by Hassan Dashti
Berries are really, really good for you, but that isn’t my secret because you probably already know this. These fruits are loaded with vitamins and minerals and have exceptional antioxidant qualities, at an expensive price. Unfortunately, berries haven’t always been popular. The emergence of Pinkberry (recently opened in Boston on Newbury Street), a premium frozen yogurt franchise, has improved the popularity and availability of the lesser-known berries, such as raspberries, blueberries and blackberries.
Dr. Barbara Shukitt-Hale of the HNRCA is currently studying the effect of berries on aging and cognition in rats. These behavioral studies indicated that the consumption of berries, including strawberries and blackberries, improved neuronal function and delayed age-related deficits in learning and memory. Although these results are astounding and highly praised by nutritionists, I was more interested in how exactly the lab measured neuronal function, memory, and cognition in rats?
Numerous nutrition studies base their conclusions on anthropometric measurements. However there is no direct way to measure cognition. Scientists rely on specific protocols to estimate cognition in animals like rats. Two of these methods are Radial arm maze and the Morris water maze.
The Radial arm maze has the ability to measure a rat’s short-term memory. The maze has a central platform with different spokes radiating out from a central core. A single food pellet is placed at the end of each arm, while the rat is placed in the central platform. To measure short-term memory, the scientists examine how often a rat visits each arm as they search for food. A rat with a good short-term memory is able to memorize which arm he has already visited and thus avoids going down the same arm twice.
In the Morris water maze, the rat is placed in a large round tub of opaque water, with small hidden platforms under the water’s surface. Rats hate being in water so once placed inside the tub, the rat will move around the pool in desperate search for the hidden platform. To estimate memory and cognition, the scientists examine how long it takes the rat to find the platform, and whether they would be able to find it quicker in a subsequent trial.
Using these two tests, Dr. Shukitt-Hale and her colleagues were able to make several observations and dietary recommendations regarding berries. Her studies showed that rats on a high blueberry diet were able to make fewer mistakes, suggesting the role of blueberries in improving cognition. However, when the strawberry diet was studied, it actually took the rats a longer time to find the platform in the Morris water maze. According to Dr. Shukitt-Hale, this suggests that strawberries and blueberries work in different areas of the brain.
By varying the amount of blueberries and other berries in the rat’s diets, scientists could get an idea of how much of a certain food is needed to have an effect on cognition and memory. However, Dr. Shukitt-Hale also stated that “too much of a good thing might not be a good thing!” This was clearly seen in a similar study conducted with walnuts. A diet with 6% walnuts turned out to improve memory in rats, while rats on a 9% walnut diet actually had reduced cognition! So even though some berries may have excellent benefits for human, there is always a limit to how much one should consume.
Going back to my title, the secret I wanted to share is not that berries are good for you, but that a lot of what we know about food and diet comes from studies conducted on animals. A lot of these results do not necessarily replicate in humans, possibly leading to different recommendations. While animal studies could suggest important and significant correlations, we require further verification of these results in humans prior to committing to a conclusion and a dietary recommendation. As a result, the field of nutrition science is always evolving, leading to newer and exciting results that affect the way we eat.
Hassan Dashti is a first-year student in the Biochemical and Molecular Nutrition program from Kuwait, and is the current editor-in-chief of the Friedman Sprout. Hassan is currently engaged in nutrigenomics research at the HNRCA, trying to identify genes that affect saturated fat metabolism in human. He is interested in collecting foods from all over the world, and in restocking his pantry.