Research Perspective and Comments & Analysis
An Examination Of Blueberry Health Research
By The Us Highbush Blueberry Council
Aside from their great taste and culinary versatility, blueberries are one of the easiest additions consumers can make to their diet to pursue a healthier lifestyle. Investigators are currently pursuing four tracks to better understand the role that blueberries may play in promoting good health — cardiovascular health, insulin response, brain health and cancer research.
A recent study conducted at Florida State University and published in the Journal of the Academy of Nutrition and Dietetics found that daily consumption of blueberries given as freeze-dried blueberry powder resulted in a reduction of blood pressure and arterial stiffness, a measure of cardiovascular disease risk, in postmenopausal women with pre- and stage 1-hypertension.1 Conducted over an eight-week period, 40 postmenopausal women were randomly assigned to receive either 22 grams of freeze-dried highbush blueberry powder (the equivalent to 1 cup of fresh blueberries) or 22 grams of placebo powder daily. They were advised to maintain their usual diet and physical activity levels.1 The results warrant further investigation and provide some evidence for including blueberries as part of healthy dietary practices.1
In laboratory studies on rats conducted at the National Institute on Aging, researchers found a diet enriched with blueberries protected the cardiac muscle (myocardium) from damage caused by reduced blood supply during a heart attack. In addition, repair of the damaged heart muscle was more efficient in those on a blueberry-supplemented diet than those on the control diet.3 More studies are needed in this area to fully see and understand the potential effects on humans.
In a human clinical trial, 32 individuals who were already diagnosed with metabolic syndrome were given similarly tasting smoothies, either with or without blueberries twice daily for 6 weeks. The researchers found that those who consumed blueberries were more able to lower their blood glucose in response to insulin than those who were not given blueberries.4 While the study is not conclusive, it strongly suggests that more research is needed to evaluate blueberries and their potential role in improving insulin sensitivity in an insulin resistant population.
While more research is needed to understand the effects on humans, studies with animals suggest that blueberries may have an effect on the way insulin does its job. In one animal study conducted at the USDA research center at Tufts University, obese mice were given high-fat diets with or without blueberries for eight weeks. The results yielded an improved insulin response with lower blood glucose levels in response to insulin in the blueberry fed mice than in the controls.5
In another study at the University of Michigan, researchers gave obese rats either a low or high fat diet supplemented with 2 percent blueberries and tested the effects against the control group. After 90 days, the rats that received the blueberry enriched diet had increased insulin sensitivity, decreased blood lipid levels and less measured abdominal fat. These results were also seen in the group that received the low fat diet supplemented with blueberries.6
Scientists at the USDA research center at Tufts University have been studying the beneficial effects of blueberries on brain function in animal models for over a decade. In a recent study, researchers there found that object memory loss that occurs normally with age can be not only prevented but actually reversed by feeding blueberries to older rats. Moreover, the improvement persisted for at least a month after they put the animals back on a standard diet.7
In a study with nine human subjects, Robert Krikorian, professor of Clinical Psychiatry and director of the Division of Psychology, and his team at the University of Cincinnati found that older adults who were given blueberry juice scored higher on memory tests than those receiving a placebo. This study establishes a basis for human research and blueberry supplementation on cognitive aging.8 These researchers are currently conducting a similar study with older subjects who already show some signs of cognitive impairment.
According to researchers at the City of Hope National Medical Center, blueberries may have an effect on breast cancer cell growth. Three studies demonstrated that both breast tumor growth and the spread of the cancer can be reduced in blueberry supplemented mice.9-11 In addition, a recent study showed that feeding rats a blueberry-supplemented diet reduced tumor growth even when feeding began after the tumors were present.12 These studies are not conclusive for humans, and more research is needed in the area of cancer and blueberry intake.
Little Changes Lead To Big Rewards
Americans know they need to make healthier food choices, but they keep tripping up when it comes to sticking with those decisions. It’s drinking an extra glass of water each day, or using blueberries to sweeten your oatmeal or yogurt, these little changes will build up to a healthier lifestyle over time.
