Personalized nutrition from a health perspective: luxury or necessity?
© Springer-Verlag 2007
Published: 19 September 2007
Scientific progress has shown the involvement of diet in a large number of diseases and disorders (e.g. colon cancer, cardiovascular disorders, diabetes mellitus type 2, a number of inflammation related health problems, etc.). This triggered the introduction of functional foods, dietary components with “added health value”. So far, only a few successful products were launched (cholesterol lowering stannols, probiotics, a number of specific fatty acids), and most of these functional foods had great difficulty to obtain scientific proof of efficacy. Why does nutritional science have such a hard job in providing evidence for health claims related to dietary components? Unlike pharmacological and biomedical research, where bioactive compounds are developed to treat a well-characterized disease, nutrition deals with prevention of disease and optimization of health. Biomarkers that quantify the health status essentially are missing, and much of the nutrition research (the large observational and intervention cohorts) relies on disease endpoints instead of health endpoints. Also in the “golden standard” of nutrition and health research, the crossover dietary intervention studies, the quantification of the effect is a major issue. Usually, the observed effects are minor and great efforts have to be made to unravel treatment related health effect from the confounding parameters. In other words, the confounding parameters have a large impact. The recent “omics”-related observations in human intervention studies confirm that intra-individual variation is much smaller than inter-individual variation. Differences between study subjects may be much larger than differences directly related to dietary treatment.
To what extent is this personal diet- and health-relationship practically valid;
How can nutritional science demonstrate this? My personal opinion is that indeed this relationship exists to a much greater extent than assumed until now, and that nutritional science will need to do a much better job in accurately identifying and quantifying the subtle differences in health status related to dietary treatment. A complete merge of nutrition with a number of fundamental scientific disciplines (molecular biology, biochemistry, bioinformatics, statistics, etc.) will be essential here.
A second major bottleneck in the nutrition and (personalized) health relationship is the inadequacy to determine effects. We all know (or suppose?) that nutrition is related to diseases and disorders. However, we fail to measure the correct effect. Slowly, we now begin to realize that between the nutritional impact on daily homeostasis and the disease (endpoints), a separate layer of “overarching processes” both controls health and drives disease onset. Think about metabolic stress, inflammatory stress, and oxidative stress. These processes are both complex and interacting. Also, they are controlled by “setpoints” adding an additional complexity related to neurology, endocrinology and epigenomics. It might be worthwhile to revisit these “overarching processes” once we have a better grip on nutritional systems biology, i.e. the ability to study these processes both in molecular detail and in their relationship, embedded in molecular physiology. Nutritional science may and very likely eventually will determine a large number of personalized nutrition and health relationships. However, this is only a small part of the equation. Food consumption nowadays is hardly related to health, but much more to convenience. “Food is pleasure” rightfully is the credo and science will have a hard job in promoting healthy diet if this aspect is compromised. So, a personalized diet needs to be both optimized towards personal health and personal convenience. What a challenge!