HEALTHY PERSPECTIVE: CTGC publishes comprehensive review of research on health benefits of grapes
HEALTHY PERSPECTIVE: CTGC publishes comprehensive review of research on health benefits of grapes
Whenever a commodity organization makes claims regarding the health benefits of its product, no matter how solid the science might be to support a "superfood" status for that product, I think one is naturally inclined to anticipate a certain degree of hyperbole and perhaps even a little spin to make the good news sound even better than it is.
I therefore naturally approached the California Table Grape Commission's new document titled The Health Potential of Grapes: A Comprehensive Review of the Literature, with a certain amount of healthy skepticism (as one rightly should).
It is a document I have been eager to get my hands on since the commission's communications director, Jim Howard, told me well over a year ago that it was in the works, as I have been following research on the health benefits of grapes in the scientific literature for some time and was eager to compare my own assessment of those studies with the commission's conclusions.
Even though Mr. Howard assured me in an interview on May 23, 2007, and on other occasions, that "from the beginning we have chosen to take a very credible science-based approach to doing research," I confess I still at least half expected the new literature review, when it finally did come out, to lean a little heavily on the public relations.
In fact, the first three sentences in the document seem to be heading in that direction: "The grape. Classically beautiful and a pleasure to eat. And within the fruit -- a potent mix of antioxidants that offer significant health benefits as well." All true, of course, but it does sound a bit like ad copy.
I read on: "Today, research is being conducted across the country with a steady stream of new, positive findings. Good science takes time, but a solid foundation regarding grapes and health is clearly in place." Now that sounds like something I might have written based on my own reading of the scientific literature. But will this review lay that solid foundation, making clear distinctions between what is actually known and what merely shows promise based on early observations?
I was delighted to discover that those distinctions were made, early on and page after page, throughout the overview and in the various analyses within the 80-plus-page literature review itself.
Significantly, by the third paragraph, the document makes a clear distinction among different types of studies and notes the purposes and limitations of each:
"The evidence that grapes reduce the risk of chronic diseases comes from cell culture, animal, human observational, and human clinical studies. The animal and cell studies establish the biological plausibility that grapes have an impact and help to define how they achieve that impact. Human observational (or epidemiological) studies help to detect associations, and human dietary intervention (or clinical) studies highlight cause and effect."
The executive summary elaborates on those points: "Animal and cell culture studies are important to establish biological plausibility, and they provide significant mechanistic support for the health benefits of grapes. Human observational studies [or epidemiological studies] provide suggestive evidence" that grapes in the diet are associated with reduced risk of some cancers, cardiovascular disease and other chronic diseases, but "although promising, the conclusions that can be drawn from the epidemiological evidence are limited."
That acknowledgement impressed me, as one of the most commonly made mistakes is to assume that an epidemiologically demonstrated association constitutes proof of cause and effect. That can be shown only by the fourth type of study, human dietary intervention studies, or clinical studies.
Evaluating the hundreds of published studies on the health benefits of grapes in that light, the document correctly concludes: "A comprehensive review of the scientific literature provides the strongest evidence that these foods [grapes and grape products] reduce the risk of CVD [cardiovascular disease], with considerable data also suggesting that grapes and grape products have anticarcinogenic properties. The evidence that these foods reduce the risk of Alzheimer's disease and a variety of other health-related conditions is emerging."
No hype there. No exaggeration. No unwarranted conclusions. Just sound science. And that is as it should be, because the news is good enough without any hyperbole -- and, as Mr. Howard stated, the message is much more credible when it remains rooted in sound science.
In a word, notwithstanding the vested interest that the California Table Grape Commission has in making grapes "look good," I regard this report as having a high degree of credibility. In fact, I find it far more credible than the majority of newspaper and broadcast news reports I encounter on health topics, which seem so often to be more sensationalism than sound science.
