[PHNUTR-L] Researcher focuses on pros, cons of antioxidants from fruits and vegetables

[Kathrynne Holden]

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Public release date: 18-Apr-2007
http://www.eurekalert.org/pub_releases/2007-04/tau--rfo041807.php

Contact: Dr. Susanne Talcott
smtalcott at tamu.edu
979-862-7095
Texas A&M University - Agricultural Communications

Researcher focuses on pros, cons of antioxidants from fruits and vegetables

COLLEGE STATION – Nutrition: It's not just the four basic food groups 
any more.

Researcher Dr. Susanne Mertens-Talcott of Texas A&M University is 
looking into how plant-based phytochemicals, including antioxidants and 
herbal supplements, can be useful in the promotion of health and 
prevention of chronic diseases.

This field is still growing. In the U.S. more than $20 billion was spent 
on dietary supplements in 2005, said Talcott, who is in a joint research 
and teaching position with the department of nutrition and food science 
and the department of veterinary physiology and pharmacology.

"Over $7 billion was spent on herbal dietary supplements in 2005." These 
supplements are plant-based, including grape seed extract, St. John's 
wort, ginseng and biloba extract, she added.

"In addition to that there is the segment of so-called 'functional 
foods,' including antioxidant foods – for example, fruit juices and 
beverages and grain-based products," Talcott said.

The amount spent on these foods each year "has increased drastically; 
however, we do not know yet how efficacious these different antioxidants 
really are in the prevention of chronic diseases such as cardiovascular 
disease and cancer," she said. "We also do not know very much about the 
mechanisms, which appear to include antioxidant and anti-inflammatory 
effects of these phytochemicals."

This can be important to health since these reactive oxygen species or 
'free radicals' may play a role in some diseases, including Alzheimer's, 
cancer and atherosclerosis, she said.

"However, other mechanisms, including the prevention of chronic 
inflammation and interaction with intracellular mechanisms, may be as 
important in the prevention of chronic diseases," she said. But are they 
safe? Are they efficient? How much is required? And how much is too 
much? Talcott is looking for the answers to these questions through her 
research.

"My overall goal is to find out more about the safety and efficacy of 
phytochemical dietary supplements," she said. Because these items are 
already popular with consumers, "we need to follow up with research. We 
know very little about (dose) recommendations and how safe (they are)."

Phytochemicals, also called secondary plant compounds – including 
antioxidants – have been defined as chemicals found in plants that have 
protective or disease-fighting properties ( http://phytochemicals.info/ ).

Pomegranate juice and extract have been the focus of much of her 
studies. Because these are used in different food products, they are 
found as ingredients in many different items in supermarkets, Talcott said.

She has also done research on the properties of muscadine grapes and 
acai, a palm fruit from Brazil, as well as isolated compounds including 
quercetin and ellagic acid, which are also sold as dietary supplements.

The results of some of her studies were published in the Oct. 13, 2006, 
edition of the Journal of Agricultural and Food Chemistry. The article 
was titled "Absorption, Metabolism and Antioxidant Effects of 
Pomegranate (Punica granatum L.) Polyphenols after Ingestion of a 
Standardized Extract in Healthy Human Volunteers."

In addition to her research, Talcott teaches a class on "Special Topics 
in Phytochemicals of Fruits and Vegetables" for students who are 
majoring in nutrition and food science. Many of the students are 
planning to enter medical or pharmacy school, she added.

"It is my goal to give students as much relevant information, which they 
directly can apply in their desired profession," Talcott said. 
"Consumers and patients have many questions about herbal dietary 
supplements, and health care professionals and (members of the) food 
industry are and will be even more confronted with these questions."

For example, Dr. Joseph M. Betz was a recent guest lecturer in Talcott's 
class. Betz is the director of the Dietary Supplement Methods and 
Reference Materials Program Office of Dietary Supplements at the 
National Institutes of Health in Bethesda, Md. He discussed Food and 
Drug Administration rules as to the differences between foods and drugs 
and how each must be labeled. With regard to herbal supplements, this 
can sometimes be a little tricky, he said.

During the question and answer period at the end of his talk, one of the 
students asked about a recent study on antioxidants. According to news 
reports, the study seemed to find that antioxidants – especially 
vitamins A and E – don't have the beneficial properties they are thought 
to have and may even increase mortality.

Talcott offered this clarification in regard to the study: "This study 
statistically analyzed many different clinical studies with vitamins A, 
E (and) C, beta-carotene and selenium. The performed statistical 
analysis indicated that vitamin A and E and beta-caraotene may increase 
mortality in some of the selected studies. The meaning of this study 
currently is being discussed."

The study looked at synthetic antioxidants, she said, which are not the 
same compounds that she is researching.

"Even though we still have a lot to learn about the efficacy, safety and 
dosing recommendations for herbal supplements and antioxidant foods, we 
can be confident to recommend a healthy balanced diet according to the 
food-pyramid rich in fresh fruits and vegetables. I also would not see a 
problem with the intake of reasonable amounts of standardized 
high-quality antioxidant dietary supplements," she said

"It is my long-term goal to see science-based intake recommendations 
developed for those herbal plant compounds which have a proven potential 
in the promotion of health and prevention of chronic disease."
-- 
Kathrynne Holden, MS, RD < fivestar at nutritionucanlivewith.com >
"Ask the Parkinson Dietitian"  http://www.parkinson.org/
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