Black Raspberries – Just The Faqs
Dr. Paul Gross
Talk to today’s medical scientists studying the
disease-prevention properties of plant foods and most would
tell you that a fast-rising star is the black raspberry — one of
Nature’s most powerful antioxidant fruits.
Particularly in the prevention of cancer, black raspberries are
revealing remarkable effects as anti-tumor agents in laboratory
research. In pursuit of this important finding, over the past
six years no other fruit has had as much progress toward human
clinical trials as the black raspberry.
Let’s have a look at the scientific and health foundations for
the benefits of including black raspberries in your diet.
How many species of black raspberries are commonly available to
the general consumer?
In Canada and the US, there are two main species called Rubus
occidentalis L. and Rubus eucodermis L. Rubus (a genus of
plants in the family Rosaceae, subfamily Rosoidea). The Rubus
is characterized by rose-like thorns along vines forming
brambles that grow as irregular canes ranging from one to four
meters in length. It is conventional to include black
raspberries among other Rubus berries (red raspberries,
blackberries, boysenberries, loganberries) as “brambleberries”
or “caneberries” that have grown native in North America since
recorded time.
How is the black raspberry different from other Rubus species?
Often called “blackcaps” by berry farmers, black raspberries
are the smallest and bluest of the Rubus berries. Scientific
assays of blackcap phytochemicals reveal the densest and most
avid pigmentation among North American plants—so strong that
the US Department of Agriculture used black raspberry juice as
stamp dye on meats for several decades. Scientific tests have
described blackcaps with the richest contents of pigment
antioxidants among North American berries (as described further
below).
Where do blackcaps grow and what markets are served?
Black raspberries grow primarily in the western US and in
British Columbia. They prefer wet, mild winters and humid, warm
summers and are harvested over the month of July. Oregon’s
Willamette Valley, especially, is noted for black raspberries
accounting for 95% of total US production or about 4 million
pounds per year. Only 5% of black raspberries are sold fresh.
The market for processing to provide year-round supplies of
frozen (immediately quick frozen, IQF), pureed or concentrated
juice products makes up the rest.
What qualities of black raspberries appeal to consumers?
The intense pigmentation qualities mentioned above derive from
a rich concentration and diversity of phenolic acid
antioxidants in blackcaps. Phenolics give black raspberries
several distinctive taste and chemical qualities, including
high acidity (pH of about 3.5), semi-sweet taste (brix of about
10 in IQF fruit, 17 in puree) and a special tangy full-bodied
taste that appeals to most people, including children.
Blackcaps are very versatile regular in dessert recipes.
Over the past few years, research primarily at Ohio State
University by Dr. Gary Stoner and colleagues has shown exciting
– even astonishing – results of black raspberry phenolic
extracts and whole berries themselves on colon and esophageal
cancers in experimental animals. The focus has been on the
antioxidant qualities particularly of ellagic and ferulic acids
(both phenolic antioxidants) from blackcaps.
Black raspberries are one of the world’s most promising tools
from plant foods in the fight against cancer. They are now
entering human clinical trials supervised by Dr. Stoner.
What are oxidants and antioxidants?
Moment by moment throughout the cells of our bodies, free
radicals (i.e., oxidants or radical oxygen species) are
continuously being generated by normal metabolism. Exposure to
toxins in the environment, or irradiation, increases free
radical production. Free radicals are unstable atoms having
potential to damage cells and alter genes if not quickly
neutralized.
Our bodies defend against oxidation through enzymes called
dismutases, catalases, reductases and peroxidases. Also, our
diet provides a host of chemicals serving antioxidant roles.
These chemicals include: vitamins A, C and E; minerals like
selenium, manganese and zinc; and pigments from the plant foods
we eat.
In black raspberries, phenolic pigments like ellagic and
ferulic acids are the major antioxidant source.
What are other pigments present in black raspberries?
The rich color of black raspberries comes from numerous
chemicals of the phenolic super-family that is a class of
several thousands of members serving plants as pigments. Black
raspberry antioxidant strength is proportional to the intensity
of the dye from its pigments.
A major subgroup of pigment phenolics is the flavonoid group
that is densely populated in blackcaps. One flavonoid class in
particular – anthocyanins – accounts for most of the
blue-red-black pigmentation of black raspberries. In addition
to anthocyanins, however, are ellagic acid, ferulic acid,
gallic acid, rutin and cyanidin glycosides (phenolics
identified by Dr. Stoner and colleagues as important
anticarcinogens in blackcaps). Vitamin C, a universal
antioxidant, is also well concentrated in black raspberries
(about 2 mg per 100 grams of fruit), as is calcium (32 mg per
100 grams).
Is there a way to measure antioxidant quality of a plant food
and how well do black raspberries perform?
Yes, a test called ORAC (oxygen radical absorbance capacity) is
performed on a food sample in a test tube. Then, the strength of
antioxidant is measure by how well it neutralizes free radicals.
At Oregon State University, black raspberries have been tested
for ORAC against other berries and plant foods (first analyzed
in a 2004 ORAC report by US Department of Agriculture
scientists). Black raspberries had the highest ORAC among other
caneberries, fruits or vegetables analyzed measuring 3 times
higher ORAC than blackberries or red raspberries.
Plants with pale skins and white pulps like pears and some
apples have low ORAC whereas dark fruit like black raspberries,
blueberries and cranberries have relatively high ORAC.
What does a high ORAC from black raspberries mean for health
protection?
The answer to this question requires actual clinical research
in humans (being performed but still preliminary) but the
scientific evidence points to widespread protection against
numerous diseases by having a diet rich in high-ORAC foods like
black raspberries.
What are some diseases that evolve from free radicals and what
can we do to counter oxidative stress?
Growing scientific evidence shows that nearly every disease
involves free radicals to some extent. Cancer, heart and
vascular disease, diabetes, inflammation and neurological
disorders all have strong components of oxidative stress.
Premature aging and diseases of the elderly such as macular
degeneration are thought to result from oxidative damage to
cells as well.
The laboratory studies by Dr. Stoner point to the importance of
oxidative factors in colon and esophageal cancer, and to the
potential protective role of phenolics from black raspberries
or other antioxidant-rich plant foods.
Consumers can enjoy the pleasures of dark berries in their
diets while likely gaining antioxidant protection from berry
phenolics. Why wait for positive results from the years of
clinical research ahead? The preliminary evidence and
pleasurable eating qualities of black raspberries should be
enough to warrant including these berry treasures in your diet
now.
Reading
* US National Library of Medicine, PubMed, http://pubmed.gov
* Oregon Raspberry and Blackberry Commission,
http://www.oregon-berries.com
* Han C, Ding H, Casto B, Stoner GD, D'Ambrosio SM. Inhibition
of the growth of premalignant and malignant human oral cell
lines by extracts and components of black raspberries. Nutr
Cancer. 2005;51(2):207-17.
* Casto BC, Kresty LA, Kraly CL, Pearl DK, Knobloch TJ, Schut
HA, Stoner GD, Mallery SR, Weghorst CM. Chemoprevention of oral
cancer by black raspberries. Anticancer Res. 2002
Nov-Dec;22(6C):4005-15.
Copyright 2006 Berry Health Inc.
About The Author: Dr. Paul Gross is a scientist and expert on
cardiovascular and brain physiology. A published researcher,
Gross recently completed a book on the Chinese wolfberry and
has begun another on antioxidant berries. Gross is founder of
Berry Health Inc, a developer of nutritional, berry-based
supplements. For more information, visit
http://www.berrywiseonline.com
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