Research from ORC International shows making small changes instead of lofty resolutions makes people feel more confident and more likely to make additional positive changes. Blueberries are a great go-to snack, because they’re available fresh and frozen all year-round, they add vitamin C and fiber to your diet, and they’re only 80 calories per cup.
1. J Acad Nutr Diet. 2015; 115:369-377. 2. PLoS One. 2009; 4: e5954. 3. J Nutr 2010; 140:1764-1768. 4. J Nutr 2009; 139 (8): 1510-16. 5. J Med Food. 2011; 14:1511-1518. 6. Nutrition 2011; 27:338-342. 7. J Agric Food Chem. 2010; 58:3996-4000. 8. Cancer Res. 2010;.70:3594-3605. 9. J Nutr. 2011; 141:1805-1812. 10. Nutr Cancer. 2014; 66:242-248. 11. J Ag Food Chem. 2014; 62:3963-3971.
Industry Funding Needed To Support Research
It is always exciting to discover research that holds out hope that a particular produce item can have real health benefits. When the item is blueberries — an easy-to-eat fruit that fits in with so many convenience trends — the idea of specific health benefits coming from the item holds out the real promise of increasing produce consumption.
Of course, we can’t let the cart get ahead of the horse. Most studies of this type are very small and have not been reproduced widely. Often, they are done on small subsets of the population and their wider applicability is unknown. Sometimes they are just animal research, and whether effects observed in animals will translate to humans remains to be seen.
Rarely do the studies actually go to health outcomes such as morbidity; instead they look to various markers, such as arterial stiffness, and the impact of such things on mortality and health is still being evaluated.
It is also true that even if an item has some healthful effect, that doesn’t mean it is more healthful than an alternative.
Then, of course, the way items are consumed under study conditions does not necessarily tell us how an item will be consumed in real life. Studies often include portion controls and restrictions on preparation. The same fruit that might offer a net health benefit at a few ounces a day might not offer health benefits at a pint-a-day served in whipped cream.
Yet consumer interest in so-called “functional foods” is very high, and if we can say that steady consumption of Item X will help with Problem Y, it can move the needle on consumption. That is great news but, alas, there is not much evidence any of this will boost overall produce consumption. Kale can be all the rage, but most of the time, consuming more kale means consuming less spinach as chefs mainly look for only one green side dish.
Of course, if we can really get to a prescriptive health message backed by convincing science — “Ten ounces of blueberries a day keeps heart disease away” — then we would probably see boosts in consumption of those commodities, which would overwhelm the substitution effect.
But getting to this point involves very substantial investment. We need to fund studies of hundreds of people in multiple institutions. The blueberry industry has done a great job in pushing this research forward, but we need an industry fund of larger scale to support this type of research.
Perhaps something that could mirror the Center for Produce Safety, but instead of focusing on understanding the science behind food safety, this “Center for the Understanding of the Health Benefits Associated with Produce Consumption” could serve as a kind of expertise center, ensuring research from various companies and commodity groups is all peer-reviewed and of a scale and type that is meaningful.
By focusing and professionalizing the industry’s health efforts, such a center might accelerate the development of knowledge as to what real benefits increasing the consumption of individual produce items could create in terms of human health.
This would be a breakthrough since we currently have only the vaguest and most general entreaties to offer the public: That increased consumption of produce, with produce substituting for less healthy foods in the diet, will favor better health and longevity. That’s good, but not nearly as effective a marketing pitch as being able to say that eating blueberries reduces your risk of high blood pressure.
Fortunately, although it is great that blueberries have a halo of healthfulness, the key to increasing consumption is probably going to come from playing up the delicious and convenient angle. Packages such as those placed in McDonald’s, which Naturipe developed, are just the tip of the iceberg.
There remain important branding challenges: different varieties, vast geographies and niche growers, as well as seasonal fluctuations, we are not quite at the point where every child can have a delicious experience every time he or she eats a blueberry.
It will be great when we can prove blueberries enhance health, but people enjoy the deliciousness of candy more than the healthfulness of produce. A focus on growing and marketing consistently flavorful fruit will move up consumption rapidly and keep produce front and center. pb