Challenging the Obesity Myths

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A recent provocative article highlights the myriad misconceptions regarding obesity (NEJM 2013; 368: 446-54).

According to the authors, many of the obesity recommendations are fallacies:

  • Myth: “Small sustained changes in energy intake will produce large long-term weight changes.” Fact: Because of changes in body mass, the energy requirements change which results in only modest improvement.
  • Myth: “Setting realistic goals for weight loss is important.” Fact: Setting realistic goals has not been shown to improve outcomes over more ambitious goals.
  • Myth: “Rapid weight loss is associated with poorer long-term weight-loss outcomes, as compared with slow, gradual weight loss.”  Fact: Ultimate success in terms of body weight is better with greater initial weight loss.
  • Myth: “It is important to assess…diet readiness.” Fact: Readiness does not predict the magnitude of weight loss or treatment adherence among those who sign up for behavioral programs or undergo weight loss surgery.
  • Myth: “Physical-education classes…play an important role in reducing or preventing childhood obesity.” Fact: Physical education, as typically provided, has not been shown to reduce or prevent obesity.
  • Myth: “Breast-feeding is protective against obesity.” Fact: “Studies with better control for confounding..involving more than 13,000 children who were followed for more than 6 years provided no compelling evidence of an effect of breast-feeding on obesity.”
  • Myth: “Sexual activity burns 100-300 kcal for each participant.” Fact: “Incremental benefit of one bout…is plausibly on the order of 14 kcal.”  (This is going to dampen the all-you-need-to-lose weight is to become a pornography star craze.)

Presumptions -also not proven:

  • Eating breakfast is protective against obesity
  • Early childhood learning regarding exercise and eating influence our weight throughout life
  • Eating more fruits and vegetables will result in weight loss
  • Snacking contributes to weight gain
  • Availability of parks and sidewalks influence the development of obesity

Facts:

  • Reducing energy intake (dieting) can be effective.
  • Increased exercise improves health.
  • Programs that involve parents promote greater weight loss.
  • Some pharmaceutical agents can help.
  • Bariatric surgery can be lifesaving treatment in some cases.
  • Heritability is not destiny.  Moderate sustained environmental changes can be effective.

 

Some related links:

Avoid breastfeeding to lower the risk of HIV

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AAP recommends against breastfeeding infants of HIV-infected mothers:

http://pediatrics.aappublications.org/content/early/2013/01/23/peds.2012-3543.abstract?papetoc

“It is critical that physicians are aware of the HIV transmission risk from human milk and the current recommendations for feeding HIV-exposed infants in the United States. Because the only intervention to completely prevent HIV transmission via human milk is not to breastfeed, in the United States, where clean water and affordable replacement feeding are available, the American Academy of Pediatrics recommends that HIV-infected mothers not breastfeed their infants, regardless of maternal viral load and antiretroviral therapy.”

Thanks to Mike Hart for sharing this link.

Antibiotic resistance: doomed to repeat

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“We’re doomed to repeat the past no matter what. That’s what it is to be alive. It’s pretty dense kids who haven’t figured that out by the time they’re ten.” Kurt Vonnegut, Bluebeard

“Those who don’t know history are destined to repeat it.” Edmund Burke

Antibiotic resistance has been occurring for billions of years and will keep on happening (NEJM 2013; 368: 299-301).  This commentary offers a different perspective and indicates that Kurt Vonnegut’s quote is more appropriate for this post.  Some key points:

  • “We live in a bacterial world where we will never be able to stay ahead of the mutation curve.” We will run out of targets to attack microbes.
  • Bacteria “invented” antibiotics billions of years ago, and “resistance is primarily the result of bacterial adaptation to eons of antibiotic exposure.” Thus, even with good antimicrobial stewardship, resistance will still occur.
  • Antibiotic resistance has been identified in bacteria found in underground caves that have been geologically isolated from the planet surface for four million years.
  • In 1945, Alexander Fleming called for stopping the overuse of penicillin to slow the development of resistance.
  • In 2009, three million kilograms of antibiotics were administered to humans and 13 million kilograms to animals.

