Precision nutrition uses the findings from nutrigenetics and nutrigenomics studies to tailor recommendations to meet the nutrition needs of a particular person or population. Although we know the transition to precision nutrition is required to meet the nutrition needs of all people and will likely play a key role in reducing widespread health disparities, the actual implementation of precision nutrition, especially for complex traits (eg, polygenic traits), remains difficult. Similar to the effective implementation of precision medicine,²⁷ that of precision nutrition will need to be carefully designed and systematic (standardized and used to integrate and analyze data gathered for each individual [eg, genomics, metabolomics, epigenomics] and to diagnose disease or predict disease risk). This process requires the use of systems biology, a relatively new field that focuses on the integration of multiple levels of biological information, including cellular data (eg, transcriptome, epigenome, microbiome), multiorgan data (eg, liver, adipose, brain), and sometimes also physiological and environmental exposure data (eg, chemical exposures).²⁸

Systems biology approaches are currently being utilized to provide a holistic view of changes occurring across multiple systems or pathways, to identify causal mechanisms more easily than if only one type of bio - logical pathway were considered at a time. Indeed, changes in one system are not isolated events and likely to yield both upstream and downstream perturbations. The identification and characterization of multisystem effects will allow for a better understanding of problems and, thus, more accurate prediction of outcomes (eg, disease risk). Systems biology approaches and implementation methods are still emerging, limited mainly by the development of new methods to more accurately and systematically analyze the ever evolving and growing quantities of data produced and the limited availability of the computational scientists with the expertise to analyze the data. Nonetheless, the potential for systems biology to increase our knowledge of nutritional needs and its roles in disease continues to spur enthusiasm for the field and further development of the required methods.

Complex chronic diseases with strong diet influences, such as obesity, diabetes, heart disease, and liver disease, are at concerning levels and on the rise across the globe (see Chapter 38: Pediatric Obesity). Evidence shows that individuals and populations differ in prevalence of these diseases and in many cases researchers have been able to link prevalence to interindividual differences in nutrient needs and responses. Precision nutrition is already being applied in simpler diseases such as many of the monogenic diseases described previously. However, for more complex diseases, it remains a promise for the future. We also require more scientific evidence to show that compared to the current generalized guidelines, precision nutrition recommendations actually lead to the required behavioral changes in dietary intake required to improve health outcomes.⁶

The technical challenges of precision nutrition are daunting. This includes the storage, management, and interpretation of the vast quantity of -omic data required. Nonetheless, the study of human nutrition will continue to be exciting and rewarding.