Originally published February 3 2009
Milk Destroys Antioxidant Benefits in Blueberries
by Barbara L. Minton
(NaturalNews) Not much is better than a bowl of fresh blueberries. Bursting with flavor and sweetness, low in calories, and packed with nutrients and antioxidants, these tiny fruits are anti-aging superstars. There is however one word of caution. Blueberries lose their power when eaten with milk.
Blueberries have a high affinity for milk protein
A new study reported in the journal Free Radical Biology and Medicine investigated whether antioxidant properties of blueberries were reduced because of their affinity for protein. They assessed the bioavailability of phenolics after consumption of blueberries with and without milk. Phenolics are the active compounds in plants that give blueberries their antioxidant potential.
Volunteers consumed 200 g of blueberries with 200 ml of either water or whole milk. Blood samples were collected at baseline and at intervals following consumption. The samples revealed that ingestion of blueberries with water increased plasma levels and concentrations of caffeic and ferulic acids. When blueberries and milk were ingested together, there was no increase in plasma antioxidant capacity. There was a reduction in the peak plasma concentrations of caffeic and ferulic acids as well as the overall absorption of caffeic acid.
Ferulic acid provides rigidity to cell walls and protects the nervous system. It has a normalizing effect on blood pressure. Caffeic acid is also a powerful protector of neurons. Other research has shown caffeic acid has the potential to prevent neurodegenerative disease.
This study suggests that the best way to gain maximum benefits from blueberries and other fruits eaten for their polyphenol content is to consume them either one hour before protein is consumed, or two hours after.
The effects of ferulic and caffeic acids on neurons may be what give blueberries their ability to influence cognition and learning. A study reported in the August, 2008 journal Nutrition and Neuroscience looked at cognitive impairment in age-related neurodegenerative diseases such as Alzheimer's as being due to long-term exposure and increased susceptibility to inflammatory insults. They investigated whether polyphenols in blueberries could reduce the deleterious effects of induced inflammation.
Rats were fed a diet that included a non-steroidal anti-inflammatory drug (NSAID), or a 2 percent blueberry diet. After two weeks and behavioral evaluation, the rats were examined and total RNA from the hippocampus was extracted to analyze the expression of inflammation-related genes. The researchers found the blueberry diet was able to improve cognitive performance to a much greater degree than was the NSAID diet. Blueberry eaters showed a reduction in several factors influencing the inflammatory response. They concluded that blueberry polyphenols can lessen learning impairments resulting from neurotoxic insult and exert anti-inflammatory actions, perhaps by alteration of gene expression.
Other studies have found that diets rich in blueberries significantly improved both the learning capacity and motor skills of aging animals, making them mentally equivalent to animals much younger.
Blueberries are antioxidant powerhouses
Researchers at Tufts University recently analyzed 60 fruits and vegetables for their antioxidant capabilities. Blueberries were tops among all that were studied, ranking highest in the capacity to destroy free radicals. Antioxidants in blueberries neutralize free radical damage to the collagen matrix of cells and tissues that can lead to cataracts, glaucoma, varicose veins, hemorrhoids, peptic ulcers, heart disease and cancer.
The pigments that give blueberries their color improve the structure of veins and the vascular system. They enhance the effects of vitamin C and inhibit enzymes from cleaving the collagen matrix. Maintaining a stable collagen matrix is essential for health of bones, tendons, cartilage and connective tissue. The collagen matrix is what keeps skin from wrinkling and sagging.
Eating 3 or more servings of fruit per day including blueberries lowers risk of age-related macular degeneration, the primary cause of vision loss in older adults. Blueberries are loaded with eye healthy and vision preserving carotenoids like lutein and zeaxanthin, and flavonoids like rutin, resveratrol and quercitin. And they contain a wealth of minerals needed for vision and overall health, like selenium and zinc.
Blueberries are high in the soluble fiber pectin, which has been shown to lower cholesterol. They provide greater cardio-protective antioxidant capability than red wine.
Blueberries' cancer fighting properties are legendary. Ellagitannins is probably the most highly prized compound in blueberries because of its ability to block metabolic pathways that can lead to the initiation and promotion of cancer. A study reported in the Journal of Agricultural and Food Chemistry found that blueberries inhibit colon cancer cell proliferation and induce programmed cell death. Blueberries contain kaempferol. This compound was shown in the Women's Health Study to reduce the risk of ovarian cancer by 40 percent in women who diets provided the greatest amounts. Blueberries also contain pterostilbene, another powerful cancer fighting compound.
Both diarrhea and constipation can be relieved with blueberries. Their tannin concentration helps reduce inflammation in the digestive tract as well as in the urinary tract. They provide safety form the bacteria that cause food borne illnesses.
Blueberries are terrific anti-depressants and mood elevators.
Choosing and using blueberries
For many people seeing the price tag for fresh organic blueberries is a real jolt. Some of the cost can be minimized by buying wild blueberries. These are often the same quality as those certified organic. Frozen blueberries provide all the antioxidant potential and other nutrients found in fresh ones. If you are looking for frozen berries, check the bag to make sure the berries move around freely and are not stuck together, indicating they have been thawed and refrozen. If you like some juice with your blueberries, frozen is the way to go.
As a general rule, the riper the fruit the greater its antioxidant content.
Organic dried blueberries are also a good choice, especially for snacking since the sweetness is accentuated by the drying process. The antioxidant potential of dried blueberries can be as much as four times greater than that of fresh. Organic dried berries will have been dried at temperatures low enough to protect their antioxidant capabilities.
Heat is a destroyer of the antioxidant potential of blueberries, making canned or other processed berries a poor choice. Fresh or frozen blueberries can be pureed and fed to babies. Blueberries in baby food jars will have lost most of their nutritional value.
Sources:
US Highbush Blueberry Council, blueberry.org.
Organic Facts, Health Benefits of Blueberries, organicfacts.net.
Blueberries, WHFoods, whfoods.com.
About the author
Barbara is a school psychologist, a published author in the area of personal finance, a breast cancer survivor using "alternative" treatments, a born existentialist, and a student of nature and all things natural.
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