Possible useful steps: more vaccines to prevent infections, smaller antibiotic clinical trials, use of rapid biomarkers to withhold antibiotics from those without bacterial infections, stopping antibiotics to help livestock growth, better waste-treatment of antibiotics, ‘self-cleaning’ hospital rooms, and better drug delivery to avoid foreign materials in intensive care patients.

Related blog entry:

Green beans for short gut syndrome

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A recent article indicates that the addition of green beans may improve diarrhea and reduce dependence on parenteral nutrition (Adding Dietary Green Beans to Formula Resolves the Diarrhea …) (ICAN. DOI: 10.1177/1941406412469403). Thanks to Kipp Ellsworth for pointing out this reference on his twitter feed.

This small retrospective study of 18 infants examined the addition of green beans to the diet of infants with short bowel syndrome (SBS) (1 jar of stage 2 baby food green beans to every 8 ounces of 30 cal formula).  The average gestational age of the patients was 32 weeks (range 23-39 weeks) and the average birth weight was 1938 gram.  Nine patients had NEC, four had gastroschisis, two had Christmas tree defect, and three had other reasons for either SBS or intestinal failure.  The IF group (n=10) was defined as being dependent on parenteral nutrition to meet nutritional needs; the SBS group (n=8), who were more severely affected, was defined as the malabsorptive state that follows a massive resection.

Products that were used:

  • Gerber Natural Select: 3 gm of fiber per 4 ounce
  • Beach-Nut Homestyle: 2 gm of fiber per 4 ounce
  • HyVee Mother Choice: 2 gm of fiber per 4 ounce
  • These products average 32% soluble and 68% insoluble fiber

While the authors note that they use only amino-acid based formulas currently, at the time of the study, 61% were receiving Peptamen Junior.

It is not clear in the manuscript exactly at what age green beans are introduced. However, a previous case study suggested addition of green beans at ~4 months or >44 weeks postconception.  This prior case study indicated that adding stage 2 green beans changed the caloric density of 30 cal formula to 22 cal/ounce (Nutrition in Clinical Practice 2005; 20: 674-77).  In addition, this adds 2 gm/kg/day of fiber.

Results from current study:

  • 9 of 10 IF patients were able to discontinue parenteral nutrition
  • 2 of 8 SBS patients were able to discontinue parenteral nutrition
  • All infants had improvements in stool consistency, typically within 24 hours of dietary change.

While the authors acknowledge the limitations of the study, they hypothesize that the reason for improvement is due to the fiber content of green beans.   Fermentation of dietary fiber produces short chain fatty acids (SCFAs) which in turn have a trophic effect on the mucosa and enhance nutrient absorption.

Studies have shown that adults with IF or SBS have improved stool consistency with the addition of fiber.  However, the authors note that there have been no studies documenting the effectiveness of dietary fiber in the pediatric SBS/IF population.

Whether green beans would outperform other sources of fiber like pectin, guar gum, bananas or benefiber is not clear.

Additional references/links:

Feeling the urge and stopping the shame

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So many parents misinterpret withholding behavior in children.  Many indicate that their child is trying to go but cannot and others indicate that their child does not feel an urge to defecate.  Now more insight into this common issue has emerged (JPGN 2013; 56: 19-22).

The authors reviewed their experience with colonic manometry (n=410).  150 patients were identifed as having functional constipation.  Among this group, 56 patients volunteered that they had no urge to defecate.

Yet, during colonic manometry, when the first high-amplitude propagating colonic contraction (HAPC) occurred, this was associated with retentive posturing, grimacing or denial of sensation.  When the HAPC occurred, the examiner would explain that it was causing pain that would improve if the child defecated.  Ultimately, “every patient acknowledged an urge to defecate and successfully defecated.”

