Volume 68, Issues 22–24, November–December 2007, Pages 2986–3008
Highlights in the Evolution of Phytochemistry: 50 Years of the Phytochemical Society of Europe
Abstract
Epidemiological
studies show a link between the consumption of plant-derived foods and a
range of health benefits. These benefits have been associated, at least
partially, to some of the phytochemical constituents, and, in
particular, to polyphenols. In the last few years, nutraceuticals have
appeared in the market. These are pharmaceutical forms (pills, powders,
capsules, vials, etc.) containing food bioactive compounds as active
principles. The bioactive phytochemicals have become a very significant
source for nutraceutical ingredients. Scientific research supports the
biological activity of many of these food phytochemicals, but the health
claims attributed to the final marketed nutraceutical products have
often little or doubtful scientific foundation. This is due to the fact
that a lot of the scientific evidence is derived from animal testing and
in vitro assays, whereas human clinical trials are scarce and
inconclusive. Some key issues such as bioavailability, metabolism,
dose/response and toxicity of these food bioactive compounds or the
nutraceuticals themselves have not been well established yet. Amongst
the phytochemicals, several groups of polyphenols (anthocyanins,
proanthocyanidins, flavanones, isoflavones, resveratrol and ellagic
acid) are currently used in the nutraceutical industry. In this report,
we have reviewed the most recent scientific knowledge on the
bioavailability and biological activity of these polyphenols (‘fact’),
as well as the health claims (which are not always supported by
scientific studies) ascribed to the polyphenols-containing
nutraceuticals (‘fiction’). The in vitro antioxidant capacity, often used as a claim, can be irrelevant in terms of in vivo
antioxidant effects. Bioavailability, metabolism, and tissue
distribution of these polyphenols in humans are key factors that need to
be clearly established in association to the biological effects of
these polyphenols-containing nutraceuticals. The future trends of
phytochemistry research regarding nutraceuticals are discussed.
