Go Nuts!

Have you ever noticed that some of your strongest food memories are of rich, fat laden meals shared with family and friends? According to new research, this may not be a coincidence. A study published last week in the Proceedings of the National Academy of Sciences demonstrates that digesting fatty foods enhances memory consolidation using the same neural pathway as emotional learning.

This finding has far reaching implications for cognitive therapies to fight over-eating, but may also suggest new, easy to implement strategies for memory enhancement. Pistachios anyone?

In the study, rats being trained on memory tasks were administered a substance called oleoylethanolamide (OEA) that normally increases in the gut after the ingestion of dietary fat (not carbohydrate or protein). Several days later, the rats given OEA performed better on the tasks than rats that were not, demonstrating enhanced learning.

To determine the neural pathway involved in this effect, the researchers chemically blocked signaling in the region of the brain that receives neural inputs from the gut (solitary nucleus), which abolished the effect of OEA. Next they selectively blocked neural transmission between this region and another region of the brain that has been shown to be critical for emotional learning (amygdala). This also eliminated the memory enhancement effect of OEA, indicating that emotional memory and memory enhancement from fatty food ingestion share the same neural network.

These findings may partially explain the emotional component that is often associated with chronic over-eating, something that frequently involves learned habits triggered by emotional situations.

However, OEA does more than enhance memory. It is also critical in feelings of satiety after a meal (decreasing hunger) and has been implicated in controlling body weight. Is it possible this new information could be harnessed for the power of good?

Low-fat diets have proved to be a colossal failure for both health and weight loss, partially because they encourage over-consumption of starchy (usually refined) carbohydrates. Moreover, vegetable and fish oils are protective against many chronic diseases that plague Western culture. Regularly seeking healthy fats in your diet can help control hunger, promote weight loss and lower risk of disease. But it now seems that healthy fats could also be a useful tool in overcoming emotional eating, a problem more complex than the standard weight gain that comes from 21^st century living.

Another interesting corollary of this study is that fat (specifically oleic acid, a healthy fat found predominantly in olive oil and nuts) may enhance learning and memory. Since the benefits of OEA were only evident when it was administered at the time of or immediately after training, the next time you study or prepare for a presentation you might want to have some nuts around to snack on. Almonds, cashews, hazelnuts, macadamia nuts, peanuts, pecans and pistachios are highest in oleic acid.

Are you interested in foods that could provide cognitive enhancement?

In honor of the food issue this week at Synapse, I compiled a list of ten essential diet and nutrition facts you might not know:

1. “Vitamins” are not the same as whole foods. Instant ramen and a multivitamin is not a healthy meal. There is no substitute for a diet of whole foods rich in vegetables, beans, grains and fish.
2. A healthy diet can prevent or even reverse four out of the six leading causes of death in the US. Evidence indicates that diet is more important than genetics in the vast majority of heart disease, stroke, cancer and type 2 diabetes cases.
3. The thinnest, healthiest people in the world eat “high carb” diets. But they definitely do not eat the processed, refined carbohydrates that flood Western culture. If you want to lose weight and live longer without disease, eat more vegetables and whole grains.
4. You get plenty of calcium. Americans consume more calcium than most countries on earth, yet still sport some of the highest rates of osteoporosis. This debilitating disease is more likely caused by insufficient vitamin D, not enough exercise and/or too much protein. Also, excess calcium is linked to prostate cancer and milk to ovarian cancer. Calcium does not support weight loss either.
5. “Fiber” is not the same as vegetables and grains. Fiber supplements do not offer the same benefits as fiber-filled foods, and do not help with weight loss or protect against disease.
6. The best sources of protein are plants and fish. It is relatively easy to get complete protein (i.e., all the essential amino acids) from a diverse diet. Protein from red meat offers more risk than reward. (Yes, pork is red meat.)
7. Fruits and vegetables protect your vision. Both cataracts and macular degeneration are strongly tied to diet.
8. Fats from factories are dangerous. Processed oils and trans fats (not total dietary fat) are associated with heart disease, type 2 diabetes, cancer and obesity. Replacing them with natural oils could save your life.
9. Fats from plants and fish are essential. Mono- and polyunsaturated fats protect against heart disease, type 2 diabetes and memory loss. In moderation they can also aid in weight loss, since they increase the satiety you feel after a meal.
10. You can lose weight on any short-term diet, but you will probably gain back more than you ultimately lose. This is often true even if you stay on the diet. Focusing on long-term health is the best strategy for sustained weight loss, but it requires patience.

What are other common myths about diet and nutrition?

UPDATE: For more information on the health value of oils from fish, please read my answer in the comments section.
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