Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
5 Feb

Eating Habits and Memory Function

Diet is a powerful force as we say time and again. Most of the studies revolve around the physical aspects: inflammation, disease risk, body composition, blood markers, etc. But there’s the promise a good diet can offer other elements of health, including cognitive performance. With climbing rates of dementia and Alzheimer’s, these correlations are nothing to shake a stick at.

In that vein, this recent study caught our eye. Researchers from the University of Muenster in Germany followed subjects who had been grouped into three practices: a caloric restriction group (30% cut in daily intake), a group that increased their consumption of essential fatty acids (20% increase), and a control group. After three months, all subjects retook tests focused on memory activities. The group that cut its calories showed a “significant increase” in scores related to verbal memory. The apparent cognitive improvement could be correlated, the researchers say, with “decreases in fasting plasma levels of insulin and high sensitive C-reactive protein.” No noteworthy changes were seen in the other subjects.

Are we coming out in favor of caloric restriction, you might ask. Not really. While study results like this do present intriguing food for thought, we’re more interested in the investigative “why” behind the observed benefits than the straight practice of CR itself. (On a related note, we do recommend intermittent fasting, but we’ll leave that comparison for another time.) In this case, our interest was definitely piqued by the authors’ comment on the power of CR to boost memory function: “Mechanisms underlying this improvement might include higher synaptic plasticity and stimulation of neurofacilitatory pathways in the brain because of improved insulin sensitivity and reduced inflammatory activity.”

Hmmm. An eating practice that enhances insulin sensitivity and reduces systemic inflammation. Why does that sound familiar? Anyone around here know anything about that? Let’s say right away, that this point does make a significant conjecture. The study results address observed benefits of CR as it was undertaken in this study by this (relatively) small group of older people. But it’s entirely legitimate to ask that “why” question and see what else it might tell us about the relationship between cognitive performance and eating habits that tend to lower insulin release and reduce inflammation.

In fact, another study published this week in Diabetes Care links higher average blood glucose levels with reduced performance on a number of cognitive activities, including those measuring memory. (Those with diabetes suffer higher rates of dementia and cognitive decline, and the development of diabetes in middle age has been shown to actually double the risk of Alzheimer’s disease in twins.) The research, which is part of the ongoing ACCORD study, stops short of defining causation until further results are gathered and analyzed. Nonetheless, the connection is more than mere suggestion in light of other research.

Is it really any surprise that what’s good for the body appears to also be healthy for the mind? The take-home message is this: keeping systemic inflammation and insulin levels in check will definitely benefit your body and reduce your chance of developing many major diseases, including heart disease, cancer, diabetes and hypertension. But beyond putting years on your life and life in your years, a healthy diet may also help you remember and fully enjoy the best of all your years.

Comments? Questions? Thanks for sharing!

Further Reading:

Calorie Restriction Only Benefits Obese Mice

Dear Mark: Post Workout Fasting

Is the Primal Blueprint for Both Men and Women?

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. The PB make us leaner, stronger, healthier AND smarter! The results from limiting sugar have been shown to be dramatic. Combine that with a REALLY powerful diet, and you become healthy, wise and hopefully wealthy. The only disappointing thing is that most wealthy people are pretty chubby. Healthy and wise are a sort of wealth in their own way.

    JE Gonzalez wrote on February 5th, 2009
  2. Interesting. Any difference between verbal memory and…oh…regular memory? Or is verbal memory just the communication of something remembered?

    Mandy wrote on February 5th, 2009
  3. I’m a little surprised the essential fatty acids group didn’t turn up anything. From what I knew, especially the omega 3s lower inflammation. With the correlation this study is making, wouldn’t that help? Unless it just wasn’t the right inflammation or the 20% wasn’t enough…?

    Holly wrote on February 5th, 2009
    • Certain fatty acids do in fact, improve cognitive function; they just have to be the right ones. Combined with the right herbs, the results can be powerful.

      Karen wrote on February 19th, 2011
  4. I find that on most days I practice CR just because the primal blueprint fills you up. I don’t make a point to calorie restrict, I eat when I am hungry, but veggies, lean protein and fat fill you up fast. Also, if I did want to practice CR for a week or two and see how it went, the primal blueprint would be ideal for it.

    Kimberly wrote on February 5th, 2009
  5. Interesting stuff coming out on this. There are some studies and real world examples finally getting some notice about the improvements in test scores for students on sugar restricted diets. It makes sense that the brain can only operate optimally on optimal fuel. Derrrrrr.

