8871 Pickards Meadow Road, Chapel Hill, NC 27516
Corner of Jo Mac and Pickards Meadow
8871 Pickards Meadow Road, Chapel Hill, NC 27516
Corner of Jo Mac and Pickards Meadow
Flailing in the swell of bestselling diet books, infomercials for cleanses, and secret tips in glossy magazines, is the credibility of nutrition science. Watching thoroughly-credentialed medical experts tout the addition or subtraction of one nutrient as deliverance—only to change the channel and hear someone equally-thoroughly-credentialed touting the opposite—it can be tempting to write off nutrition advice altogether. This month we hear something is good, and next we almost expect to hear it’s bad. Why not assume the latest research will all eventually be nullified, and just close our eyes and eat whatever tastes best?
That notion is at once relatable and tragic, in that diet is inextricable from the amount of healthy time we spend on Earth. Improvements in diet are clearly associated with significant lengthening of lifespan and dramatic decreases in risk of most chronic diseases. Combining disease and longevity into the concept of healthspan, the number of healthy years of life—fundamentally more important but less readily quantifiable than lifespan—the data in favor of optimizing our diets are even more compelling. No one is arguing that diet is less than extremely important to health and well-being, but seemingly everyone is arguing as to what constitutes the best diet.
The voices that carry the farthest over the sea of diet recommendations are those of iconoclasts—those who promise the most for the least, and do so with certainty. Amid the clamor, Dr. David Katz is emerging as an iconoclast on the side of reason. At least, that’s how he describes himself. From his throne at Yale University’s Prevention Research Center, where he is a practicing physician and researcher, said sea of popular diet media is the institution against which he rebels. It’s not that nutrition science is corrupt, just that the empty promises of memetic, of-the-moment diet crazes are themselves junk food. To Katz they are more than annoying and confusing; they are dangerous injustice.
Scientific publisher Annual Reviews asked Katz to compare the medical evidence for and against every mainstream diet. He says they came to him because of his penchant for dispassionate appraisals. “I don’t have a dog in the fight,” he told me. “I don’t care which diet is best. I care about the truth.”
Katz and Yale colleague Stephanie Meller published their findings in the current issue of the journal in a paper titled, “Can We Say What Diet Is Best for Health?” In it, they compare the major diets of the day: Low carb, low fat, low glycemic, Mediterranean, mixed/balanced (DASH), Paleolithic, vegan, and elements of other diets. Despite the pervasiveness of these diets in culture and media, Katz and Meller write, “There have been no rigorous, long-term studies comparing contenders for best diet laurels using methodology that precludes bias and confounding. For many reasons, such studies are unlikely.” They conclude that no diet is clearly best, but there are common elements across eating patterns that are proven to be beneficial to health. “A diet of minimally processed foods close to nature, predominantly plants, is decisively associated with health promotion and disease prevention.”
Katz, Meller/Annual Reviews
Among the salient points of proven health benefits the researchers note, nutritionally-replete plant-based diets are supported by a wide array of favorable health outcomes, including fewer cancers and less heart disease. These diets ideally included not just fruits and vegetables, but whole grains, nuts, and seeds. Katz and Meller found “no decisive evidence” that low-fat diets are better than diets high in healthful fats, like the Mediterranean. Those fats include a lower ratio of omega-6 to omega-3 fatty acids than the typical American diet.
The Mediterranean diet, which is additionally defined by high intake of fiber, moderate alcohol and meat intake, antioxidants, and polyphenols, does have favorable effects on heart disease, cancer risk, obesity, metabolic syndrome, and “is potentially associated with defense against neurodegenerative disease and preservation of cognitive function, reduced inflammation, and defense against asthma.”
They also found carbohydrate-selective diets to be better than categorically low-carbohydrate diets, in that incorporating whole grains is associated with lower risks for cancers and better control of body weight. Attention to glycemic load and index is “sensible at the least.” Eating foods that have high glycemic loads (which Katz says is much more relevant to health outcomes than glycemic index—in that some quality foods like carrots have very high indices, which could be misleading) is associated with greater risk of heart disease.
