Blueberries and health – the research case

In a July blog post Warding off Alzheimer’s Disease and things in my diet, I talked about My usual breakfast: a sugar-free bran cereal with blueberries, walnuts and a sliced half-banana.  I cited research on the health benefits of the walnuts.  But what about the blueberries, the cupful or so I consume each morning?  It is common knowledge that they have strong antioxidant properties and “are good for you.” But what is known about their actual health benefits?  Actually, a great deal if animal models are to be trusted.  I reviewed some recent research on this subject and share the results here, mostly by listing quotes from the publications cited. I end each item with a simple summary of my own which is italicized.

·        Dietary blueberry attenuates whole-body insulin resistance in high fat-fed mice by reducing adipocyte death and its inflammatory sequelae, a new study, August 2009. “Salutary effects of BB on adipocyte physiology and ATMPhi gene expression may reflect the ability of BB anthocyanins to alter mitogen-activated protein kinase and nuclear factor-kappaB stress signaling pathways, which regulate cell fate and inflammatory genes. These results suggest that cytoprotective and antiinflammatory actions of dietary BB can provide metabolic benefits to combat obesity-associated pathology.” Blueberries can combat obesity and its problems.

·        Blueberries make their mark on cardiovascular and diabetes risks, U-M animal study finds, April 2009. “The researchers studied the effect of blueberries (freeze dried blueberries crushed into a powder) that were mixed into the rat diet, as part of either a low- or high-fat diet. They performed many comparisons between the rats consuming the test diets and the control rats receiving no blueberry powder. All the rats were from a research breed that is prone to being severely overweight. — In all, after 90 days, the rats that received the blueberry-enriched powder, measured as 2 percent of their diet, had less abdominal fat, lower triglycerides, lower cholesterol, and improved fasting glucose and insulin sensitivity, which are measures of how well the body processes glucose for energy. — While regular blueberry intake reduced these risks for cardiovascular disease and metabolic syndrome, the health benefits were even better when combined with a low-fat diet.” Blueberries can reduce risk of cardiovascular disease.

·        A blueberry-enriched diet protects rat hearts from ischemic damage,  June 2009. “CONCLUSION: A blueberry-enriched diet protected the myocardium from induced ischemic damage and demonstrated the potential to attenuate the development of post MI chronic heart failure.” Blueberries can help protect against heart attack damage.

·         Antiobesity and antidiabetic effects of biotransformed blueberry juice in KKAy mice, August 2009.  This study is based on Juice extracted from North American lowbush blueberries which has been biotransformed with Serratia vaccinii, a bacteria from the skin of the fruit.  The KKAy mice provide a rodent model of leptin resistance.  “Incorporating BJ (the biotransformed blueberry juice)in drinking water protected young KKAy mice from hyperphagia and significantly reduced their weight gain. Moreover, BJ protected young KKAy mice against the development of glucose intolerance and diabetes mellitus.” “Results of this study clearly show that biotransformed blueberry juice has strong anti-obesity and anti-diabetic potential,” says senior author Pierre S. Haddad, a pharmacology professor at the Université de Montréal’s Faculty of Medicine. “Biotransformed blueberry juice may represent a novel therapeutic agent, since it decreases hyperglycemia in diabetic mice and can protect young pre-diabetic mice from developing obesity and diabetes(ref).”  Biotransformed blueberry juice can be protective against obesity and diabetes.

·        Wild Blueberries May Help Protect Arteries, Reduce Risks From Cardiovascular Disease, November 2003. “The apparent benefit of the blueberry enriched diet carried over to older rats which received blueberries later in the study. The implication is that the addition of wild blueberries to the diet later in life may still have a protective effect on arteries.” Wild blueberries can protect against cardiovascular disease in the old as well as young.

·        Blueberry polyphenols attenuate kainic acid-induced decrements in cognition and alter inflammatory gene expression in rat hippocampus, “These results indicate that blueberry polyphenols attenuate learning impairments following neurotoxic insult and exert anti-inflammatory actions, perhaps via alteration of gene expression.” It was observed that blueberries attenuated the expression of NF-kappaB induced by the neurotoxic kainic acid and augmented the expression of IGF-1. Blueberries can be protective of mental capability when exposed to brain toxins.

·        Inhibition of cancer cell proliferation and suppression of TNF-induced activation of NFkappaB by edible berry juice, March-April 2007.  “The potential chemopreventive activity of a variety of small berries cultivated or collected in the province of Québec, Canada were evaluated here. — RESULTS: The growth of various cancer cell lines, including those of stomach, prostate, intestine and breast, was strongly inhibited by raspberry, black currant, white currant, gooseberry, velvet leaf blueberry, low-bush blueberry, sea buckthorn and cranberry juice, but not (or only slightly) by strawberry, high-bush blueberry, serviceberry, red currant, or blackberry juice. No correlation was found between the anti-proliferative activity of berry juices and their antioxidant capacity (p > 0.05). — juice of 6 significantly inhibited the TNF-induced activation of COX-2 expression and activation of the nuclear transcription factor NFkappaB.” Blueberry and other berry juices can be protective against some cancers. 

·        Blackberry, black raspberry, blueberry, cranberry, red raspberry, and strawberry extracts inhibit growth and stimulate apoptosis of human cancer cells in vitro, December 2006.  “The berry extracts were evaluated for their ability to inhibit the growth of human oral (KB, CAL-27), breast (MCF-7), colon (HT-29, HCT116), and prostate (LNCaP) tumor cell lines at concentrations ranging from 25 to 200 micro g/mL. With increasing concentration of berry extract, increasing inhibition of cell proliferation in all of the cell lines were observed, with different degrees of potency between cell lines.”  Blueberry and other edible berry extracts can kill cancer cells.

·        Berry fruits: compositional elements, biochemical activities, and the impact of their intake on human health, performance, and disease, February 2008.  “An overwhelming body of research has now firmly established that the dietary intake of berry fruits has a positive and profound impact on human health, performance, and disease.” Blueberries and other berries are great for health.

·        Whole berries versus berry anthocyanins: interactions with dietary fat levels in the C57BL/6J mouse model of obesity, February 2008.  “After 8 weeks, mice fed the HF60 (high fat) diet plus purified anthocyanins from BB in the drinking water had lower body weight gains and body fat than the HF60-fed controls. Anthocyanins fed as the whole blueberry did not prevent and may have actually increased obesity. However, feeding purified anthocyanins from blueberries or strawberries reduced obesity.”  The berries used in the study were blueberries and strawberries.This study is interesting because it suggests the additional calories from the whole berries possibly led to weight gain but the anthocyanin extracts led to weight loss.  If this result is further confirmed, it would provide an argument for consuming berry anthocyanin extracts supplements instead of the whole berries themselves. Berry anthocyanin supplements might be better for weight loss than the berries themselves.

·        Purple Berries’ Rank High In Antioxidants, USDA Study Says, November 2003.  Some berries may be even better for you than blueberries, ones like elderberries, black currants and chokeberries.  “In preliminary laboratory studies, the researchers found that the elderberry, black currant and chokeberry — collectively known as the “purple berries” due to their dark color — are as much as 50 percent higher in antioxidants than some of the more common berry varieties and have the potential to provide more health benefits, such as protection against cancer, heart disease and Alzheimer’s.”  The darker and more purple the berry colors the better thay are for you, possibly.