With that preface, here are a few highlights from the document's overview:
"Grapes are a rich source of bioactive compounds or phytonutrients, the biologically active substances in plant foods that appear to help fight disease and enhance health. Grapes contain an abundance of polyphenols, including flavonoids, and are also one of the main dietary sources of resveratrol, a stilbene. Resveratrol is found in the skins of grapes of all colors and is known for its antioxidant and anti-inflammatory properties. Grape flavonoids include quercetin, catechins, tannins, anthocyanidins and proanthocyanidins. These compounds are found in all parts of the grape including skin, flesh and seeds. A recent review of documented natural grape compounds totaled 1,610, including the presence of the carotenoids lutein and beta-carotene."
The antioxidant capabilities of grapes as well as grape juice have been "clearly demonstrated" in "a number of human intervention studies," the overview states.
Studies on the antioxidant and anti-inflammatory properties of resveratrol "suggest that it may offer intriguing disease-fighting capabilities, and scientists have enthusiastically jumped in to study it." Since "groundbreaking research detailing resveratrol's ability to fight cancer at three critical stages appeared in the journal Science in 1997, there have been more than 1,900 published papers on resveratrol, the review states.
Grapes are "the predominant natural dietary source of this unique and powerful phytonutrient," it states.
Much attention has been given in the media about the resveratrol in red wine and the resultant health benefits, but studies have demonstrated that the same benefits are derived from grapes and grape juice. Since white wine does not have the same benefits as red wine, many people incorrectly concluded that resveratrol was found only in red grapes and not in green grapes (or white grapes, as they are known in the wine and grape juice industries). But in fact, resveratrol is found in the skins of all colors of grapes and is actually higher in some green varieties than in some red varieties. Unlike anthocyanins, resveratrol is not related to pigmentation.
So why does white wine not contain significant amounts of resveratrol? "Red wine is typically made using grape skins," while "white wine is not," according to a side note in the "Overview of Heath Benefits."
Human intervention studies with grapes and grape products "provide consistent support for the premise that grapes and grape juice have a beneficial role in reducing the risk of cardiovascular disease," the document states. In various studies, "grape intake positively [affected] a variety of cardiovascular biomarkers including plasma lipid and lipoprotein concentrations, endothelium response, platelet activation and inflammatory biomarkers."
And that's just scratching the surface.
With all the good things grapes have going for them in terms of health benefits, who can blame the document's writers for adding the obvious and somewhat glowingl statement, that grapes are "classically beautiful and a pleasure to eat."
(For more on California grapes, see the July 28 issue of The Produce News.)
I therefore naturally approached the California Table Grape Commission's new document titled The Health Potential of Grapes: A Comprehensive Review of the Literature, with a certain amount of healthy skepticism (as one rightly should).
It is a document I have been eager to get my hands on since the commission's communications director, Jim Howard, told me well over a year ago that it was in the works, as I have been following research on the health benefits of grapes in the scientific literature for some time and was eager to compare my own assessment of those studies with the commission's conclusions.
Even though Mr. Howard assured me in an interview on May 23, 2007, and on other occasions, that "from the beginning we have chosen to take a very credible science-based approach to doing research," I confess I still at least half expected the new literature review, when it finally did come out, to lean a little heavily on the public relations.
In fact, the first three sentences in the document seem to be heading in that direction: "The grape. Classically beautiful and a pleasure to eat. And within the fruit -- a potent mix of antioxidants that offer significant health benefits as well." All true, of course, but it does sound a bit like ad copy.
I read on: "Today, research is being conducted across the country with a steady stream of new, positive findings. Good science takes time, but a solid foundation regarding grapes and health is clearly in place." Now that sounds like something I might have written based on my own reading of the scientific literature. But will this review lay that solid foundation, making clear distinctions between what is actually known and what merely shows promise based on early observations?
I was delighted to discover that those distinctions were made, early on and page after page, throughout the overview and in the various analyses within the 80-plus-page literature review itself.
Significantly, by the third paragraph, the document makes a clear distinction among different types of studies and notes the purposes and limitations of each:
"The evidence that grapes reduce the risk of chronic diseases comes from cell culture, animal, human observational, and human clinical studies. The animal and cell studies establish the biological plausibility that grapes have an impact and help to define how they achieve that impact. Human observational (or epidemiological) studies help to detect associations, and human dietary intervention (or clinical) studies highlight cause and effect."