Finally, in a notable blow to some interpretations of the Paleo diet, Katz and Meller wrote, “if Paleolithic eating is loosely interpreted to mean a diet based mostly on meat, no meaningful interpretation of health effects is possible.” They note that the composition of most meat in today’s food supply is not similar to that of mammoth meat, and that most plants available during the Stone Age are today extinct. (Though it wouldn’t surprise me to learn that Paleo extremists are crowd-funding a Jurassic Park style experiment to bring them back.)
Just because Katz is not one to abandon his scientific compass under duress of passion does not mean he is without passion, or unmoved by it in his own ways. The subjects of media headlines and popular diet books are dark places for Katz. “It’s not just linguistic, I really at times feel like crying, when I think about that we’re paying for ignorance with human lives,” he told me. “At times, I hate the people with alphabet soup after their names who are promising the moon and the stars with certainty. I hate knowing that the next person is already rubbing his or her hands together with the next fad to make it on the bestseller list.”
“The evidence that with knowledge already at our disposal, we could eliminate 80 percent of chronic disease is the basis for everything I do,” Katz said. Just as he was finishing his residency in internal medicine in 1993, influential research in theJournal of the American Medical Association (“Actual Causes of Death in the United States“) put diet on a short list of the lifestyle factors blamed for half of deaths in 1990. “Here we are more than 20 years later and we’ve made just about no progress.”
A nod to the fact that popular media is not totally lost, Katz borrows from the writer Michael Pollan, citing a seminal 2007 New York Times Magazine article on “nutritionism” in concluding that the mantra, “Eat food, not too much, mostly plants” is sound. “That’s an excellent idea, and yet somehow it turns out to be extremely radical.”
Though Katz also says it isn’t nearly enough. “That doesn’t help you pick the most nutritious bread, or the best pasta sauce. A member of the foodie elite might say you shouldn’t eat anything from a bag, box, bottle, jar, or can.” That’s admittedly impractical. “We do need to look at all the details that populate the space between where we are and where we want to be.”
The current review is in pursuit of that, as is a system for determining the nutritional value of foods that Katz recently spent two years developing. It’s calledNuVal, and it offers consumers a single numeric value to determine foods’ worth, as opposed to a complex nutritional panel. The number does things like differentiate intrinsic from added nutrients. “If you don’t do that, the best thing in the whole damn food supply is Total cereal. Total is basically a completely vapid flake delivery system for multivitamins. You could skip the cereal and take the multivitamin.”
“If you eat food direct from nature,” Katz added, “you don’t even need to think about this. You don’t have to worry about trans fat or saturated fat or salt—most of our salt comes from processed food, not the salt shaker. If you focus on real food, nutrients tend to take care of themselves.”
The ultimate point of this diet review, which is framed like a tournament, is that there is no winner. More than that, antagonistic talk in pursuit of marketing a certain diet, emphasizing mutual exclusivity—similar to arguments against bipartisan political rhetoric—is damaging to the entire system and conversation. Exaggerated emphasis on a single nutrient or food is inadvisable. The result, Katz and Meller write, is a mire of perpetual confusion and doubt. Public health could benefit on a grand scale from a unified front in health media: Endorsement of the basic theme of what we do know to be healthful eating and candid acknowledgement of the many details we do not know.
“I think Bertrand Russell nailed it,” Katz told me, “when he said that the whole problem with the world is that fools and fanatics are so sure, and wise people always have doubts. Something like that.”
