B Blackberries are a delicious little “aggregate fruit” that grow wild on thorny bushes and are cultivated on every temperate continent, including Africa and Asia. Composed of many individual drupelets, each like a small berry with one seed, each drupelet contributes extra skin, seeds and pectin with dietary fiber value to the nutritional content of blackberries, making them among the highest fiber content plants in the world. Blackberries can be eaten fresh, frozen and canned and are popularly made into jams, juices, desserts and even wine. Rich in vitamins, minerals and fiber, blackberries are highly nutritious and rich in antioxidants. They are also low in calories, carbohydrates, and fat, making them one of the best fruits out there for a balanced diet.
Anthocyanins, which give blackberries their dark color, are an antioxidant shown to reduce inflammation. As an antioxidant, they destroy free radicals in the body that harm cells and lead to cancer. Research has also shown that the ellagic acid in blackberries may have anti-cancer properties. One cup of blackberries contains half of the daily recommendation of the antioxidant vitamin C, which protects the immune system and may lower the risk of developing certain types of cancer. Researchers have found that blackberries may reduce esophageal cancer by relieving the oxidative stress caused by Barrett’s esophagus, a precancerous condition usually brought about by gastroesophageal reflux disease. Perhaps the greatest benefit from eating blackberries is their high level of phenolic acids which, besides having many other potential health benefits, are antioxidant compounds known as powerful anti-carcinogenic agents. Because of these compounds, blackberries have been given an ORAC value (oxygen radical absorbance capacity) of about 5350 per 100 grams, placing them near the top of ORAC fruits.
As are all berries, blackberries are a great source of ellagic acid, an antioxidant shown to protect the skin from damage from ultraviolet light. Studies have also shown that ellagic acid may also repair skin damaged by the sun. Vitamin C helps heal wounds, and studies also show vitamin C may even lessen the appearance of wrinkles. Studies of cyanidin-3-glucoside, a compound found in blackberries showed it prevents skin cancer by inhibiting tumors from growing and spreading.
Vitamin C functions as an antioxidant in blackberries and one cup contains half of the daily recommendation of vitamin C. The body uses vitamin C for protection from immune system deficiencies, and may reduce the chances of macular degeneration, a condition in which fine vision deteriorates, resulting in central vision loss and is the leading cause of blindness in people over 50.
Phytoestrogens are naturally occurring plant estrogens found in blackberries that may help relieve the common symptoms of PMS like bloating, food cravings, and even menopausal symptoms including hot flashes.
Just one cup of blackberries contains over thirty percent of the daily recommended amount of fiber, which promotes healthy digestion and aids in maintaining bowel regularity by bulking up the feces and reducing the time it takes matter to pass all the way through the intestines. Bowel regularity is commonly associated with a decreased risk for colon cancer.
Thirty percent of the daily recommended amount of fiber is to be found in just one cup of blackberries. The steady movement of fiber through the digestive system allows for a measured breakdown of food into its component parts. This even breakdown of food helps to curtail extremes regarding simple sugar uptake from the digestive tract. An excess of simple sugar uptake all at once can produce an unwanted blood sugar spike. A lack of simple sugar uptake may produce a rapid blood sugar drop. Either extreme can upset blood sugar balance. The quantity of fiber in blackberries helps avoid both extremes.
Blackberries are a good source of vitamin K, offering 36% of the daily recommended amount of this nutrient used by the body for the clotting of blood and to aid the absorption of calcium.
One of the most exciting new areas of research on blueberries is the area of cognitive benefits. In one study involving older adults (with an average age of 76 years), 12 weeks of daily blueberry consumption was enough to improve scores on two different tests of cognitive function including memory. While participants in the study consumed blueberries in the form of juice, three-quarters of a pound of blueberries were used to make each cup of juice. As participants consumed between 2 and 2-1/2 cups per day, they actually received a very plentiful amount of berries. The authors of this study were encouraged by the results and suggested that blueberries might turn out to be beneficial not only for improvement of memory, but for slowing down or postponing the onset of other cognitive problems frequently associated with aging. Lab and animal research studies on blueberry intake suggest that a large part of this cognitive protection is most likely due to nerve cell protection from oxygen damage by blueberries’ vast array of antioxidant nutrients. Nerve cells have a naturally high risk of oxygen damage and they require special antioxidant protection at all times in life. Their ability to send information throughout the body depends on the presence of balanced oxygen metabolism, and that balance cannot be achieved without ample intake of antioxidant nutrients. By lowering the risk of oxidative stress in our nerve cells, blueberries help us maintain smoothly working nerve cells and healthy cognitive function.
Persons diagnosed with type 2 diabetes, metabolic syndrome, and insulin resistance have a special challenge with respect to blood sugar balance. In many cases, persons diagnosed with obesity also have special challenge maintaining a balanced blood sugar level. It’s simply more difficult for these individuals to keep their blood sugar levels from spiking too high (or sometimes also from dropping down too low). Research on blood sugar balance and blueberry intake has been conducted on individuals who have been diagnosed with type 2 diabetes, metabolic syndrome, or insulin resistance, and the results of this research have been consistent. They have shown that blueberries (along with other berries) have a favorable impact on blood sugar regulation in persons already diagnosed with blood sugar problems. When compared to other berries, blueberries are not particularly low in terms of their glycemic index (GI) value. Studies show the GI for blueberries falling somewhere in the range of 40-53, with berries like blackberries, raspberries, and strawberries repeatedly scoring closer to 30 than to 40. However, recent studies have shown that blueberries definitely function as a low-GI fruit in terms of their blood sugar impact. In one study on individuals diagnosed with type 2 diabetes, study participants who consumed at last 3 servings of low-GI fruits per day (including blueberries) saw significant improvement in their regulation of blood sugar over a three-month period of time. Their blood levels of glycosylated hmmoglobin, or HgA1C were used as the standard of measurement in this study. The blood sugar benefits of blueberries should not be surprising. Even at 40-53 in terms of glycemic index, blueberries typically fall into the “low-GI” category of foods (usually defined as any food with a GI of 50 or below). They also provide a very good amount of fiber (nearly 4 grams per cup). Most low-GI foods with strong fiber content are foods we can count on to be helpful in blood sugar regulation.
