Research Perspective and Comments & Analysis
Grapes And Health: Research Findings
By Kathleen Nave, President, California Table Grape Commission
When it comes to produce and health, the evidence of benefits is overwhelming, and the role of fruits and vegetables in promoting health is recognized by major public health entities and advocacy groups worldwide. Within the produce industry, much effort has gone into better defining and understanding those benefits with new findings emerging on a regular basis that reinforce the promise of produce.
For nearly 20 years, the California table grape industry has supported research into the health benefits of grapes. The program was created to better understand the beneficial compounds in grapes that could play a role in health and disease prevention, as well as to help build the body of scientific evidence on grapes and health. The program funds investigator-initiated studies on a wide range of topics, all of which are run independently of Commission involvement. The researchers are free to publish their findings, no matter what the study outcome. The result has been strong interest by the research community nationwide to apply for and conduct research on grapes and health.
Most recently, a newly published study heralded new hope in the area of brain health: a grape-enriched diet was shown to protect against metabolic brain decline in Alzheimer’s-related areas of the brain. Specifically, in a pilot study of people with early memory decline, subjects were either fed whole grape powder equivalent to just 2 ¼ cups of grapes per day, or a placebo powder. The results showed that consuming grapes preserved healthy metabolic activity in regions of the brain associated with early Alzheimer’s disease, where metabolic decline takes hold. Subjects who didn’t consume grapes exhibited significant metabolic decline in these critical regions. Additionally, those consuming the grape-enriched diet showed beneficial changes in regional brain metabolism that correlated to improvements in cognition and working memory performance.
While research in the area of grapes and brain health is emerging, the evidence surrounding grapes and heart health is well-established, including the protective effects of grape polyphenols against the development of atherosclerosis. Heart-healthy grapes may also play a role in healthy aging as presented in the chapters of a recently published monograph titled, Grapes and Health, which covers a broad range of grape research conducted on relevant health issues, including:
Inflammation — Intake of grape products can help modify both local and systemic inflammation by acting in a variety of ways that go beyond antioxidant effects. Inflammation plays a critical role in most chronic diseases, so the ability to modulate inflammation has far-reaching implications.
Cancer — A high intake of fruits and vegetables is associated with disease prevention, and grapes are a food that should be included in a healthy diet. Many studies have been conducted to evaluate the potential for grapes and grape products to inhibit cancer, with intriguing results in the area of colon cancer.
GI Health — The link between intestinal health and overall health is an exciting new field of research. Polyphenols may influence nutrient absorption and intestinal bacteria and their fermentation products; since they are not well absorbed in the upper GI tract, they do arrive in the colon where they have been shown to influence microbial growth and metabolism.
Brain Health — Various grape products have been studied and shown to reduce symptoms of post-traumatic stress disorder, including anxiety, depression and memory loss; and improve learning and memory in mice with Alzheimer’s and in animals exposed to stress, aging and disease.
Joint Health — Grapes have been shown to exert a beneficial effect in osteoarthritis and some inflammatory arthritis forms, including rheumatoid arthritis.
Bladder Health — A series of animal studies have shown a grape-enriched diet protects the bladder from dysfunction associated with partial bladder outlet obstruction. In humans, more than 80 percent of men older than 50 are affected by this issue due to an enlarged prostate gland. Grapes provide an antioxidant effect that helps counter the damaging effects of oxygen deprivation and free radical generation that occur and disrupt normal cell function, ultimately injuring the nerves and smooth muscle cells in the bladder wall.
Eye Health —Grapes may contribute to eye health by promoting antioxidant actions that protect the retina’s structure and function; preventing activation of inflammatory pathways and inhibiting abnormal and harmful blood vessel growth in the eye.
Just as science has made clear the health benefits provided by daily consumption of a mix of fruits and vegetables, it is making clear the broad-scale benefits consumption of fresh grapes provides. This growing evidence reinforces the benefits of produce intake generally. The fact that grapes are a favorite fruit for consumers of all ages and they are readily available — California’s season is May through January — makes adding them to the list of items eaten on a regular, or maybe even on a daily basis, easy.