    The SoG

    Son of Grok wrote on February 5th, 2009
  6. I saw this study posted elsewhere last week and my first thought was:

    “Is it really the CR at work? Or is it really just Sugar Restriction?”

    Giving your brain an excessive glucose/insulin bath not only damages your brain’s glucose metabolism, but also its serotogenic and dopamine systems — both (especially dopamine) are crucial for memory.

    I’ve found it odd that CR gets so much hype. On a Paleo diet I can eat 1,000 calories a day for weeks without flexing a single self-discipline muscle.

    There’s gotta be a better “why” to all this other than just the oversimplified CR “theory”.

    Jeff wrote on February 5th, 2009
  7. Improving memory through caloric restriction is all well and good, but if you follow the CR lists at all, it’s interesting to note the general lack of vigor for life exhibited by the group. You can sense the deprivation just by reading their posts. I’d much rather improve my insulin sensitivity by following the Primal Blueprint, thank you very much!

    Jesse Bastide wrote on February 5th, 2009
  8. This is on t-nation today.

    And hormones like insulin are under huge dietary control. Managing insulin effectively can help out a physique athlete in several ways. A moderate insulin level throughout the day is handy, not only for protein synthesis, but because insulin in the blood tends to free up bound Testosterone in the body. That’s why a higher carb intake helps for mass gains. There are positive hormonal changes when you up your carbs, and those pan out over time.

    I know your opponion about this Mark, but it goes against what is normal here. That higher carbs have a positive effect.

    Kasper wrote on February 5th, 2009
  9. There was a piece on CR on 60 Minutes a week or so ago. Mostly with mice, showing how much longer they lived.

    What I would like to see is a study that includes IF. Why the “all or nothing” approach.

    As I see it, IF in the “primal” sense offers the (possible) best of both worlds. The benefits of CR without the lack of vigor Jesse noted.

    j d wilson wrote on February 5th, 2009
  10. first thought that comes to mind – “Duh”.

    Another tick in your (our) court Mark…

    Ryan Denner wrote on February 5th, 2009
  11. I have noticed at least 4 tbsp of milled flax, 1 cup of homemade kefir, fish oil, and a healthy paleo diet with IF have made my memory sharp.

    Zen Fritta wrote on February 5th, 2009
  12. Hey Mark,

    Sorry for the long comment/question that’s about to happen, but I’d really appreciate your advice! I’m a religious MDA reader; love love love it.

    I’m trying to lose some weight (20ish lbs.), so I’m practicing calorie restriction (about 1500 most days) with a PB/Atkins-style approach. I’ve sworn off sugar and grains (19 days and counting!) so my carbs are always pretty low (trying to stay around 20 net), but I still have a tendency to binge on cheese and chopped liver about once a week (weird, I know… it used to be candy nightly but now I’ve replaced that behavior with this). This brings carbs up to around 70 net, calories between 4000 and 5000. I tend to fast a day/restrict heavily for a couple days to make up for it to have an overall weekly caloric deficit. This has been working okay weight loss-wise but pretty much sucks to do. Do you think this behavior screws the benefits people usually get from the PB/fasting etc.? Also, does it really count as a fast if I have coffee with cream in the morning in the middle of a fast? I’m a 21-year-old woman, 155 lbs. (down from 164 a month ago), I power lift three times per week, walk a lot.

    Thanks for any input you may have! I know this isn’t exactly 100% related to this post, but I hope you’ll forgive me.


    JL wrote on February 6th, 2009
  13. Maybe they’re looking at it the wrong way round?

    Just as “normal” carb intake is actually toxic and “low carb” is actually normal in terms of physiological response, maybe “normal” calorie levels are toxic and “restricted” levels are actually “normal”?

    Trinkwasser wrote on February 7th, 2009
  14. Amazing how focused researchers get on calorie restriction, as if it were the only way to reasonably control insulin levels. Guess it’s easy for them to do, especially when working with rats. But there are better ways to get the job done.

    Karen wrote on February 19th, 2011
  15. Thanks for the nice post. Many research studies have proved that that consumption of certain foods such as blueberries,clam, salmon and nuts can sharpen your memory and enhance your mental health.

    Albert wrote on March 7th, 2011
  16. Calcium improves memory and is essential for concentration, but also protects the brain from infection. Contain its apples, apricots, beets, cabbage, carrots, cherries, cucumbers, grapes, green vegetables, almonds, oranges, peaches, pineapple, strawberries, whole grains.

    Vanda wrote on May 17th, 2011

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