What’s blue, round, sweet, grows on a bush and can boost your brainpower? If you answered blueberries, you would be right. Or that should be: ‘mostly right’. The ‘brain-boosting’ part needs a bit more science to catch up to the headlines, but it is looking promising that blueberries may be one food worthy of the ‘superfood’ title. In this podcast, I’ll look at the science behind how blueberries can help keep your brain healthy and functioning well throughout life.
There is so much to be gained by having plenty of plant-based foods in your diet. While it may be tempting to stake your claim that health is all about the superfood du jour, it is the variety of foods you eat that are key to good health. But there may just be something to the claims made about berries, in particular, the humble blueberry.
Blueberries are one food that pops up regularly on ‘superfood’ lists. Blueberries (and other berries such as raspberries and blackberries) are an excellent source of vitamin C, which helps protect cells against damage and aids in the absorption of iron. They also contain a decent amount of soluble fibre, which slows down the rate at which sugar is released into the bloodstream and helps to keep the digestive system happy.
Blueberries have long been promoted for their brain-boosting power, but is there much merit to the claims? The link between blueberries and the brain has grown out of observations that people who eat lots of fruits and vegetables over their lifetime have a lower risk of dementia. Scientists have singled in on one particular class of chemicals found in plant foods, called flavonoids, that may be the ‘active ingredient’ that could be protecting the brain from damage.
A collection of flavonoids called anthocyanidins have been getting even closer attention because of their antioxidant and anti-inflammatory properties. Anthocyanidins are abundant in berries and give these foods their bright blue, red and purple colours.
So how could the anthocyanidins in berries be of benefit for the brain? The high amounts of antioxidants in blueberries may be one way they help protect brain cells from damage. In cell and animal models, berries change the way that neurons in the brain communicate in pathways involved in inflammation and cell survival. Yet more research has shown that in humans, berries can also improve cognition, motor control and enhance neuroplasticity.
An ageing population means a greater number of diseases linked to older age such as dementia. There is no certain way to prevent dementia, but scientists have been looking closer at the role that diet can play in reducing the risk of developing it and blueberries have attracted their interest.
One recent clinical trial that attracted a lot of media attention used a concentrated form of blueberry juice – high in anthocyanidins. The trial involved 26 healthy adults aged between 65 and 77. And I’ll link to the study in the show notes. https://pubmed.ncbi.nlm.nih.gov/28249119
Half of the people drank concentrated blueberry juice each day for 12 weeks. The blueberry concentrate was equal to eating 230 grams of whole blueberries each day. The other half of the volunteers drank a placebo drink that had a blackcurrant taste, but no anthocyanidins in it. After 12 weeks, people drinking the blueberry juice showed improvements in cognitive function, blood flow to the brain and activation of brain areas linked with cognitive function. There was also evidence suggesting an improvement in working memory too.
Several studies have also found that blueberries may also have benefits for the brain by keeping it active and improving mood with improved mood and mental sharpness seen within a few hours of drinking a blueberry drink compared to a placebo drink.
Eating berries regularly is also linked to improved heart health. Berries can have a range of cardiovascular benefits from their anti-inflammatory, antihypertensive, hypoglycaemic and anticoagulant actions.
Brain health is closely linked to metabolic health and it is not surprising that risk factors for developing dementia include high blood pressure, poor glucose control, elevated blood lipids and central obesity. So how do berries fare in improving these metabolic problems? From a review of 22 randomised-controlled trials involving over 1200 people which I’ll link to in the show notes, regularly eating berries was found to significantly lower LDL-cholesterol, blood pressure, fasting glucose, body mass index and markers of glycaemic control. A cell signalling molecule involved in inflammation called tumour necrosis factor-α also drops when people switch to eating more berries. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4804301
Fresh blueberries are great, but for convenience and price and when they are out of season, you can’t go past having frozen blueberries on hand. And as a bonus for choosing frozen, because they are processed and frozen soon after picking, the nutrient losses are small. In fact, a study from the Journal of Biomedicine and Biotechnology which I’ll link to in the show notes found that drying and freezing blueberries has no impact on the antioxidant activity of anthocyanin extracts. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1082901
An ageing population means a greater number of diseases linked to older age and brain decline such as dementia. There is no certain way to prevent dementia, but scientists are looking closely at the role that diet can play in reducing the risk of developing it. Choosing a diet high in a variety of fruits and vegetables and including some delicious blueberries and other berries may go some way to reducing the risk of declining brain function in older age. And when it comes to blueberries, this is a case where the superfood hype may have a bit of solid science to support it.
Research Wrap Up
Now on to my research wrap up segment where I profile a study that has grabbed my attention during the week. And for this week is about using fish oil to treat rheumatoid arthritis.
Rheumatoid arthritis is a chronic, inflammatory disorder caused when the immune system turns on itself and attacks the joints. For sufferers, it is a disabling and painful condition which can lead to substantial loss of mobility due to pain and joint destruction.
One of the more popular over-the-counter treatments for rheumatoid arthritis is fish oil. Well known for its anti-inflammatory role, fish oil supplements have received a lot of attention in clinical trials evaluating how effective it can be in easing the pain of rheumatoid arthritis. Not all clinical trials though show a benefit of fish oil in treating rheumatoid arthritis, but this could be related to the amount of time a person is treated and the dose of fish oil taken.
A new review of randomised placebo-controlled clinical trials that used fish oil containing more than 2 grams of long-chain omega-3s fatty acids (which is a combination of EPA and DHA) and ran for a minimum of a month has just been completed and I’ll link to it in the show notes. Eighteen studies made the grade and involved 1,143 people all up. Doses of long-chain omega-3 fatty acids ranged from 2.1 up to 9.1 grams per day. The longest study ran for a year. https://pubmed.ncbi.nlm.nih.gov/28606571
Ten of the 18 studies in the review found a significant reduction in symptoms rheumatoid arthritis with fish oil treatment. Eight studies though found no benefit. All but one of the negative studies used doses of omega-3 fatty acids near the lower end of the range at 3 grams per day. In general, it appears that doses of omega-3 fatty acids between 3 and 6 grams per day seem the most likely to have a pain-reducing effect in rheumatoid arthritis.
Fish oil supplements can be an effective treatment for rheumatoid arthritis pain, but a person’s mileage can vary greatly. Not all studies show a benefit, but even within a clinical trial, there is a spectrum of responses where some people receive great relief and others very little. If you are considering trying fish oil to help with rheumatoid arthritis, then an effective dose of long-chain omega-3s appears to be around 3 grams per day. For context, a typical 1 gram fish oil capsule contains around 300 milligrams of the long-chain omega-3s of DHA and EPA combined so that can add up to a lot of supplements that need to be taken each day.
So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.
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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.