I found this recipe in “the complete ‘I’ (…ntelligent’s) guide to gluten-free vegan cooking” 🙂
I replaced few ingredients to make it more Tridoshic 😉
1( 8 oz) pgk. Tempeh (crumble it with your fingers)
6 oz. Crimini mushrooms (around 1 1/2 Cups)
“just” 1/4 Cup red onion, diced
7 TB vegetable broth
1 TB Coconut oil
“just” 1/2 garlic, minced
1 TB herbs de Provence
one pinch of each: cinnamon, cardamon
1/4 tsp coriander
1/8 tsp grated fresh ginger
1/4 Cup (the best quality you can) Balsamic vinegar
1 1/2 TB Tamari
1/2 tsp maple syrup
1 tsp sweet miso (low sodium miso preferable)
1) place in a large skillet the oil, 4 TB of veggie broth, crumbled tempeh, mushrooms, red onion, and the herbs de Provence, cook in medium for about 4-5′ stirring constantly
2) add garlic, the rest of spices and the rest of the veggie broth. cook for 2-3′
3) add vinegar, tamari, and maple syrup and cook for 2′ or until the liquids are absorbed. let it cool for about 10′
4) Place the mixture in a food processor, add the miso. Process until smooth.
~ Wishing You All A Sunny Day~
Suggested citation for this article: Di Noia J. Defining Powerhouse Fruits and Vegetables: A Nutrient Density Approach. Prev Chronic Dis 2014;11:130390. DOI: http://dx.doi.org/10.5888/pcd11.130390.
National nutrition guidelines emphasize consumption of powerhouse fruits and vegetables (PFV), foods most strongly associated with reduced chronic disease risk; yet efforts to define PFV are lacking. This study developed and validated a classification scheme defining PFV as foods providing, on average, 10% or more daily value per 100 kcal of 17 qualifying nutrients. Of 47 foods studied, 41 satisfied the powerhouse criterion and were more nutrient-dense than were non-PFV, providing preliminary evidence of the validity of the classification scheme. The proposed classification scheme is offered as a tool for nutrition education and dietary guidance.
Powerhouse fruits and vegetables (PFV), foods most strongly associated with reduced chronic disease risk, are described as green leafy, yellow/orange, citrus, and cruciferous items, but a clear definition of PFV is lacking (1). Defining PFV on the basis of nutrient and phytochemical constituents is suggested (1). However, uniform data on food phytochemicals and corresponding intake recommendations are lacking (2). This article describes a classification scheme defining PFV on the basis of 17 nutrients of public health importance per the Food and Agriculture Organization of the United Nations and Institute of Medicine (ie, potassium, fiber, protein, calcium, iron, thiamin, riboflavin, niacin, folate, zinc, and vitamins A, B6, B12, C, D, E, and K) (3).
This cross-sectional study identified PFV in a 3-step process. First, a tentative list of PFV consisting of green leafy, yellow/orange, citrus, and cruciferous items was generated on the basis of scientific literature (4,5) and consumer guidelines (6,7). Berry fruits and allium vegetables were added in light of their associations with reduced risks for cardiovascular and neurodegenerative diseases and some cancers (8). For each, and for 4 items (apples, bananas, corn, and potatoes) described elsewhere as low-nutrient-dense (1), information was collected in February 2014 on amounts of the 17 nutrients and kilocalories per 100 g of food (9). Because preparation methods can alter the nutrient content of foods (2), nutrient data were for the items in raw form.
Second, a nutrient density score was calculated for each food using the method of Darmon et al (10). The numerator is a nutrient adequacy score calculated as the mean of percent daily values (DVs) for the qualifying nutrients (based on a 2,000 kcal/d diet ) per 100 g of food. The scores were weighted using available data (Table 1) based on the bioavailability of the nutrients (12): nutrient adequacy score = (Σ [nutrienti × bioavailabilityi)/DVi] × 100)/17. As some foods are excellent sources of a particular nutrient but contain few other nutrients, percent DVs were capped at 100 so that any one nutrient would not contribute unduly to the total score (3). The denominator is the energy density of the food (kilocalories per 100 g): nutrient density score (expressed per 100 kcal) = (nutrient adequacy score/energy density) x 100. The score represents the mean of percent DVs per 100 kcal of food.
Third, nutrient-dense foods (defined as those with scores ≥10) were classified as PFV. The Food and Drug Administration defines foods providing 10% or more DV of a nutrient as good sources of the nutrient (3). Because there are no standards defining good sources of a combination of nutrients-per-kilocalories, the FDA threshold was used for this purpose. The 4 low-nutrient-dense items were classified as non-PFV.
To validate the classification scheme, the Spearman correlation between nutrient density scores and powerhouse group was examined. The robustness of the scheme with respect to nutrients beneficial in chronic disease risk also was examined by comparing foods classified as PFV with those separately classified as such based on densities of 8 nutrients protective against cancer and heart disease (ie, fiber, folate, zinc, and vitamins B6, B12, C, D, and E) (2,4).
Of 47 foods studied, all but 6 (raspberry, tangerine, cranberry, garlic, onion, and blueberry) satisfied the powerhouse criterion (Table 2). Nutrient density scores ranged from 10.47 to 122.68 (median score = 32.23) and were moderately correlated with powerhouse group (ρ = 0.49, P = .001). The classification scheme was robust with respect to nutrients protective against chronic disease (97% of foods classified as PFV were separately classified as such on the basis of 8 nutrients protective against cancer and heart disease). For ease of interpretation, scores above 100 were capped at 100 (indicating that the food provides, on average, 100% DV of the qualifying nutrients per 100 kcal). Items in cruciferous (watercress, Chinese cabbage, collard green, kale, arugula) and green leafy (chard, beet green, spinach, chicory, leaf lettuce) groups were concentrated in the top half of the distribution of scores (Table 2) whereas items belonging to yellow/orange (carrot, tomato, winter squash, sweet potato), allium (scallion, leek), citrus (lemon, orange, lime, grapefruit), and berry (strawberry, blackberry) groups were concentrated in the bottom half (4–7).
The proposed classification scheme is offered in response to the call to better define PFV and may aid in strengthening the powerhouse message to the public. The focus on individual foods in terms of the nutrients they provide may facilitate better understanding of PFV than green leafy, yellow/orange, citrus, and cruciferous food groups that are emphasized. Messages might specify PFV to help consumers know what they are and choose them as part of their overall fruit and vegetable intake. As numeric descriptors of the amount of beneficial nutrients PFV contain relative to the energy they provide, the scores can serve as a platform for educating people on the concept of nutrient density. Expressing the nutrient desirability of foods in terms of the energy they provide may help focus consumers on their daily energy needs and getting the most nutrients from their foods. The rankings provide clarity on the nutrient quality of the different foods and may aid in the selection of more nutrient-dense items within the powerhouse group.
Foods within particular groups were studied; thus, other nutrient-dense items may have been overlooked. Because it was not possible to include phytochemical data in the calculation of nutrient density scores, the scores do not reflect all of the constituents that may confer health benefits. Warranting study is the utility of approaches defining PFV based on the presence (regardless of amount) of nutrients and phytochemicals. Although nutrient density differences by powerhouse group were examined, a true validation of the classification scheme is needed. Future studies might identify healthful diets and examine correlations with PFV or look for correlations between intake of PFV and health outcomes (3).
This study is an important step toward defining PFV and quantifying nutrient density differences among them. On the basis of the qualifying nutrients, 41 PFV were identified. The included foods may aid in improving consumer understanding of PFV and the beneficial nutrients they provide.
Jennifer Di Noia, PhD, William Paterson University, 300 Pompton Rd, Wayne, NJ 07470. Telephone: 973-720-3714. E-mail: email@example.com.
|Item||Nutrient Density Score|
|Winter squash (all varieties)||13.89|
|Grapefruit (pink and red)||11.64|
The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors’ affiliated institutions.