One other interesting part of this publication is the discussion of psychological aspects.  Do you remember Erikson’s stages (Erik Erikson – Wikipedia, the free encyclopedia)?  The authors note, “if toilet training is not achieved or the process involves negative experiences including being shamed into the process, shame and doubt will persist.  Shame, according to Erikson, is an infantile emotion and leads to secretive behavior.  Therefore, children who failed toilet learning may deny sensations of the urge to defecate…all the while having shame and embarrassment.”

These psychological issues are important in the propagation of constipation. The authors note that, even in children with rectal distention due to chronic constipation which could result in decreased sensation, studies have shown rectal compliance was not associated with treatment failure.  Therefore, constipation and soiling are not simply due to a mechanical issue of not knowing when to go.

Related posts:

Colic Microbiome

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A new study identifies a potential microbiome signature that is associated with colic (Pediatrics 2013; 131: e550-58). Thanks to Mike Hart for this reference.

With new technology, the microbiome’s role in many gastrointestinal conditions is being unraveled.  For colic, there has been concern about that an abnormal microbiome has been contributing to the pathophysiology.  On a personal level, I have had an interest in this subject for quite a while:

In this current study, the authors serially followed the microbiome infants in a prospective longitudinal project.  Nine stool specimens were obtained from each infant. Four were obtained in the first month at day of life 2, 7, 14, and 28 days.  Five were obtained at 3 to 5 months.  All specimens were stored at -20°C until analyzed by the “Human Intestinal Tract Chip (HITChip).” The HITChip microarray was considered satisfactory if 2 independent hybridizations had >95% correlation.  These microarrays “showed a dynamic range of >10,000-fold and >200 independent microarray readouts were used.”

Of 160 healthy term infants, the authors identified colic in 25% who averaged >180 minutes of crying per day over a four-day period.  Then, the authors selected the 12 infants who cried the most and compared them to the 12 infants who cried the least.

Results:

  • In the infants who were highly similar, the “infants with colic showed a significantly reduced microbiota diversity at 14 and 28 days of life.”  Proteobacteria, including Enterobacter aerogenes, Escherichia coli, and Klebsiella pneumoniae, were increased with more than a doubled abundance.  Bifidobacteria and lactobacilli were decreased in colicy infants.
  • At about 3-4 months of age, the colic group had a similar microbiome as the non-colicy group.
  • The authors speculate that proteobacteria might cause inflammation and may displace helpful bacteria.  Certain butyrate-producing bacteria like Butyrivibrio crossotus and Coprococcus estates were more commonly present in the non-colicy group.  The authors note that butyrate reduces the pain sensation in adults.

Bottom-line:

These results could explain why administration of probiotics (and possibly antibiotics) can result in a decrease in colic symptoms.

Related blog entries:

Additional references:

  • -Pediatrics 2010; 126: e526.  Double-blind randomized placebo-controlled trial of Lactobacillus reuteri.
  • -J Pediatr 2009; 155:823. Increased calprotectin in colicy infants. n=36. editorial pg 772.
  • -J Pediatr 2009; 154: 514-20. Colic and reflux. (Orenstein et al), & 475 (editorial -Putnam). PPIs (lansoprazole) do not help colicy Sx in infants c GERD. n=162. Increased resp infections in pts on PPIs. 44% response in Rx & control group.
  • -J Pediatr 2008; 152: 801. Probiotic helped reduce colic sx in 30 preterm infants, Lactobacillus reuteri
  • -Pediatrics 2007; 119; e124. Probiotics reduced colic in breastfed babies more than simethicone. n=83, lactobacillus reuteri, 10-8th power per day. Decreased crying 18 minutes per day at 1 week compared to simethicone & by 94 minutes/day at 4 weeks (95% response vs 7% of simethicone)
  • -Pediatrics 2005; 116: e709. Low-allergen maternal diet was helpful.
  • -Arch Pediatr Adol Med 2002; 1183 &1172. lack of sequelae on maternal mental health.
  • -Arch Pediatr Adol Med 2002; 156: 1123-1128. colic 24% of infants, breastfeeding did not help.
  • -Pediatrics 2002; 109: 797-805. carbohydrate malabsorption with breath testing in colicy infants, n=30. 2 hour fasting period.
  • -Arch Dis Child 2001; 84: 138-41. Lack of benefit (vs placebo) of chiropractic manipulation for colic, n=100. 86 completed study. 70% improved vs 60% in placebo.
  • -JPGN 2001; 33:110-111. Lack of assoc c GER
  • -Pediatrics 2000; 106: 1349. Use of hydrolysate decreased crying by 63mins/day
  • -Pediatrics 2001; 108; 878-882. No assoc between colic and markers of atopy/asthma/allergy.

