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Student Blogger for Global Nutrition Council at ASN’s Scientific Sessions and Annual Meeting at EB 2016

By: Sheela Sinharoy, MPH

A symposium titled Program Effectiveness for Addressing Undernutrition during the First 1,000 Days provided attendees with examples of programs in Bangladesh, Guatemala, and Burundi.

In Bangladesh, the Rang-Din Nutrition Study tested lipid-based nutrient supplements (LNS) in a community-based program. According to presenter Kay Dewey, the study found that giving LNS to mothers prenatally reduced the prevalence of stunting and increased the birth weight, head circumference, and body mass index (BMI) in infants at birth. LNS and multiple micronutrient powders (MNP) for children were also associated with better developmental and cognitive outcomes. Dr. Dewey noted that the impact on child anthropometry was much larger in food insecure households, so future programs may want to target based on this and other criteria.

Moving from Asia to Africa, Marie Ruel presented results from an impact evaluation of a food-assisted integrated health and nutrition program in Burundi. The program gave food rations to mothers and children and also provided behavior change communication. Interestingly, the nutrition situation in Burundi deteriorated sharply during the program period, but decreases were less severe in the treatment groups. For example, while the prevalence of stunting increased dramatically in the control group, the prevalence in the treatment group remained essentially flat. Thus, although the treatment group did not improve, the results suggest that the intervention protected families who otherwise would have been vulnerable to economic shocks.

Guatemala is another country with a very high prevalence of chronic undernutrition, and Deanna Olney presented results from a study of a similar food assistance program. The impact of the program was greatest among those who received a full family food ration plus an individual ration of corn-soy blend. In these households, mothers had significantly higher mean BMIs, children had a lower prevalence of stunting, and both mothers and children had a lower prevalence of anemia. However, there were no significant impacts on child underweight, wasting, or language or motor development.

The differing impacts of various programs was the impetus for a talk by Per Ashorn, who discussed pathways of impact for fetal growth, linear growth, and cognitive function. He explained that the pathways for linear, ponderal, and head growth are partially different, and there are possibly partially different pathways to childhood length gain and brain function. This suggests a need for multipronged interventions targeting pathways including infection, nutrition, and inflammation, as well as a variety of outcome measures to assess the interventions’ impact.

Of course, cost is an important – and often challenging – issue when planning interventions. The final talk of the symposium was given by Steve Vosti, who explained that programs must balance need, acceptability, use, and both short-term and persistent demand in order to achieve impact. These and many other factors, such as the costs of manufacturing supplements in country and the proportion of locally available ingredients being used, can affect the cost of an intervention. In addition to deciding on the most appropriate intervention to meet a need, practitioners must take these factors into account when planning their programs.

By Sheela Sinharoy

Tuesday’s minisymposium ‘Nutrition and Inflammation’ covered a wide range of topics and research designs from clinical, lab, and public health perspectives.

Starting with clinical research, Wendy Ward of Brock University (Canada) presented on associations of dietary intake with periodontal healing. She explained that 42% of adults in the US are affected by periodontal disease, which is characterized by inflammation of tissues around the teeth that can eventually lead to loss of alveolar bone. One treatment is the mechanical removal of bacteria below the gum line through sanative therapy. Dr. Ward’s group found that higher dietary intakes of fruits and vegetables, β-carotene, vitamin E, and α-linolenic acid were associated with greater healing following sanative therapy.

Taking a more public health-oriented perspective, Mercedes Sotos Prieto of Harvard University spoke about the development of a healthy lifestyle score (HLS) and its association with inflammatory markers among Puerto Rican adults in Boston. The HLS included five components: diet, physical activity, smoking, social network and support, and sleep. Dr. Sotos Prieto found that a 20-unit increase in the HLS was associated with a decrease in the inflammatory biomarkers IL-6 and TNF-α when adjusted for a number of covariates. These in turn were associated with obesity and hypertension but not with diabetes or heart disease.

Presentations from Yaw Addo and Leila Larson of Emory University also had clear public health implications. They looked at biomarkers of iron and vitamin A status, respectively, and their relationship with biomarkers of inflammation. First, Dr. Addo explained that transferrin receptor was strongly associated with α-1 acid glycoprotein (AGP) in women of reproductive age across six countries, though the magnitude of the association varied by country. Next, Ms. Larson showed that retinol binding protein (RBP) was significantly associated with both C-reactive protein (CRP) and AGP among preschool children in Liberia. Both of these analyses suggested that it may be important to account for inflammation, particularly with RBP, where adjusting for inflammation through linear regression decreased the prevalence of vitamin A deficiency by almost 20 percentage points.

