Dark berries like blueberries and cranberries are increasingly recognized in the public as health icons. Not only nutritious by their contents of vitamins, minerals, amino acids, protein and dietary fiber, berries are also synonymous with antioxidant health benefits.
Antioxidants are an important nutrient category thought to be the major health characteristic of colorful fruits and vegetables. Antioxidants are substances synthesized in our bodies or obtained via edible plant chemicals that can prevent or slow oxidative stress to our body’s cells. More than 60 diseases, including cancer, diabetes, inflammatory, neurological and cardiovascular diseases, are linked to oxidative stress that may be relieved by dietary antioxidants.
Scientists believe that plants make antioxidant chemicals to protect the plant’s regenerative capacity from the damaging effects of constant exposure to sunlight, ultraviolet radiation, infections, pests, injury and oxygen radicals produced during photosynthesis. These antioxidants are found in their highest concentrations in the fruit skin (or rind) and seeds.
Antioxidant phytochemicals, such as the blueberry anthocyanins, contribute scent and blue pigment to the berry skin. This plays a useful regenerative role to attract insect pollinators and birds that eat the fruit and then disperse the seeds in their droppings.
Plants also benefit from antioxidant protection in their skin against ultraviolet radiation, photo-oxidative processes, and viral or bacterial pathogens. These are benefits that can be passed on to animals and humans who consume the berries.
Oxidative Stress and “Pigment Power”
Without protective antioxidants from pigments like anthocyanins in berry skin, reactive oxygen species (ROS) are created during normal photosynthesis leading to oxidative injury. These injuries affect proteins, lipids and nucleic acids, and can cause alteration in gene transcription and even lead to programmed cell death (a process scientists call “apoptosis”, eh-poh-toe-sis) in the fruit or its seeds. Some botanists and food chemists refer to this protective benefit as “pigment power”, which is desirable to obtain through the human diet. We acquire this transfer of protection by eating fruits, vegetables and animal sources that have color-rich pigments. Dark berries are an excellent source of these pigments.
Within colorful berries we can find many members of the pigment group called “phenolics.” Each member provides antioxidants, color, scent, and flavor qualities. The following is just a sampling of the thousands of edible plant phenolics. Any one berry species may contain dozens of antioxidant pigments. Each of the berries below is a rich source of anthocyanin pigments; a few of which are listed where medical and food science have revealed preliminary evidence for health benefits.
Here is a list of the antioxidants found in the following berries:
o Blackberries: gallic acid
o Black raspberries: ferulic acid
o Blueberries: anthocyanins, chlorogenic acid, peonidins
o Cranberries: proanthocyanidins, catechins, quercetin
o Elderberries: myricetin
o Red raspberries: ellagitannins, procyanidins
o Red grapes: resveratrol, proanthocyanidins (seeds), catechins
o Strawberries: ellagic acid
ROS – Radical Oxygen Species
When human cells use oxygen, they naturally produce ROS as by-products of normal metabolism. This can lead to cell damage if normal counter-balances are absent in the environment inside and around cells. ROS are also called “oxygen free radicals” or elements so reactive they are “free” to interact with numerous cells and chemicals in the body, often in a way that is damaging.
Antioxidants synthesized internally or introduced from our diets act as neutralizing sponges or “scavengers” of ROS. By donating electrons sought by the free radical, antioxidant molecules serve to counterbalance, absorb, quench, prevent or repair damage done by ROS.
However, when balancing mechanisms are ineffective, perhaps because of a diet poor in antioxidant foods or during the decline of body functions with disease or aging, ROS disperse randomly in a concentration gradient from their point of formation. There, if unchecked by antioxidants, they can cause damage within cells and to nearby cells, that can contribute to disease and aging. This is one of the leading theories for how Alzheimer’s disease progressively destroys neurons.
Oxidative Stress and Dietary “Therapy”
Most diseases are initiated and perpetuated to some degree by ROS and by insufficient amounts of internal and dietary antioxidants. These are the underlying conditions for “oxidative stress” which may explain a sizable component of aging.
If chronic, oxidative stress can lead to an increased risk of developing the following diseases:
o Cardiovascular and inflammatory disorders
o Neuronal degeneration (e.g., Alzheimer’s and Parkinson’s disease)
o Macular degeneration causing vision loss and general deterioration of aging
o Chronic sickness
Measuring Antioxidant Strength: ORAC
The term ORAC, standing for “oxygen radical absorbance capacity”, is a numerical way of representing antioxidant strength in berries and other foods. When antioxidants are present in a food, their collective strength can be measured in the test tube assay called ORAC.
Recently, scientists working with the US Department of Agriculture published a database of ORAC values.