Thrombophilia and Portal Vein Thrombosis

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Most cases of portal vein thrombosis (PVT) remain without apparent explanation (JPGN 2012; 55: 599-604).

In this study from Brazil, 32 children with portal vein clots (1990-2011) were reviewed in this cross-sectional study.  The median age at diagnosis was 2.4 years.  Hereditary or acquired thrombophilia was detected in 34% and 9 of these patients had identified risk factors.

The most common thrombophilia factor was the presence of heterozygous state for methylenetetrahydrofolate reductase (MTHFR) C677T which was present in 11 patients.   2 of these patients had a cofactor, including G20210A prothrombin gene, and factor V Leiden.

Risk factors included umbilical catheterization in 13 patients (40.6%).

18 (56%) had no risk factors. 

Related blog entry:

VTE with IBD | gutsandgrowth

Additional references:

  • -Hepatology 2009; 39: 1729.  AASLD practice guidelines on vascular disorders. Recs mesoRex shunt for PVT.
  • -JPGN 2008; 47: 630. n=108. Infrequent thrombophilia d/o with PVT. Banding/sclero -effective.
  • -J Pediatr 2006; 148: 735. PVT more common than previously thought; umbilical vein catheter, esp if misplaced, is risk factor.
  • -NEJM 2011; 365: 147. Review. In cirrhosis pts, platelet count as low as 60K usually sufficient to preserve thrombin generation equivalent to lower limit of normal range in healthy subjects. PVT occurs in 8-25% of pts listed for OLTs. Thus, many procoagulant factors as well as potential propensity for bleeding.
  • -J Pediatr 2003; 142: 197. Rex procedure corrects clotting abnormalities.
  • -J Pediatr 2005; 146: 568. Portal vein -cavernous transformation –associated with cholestasis.
  • -J Pediatr 2000; 136: 805. 49% of children with PV clot had bleeding by 16 yrs & 76% by 24 yrs. (n=44).
  • -Gastroenterol 2001; 120: A-49, #256. Attention span deficits can be corrected c REX.
  • -Hepatology 2000; 31: 345-348 & 587-591. Hyperhomocysteine mutation frequent when PVT assoc c cirrhosis. Etiologic factors. 87% c thrombophilic d/o.
  • -Gastroenterol 2001; 120: 490-497 & 579. Anticoagulation helpful.
  • -J Peds 2006; 149: 275. Reference values.
  • -NEJM 2005; 352: 1791. Thrombosis of cerebral veins & sinuses (review); includes assoc c IBD.  Specific thrombophilia disorders: Antithrombin deficiency, protein S and C deficiencies,Factor V Leiden mutation, (the A for G 20210) prothrombin gene mutation, lupus anticoagulant, antiphospholipid antibodies, factor XI, and MTHFR-hyperhomocysteinemia (thermolabile variant of methylenetetrahydrofolate reductase- C677T MTHFR-). The later was paricularly interesting in view of the recent report of hyperhomocysteinemia in patients with inflammatory bowel disease (Thromb Haemost 1998,80;542-5)

For the smoking skeptics

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How bad is secondhand tobacco smoke (SHS)?  This has been debated.  When I come out of an office room and the entire room smells of smoke, even though no one has smoked in the room, I know this is detrimental.  More proof of this comes from an article which shows that SHS is associated with an increase in the severity of children hospitalized with influenza (J Pediatr 2013; 162: 16-21).

