invasive diagnosis with MRI.

On a related topic, briefly noted: “Obesity in Adolescents and Youth: The Case for and against Bariatric Surgery” (A Khattab, MA Sperling. J Pediatr 2019; 207: 18-22). In this review, the authors refer frequently to endocrine society guidelines (J Clin Endocrinol Metab 2017; 102: 709-57).    These guidelines generally recommend bariatric surgery only under specific conditions (eg. completion of Tanner 4 or 5 along with a BMI of 40 kg/m-squared or BMI of 35 with significant extreme comorbidities after failure of lifestyle modifications & without untreated psychiatric illness).  This review predicts increasing use of bariatric surgery in adolescents “as more data on long-term outcomes in larger cohorts become known.”

Related blog posts on fatty liver disease:

Related blog posts on bariatric surgery:

 

Time to Revise ImproveCareNow Micronutrient Recommendations

Posted on by

With ImproveCareNow, there have been efforts to minimize variation in care.  As such, there have been suggestions to monitor labs like vitamin D, vitamin B12, and folate routinely. I have voiced concern that some of this testing is unnecessary.  For vitamin B12, deficiency in pediatrics is rare; at risk populations include those with extensive small bowel resections, gastric resections or strict vegan diet.

A recent article (J Fritz et al. Inflamm Bowel Dis 2019; 25: 445-59) which is a systematic review of micronutrients in pediatric inflammatory bowel disease provides further support for the approach of less testing.

Key points:

  • A total of 39 studies were included in the final review (2903 subjects, 1115 controls)
  • Iron deficiency and vitamin D deficiency are common in pediatric patients with IBD
  • Vitamin B12 and folate deficiency are rare
  • Zinc deficiency is uncommon but increased in patients with Crohn’s disease compared to healthy controls.
  • The authors recommend routine (at least yearly) testing for iron, vitamin D and zinc and that there is “insufficient evidence to support routine screening for other micronutrient deficiencies.”

My take: Except in patients with surgical resections and in those with unusual diets (eg. vegan), routinely checking vitamin B12, folate and most other micronutrients is unnecessary & low value care.

Related blog posts:

Vitamin B12:

Vitamin D:

Iron:

Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications/diets (along with potential adverse effects) should be confirmed by prescribing physician/nutritionist.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

Big Data for Personalized Diets

Posted on by

A recent commentary in the NY Times discusses the future of personalized diets.  Along the way, the commentary notes how little we know about the best diet and how difficult nutrition research is to complete.

The A.I. Diet by Eric Topol who is the author of the forthcoming “Deep Medicine,” from which this essay is adapted

An excerpt:

It turns out, despite decades of diet fads and government-issued food pyramids, we know surprisingly little about the science of nutrition. It is very hard to do high-quality randomized trials: They require people to adhere to a diet for years before there can be any assessment of significant health outcomes…

Meanwhile, the field has been undermined by the food industry, which tries to exert influence over the research it funds.

Now the central flaw in the whole premise is becoming clear: the idea that there is one optimal diet for all people…

Only recently, with the ability to analyze large data sets using artificial intelligence, have we learned how simplistic and naïve the assumption of a universal diet is. It is both biologically and physiologically implausible: It contradicts the remarkable heterogeneity of human metabolism, microbiome and environment, to name just a few of the dimensions that make each of us unique. A good diet, it turns out, has to be individualized.

My take: Dr. Topol makes some important observations and he is right that there is not a simple diet solution for everyone.  Nevertheless, in the near future, personalized medicine is not coming to our dinner tables and we have to rely on what we know right now –don’t eat too much sugar, do eat more fruits and vegetables, and don’t eat too much.

Related blog posts:

Why Fiber Matters?

Posted on by

A recent review article (J O’Grady et al. Aliment Phamacol Ther; 2019; 49: 506-15) highlights how fiber is important for health and its potential role in fostering a diverse microbiome. Some of the material has been covered before in a previous blog/presentation: It’s Alimentary!  “The Fiber Movement: Why Kids Need It and How to Get It” by Maria Oliva-Hemker .

In the introduction, the authors note that there had been a period of disappointment that fiber did not seem to help irritable bowel syndrome.  Though with expanding knowledge of the diet-, microbiome- host interactions, clinicians have started to appreciate the health impact of dietary fiber.

In subsequent sections, the authors detail the different types of fiber based on solubility, viscosity and fermentation.

Key actions of fiber:

  • Anti-inflammatory effects
  • Immune system modulation
  • Regulation of cell proliferation and differentiation
  • Richer microbiome diversity (may lower risk of C difficile)

The authors note that a low-fiber diet in germ-free mice can result in a reduced microbial diversity and interestingly, the “missing taxa is transmitted to subsequent generations” even if fiber is re-introduced.

Potential beneficial fiber effects beyond bulking up stools:

  • Reduced adiposity
  • Lower metabolic disease including lower cholesterol and better glucose metabolism
  • Lower incidence of chronic inflammatory diseases
  • “Potential for fiber to prevent… diverticular and neoplastic disorders”

Western Diet is Deficient in Fiber.

  • Recommendations for fiber intake of 14 g per 1000 kcal consumed, which equates to approximately 25 g for females and 38 g for males (depending on energy intake).
  • In underdeveloped countries and historically, intakes are more than 50 g (in Africa) and up to 100 g/day in ancestral humans
  • Actual intake in U.S. is only 12-18 g/day.

The authors recommend efforts to gradually titrate increased fiber in the diet as abrupt changes may be poorly tolerated due to gas and bloating.

My take: This article explains that the connection between fiber intake and a number of health outcomes is likely due, at least in part, to its modulation of the microbiome. Thus, fiber is important for much more than a good poop.

Related blog posts: