California Grapes and Health

Fresh grapes of all colors — red, green and black – are classically beautiful and a pleasure to eat.  But there is more: Grapes contain a natural mix of antioxidants that help support a healthy heart and may offer an array of other health benefits.  Additionally, emerging laboratory research on grapes or grape constituents has demonstrated anti-cancer activities and the potential to help maintain brain health.

How do grapes promote heart health?

Studies have shown that grapes may help support a healthy cardiovascular system in the following ways:

  • by preventing platelet aggregation (which can lead to clot formation)
  • enhancing arterial flexibility and function
  • reducing inflammation
  • inhibiting the oxidation of “bad” LDL cholesterol
  • lowering blood pressure

Beneficial Antioxidants

Grapes contain an abundance of polyphenols, including flavonoids, and are also one of the main dietary sources of resveratrol.  Resveratrol is found in the skins of grapes of all colors and is known for its antioxidant and anti-inflammatory properties.  Grape flavonoids are found in all parts of the grape including skin, flesh and seeds. A recent review of documented natural grape compounds totaled 1610, including the presence of the carotenoids lutein and beta-carotene.  There are likely still hundreds of compounds yet to be identified.

Antioxidants:

  • Help protect cells by neutralizing the damaging effects of free radicals present in the environment
  • Help reduce oxidative stress, a condition associated with the development of many chronic diseases

Green Grapes Have Antioxidants Too

Contrary to popular belief, green (white) grapes also contain antioxidants.  A recent study that looked at the total antioxidant capacity (as measured by ORAC) of green grapes and red grapes found significant levels in each:  The red grapes had an antioxidant capacity of 2016 while the green grapes had an antioxidant capacity of 1789.

The bottom line is that grapes of all colors contain antioxidants.  It’s just that red and black grapes also contain anthocyanins, which are a type of phytonutrient responsible for red and blue pigment in fruits and vegetables.

A Word About Antioxidant Capacity Values Such as ORAC

The antioxidant power of a food is often equated to its ORAC value, a test tube analysis that measures Oxygen Radical Absorbance Capacity (ORAC).  However, it is important to understand that the antioxidant capacity of a food is not fully measured by ORAC, and it does not reflect its ability to alter antioxidant status in humans.

While the ORAC test measures the free radical scavenging activity against one type of free radical — the peroxyl radical — there are other types of free radicals, and there are numerous other assays that measure activity against them.

Additionally, what is most important about antioxidants is whether they are bioavailable, or able to be taken up and used by the body.  Phytonutrients have varying degrees of bioavailability after being consumed and may affect biological processes differently once absorbed into the body.

Thus, taken by itself, an ORAC value provides just a partial picture of antioxidant capacity and is not the sole indication of health benefits.

Grape Antioxidants Are Bioavailable In Humans

Research studies in humans have proven that grapes provide phytonutrients that are readily bioavailable and that significantly raise antioxidant capacity in humans.  Research conducted by Dr. Ronald L Prior of the USDA’s Arkansas Children’s Nutrition Center also indicates that grapes may demonstrate a stronger propensity to raise antioxidant levels in humans than other high antioxidant fruits showed in separate studies.

“Grapes give a really good dose of antioxidants.  You may actually have to eat more of other foods high in anthocyanins to show a similar response in antioxidant levels.”  Dr. Ronald L. Prior, USDA Arkansas Children’s Nutrition Center.

What’s Next?

Today, research is being conducted across the country with a steady stream of new findings. Good science takes time, but already a solid foundation of scientific evidence regarding grapes and health is clearly in place.