Oh Chatelaine, you never fail to provide me with material to blog about. I read it for the recipes and the inaccurate nutrition information.
The latest article to spark my ranting was a brief piece recommending eating berries to improve memory; or more specifically, to “slow cognitive aging by up to 2.5 years.” What does this really mean? After a little digging for the journal article upon which the piece was based (why don’t magazines have to provide references?) I found it: Dietary intakes of berries and flavonoids in relation to cognitive decline. The first thing I did was check to see who the study was sponsored by. What a surprise, The California Strawberry Commission. Naturally, it would be in their best interests to find a positive association between strawberry consumption and decreased cognitive decline.
Looking at the study itself, I’m even less accepting of the conclusion that berries help to maintain cognitive function. They used the data from the Nurses’ Health Study which means that their results were based on food frequency questionnaires. Food frequency questionnaires are notoriously inaccurate, even more so than food recall questionnaires. Think about it, you try to recall how many times you ate berries (specifically strawberries and blueberries) over the past year. Even if you could remember that much, would you be able to remember how much you had on each occasion?
Cognitive assessment was done via a series of telephone administered tests. I don’t have any quibbles with this.
The researchers accounted for a number of potential confounding factors; however, despite mentioning that physical activity, annual household income, and fish consumption were all higher among those consuming the most berries, they appear to have only adjusted for age and education. When comparing those who ate the most berries to those who ate the least, the mean difference in global decline was determined to be 1.5-2.5 years. Women with the lowest cognitive scores were excluded from the analysis as it was surmised that they may have been experiencing the early stages of dementia. It makes me wonder what the results would have shown if they had included all of the sample in their results. I also question why they didn’t include the table showing the results when they controlled for all potentially confounding factors.
I’m all for berries. They’re delicious and nutritious and I don’t want my dissection of this study to discourage anyone from consuming them. I just don’t like seeing the benefits of consuming any one food overstated.