I am just back (on the red eye, no less) from the annual Scientific Advisory Committee meeting of the California Walnut Commission held in Napa Valley. If you could live in Napa Valley, why would you live anywhere else? If you've been, you know what I mean.
The California Walnut Commission is the trade group representing walnut growers in the U.S., most of whom have their ranches in California. The commission is involved in some marketing, messaging and PR -- but overwhelmingly oversees the research agenda examining the health effects of walnut intake. And that, of course, is where I come in -- and why I was at the meeting.
My lab has completed two studies of walnuts, and I was in Napa to present the second, as well as to participate in discussions of future research priorities.
Our first study, published in Diabetes Care in 2010, showed that adding walnuts to the daily diet of adults with Type 2 diabetes for two months significantly improved blood vessel health, as measured by something called endothelial function.
Well known to clinicians, especially cardiologists, and to researchers, endothelial function is not generally familiar to the public at large. In brief, ultrasound is used to measure the ability of blood vessels to dilate when they should. Normal endothelial function is a very strong indicator of low heart disease risk; endothelial dysfunction portends the converse.
Walnuts added to the diet improve endothelial function in Type 2 diabetes. Our study also showed that even though we were adding walnuts, and thus calories, to the diet -- weight gain did not result. Our study subjects did not gain weight, because they made room in their diets for the walnut calories.
Like other nuts, walnuts are energy dense (i.e., high in calories) -- but especially when eaten as nature provides them, without additions of sugar or salt, they are very satiating, providing a lasting feeling of fullness. Satiety is, in essence, the ROI for calories consumed, and it appears to be very high for nuts in general, and walnuts specifically.
Our more recent study examined a potential role for walnuts in diabetes prevention. Using a similar design, and measures, we examined effects of roughly 14 walnuts a day for two months in overweight adults with signs of the metabolic syndrome, a state that anticipates diabetes. Our results are just in, and will be submitted for publication shortly. In brief, they closely mimic the results of study one: endothelial function improved, as did blood pressure, with no weight gain.
Results from my lab were just a small part of a rich, two-day conversation about the diverse health effects of walnut intake, and underlying mechanisms. Scientists from throughout the U.S., from Spain and from Australia contributed.
Studies were presented indicating that walnuts confer health benefits when included in the Mediterranean diet; are effective at increasing satiety and controlling appetite; contain uniquely active antioxidants; may prevent cancer progression; reduce inflammation; influence gene expression; and may help reduce body fat. They may also enhance male fertility.
With regard to mechanisms -- and the active ingredients in walnuts -- discussion was equally far-ranging. Like most nuts, walnuts are rich in unsaturated oils, minerals (magnesium, calcium and potassium), fiber, protein and antioxidants. Unlike other nuts, walnuts are rich in omega-3 fat, in the form of ALA (alpha linolenic acid).
There is, as some of you likely know, ongoing debate about the relative health benefits of plant omega-3 in the form of ALA, and marine animal omega-3, which comes as EPA and DHA. As was explored in some detail by the biochemists at our meeting, ALA converts inefficiently into EPA and DHA in the human body. But, on the other hand, it may exert complementary health benefits of its own, and clearly influences the composition of our cells, and hormone production.
While much discussion focused on the "active" ingredients in walnuts -- an inevitable consequence of our often reductionistic approach to science -- the consensus was clear that the active ingredient in walnuts is almost certainly ... walnuts. Studies were presented indicating explicitly that many of those parts exert benefits even in isolation, but that the health effect of the whole is greater than a mere summing of the parts we know.
Even as we met, results of a meta-analysis by Harvard researchers, involving some 200,000 study participants, were published online in the American Journal of Clinical Nutrition. The study shows that regular intake of processed meat, and to a lesser extent any red meat, increases diabetes risk substantially. Conversely, more intake of nuts (as well as whole grain and low-fat dairy) and less intake of meat can reduce diabetes risk by as much as 35 percent. So says Dr. Frank Hu, senior author of the meta-analysis, and a participant at the Napa meeting.
I can say one more thing about walnuts: when the overall nutritional quality of nuts is measured comprehensively, they come out on top. On the NuVal scale from 1 to 100, which has itself been validated against health outcomes in 100,000 people, walnuts score 82. Almonds are close behind at 81, but virtually no other nut comes close. Pistachios score 69; pecans, 67; peanuts, 29; and cashews, 25.
It is perhaps to be expected that a group of scientists studying walnuts, and attending a walnut commission meeting, would be walnut fans. In other words, you might dismiss our enthusiasm as bias. But there are two reasons why I believe you shouldn't.
First, the peer-reviewed science supporting health benefits from walnut intake is broad, and deep, and has had to run a gauntlet of filters designed to weed out biased work. Second, the groups' bias in favor of walnuts is cart, not horse. The evidence generated by robust research has made proponents of us all -- we didn't just start out that way.
Nuts are encouraged in the Dietary Guidelines, and are a potentially valuable addition to most diets (assuming no allergies to them, of course). Walnuts are the pick of the nut crop in my opinion, as well as that of my many colleagues at the Napa meeting. There are likely benefits to weight and health from adding roughly 1 oz of them (seven nuts) to your diet most days.
That, in a nut shell, is the conviction I brought home with me from California. Chew on it as you see fit.
-fin
Dr. David L. Katz; www.davidkatzmd.com
www.turnthetidefoundation.org
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It sounds to me like one thing is measured, endothelial function, then claims of improved blood vessel health implied, and with the inclusion of Type 2 diabetes sounds like this is being suggested as a cure or treatment for diabetes - but all in a rather vague way.
Then eat walnuts and don't gain weight ... sounds like another marketing campaign.
I am all for walnuts, I eat them regularly, and not just in chocolate chip cookies as I used to when I was a kid, but as universal panacea ... I am getting tired of food being treated like football teams in which people cheer and go on about the greatness and superiority of one team over another. ... and at the finish line, there's walnuts first ... almonds coming in a close second with pistachios grabbing third place.
It does seem like a kind of conflict of interest to having people involved in the industry doing studies about the health effects of their products ... just as much as the Wall St. rating firms being paid by the companies they rate. I thought America was so great at using the free market, but we have found all these ways to break it and make it questionable.
Anyway ... back to my walnuts, almonds and cashew snack ... though I guess I may have to drop the cashews for a while until the cashew guy writes a cashew article.
Because I live in New York City and there is no better place in the world to live!!!
health claims that weren't approved by the FDA.
http://www.dailymail.co.uk/news/article-2018807/Walnuts-DRUGS-FDA-makes-bizarre-claim-seller-says-reduce-risk-heart-disease-cancer.html
Also, I make chicken salad with grapes, apples and walnuts and add just a tiny bit of mayonnaise and applesauce. Some people just use applesauce for health and less calories.
You can also serve the chicken salad on top of a vegetable salad or just romaine.
And Sam, I agree with you. Pecans are the best. Love that pie. They're just to expensive here in California.
Walnuts, when eaten raw is still - just walnuts as an ingredients, much better than any processed ( Healthy so called foods ).
There should be more studies like this, and articles like this, to educate the public about nutrition. Because the FDA sure doesn't a damn about anything but making money from the big companies that pay them.
Thank you for this article by the way.
by this type of reasoning, Popeye would be yanked off the air for spinach propaganda and sued by the Beef Association (remember that Whimpy ate burgers) and your mom would be doing time in prison for making unsubstantiated claims about carrots and eyesight!
what kind of country is this where we've outlawed common sense?
I have also heard (and sometimes observed) that walnuts, once shelled, go rancid quickly. I wish they were obtainable in the shell year round.