The P/B-24 Project: Examining the Evidence

SETTING THE FOUNDATION FOR DIETARY GUIDANCE FOR WOMEN WHO ARE PREGNANT AND CHILDREN BIRTH-24 MONTHS

When I became pregnant with my son, I read everything I could get my hands on about healthy eating during pregnancy. Yes I am a dietitian, but when it comes to the health of your future child, you need a little reassurance. To my dismay, I had a lot of trouble finding evidence-based guidelines for nutrition during pregnancy. What I did find was a lot of resources that made very generalized dietary recommendations, or offered poor advice, such as how to follow the latest fad diet while pregnant. Even several health professionals I interacted with during my pregnancy gave me bad nutrition advice. Did you know that if you avoid fruit while pregnant, it will keep you from gaining too much weight?! I am being sarcastic by the way, pregnant women should not be told to avoid fruit unless there is a medical reason.... 

After Ewan as born, I found the landscape of information around nutrition/feeding infants and toddlers is even more vast. Everyone has an opinion on the topic from scientists to mommy bloggers. I spent hours and hours reading about varying opinions on the topic while I rocked and breastfed my infant, many from fellow dietitians and lactation consultants. But what I found is, depending on the topic and age group, very little of these recommendations were/are actually based in scientific evidence. In the US, we are often on the forefront of these issues, but not in this case. The obvious first place I start when looking for dietary guidelines were the Dietary Guidelines for Americans. If you are like me, you may not have thought twice about how the national Dietary Guidelines for Americans (DGA) have traditionally excluded pregnant women and children under 2 years.(1) At least not until you had reason to seek out these guidelines in a desperate attempt to make sense of the lack of or over abundance of evidence-based nutrition recommendations...

WHY THE LIMITED PREGNANT WOMEN AND CHILDREN UNDER 2 YEARS?

While some early renditions of the DGAs have referred to dietary guidance for these groups (see Raiten et al, 2014 - Table 1), traditionally, pregnant women and children under 2 have been entirely excluded from the DGAs. Why? Pregnant women and young children (<2 years) have unique nutritional needs, eating patterns, and developmental stages that have to be considered when developing dietary and physical activity advice. Unfortunately, concerns have been raised in terms of the number (i.e. quantity of well designed randomized controlled trials (RCTs)), and quality (e.g. control variables) of studies available to actually support the development of dietary guidelines that could be communicated broadly to the public.(4) 

What we do know is that good nutrition during the earliest stages of life is vital for child growth and development, promotion of positive health, and disease prevention later in life. A child's first 1,000 days of life (covering pregnancy through 2 years) represents a highly sensitive period. In terms of nutrition, children will learn to accept and like healthy foods during this time.(5) While more research is needed, some studies have demonstrated that food preferences/liking established in the first 3 years of life often persist into adulthood.(6,7) Further, interventions made after a child's 2nd birthday do little to undo any damage done due to undernutrition in the first 1,000 days.(4) Having national DGAs emphasizing healthy habits among our most vulnerable populations could go a long way to improving the short- and long-term health of pregnant women and young children across the US.

Thankfully, this is all about to change. In 2020, the US will release the first set of Dietary Guidelines that will include recommendations for pregnant women, infants, and toddlers. The release of these guidelines will be nothing less than historic. While we are still 3 years aways from their release, the ball has already started rolling.(2,3) 

The Agricultural Act of 2014 (aka the Farm Bill) mandated the DGAs to include guidelines for our most vulnerable citizens beginning with the 2020-2025 edition. In response, the U.S. Department of Health and Human Services (DHHS) and U.S. Department of Agriculture (USDA) initiated the Pregnancy/Birth to 24 Months Dietary Guidance Project (P/B-24) in 2012 to develop guidance for these groups using a similar evidence-based approach used by the Advisory Committee to develop the DGAs.(2,3) Before I tell you more about P/B-24, it is important you understand a little more about the DGAs and how they are developed. Feel free to skip this part if you are already well versed in the DGAs and all their glory.

A LITTLE HISTORY ON THE DGA

The DGAs were first released in 1980. After releasing a couple versions of the DGAs, the National Nutrition Monitoring and Related Research Act of 1990 was passed by Congress. This act stated that U.S. Department of Health and Human Services (DHHS) and the U.S. Department of Agriculture (USDA) must jointly review, update, and publish the DGAs every 5 years, making this process a little more standardized. The last set of DGAs was released in 2015, with new guidelines expected in 2020.(1) For those of you who are history buffs, you can find each rendition of the DGAs since 1980 here.

