Published in 'Annual Review of Nutrition', the new report notes that there's a growing focus on precision nutrition based on the concept that population subgroups may react in similar ways to dietary exposures and understanding this variation enables the ability to tailor recommendations more specific than those given at the population level.
However, the authors Dr Regan Bailey, associate director of the precision nutrition, and Dr Patrick Stover, director at the Institute for Advancing Health Through Agriculture, at Texas A&M University, say current knowledge on precision nutrition interventions is severely lacking.
The need for precision
Despite all our scientific advances and efforts to improve health through nutrition, the report notes that our nations face an unprecedented burden of diet-related chronic disease, increased prevalence of overweight and obesity starting in young children, and declines in life expectancy that are not evenly distributed among racial-ethnic groups.
Targeted dietary guidance toward primary prevention of chronic disease is recognised as more beneficial than treatment of chronic disease. As such, efforts in dietary guidance now extend beyond nutrient deficiencies and toward chronic disease reduction.
The report notes that this new approach must consider individual responses to nutrition: "The multifactorial etiology of chronic diseases, the complexity of food composition and the multitude of interactions of foods with physiological systems, nutrition behaviors, the aging process, and knowledge of human biological variation among individuals all contribute to differences in the diet–disease relationship, indicating the need for greater precision in achieving health through diet that must be largely reflected in more nuanced dietary guidance, practice, and food policy.
"The new omics-based approaches have affirmed inherent individual differences in our genetics, metabolism, and response to environmental and lifestyle changes and have extended our fundamental knowledge of biology, but the costs of translating these data for classifying responders and non-responders with respect to diet and nutrition for public health improvement are prohibitive and not practical at this time."
Evidence weak spots
The authors point out that given the long latency of most chronic diseases, the research on and the association between chronic disease and diet tend to be observational in nature, a weaker form of evidence that makes it difficult to establish cause and effect relationships.
They ask an important question about how we can advance our provisions in this field without overpromising, writing: "As a scientific community, how do we meaningfully actualize the concept of precision nutrition with urgency without overpromising the public with recommendations based on weak evidence that do not stand the test of time?"
They note the complexities that make research so challenging: "The diet–chronic disease relationship is modified with interactions among diet and most other lifestyle behaviors.
"Because the antecedents of chronic disease and its progression are so multifactorial, considerable heterogeneity in response to different dietary patterns and nutrients among individuals and population subgroups exists, coupled with the complex interplay of foods and nutrients in the diet."
They also argue that while the scientific community does have some good longitudinal data, nutrition researchers are "woefully untrained to capitalize on the advances in machine learning and artificial intelligence that have been so powerful in other fields, such as environmental health".
"Moreover, we are faced with ever-evolving advances in factors that may mediate the relationship between exposure and outcome such as the microbiome," they add.
They discuss the increased awareness and scientific interest in the microbiome but, again, say our knowledge is lacking.
"The microbiome, and its importance, remains elusive, limiting its current usefulness when developing recommendations. Given that the host microbiome can be easily manipulated within days with diet and within hours with antibiotics, have we put too much reliance on its role in how nutrition modulates the host response?"
The report concludes that we know next to nothing about how to implement precision nutrition and suggests a more holistic approach to create a more robust knowledge base.
"Now is the time to pause—now is the time to collect the requisite data—now is the time to admit that we know next to nothing about how to implement precision nutrition. We need investment in better methods to assess exposure and then to assess how that exposure manifests in disease. Currently, we have weak methods for exposure assessment, and as a scientific community we suspend disbelief on the black box between exposure and outcome.
"The first step in precision nutrition is precision dietary assessment: We must know much more than what factors need to be captured; we must also understand the context of food behaviors if our recommendations are to be actionable and meaningful. Quantifying not only what we eat but also the context, timing, food preferences, cultural practices, agency, access, and so forth all must be implicit in moving the needle on food behavior changes. Finally, real-time monitoring, data science, and integrated efforts across disciplines will be the only reasonable solution."
Source: Annual Review of Nutrition
"Precision Nutrition: The Hype Is Exceeding the Science and Evidentiary Standards Needed to Inform Public Health Recommendations for Prevention of Chronic Disease"
Authors: Regan L. Bailey and Patrick J. Stover