The retina of the eye is a unique place in our body and it is also a place that is at higher than normal risk of oxidative stress. Foods unique in phytonutrient antioxidants are often investigated for their ability to help protect the retina from oxygen damage, and blueberries are no exception! In preliminary studies on laboratory animals, the anthocyanins in blueberry protected the retina from unwanted oxygen damage. Interestingly, they have also been determined to help protect the retina from damage from sunlight. Like the area of cancer protection, we look forward to future research on human eye health and the potential for blueberry intake to help protect the human eye from damage by sunlight and oxidative stress.
While almost exclusively coming in the form of laboratory studies on human cells or laboratory animal studies, an increasing percentage of the blueberry research is being focused on anti-cancer benefits. Types of cancer already studied with respect to blueberry intake include breast cancer, colon cancer, esophageal cancer, and cancers of the small intestine. We look forward to the results of large-scale human studies on the potential ability of blueberry intake to lower risk of these cancer types. What’s New and Beneficial About Blueberries After many years of research on blueberry antioxidants and their potential benefits for the nervous system and for brain health, there is exciting new evidence that blueberries can improve memory. In a study involving older adults (with an average age of 76 years), 12 weeks of daily blueberry consumption was enough to improve scores on two different tests of cognitive function including memory. While participants in the study consumed blueberries in the form of juice, three-quarters of a pound of blueberries were used to make each cup of juice. As participants consumed between 2 to 2-1/2 cups each day, the participants actually received a very plentiful amount of berries. The authors of this study were encouraged by the results and suggested that blueberries might turn out to be beneficial not only for improvement of memory, but for slowing down or postponing the onset of other cognitive problems frequently associated with aging. New studies make it clear that we can freeze blueberries without doing damage to their delicate anthocyanin antioxidants. There’s no question about the delicate nature of many antioxidant nutrients found in blueberries. These antioxidants include many different types of anthocyanins, the colorful pigments that give many foods their wonderful shades of blue, purple, and red. After freezing blueberries at temperatures of 0°F (-17°C) or lower for periods of time between 3-6 months, researchers have discovered no significant lowering of overall antioxidant capacity or anthocyanin concentrations. Anthocyanins studied have included malvidins, delphinidins, pelargonidins, cyanidins, and peonidins. These findings are great news for anyone who grows, buys, or picks fresh berries in season and wants to enjoy them year round. They are also great news for anyone who has restricted access to fresh blueberries but can find them in the freezer section of the market. Berries in general are considered low in terms of their glycemic index (GI). GI is a common way of identifying the potential impact of a food on our blood sugar level once we’ve consumed and digested that food. In general, foods with a GI of 50 or below are considered “low” in terms of their glycemic index value. When compared to other berries, blueberries are not particularly low in terms of their GI. Studies show the GI for blueberries as falling somewhere in the range of 40-53, with berries like blackberries, raspberries, and strawberries repeatedly scoring closer to 30 than to 40. However, a recent study that included blueberries as a low-GI fruit has found that blueberries, along with other berries, clearly have a favorable impact on blood sugar regulation in persons already diagnosed with type 2 diabetes. Participants in the study who consumed at last 3 servings of low-GI fruits per day (including blueberries) saw significant improvement in their regulation of blood sugar over a three-month period of time. (Their blood levels of glycosylated hemoglobin, or HgA1C were used as the standard of measurement in this study.) It’s great to see blueberries providing these clear health benefits for blood sugar regulation!
In our Healthiest Way of Eating Plan, we encourage the consumption of 5-10 servings of fruits-plus-vegetables (combined) each day. We believe that the balance between fruits and vegetables can vary from day to day, depending upon personal health factors, personal taste preferences, and optimal combining of foods in recipes as well as meals. We recognize that our recommendation calls for a more generous amount of fruits and vegetables than the amount recommended by the Centers for Disease Control (CDC) at the U.S. Department of Health and Human Services (DHHS). The CDC recommends between 1.5-2.5 cups of fruit and 2.5-4.0 cups of vegetables per day, as well as a target goal of at least 5 fruit-plus-vegetable servings (combined) per day. We recommend that you set your fruit goals higher than these CDC amounts. Based on the scientific research, we believe it’s going to take closer to 3 fruit servings per day (consisting of one cup’s worth of fruit per serving, or 3 cups total per day) to provide you with optimum health benefits. With respect to berries in particular, we recommend that you include berries at least 3-4 times per week within your fruit servings. In several of our sample meal plans, we include berries on a daily basis! It would definitely not be a mistake for you to include a serving of berries in your daily meal plan! With respect to blueberries in particular, you might be surprised about the number of blueberries that can fit into a single cup. The average weight for a small, lowbush blueberry (also sometimes called a “wild blueberry”) can be close to 1-2 grams, meaning that a weighted cup’s worth of wild blueberries will contain 100-150 berries!