Dark berries, especially wild and cultivated blueberries, blackberries and cranberries, stood out with the highest ORAC values among some 25 fruits tested. Their values were in a range of about 7,000-13,000 ORAC units per Cup or 250 ml serving.
Preliminary North American guidelines recommend at least 5,000 ORAC units per day for the adult diet. Doubling that number would not only be safe for antioxidant reserves, but would also provide antioxidant qualities that would supply numerous essential macro- and micronutrients. Most importantly though, it would make for enjoyable eating!
The ORAC test will likely gain public acceptance as a standard measure allowing comparisons of freshness and antioxidant strength in different foods. This standard will facilitate selection of high ORAC foods and relate antioxidant capacity to potential protection of health. For example, there is already scientific evidence for an inverse correlation between dietary intake of antioxidant foods and incidence of some cancers (US National Cancer Institute).
Wild Blueberry (Vaccinium angustifolium).
Wild lowbush blueberries have nearly 50% greater antioxidant strength than their cultivated cousins – the highbush blueberry – that is so popular in grocery stores. Wild blueberries score highest in ORAC among common (but not all) berries, having about 13,000 ORAC units per Cup or 250 ml. Over the past 10 years, the focus of food scientists on health properties of wild blueberries has revealed a compelling story of nutrient richness and diversity of potential health benefits, including:
o Urinary tract health (identical in strength to cranberries)
o Inhibition of cancer development
o Cardiovascular protection
o Mental alertness
o Vision support
Blackberry (Rubus ursinus)
The juicy delicious dark blackberry has great taste and nutrient richness. Confirming the idea that the darkest berries correlate with the strongest antioxidant activity, science has recently demonstrated that blackberries have some of the densest concentrations and widest diversity of phenolics found in the plant world. Blackberry’s ORAC is nearly 8000 units per Cup or 250 ml.
Black raspberry (Rubus occidentalis)
“Blackcaps” are a little-known powerhouse of antioxidant richness and outstanding taste. Isolates from black raspberries were shown in laboratory tests to specifically starve tumor cells by preventing growth of new tumor blood vessels. Overall a more powerful antioxidant berry than even the wild blueberry (ORAC > 15,000 per Cup or 250 ml), blackcaps contain a toolkit of flavors and nutrients.
Cranberry (Vaccinium macrocarpon)
The North American cranberry has become famous for its popular juice. Known well for its anti-adhesion properties, which inhibit bacterial infections in the urinary tract, cranberry extracts have shown anti-cancer and cardio-protective effects in laboratory studies. These results occur mainly from the cranberry’s abundant supply of antioxidant phenolics that also make it a promising agent for blood, brain and vision health.
Elderberry (Sambucus nigra)
Another phenolic-rich dark berry with a delectable taste, the elderberry has been associated with many of the potential health benefits already mentioned. It has stood out particularly in laboratory tests for its anti-inflammatory and urinary tract benefits. The elderberry also shows promise for anti-bacterial and anti-viral effects that may offer protection against such virulent pathogens as Salmonella, E. coli, H. pylori and Staphylococcus.
Red Raspberry (Rubus idaeus)
The red raspberry is well loved for its subtle distinct flavor but is also a wonderful store of antioxidant phytochemicals, particularly one called ellagic acid. One of its other constituents, a ketone, was shown in recent laboratory studies to stimulate fat metabolism, causing experimental animals to lose significant weight.
Red Grape (Vitus vinifera)
The red grape is valued for its familiar popular taste and diverse number of phenolics residing mainly in its skin and seeds. Especially rich in the phenolic called resveratrol, a powerful antioxidant, red grapes are linked to having a possible beneficial effect on:
o Alzheimer’s disease
o Heart disease
o Other aging disorders
Strawberry (Fragaria vesca)
Containing a host of antioxidant phenolics, the strawberry’s constituents may be particularly important as natural blood-thinners, anti-fungal agents and inhibitors of oxidizing effects on cells from chronic stress.
Other phenolic antioxidants mentioned in current public media include:
o Caffeic acid
o Hydroxycinnamic acid
o Tannic acid
o Salicylic acid (similar to aspirin)
These pigment chemicals belong to the flavonoid subclass of the phenolic super-family and are present among dark berries.
Color-rich plant foods like berries offer a delicious, nutritious way of keeping dietary intake of antioxidants high. Eat color! Gain ORAC! Live Well!
* PubMed, US National Library of Medicine, http://pubmed.gov
* Wild Blueberry Association of North America, http://www.wbana.org
* Wu X et al., Lipophilic and hydrophilic antioxidant capacities of common foods in the United States. J Agric Food Chem 52:4026-37, 2004.
Copyright 2006 Berry Health Inc.