In this study of 117 children, 40% were exposed to SHS.  They had increased need for intensive care (30% vs. 10%), increased intubation (13% vs. 1%), and longer length of stay (LOS) (4 days vs. 2.4 days). In children with chronic conditions, the LOS was 10 vs. 3.5.  After controlling for multiple variables, the authors found that SHS exposure was associated with a 4.7 fold increase in the likelihood of ICU admission and a 70% LOS.

This study had many limitations.  It was a retrospective chart review.  Patients between 2002-2009 were identified initially by the discharge diagnosis of influenza.  Among the 171 charts identified, 117 had a positive influenza culture and adequate data to retrieve.  As a retrospective review, it is possible that screening for smoke exposure was more common in the more severely affected cases.

Additional references:

Predictors of colectomy in pediatric UC

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A recent review of children in the Pediatric Inflammatory Bowel Disease Consortium (PediIBDC) examined risk factors for proctocolectomy in children with Ulcerative Colitis (UC) (JPGN 2012; 55: 534-40).  Two of the investigators (Stanley Cohen and Ben Gold) are colleagues of mine at GI Care for Kids.

In total, 406 children with UC were reviewed.  The average age at diagnosis was 10.6 years.  The average followup was 6.8 years.  57 (14%) underwent surgery with a median time to surgery of 3.8 years.  Overall risk factors for colectomy included the following:

  • Presenting with weight loss, HR 2.55
  • Presenting with hypoalbuminemia (<3.5 g/dL), HR 6.05
  • First-degree relative with UC, HR 1.81
  • Treatment with cyclosporine, HR 6.11
  • Treatment with tacrolimus, HR 3.66

While this data expands on the knowledge of these factors in children, the findings are not unexpected.  Low albumin levels and poor nutritional status have been identified in other studies as risk factors for UC relapse and for colectomy.

With regard to first-degree relatives, the findings imply that children with a first-degree relative are more likely to have a more severe form of UC.

The use of calcineurin inhibitors, cyclosporine and tacrolimus, are given only in the presence of severe disease.  Thus, while use of these agents is associated with an increased risk of colectomy, it is unlikely that this is a causal relationship.  Interestingly, the use of infliximab was not identified as a risk factor.  However, this retrospective study examined patients between 1999-2003.  Since this timeframe, there has been increased use of infliximab for refractory UC.

Going forward, it is likely that contemporary studies would incorporate PUCAI (pediatric UC activity index) measurements and would have the ability to enroll far greater numbers of patients from database consortiums.

Related blog posts:

Outgrowing the growth charts

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Unfortunately, there is a need for extreme growth charts (Pediatrics 2012; 130: 1136-40).

The authors of this study designed growth charts for morbidly obese children.  The reason for these charts is that there are many pediatric patients who cannot be plotted using the CDC  growth chart which has a maximum BMI of 36 kg per meter-squared.  The CDC charts are based on a preobesity epidemic population data set (1963-94) and has sparse data for those above the 97th percentile.  The manuscript describes how these initial charts were derived.

These new growth charts calculate the BMI as a percentile of the 95th percentile.  For example, multiplying the BMI 95th % by 1.2 would yield a result of 120% of the 95th%.  The authors calculated 1.1 through 1.9 multiples of the 95% for all ages between 2 and 20 years.  On their curve, a BMI as high as 64 kg per meter-squared can be plotted.  This allows easier visual tracking of a patient’s progress.

Drawbacks:

  • Difficult to explain to parents due to confusing phraseology –use of two percentages
  • Many of the patients are now on the growth curve and could appear to be graphically normal despite being morbidly obese

The authors note that their growth charts were incorporated into their electronic medical record (Epic software).

Related blog entry: