One Cup of Berries: Confessions of a Heavy Blueberry User

The average person eats about 2.5 cups of blueberries a year; a moderate user eats somewhere more than 3 cups a year; and a heavy blueberry user, which comprises 25% of the population, consumes more than 19 cups per year. Then there’s me. I can’t remember the last time I went a full week without eating a blueberry.

They’re absolutely delicious, fun and easy to eat and best of all, they’re a well known nutritional hero. I eat them fresh with walnuts, blend them frozen in smoothies, make blueberry almond muffins out of them, make blueberry compote for overnight oats. I eat them on a plane, on a train, in a bus in the rain…

I wasn’t always this way. I spent the majority of my adolescence and twenties in a processed food-fueled daze, downing ramen noodles, pizza, frappuccinos, and my all-time favorite: a wrap called mega-wrap, a white flour tortilla with fried chicken, cheese, ranch, and iceberg lettuce. This was supposed to be healthy (and I thought I was healthy) because the fried chicken came briefly in contact with iceberg lettuce, my one fruit/vegetable at my meals. I was so used to a continuous stream of hyperpalatable foods that, as Louis C.K. would say, at that point I probably would not have be able to taste the natural sweetness of an apple. And honestly, I was that person who put sugar on fruit.

“What we’ve done with our modern food supply is absolute insanity. It’s not even real anymore. You used to be able to give a kid an apple and they would love it. Kids can’t even taste apples anymore. Apples taste like paper to kids now.” – Louis C.K.

It wasn’t until I took my first nutrition course (nutritional biochemistry) that I discovered the effects of what increasing nutrient-dense foods, like blueberries, in my diet had on my health, quality of life, cognition, epigenetics and even mood that affected my daily life. Improving my diet made me feel better overall. You would have thought that being a Neuroscience major, I would have understood the link between diet and brain function a lot sooner. But that was hardly mentioned and was still a novel topic. Or I don’t know, I might have skipped that class because I was busy finding free food on campus after experiencing a major sugar crash. Times have certainly changed since my undergrad as we know have much more understanding on how food affects the brain. If only I knew this before!

Blueberries were my gateway super food. Blueberries got me used to eating something that wasn’t so overwhelmingly sweet and palatable. I began to enjoy the natural flavor of foods, sometimes craving the distinct mildly bitter/tartness of highly nutritious produce. It was all downhill from there: I started making kale smoothies, eating bitter Brussels sprouts,  broccoli sprouts, and grapefruits.

The Rise of the Blueberry

Blueberries have been used medicinally in Native American tribes and were believed to be sent by the Great Spirit during a great famine to relieve the hunger of their children. Blueberries were used year-round: consumed fresh when in season and were dried to preserve them for use in the winter for soups and stews. Nowadays they’re commonly discussed in news articles and health food blogs as we continue to realize that there is something very special about blueberries.

Often called a super-fruit or brain-berry, blueberries are the dominating berry. And everyone knows it. The psychographic associations of the blueberries are status-oriented, demanding and high-tech.  Thoreau calls blueberries, “that most Olympian of fruits”. Compared to its silly strawberry friend, you can count on the blueberry for getting things done.

Thank you blueberry! Now we know what antioxidants are

Compared to its silly strawberry friend, you can count on the blueberry for getting things done. Blueberries popularized the term “antioxidant”, known for zapping free radicals, and contributed to phytochemical research. In fact, blueberries are the most researched fruit. An article in The Atlantic, How People Came to Believe Blueberries Are the Healthiest Fruit by James Hamblin, describes the history of blueberry research to give us insight as to why blueberries became so popular. It is because of this research and blueberry’s association with brain health, blueberry consumption is ever growing and are the only fruits expected to continue to increase in its consumption.

When most people think of blueberries and their health benefits, the word antioxidant must come up. It’s required.

Reactive Oxygen Species (ROS) are reactive molecules with oxygen (H2O2 or O2∙). ROS are produced when we breathe, everyday metabolic functioning and are part of defenses of our immune system and play an important role in our body. Free radicals are atoms, ions or molecules that have at least one unpaired electron in their structure. These could start to react with other substances like cell membranes, fatty acids, proteins, and DNA. Under normal conditions, our body can handle ROS with antioxidants. But sometimes, it can be too much for our body to handle when there are more ROS:antioxidants, and it is implicated in many diseases.

We can make antioxidants in our body or we can get them in our diets. Polyphenols are antioxidant substances present in natural products and share the structure of pigments composed of multiple aromatic rings with hydroxyl groups. This structure allows it to scavenge free radicals and provide a myriad of health benefits including preventing cell damage and protect against several types of chronic diseases.

But, blueberries are SO much more than an antioxidant

Other than being awesome at quenching free radicals, blueberries serve many other overlooked functions, that I think they should be better known for. Blueberry derived anthocyanins can cross the blood brain barrier and congregate in regions involved in learning and memory (the hippocampus). They also help to upregulate genes that fight inflammation, improve metabolic profile, reduce mitochondrial dysfunction, produce new neurons and strengthen neuronal communication.

The anthocyanins can recognize a sequence of DNA, known as antioxidant response elements. Anthocyanins activate a gene called NRF2, which then activates genes within the antioxidant response element. NRF2 is a master regulator of many genes involved with inflammation and antioxidant activity, and neuroprotective proteins like BDNF, PGC1a and superoxide dismutase. It also decreases production of proinflammatory cytokines like TNF1, IL-1B and ROS (1).

No wonder they are constantly on the top 10 list of super foods.

Blueberries as a super food not a super fad

While there is much controversy about super foods in the dietitian community, I really like this movement of popularizing actual foods. In a world fixated on calorie and carbohydrate counting, I ultimately would like to see more individuals gravitate towards eating an actual food for nutrients instead of relying on low-calorie, low-carbohydrate “health” food-like substances and diets completely devoid of produce. This is a serious problem as only 1/10 adults consume the recommended 5 servings of fruits and vegetables a day.

One of the main arguments against calling a food a super food is that you don’t get enough nutrients from a normal dose or you can get the same nutrients in other fruits, like an apple or banana. But, that is actually not true in the case of blueberries.

Let’s take resveratrol, found in red wine for instance. You’d need to drink at least 9 gallons of red wine to even obtain the level of resveratrol needed to provide benefit! But with blueberries, you only need to eat 1 cup of blueberries a day to get enough anthocyanins (the main polyphenol in blueberries known for antioxidant and anti-inflammatory properties and is what provides its blue color). Blueberries also have a much more diverse anthocyanin species compared to other berries containing 26 different anthocyanins compared to other berries that may only have 2-3.

What happens to your cognition when you consume 1 cup of berries? What the research says.

As we grow older, there seems to be a decline in how fast we can process information and how much we can store in our working memory (WM), so we need to use more of our brain to accomplish tasks. The role of diet and exercise on preserving and improving cognitive function have recently been examined in hopes to keep our brains young and working optimally. Blueberries, especially, as it can combat inflammation and reactive oxygen species that could lead to neurodegeneration and can increase BDNF and strengthen neuronal connections (1). Whereas, the Standard American Diet has been linked to decreased cognitive performance and memory

Anecdotally, I experienced a dramatic improvement in my own ability to focus and retain information when I centered my diet around foods that have a lot of nutrients and special functions like blueberries.

But, you don’t need to just take my word for it. I found several studies using an achievable dose of 1 cup of blueberries a day (or less) examining the relationship between blueberry consumption and cognitive functioning.

 

 

Study Subjects/Duration Dose Outcome
Devore 2010
16,010 Adult Women (>70 years) from Nurses Health Study
Epidemiological Study

FFQ: 61-130 items, either <1 serving/month, 1-3 servings/month, >1 serving/week

Increased intake of berries associated with slower rate of cognitive decline by 2.5 years (using 6 cognitive tests). P-trend = 0.014
Krikorian 2010
9 Older Adults with Early Memory Decline

12 weeks

6 – 9 mL/kg Wild blueberry juice (on avg 2 cups/day)

Placebo

Improved paired associated learning (p=0.009), word list recall (p=0.04), reduced depressive symptoms (p=0.08), lower glucose level (p=0.10)
Krikorian 2016

Presented at a conference

47 Adults (Age= 68+) with MCI

16 weeks

1 cup of berries (freeze-dried blueberry powder)* or Placebo Powder
MRI: increased brain activity, 72% improvement in semantic access, 13% improvement in visual-spatial memory
Whyte 2016
21 Children (Age 7-10)

One time Acute Dose.

Placebo, 15 gram or 30 grams freeze dried wild blueberry powder.

Cognitive performance tested at 1.15, 3 and 6 hours.

Significant WBB related improvements: final immediate recall at 1.15 h, accuracy on interference task at 3h.
McNamara 2018
66 Adults (62-80 years) With Subjective Memory Decline.

24 weeks

Blueberry Powder (BB)

Fish Oil (FO)

Blueberry Powder + Fish Oil (Both)

Placebo

FO (p=0.03), BB (p=0.05) reported fewer cognitive symptoms, BB improved memory discrimination (p=0,04)
Miller 2018
37 Healthy Adults (60-75 years)

90 days

1 cup of berries (24g freeze dried powder)* or Placebo
Blueberry group had fewer repetition errosr in the California Verbal Learning Test (p=0.031) and reduced switch cost on a task-switching test (p=0,033).
  • *Note these are of the high bush variety – not the wild blueberries (wild blueberry, is known to have 3x more anthocyanin compared to the high bush variety. It is still promising to see significant improvement even with the more accessible berry.)
  • *CVLT: California Verbal Learning Test: neuropsychoogical test which can be used to access verbal memory abilities.
  • *Task Switching Test: task switching measures executive function.

In an epidemiological study conducted by Devore et al. Nurses Health Study participants, >70 year old women, filled out a Food Frequency Questionnaire. When adjusted to potential confounders, women in the highest berry consumption (>1 time per week) had a slower rate of cognitive decline by 2.5 years compared to the lowest berry consumption group (>1x per month).

Usually it would be pretty difficult to conduct double-blind randomized controlled trials (RCT) when it comes to food! However, it was done by creating a powder out of freeze-dried berries so the participants did not know what group they were in. In 4 RCTs, participants were given either ~24g freeze dried berries (equivalent to 1 cup of berries) or a placebo powder for several months.

After 90 days in Miller 2018 study, there was significant improvement in the cognitive test (CVLT) and fewer errors on an executive function test in participants. Krikorian study on individuals with Mild Cognitive Impairment, after 16 weeks, the berry group had increased brain activity on an MRI, 72% improvement in semantic access and 13% improvement in visual-spatial memory. Krikorian stated: “The other interesting result was that the blueberry-supplemented participants felt they were performing better in their everyday lives. They had a better sense of well-being and were making fewer memory mistakes and were less inefficient than they had been relative to those that received the placebo powder”.

McNamara 2018 study included a fish oil group as well but found that the participants with early memory decline who consumed the blueberry powder had a more dramatic improvement in cognitive function in 24 weeks. Blueberries had an acute effect as well. Whyte found that children who ate blueberry powder had improved accuracy on recall and interference tasks after 3 hours.

I was surprised to see that this recommendation to eat berries has not been well integrated for treatment of neurological disorders or other chronic diseases where the root cause is related to increased Reactive Oxygen Species (ROS). I’ve noticed that this is because the articles negating the blueberry power often look at studies that only take a look at its antioxidant roles, in vitro, and with supplements. But as we know now, that is not a fair assessment. Especially knowing how berries have many other effects, including epigenetic effects in addition to being a potent antioxidant.

I’m also well aware that eating more blueberries is not the only change one needs to make to prevent and treat chronic diseases. But, it would be a great starting point. Blueberries are tasty and this is easy to incorporate into the diet. Being a Registered Dietitian, I know that small, manageable changes like this is doable for patients to accomplish long term.

It is now becoming clear that the consumption of a diet rich in phytochemicals results in an improved metabolic profile, reduces inflammation and increases expression of genes that are protective. But, despite being a well known super food, the average consumption remains only 2.5 cups a year. What would happen if we strive to consume 1 cup a day, all becoming heavy blueberry users like me?

 

References:

  1. “Chapter 2- Blueberry Polyphenols and Neuroprotection ” BIOACTIVE NUTRACEUTICALS AND DIETARY SUPPLEMENTS IN NEUROLOGICAL AND BRAIN DISEASE, by RONALD ROSS. WATSON, ELSEVIER ACADEMIC PRESS, 2017

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