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Every new edition of the DGAs is representative of the most current nutrition science available."

Every new edition of the DGAs is representative of the most current nutrition science available for creating dietary and physical activity recommendations. The intent is to provide Americans with the information they need to make good health decisions; hopefully ones that will lead to the promotion of good health, prevention of chronic diseases, and help Americans reach and maintain a healthy weight status. Whether you realize it or not, the DGAs touch every part of your life. These recommendations directly affect the goals of public health agencies, health care providers, educational institutions, the food industry, and more. Do you know a child that eats meals at school? The DGAs help form the foundation for federal nutrition policies and programs like the Health Hunger Free Kids Act. As researchers, my colleagues and I are also directly impacted by the DGAs. We develop nutrition education programs at the local, state, and national levels that are guided by the DGAs. Even the food industry is directly impacted by the DGAs in terms of how they develop and market food and beverage products to the general public. If this topic interests you, I recommend reading Marion Nestle's Food Politics book and blog. But I digress....

To create the DGAs each cycle, the DHHS and USDA convene a Dietary Guidelines Advisory Committee (aka the Advisory Committee) that is tasked with reviewing the most current nutrition science. The committee is typically comprised of nationally recognized nutrition and medical researchers, academics, and practitioners. The committee holds a series of public meetings, one of which is open for oral comments from the public. The public also has an opportunity to provide feedback on the drafted DGAs through written comments throughout the process of development. 

The Advisory Committee develops an Advisory Report synthesizing the current scientific and medical evidence in nutrition and outlining their science-based recommendations. This report is NOT the DGA policy or even a draft of the policy, but rather a set of recommendations the federal government will then use to develop the next set of DGAs.

After the committee completes its Advisory Report, the public is given the opportunity to respond with written comments and oral testimony in a public forum. These comments, along with comments from federal agencies and the Advisory Committee's Advisory Report, are used by the HHS and USDA to finalize the new edition of the DGA. 

Whew - okay, enough of that, back to P/B24....

WHAT IS THE P/B-24 PROJECT?

The Pregnancy/Birth-24 Months Project is an effort to evaluate the current research we have available to support the development of DGAs for women who are pregnant, infants, and toddlers. The project is being led by the DHHS and USDA and is officially titled "Evaluating the evidence base to support the inclusion of infants and children from birth to 24 months of age in the Dietary Guidelines for Americans - the B-24 Project". A mouthful, I know. The goals of the P/B-24 project are to: (1) develop guidance for the pregnant women and birth to 24 month age groups; (2) use a rigorous and transparent process informed by a broad range of expertise; and (3) provide foundational guidance that could then be integrated and updated in future DGAs.

To meet these goals, the HHS and USDA set forth a five phase plan, with the first phase having been completed in 2013. 

Phase I identified high priority topics that needed to be addressed in order to address the B-24 DGAs. Clear research needs were identified, such as our need to better understand what nutrients are in human milk. Below is a list of the identified topics, grouped by age and maternal/caregiver influences. If you are interested, click the link to access the specific questions that were developed.

This phase was followed by a 2 year interim period to allow for further refinement of the research questions and development of plans to write a series of systematic reviews. It was also anticipated that the 2 year break would allow researchers time to identify high-priority topics for publication of related projects they may have already in progress, and allow time for new data to be collected of analyzed from preexisting data sets. If you know anything about the research process, this second goal was a bit lofty. Research is a time consuming process. Unless the project was already in the works, it would have been a challenge for original studies to have been developed, executed, and findings published in time to benefit the Advisory Committee of the 2020 guidelines... Some researchers have already been successful at publishing research on the topic. For example, Nutrition Today released a series of papers addressing sugar intake in the Birth-24 Months age group in their March/April Supplement. Regardless, I am looking forward to the explosion of research that will hopefully be available to inform the 2025 guidelines. 

Phase II started in 2014 with the development of a series of review papers and data analyses derived from topics during Phase I. Many of these papers are being submitted for publication now.

Phase III will feature the actual development of dietary guidance evidence for the P/B-24 populations. The goal would be to make this evidence available in 2018 for consideration by the 2020-2025 Dietary Guidelines for Americans Advisory Committee. Phase IV will be the provision of the policy document to the 2020-2025 DGA Advisory Committee for use in the development of their 2020 DGA Advisory Committee report. This processs will follow standard procedures for developing DGAs (see above section on the DGAs). In accordance with standard procedure, this process will be transparent and public input will be collected and considering at all phases. 

