Chronic diseases like diabetes, heart disease, arthritis, cognition diseases and cancer have
been linked to "oxidation" of proteins and fats - this is where oxygen molecules attach to
proteins/fats in cells and cause damage and inflammation. This is why "antioxidants"
have received so much media attention because they help to remove the damaging
oxygen molecules from proteins. Some of the most important antioxidants are
phytochemicals, especially the phenoles, found in plant foods (e.g grapes, olives), herbs
(e.g oregano) and spices (e.g cumin). A new theory has been put forward by nutrition
scientists (Professor Shetty and Professor Wahlqvist which will be published in the next
issue of APJCN March 2004) about how these phenoles may be using an energy
producing pathway (pentose phosphate) which also involves a protein amino acid
(proline) to stimulate this antioxidant response. This also means that foods high in
protein/proline (e.g fish, legumes) may help the antioxidant response. This is an
interesting theory. Till the details of the pathways are worked out, remember to eat a
variety of plant foods and to use herbs and spices where ever possible.
Preventive management of diseases and phytochemicals: A New Perspective
Kalidas Shetty, PhD, Department of Food Science, University of Massachusetts,
Amherst, MA 01003, USA (e-mail: kalidas@foodsci.umass.edu)
In a recent insightful article in APJCN Professor Mark Wahlqvist ( Wahlqvist, M.L.
(2002) Asia Pacific J. Clin Nutrition, 2002; 11(S): S759-S762) stated that the
combination of immuno-deficiency, inflammatory process and nutritional status that is
characteristic of infective and food-borne illness is more evident in chronic diet- and
environment-influenced chronic diseases such as diabetes, obesity, cardiovascular
disease, cancer, arthritis and neuro-degeneration diseases. These chronic diseases tend to
be oxidation-linked and may manifest in communities around the world, irrespective of
income. In addressing the challenges of the above diseases, a significant role for dietary
phytochemicals is emerging. Phytochemicals are required from a spectrum of diet for at
least their antioxidant role, if not for other properties, to protect tissues from activities
that manifest themselves into what we call chronic disease. Among the diverse groups of
phytochemicals, phenolic antioxidants and antimicrobials from dietary plants are being
targeted for designed dietary intervention to manage major oxidation-linked diseases such
as diabetes, cardiovascular diseases, arthritis, cognition diseases and cancer. Foods
containing phenolic phytochemicals are also being targeted to manage bacterial infections
associated with chronic diseases such as peptic ulcer, urinary tract infections, dental
caries and food-borne bacterial infections. In our extensive review (“A Model for the
Role of Proline-Linked Pentose-Phosphate Pathway in Phenolic Phytochemical
Biosynthesis and Mechanism of Action for Human Health and Environmental
Applications; A Review” by Kalidas Shetty from University of Massachusetts, Amherst,
USA & Mark L. Wahlqvist, Monash University, Melbourne, Australia in APJCN,
March/April, 2004) we have offered a novel and an integrated perspective about how
dietary phenolic phytochemicals (from fruits, vegetables, beverages, herbs and spices and
their products) can have an important role in preventive management of chronic oxidation
and infectious diseases. In our model for role of dietary phytochemicals in preventive
management of diseases we have focused on how phenolic phytochemicals at the cellular
level could counter oxidation-linked biochemical reactions and in particular how an
alternative mode of energy metabolism through the use of proline (an amino acid) may be
more important for providing energy and reducing equivalents such as NADPH2
(involved in energy production in cells) for stimulating protective antioxidant response.
An interesting aspect of our model is that the role of phenolic phytochemicals in
preventive management of diseases also integrates a role for easily and readily
assimilated sources of protein foods (particularly legume and fish proteins) for improved
antioxidant response through the proline-linked metabolism.
From our initial investigations we have specifically proposed that the prolinelinked pentose-phosphate pathway may be critical for modulating protective antioxidant
response pathways in diverse biological systems, including biochemical and cellular
pathways important for human health. The proposed proline-linked pentose-phosphate
pathway model provides a mechanism for understanding the mode of action of phenolic
phytochemicals and proteins from the diet in modulating antioxidant pathways and
provides avenues by which dietary approaches may manage oxidation-linked chronic and
infectious diseases. The model also has implications for the development of
antimicrobial phenolic phytochemicals against bacterial pathogens in an era of increasing
antibiotic resistance and for improved strategies for drug discovery and design. Further
this model also has relevance for designing clonal phytochemical profiles of single
genetic origin and for improving fungal and yeast-based food bioprocessing for designing
functional foods. In terms of environmental challenges the model provides strategies for
environmental bioremediation using plant and microbial systems, as well as for
improving agricultural and food production systems in harsh environments.