The California Table Grape Commission was established by an act of the state’s legislature in 1967. Approved by a grower referendum in 1968, the commission has been affirmed through grower referenda every five years since its inception. The commission’s importance to the state and its mandate – to maintain and expand markets for fresh California grapes and to create new and larger intrastate, interstate and foreign markets – was reaffirmed and its authorities broadened by the legislature in 1995, 1997 and again in 2001. The commission’s activities are divided into five areas: research, trade management, issue management, education and outreach, and advertising.
Infusion Of Health Message Is Good For Grape Sales
The California Table Grape Commission deserves recognition for its willingness to encourage research of high quality. In the end, this means taking a risk that, sometimes, researchers will not find the results the grape industry might hope for. But only by allowing researchers to publish the results, come what may, can the research have credibility or the industry attract the best researchers.
Of course, the grape industry has been fortunate as most of the research has, in fact, pointed to the possibility that grapes offer many positive health benefits.
This is very important, as this kind of research represents the opportunity for the produce industry to use health as a lever to increase consumption in a way that existing research has not really allowed. If you look at industry promotions such as 5-A-Day or the Fruits & Veggies More Matters program, they are based on a general thesis that eating more fruits and vegetables offers health benefits.
This is what the preponderance of the evidence shows, but this fact has not been sufficient to motivate increased levels of consumption. There is reason to believe that this is, at least in part, because the proven benefits of increased produce consumption are too amorphous, too vague, to motivate behavioral change.
Is the benefit actually from eating more produce in and of itself, or is it that eating more produce displaces other, less healthy foods? And what exactly is the benefit? How much longer, on average, will a person live if he or she consumes a produce-rich diet? How much less likely is he or she to get cancer? Have heart disease? Experience a stroke?
There are no clear answers to any of these questions, and probably never will be. It is extremely difficult and expensive to do controlled experiments in which we can measure how a dietary change over a lifetime impacts mortality. Most of the studies that we have leave open questions of causality. Even if we can establish that people who eat produce-rich diets live longer and healthier lives, it is very difficult to distinguish if it is the produce that causes this effect or if people with good attitudes toward health eat more produce and do other things such as exercise — and these other things lead to the positive outcome.
The kind of research the California Table Grape Commission is funding — focused on specific benefits of consumption of a specific item — holds the potential to motivate consumption in a way more generalized studies never could.
At the same time, the research points to the challenges ahead for the fresh industry. After all, a lot of the buzz concerning the benefits of grape consumption has focused on resveratrol and red wine. Other research has involved grape powder or other grape products — all non-fresh items.
Fresh produce has enjoyed a healthy image; and indeed, many studies have questioned the value of supplements, suggesting that nutritional benefits may be complex and dependent on the interplay of numerous factors and thus not easily amenable to isolating in one supplement. Yet, it still is not obvious the research will establish that fresh is better than canned, frozen, dehydrated, beverage or other product variants. Will table grapes be better than wine, raisins, powdered grapes, etc.? These points are not trivial; table grapes can come from limited places at a given time, whereas grape powder can come from anywhere.
For now, though, thanks to the California Table Grape Commission, we are presented the tantalizing images of grapes as a snack chock-full with benefits most only guessed at. And there is something extraordinary about the fact that produce in general, and grapes in particular, draw from the earth, the water, and the sun a panoply of riches, and that life in humans can be strengthened by drawing on the elements of life that find their way into fresh produce.
For the industry, these efforts are a model to be emulated. Instead of just selling what we have always sold, these efforts are ways of identifying previously unknown benefits to start to sell anew. And, in the grape industry, where new varietal development proceeds apace, this research raises the question of whether new varietal development, in addition to focusing on horticultural and flavor advantages, could also focus on enriching health benefits. After all, if we are going to market with a health message, won’t it be worth developing grapes that justify even stronger and more specific health messages?
Grapes that are both delicious and offer specific health benefits will appeal to supermarkets and consumers alike. It is a sure-fire route to better sales.