It is important to note that the P/B-24 is not a formal step in the development of the 2020-2025 DGA, meaning the evidence gathered and published from this project will not include official dietary recommendations or advice. This job will be left up to the Advisory Committee. Rather, the intent of P/B-24 project is to provide the scientific foundation for dietary guidance within these population groups that will inform the Advisory Report that is ultimately written by the next Dietary Guidelines Advisory Committee.

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"The P/B-24 Project is not a formal step in the development of the 2020-2025 DGA."

WHAT IS NEXT FOR THE P/B-24 PROJECT?

Under Phase II, a big goal of the P/B-24 project is to identify topics of public health that are important, and conducting systematic reviews on the diet and health of women who are pregnant, infants, and toddlers. Over 50 experts, nutrition scientists, clinicians, epidemiologist, methodologists, and communicators were involved with staff support from DHHA and USDA. The purpose of these reviews is to evaluate existing evidence needed to inform dietary guidance and to determine if the existing evidence is sufficient to inform policy.  

The work groups (there were 4) developed topics and specific questions for the focus of the future systematic reviews, identified research priority areas, and the need for additional surveillance data (e.g. NHANES). Below are a list of the specific questions expected to be addressed by the systematic reviews.(2)

  • What is the relationship between infant milk feeding practices and: 
    • 1) growth, size, and body composition; 2) food allergies and other atopic allergic diseases; 3) chronic disease; and 4) childhood leukemia?
  • What is the relationship between complementary feeding and:
    • 1) micronutrient status; 2) growth, size, and body composition; 3) developmental milestones; 4) food allergies and other atopic allergic disease; and 5) bone health?
  • What is the relationship between exposure to foods and early food acceptance?
  • What is the relationship between maternal diet and infant/toddler food acceptance and dietary intake?
  • What is the relationship between parental and caregiver feeding practices and growth, size, and body composition?
  • What is the relationship between dietary patterns during preconception/ pregnancy and:
    • 1) risk of gestational diabetes; 2) risk of hypertensive disorders during pregnancy; 3) gestational age at birth; and 4) birth weight standardized for gestational age and sex?

It is my understanding that some of these reviews are in the final stages and are expected to be submitted for publication sometime next year. 

I am excited to see the local, state, and federal impact the P/B-24 project and eventual DGAs for women who are pregnant, infants, and toddlers will bring. We will surely be realizing the impact of decades to come.

 

REFERENCES

  1. Dietary Guidelines for Americans: https://health.gov/dietaryguidelines/

  2. Pregnancy and Birth to 24 Months Project: https://www.cnpp.usda.gov/birthto24months

  3. Rihane, C. (2014). Developing National Dietary Guidance for the Birth to 24 Months Age Group: https://www.usda.gov/media/blog/2014/05/6/developing-national-dietary-guidance-birth-24-months-age-group
  4. Raiten DJ, Raghavan R, Porter A, Obbagy JE, Spahn JS. Executive summary: evaluating the evidence base to support the inclusion of infants and children from birth to 24 mo of age in the Dietary Guidelines for Americans—"the B-24 Project." Am J Clin Nutr. 2014;99 663S-691S.
  5. Pérez-Escamilla R, Segura-Pérez S, Lott M, on behalf of the RWJF HER Expert Panel on Best Practices for Promoting Healthy Nutrition, Feeding Patterns, and Weight Status for Infants and Toddlers from Birth to 24 Months. Feeding Guidelines for Infants and Young Toddlers: A Responsive Parenting Approach. Guidelines for Health Professionals. Durham, NC: Healthy Eating Research, 2017. Available at http://healthyeatingresearch.org.
  6. Bjelland M, Brants&ter AL, Haugen M, Meltzer HM, Nystad W, Andersen LF. Changes and tracking of fruit, vegetables and sugar-sweetened beverages intake from 18 months to 7 years in the Norwegian Mother and Child Cohort Study. BMC Public Health. 2013;13:793.
  7. Lioret S, Betoko A, Forhan A, et al. Dietary patterns track from infancy to preschool age: cross-sectional and longitudinal perspectives. J Nutr. 2015;145:775Y782. 
  8. Obbagy JE, Blum-Kemelor DM, Essery EV, Lyon JMG, Spahn JM. USDA Nutrition Evidence Library: Methodology used to identify topics and develop systematic review questions for the birth-24 month population. Am J Clin Nutr. 2014; 99:1-5.
  9. Additional related articles from the B-24 Topic Identification Project are available in: Am J Clin Nutr.2014;99 (suppl).

NOTE: Food Guides date back to the early 20th century. The DGAs and the USDA's Food Guides are now related, but technically two different things. Click here for a history of USDA's Food Guides. It's pretty cool.