The executive summary elaborates on those points: "Animal and cell culture studies are important to establish biological plausibility, and they provide significant mechanistic support for the health benefits of grapes. Human observational studies [or epidemiological studies] provide suggestive evidence" that grapes in the diet are associated with reduced risk of some cancers, cardiovascular disease and other chronic diseases, but "although promising, the conclusions that can be drawn from the epidemiological evidence are limited."
That acknowledgement impressed me, as one of the most commonly made mistakes is to assume that an epidemiologically demonstrated association constitutes proof of cause and effect. That can be shown only by the fourth type of study, human dietary intervention studies, or clinical studies.
Evaluating the hundreds of published studies on the health benefits of grapes in that light, the document correctly concludes: "A comprehensive review of the scientific literature provides the strongest evidence that these foods [grapes and grape products] reduce the risk of CVD [cardiovascular disease], with considerable data also suggesting that grapes and grape products have anticarcinogenic properties. The evidence that these foods reduce the risk of Alzheimer's disease and a variety of other health-related conditions is emerging."
No hype there. No exaggeration. No unwarranted conclusions. Just sound science. And that is as it should be, because the news is good enough without any hyperbole -- and, as Mr. Howard stated, the message is much more credible when it remains rooted in sound science.
In a word, notwithstanding the vested interest that the California Table Grape Commission has in making grapes "look good," I regard this report as having a high degree of credibility. In fact, I find it far more credible than the majority of newspaper and broadcast news reports I encounter on health topics, which seem so often to be more sensationalism than sound science.
With that preface, here are a few highlights from the document's overview:
"Grapes are a rich source of bioactive compounds or phytonutrients, the biologically active substances in plant foods that appear to help fight disease and enhance health. Grapes contain an abundance of polyphenols, including flavonoids, and are also one of the main dietary sources of resveratrol, a stilbene. Resveratrol is found in the skins of grapes of all colors and is known for its antioxidant and anti-inflammatory properties. Grape flavonoids include quercetin, catechins, tannins, anthocyanidins and proanthocyanidins. These compounds are found in all parts of the grape including skin, flesh and seeds. A recent review of documented natural grape compounds totaled 1,610, including the presence of the carotenoids lutein and beta-carotene."
The antioxidant capabilities of grapes as well as grape juice have been "clearly demonstrated" in "a number of human intervention studies," the overview states.
Studies on the antioxidant and anti-inflammatory properties of resveratrol "suggest that it may offer intriguing disease-fighting capabilities, and scientists have enthusiastically jumped in to study it." Since "groundbreaking research detailing resveratrol's ability to fight cancer at three critical stages appeared in the journal Science in 1997, there have been more than 1,900 published papers on resveratrol, the review states.
Grapes are "the predominant natural dietary source of this unique and powerful phytonutrient," it states.
Much attention has been given in the media about the resveratrol in red wine and the resultant health benefits, but studies have demonstrated that the same benefits are derived from grapes and grape juice. Since white wine does not have the same benefits as red wine, many people incorrectly concluded that resveratrol was found only in red grapes and not in green grapes (or white grapes, as they are known in the wine and grape juice industries). But in fact, resveratrol is found in the skins of all colors of grapes and is actually higher in some green varieties than in some red varieties. Unlike anthocyanins, resveratrol is not related to pigmentation.
So why does white wine not contain significant amounts of resveratrol? "Red wine is typically made using grape skins," while "white wine is not," according to a side note in the "Overview of Heath Benefits."
Human intervention studies with grapes and grape products "provide consistent support for the premise that grapes and grape juice have a beneficial role in reducing the risk of cardiovascular disease," the document states. In various studies, "grape intake positively [affected] a variety of cardiovascular biomarkers including plasma lipid and lipoprotein concentrations, endothelium response, platelet activation and inflammatory biomarkers."
And that's just scratching the surface.
With all the good things grapes have going for them in terms of health benefits, who can blame the document's writers for adding the obvious and somewhat glowingl statement, that grapes are "classically beautiful and a pleasure to eat."
(For more on California grapes, see the July 28 issue of The Produce News.)