Moving to lab studies, Marie-Caroline Michalski of the University of Lyon (France) presented research on the effects of dietary lipids on plasma endotoxins and lipopolysaccharides (LPS), which contribute to low-grade inflammation. She showed that in a sample of normal weight and obese men, ingestion of a higher-fat test meal led to postprandial endotoxemia only in obese subjects. Qiaozhu Su of the University of Nebraska then presented data showing that the cAMP responsive element binding protein H (CREBH), which is activated by the inflammatory cytokine TNF-α, induces expression of apolipoprotein B. This in turn increases secretion of very low density lipoproteins (VLDL) and may play a role in hepatic steatosis, hyperlipidemia, and insulin resistance. Finally, Sadiq Umar of Washington State University showed that thymoquinone, a compound derived from Nigella sativa, or black cumin, inhibits TNFα-induced production of the inflammatory cytokines IL-6 and IL-8 as well as the pro-inflammatory mediator ASK1.

Given the associations between inflammation and many chronic diseases, we will likely hear a great deal more about these topics in years to come.

By Colby Vorland, Student Blogger

Could a “fatty intestine” be related to insulin resistance and energy balance? These and other provocative questions were addressed by Dr. Elizabeth Parks during ASN’s Scientific Sessions in San Diego. Organized by the Energy and Macronutrient Metabolism Research Interest Section, Dr. Parks gave a seminar titled, “Going with your gut: Individual responses in dietary fat absorption.”

Dr. Parks’ research often focuses on the cephalic phase of digestion – or the early physiological response before food is even ingested. She presented a story that led her to her current path: Teff and Engelman demonstrated in 1996 with a sham feeding model that taste has an important effect on glucose metabolism and, in 2002, Robertson and colleagues published data showing that, compared to a high fat meal, consuming a high carbohydrate meal at night resulted in better glucose tolerance in the morning. Concurrently, they demonstrated a high fat meal at night yields a better fat tolerance the following day. These data suggest that there is some adaptive priming occurring and that, as Dr. Parks put it, “you best metabolize what you’ve just eaten.” She noted that we need to better match the challenge test with the eating pattern of interest.

In 2003, Robertson and colleagues published the results of an experiment in 10 healthy participants scheduled for an endoscopy who were fed a high fat meal, then 5 hours later were fed 50 grams of fat with either 38 grams of glucose or water. The participants who consumed the glucose along with the fat in the second meal showed less lipid in the jejunum. In other words, some dietary fat was stored in the intestine from a meal and its release was accelerated when glucose in combination with fat was consumed. Since then, Dr. Parks and others have shown that simply tasting fat without ingesting it, or just consuming carbohydrate, can cause an early rise in chylomicron secretion and blood triglyceride levels. This means that the intestine stores some of the fat from previous meals; in fact, Parks estimates that ⅕ to ¼ of the fat in your meal is stored in the intestine for at least 16 hours, and it is released in response to taste. Their data also suggests that body fat is negatively correlated with the amount of fat coming from the intestine and entering the blood at a subsequent meal. If intestinal fat stores serve a regulatory function to control energy balance (by releasing in response to taste), this raises the possibility that the mechanism that controls how much is release is perturbed.

Parks then discussed research supporting that we can taste fat. As further evidence, they have scoured literature for kinetic data and devised a mathematical model to show that rate of release of fat from the gut is consistent with the idea that this physiological response is due to our ability to taste fat. She also noted that chylomicrons may be supported in the absence of dietary fat by fatty acids in circulation entering the enterocyte, being packaged into chylomicrons, and secreted. Some data suggest that high free fatty acids increase the contribution from plasma to chylomicrons.

Dr. Parks has also been asking: does the rate of fat absorption impact health? Dr. Jennifer Lambert and Parks have unpublished data showing that the time-course of triglyceride absorption between people can vary substantially – about 1 to 4 hours. She showed graphs of the fat absorption curves of individual participants, and the patterns were often variable, emphasizing that much remains to be understood about why this occurs. Finally, she showed that stratifying by an early or late absorption peak revealed differences in participants in each group. For example, participants with an early peak tended to be more insulin resistant than those with a later peak.

Dr. Parks has been innovative in her use of stable isotopes for exploring lipid metabolism in health and disease. Clearly the intestine is an underappreciated tissue in fat storage and we are just on the cusp of understanding the role in which it mediates health and energy balance.