Some people argue that the shape of food tells you what part of the body the food is good for. The idea is a bit absurd and in most cases, it simply isn’t true. But, when it comes to walnuts, the concept might actually be true.
After all, walnuts do look a lot like the human brain. Needless to say, the shape itself isn’t what causes any health benefits.
But, are walnuts good for the brain?
Recently, I’ve been fascinated by the health benefits of nuts (including almonds, peanuts and walnuts) and even the benefits of nut butters. This fascination comes from the way that nuts have had a bad reputation for quite some time (because of the fat content), but we’re starting to realize that they are actually really healthy.
I found one fairly recent study (Arab & Ang, 2015) that specifically addresses the potential relationship between walnuts and the brain. This included a strong focus on the consumption of walnuts and the cognitive function of participants.
I don’t know about you, but I find the concept absolutely fascinating. Being able to improve our cognitive function is a pretty appealing goal for anyone.
The Study Itself
This study made use of data collected through the National Health and Nutrition Examination Survey (NHANES). Specifically, the authors focused on two rounds of data collection. One was from 1988 to 1994 while the other was from 1999 to 2002.
From the participants of the study, the authors chose a representative sample of adults ranging from 20 to 90 years of age. They also used a range of outcomes from the study that considered cognitive function, such as a story recall test and reaction time text.
Within the study, walnut consumption was measured using 24-hour food recall. This involved participants providing information about what they had consumed in the past 24 hours. The authors focused on individuals who consumed walnuts exclusively or walnuts with other nuts, and calculated the total grams of walnuts consumed.
The authors found significant positive associations between walnut consumption and cognitive functions. This was true for participants who ate walnuts in conjunction with other nuts and those that just consumed walnuts.
The outcomes also varied by age. In participants who were between 20 and 59 years of age, improvement in cognition was seen across three different cognitive domains.
In contrast, for participants aged 60 and above, improvements in different cognitive areas were noted. These results were still true after the authors had accounted for potential confounding factors, such as gender, physical activity and alcohol intake.
Additionally, higher levels of walnut consumption were associated with improved cognitive outcomes overall. This indicates that the impacts of walnuts on cognition are dose-dependent, with higher walnut consumption contributing to better cognitive improvement.
Based on this, are walnuts good for your brain?
I’d say that the answer is yes because there does seem to be a strong connection between walnuts and cognition. However, it’s still important to consider the strengths and limitations of this particular study.
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Strengths and Limitations
One major strength of this study was that it specifically focused on walnuts. Most research studies have either focused on nuts in general or on almonds. As such, there haven't been many studies looking at the benefits of walnuts.
The measurement of walnut consumption for this study was also interesting.
Many research studies simply look at whether people consumed nuts on their own (such as eating a handful of walnuts). However, that approach isn’t always realistic, because people consume nuts in many different ways.
In this study, the authors considered total walnut consumption. This included snacking on walnuts, but also many other options, like muffins containing walnuts, walnut cake, a salad with walnuts and walnuts sprinkled on yogurt. In general, that approach is an advantage because it provides a more accurate picture of total walnut consumption.
For this research, the study design acted as both an advantage and a disadvantage. Now, the overall design of the study was cross-sectional in nature. This is a type of observational study where the authors take data from a population at one specific point in time.
This design allowed the authors to see outcomes from a diverse population, which included a wide range of age groups. Because of this, the authors were able to look at the relationship between walnuts and cognition in different age groups. That ability is a major advantage, as the impacts of walnuts on cognition may well be different between one age group and another.
However, this design means that researchers cannot see how outcomes change over time. For example, this makes it impossible to see whether the people with higher walnut consumption had consistently improved cognition. Additionally, the design introduces some bias into the study because it doesn’t take differences between the groups into account.
Another aspect of the design was that the study was observational.
Observational studies are always limited because they cannot test cause and effect. Instead, they just look at patterns. Now, these patterns can still offer a lot of important information. Nevertheless, there are always other possible explanations for the patterns observed. So, the results of any observational study need to be read with caution.
The study did also have one other significant disadvantage – the way that walnut consumption was measured.
To do this the authors just looked at data for the previous 24 hours. Now, this data can certainly offer some insight into walnut consumption patterns. However, it does mean the authors have on way of knowing whether people consistently consume walnuts.
For example, if you look back at your last 24 hours of eating, would that be representative of your eating patterns in general? Perhaps it would be but not necessarily. I mean, if you had a bad day, went out for dinner or had hardly any food in the house, your eating patterns could be pretty different than normal.
To make matters worse, there’s a good chance that it is long-term walnut consumption that affects cognition.
This means that the results of the study may well be inaccurate about the impact of walnuts on cognition. The authors argue that these limitations are likely to underestimate people’s walnut consumption. As such, the impacts of walnuts on cognition are likely to be greater than the outcomes of the research state.
Are Walnuts Good for Your Brain?
The results from this study did show a positive association between walnut consumption and various measures of cognition for patients between 20 and 59 years of age as well as for those aged 60 and above.
The authors also note that these outcomes agree with the results from other cross-sectional studies that have been conducted for nuts in general.
Realistically, more research is needed before we truly know the connection between walnuts and cognition. Personally, I’d like to see a few well-designed experimental studies, as these would offer the best information about the topic.
But, even without those studies, this particular research does support the growing idea that nuts in general, and walnuts specifically, are good for your brain. Besides, walnuts are a healthy addition to the diet anyway, so it’s worth starting to eat more of them now, rather than waiting until all of the research results are in.
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People tend to vary when it comes to nuts, so what's your preference? Do you like walnuts or do you tend to eat a different type of nut?