Eating by the Numbers

The new ANDI and NuVal food-rating systems strive to make healthy choices easier. But they can be misleading, too. Here’s how to make sense of the numbers – and their limitations.

For better or worse, most Americans have been guided by nutritional directives — food pyramids, recommended daily intakes, guidelines and allowances — that exhort them to eat by the numbers: Five servings of this, 10 grams of that, and count those calories, please!

Well-intentioned though they may be, these dictums have given rise to a rigid, formulaic mindset, one that has left many eaters confused. An apple a day may keep the doctor away, they figure, but who knows — maybe a 100-calorie snack pack of low-fat, vitamin-enriched, high-fiber apple chips would be even better?

Two new numerical food-rating systems — the NuVal Nutritional Scoring System and the Aggregate Nutrient Density Index (ANDI) — are attempting to simplify matters. Piloted in some Kroger and Whole Foods Market stores, respectively, both share a common goal of streamlining the process of evaluating various foods’ nutritional merits. Although they differ in their approach and delivery, both systems ultimately distill the nutrient density of each food into a single numerical score.

The stated objective of both these rating systems is to help shoppers make healthier choices in the grocery aisles. And they may. But because they rely on a massive aggregation and simplification of complex information, they may also lead consumers to some mistaken conclusions — about the true nutritional merits of certain foods, about how whole and processed foods compare, and more.

That’s why, for those health-motivated shoppers who want to understand what these food ratings are reflecting (and what they are not), it’s helpful to know not just the numbers, but also a little something about the logic and assumptions built into the algorithms that produced them. Once you understand both the advantages and pitfalls of each system, you stand a better chance of interpreting their results in a way that serves your own healthy-eating goals.

The Right and Wrong of Ratings

ANDI is the brainchild of Joel Fuhrman, MD, chief medical officer of Eat Right America and author of Eat for Health (Gift of Health Press, 2008). ANDI rates mostly whole foods, such as vegetables, fruits and legumes, but includes some processed fare as well. It bases its rankings primarily on   the amount of beneficial nutrients (such as calcium, carotenoids, fiber, vitamins, minerals and antioxidants) present in a given food in relation to its caloric value.

By comparing nutrient values from an equal caloric portion of food, ANDI adds up 23 different nutrients to assign each food a number on a scale from 1 to 1,000. For example, kale and collards earn a perfect 1,000, while a white potato rates only a 31.

“It’s a micronutrient score,” explains Fuhrman. “The basic science behind this is that foods give us macronutrients [carbohydrates, proteins, fats, etc.] and micronutrients [vitamins, minerals, phytonutrients]. The more macronutrients we eat, the shorter our life span. The more micronutrients you eat, the longer your life span.”

ANDI’s approach, accordingly, reflects the extraordinary nutritional value of low-calorie, high-nutrition foods like vegetables. Yet, it also produces some counterintuitive results, giving a number of very healthy foods surprisingly low ratings. Walnuts, for example, get a rating of only 34 out of 1,000, despite their beneficial sterols and stenoids. That’s not much better than the aforementioned white potato.

Fuhrman’s algorithm penalizes walnuts for their relatively high fat and calorie content. And that can send a skewed message to consumers, says Kathie Swift, MS, RD, a nutrition educator at The Center for Mind-Body Medicine in Washington, D.C. “Do we really want to give a lower score to walnuts than to kale just because they are more calorie dense?” Swift asks. “To me, the big picture is that we need to get Americans to eat more vegetables and nuts.”

Fuhrman says he agrees that people need to be eating a variety of foods, including nuts and seeds, legumes, and fruits. His intent with the ANDI rating scale is not to steer shoppers away from these healthy choices, he notes, but rather to get them more excited about super-nutritious foods, like dark leafy greens, that too many shoppers currently overlook.

The Frozen-Pizza Factor

Like ANDI, the NuVal system rates both whole and processed foods, but it rates many more processed options. Developed by a team led by David Katz, MD, MPH, director of the Yale Prevention Research Center, NuVal takes U.S. government nutrition data from food labels and calculates a single score for foods based on a scale from 1 to 100, with 1 having the lowest overall nutrition quality and 100 having the highest.

“Our algorithm starts as a simple mathematical equation,” explains Annette Maggi, RD, NuVal’s senior director of nutrition. “In the numerator are factors that have a positive impact on health: vitamins, fiber, omega-3 fatty acids. In the denominator are factors that have a negative impact: sodium, sugar, saturated fat and trans fats.” (For the skinny on saturated fat, see “Big Fat Confusion,” next page.) The formula also factors in “weighting coefficients” that measure a food’s impact on conditions such as obesity, heart disease and diabetes.

Appropriately, fresh vegetables, legumes, fruits and other whole foods score higher than salty, fatty, processed foods. A mango, for example, rates a 93 while Chex Mix scores a 13. But the same calorie penalty inherent in ANDI applies to NuVal. And canned vegetables (provided they don’t contain salt, sugar or any sauces) can score just as well as fresh vegetables, which undergo no processing at all.

For example, both fresh broccoli and canned Del Monte Fresh French Green Beans (No Salt Added) rate a 100. Part of the reason, says Maggi, is that the government doesn’t measure the difference in phytonutrients between, for example, raw green beans and canned green beans. NuVal crunched numbers based on “the tools that are available in the marketplace today, and that [government] nutrient database is based on raw fruits and vegetables.”

Nutritionist Liz Lipski, PhD, CCN, author of Digestive Wellness (McGraw-Hill, 1999), declined to comment directly on NuVal or ANDI, but she notes that “any system is only as good as the philosophy that underlies it.” And most nutritional experts agree that the government’s food philosophy leaves quite a lot to be desired.

The USDA Food Pyramid, for instance, doesn’t distinguish between the carbohydrates found in whole brown rice or quinoa and those found in the flours of store-bought breads. In Lipski’s mind, it should. She’d also like to see food-rating systems consider whether a food is fresh, frozen or canned, and whether or not foods are organic.

But Maggi contends that the NuVal system syncs well with the way most Americans really eat — and shop. “The average shopper spends 26 minutes to buy 60 items,” she explains. “That’s less than 30 seconds per item, which doesn’t leave much time to compare brands, much less nutrition.”

NuVal, says Maggi, is designed to help consumers trade up within a category. So, she says, if you’re looking for a cold cereal, go with Post’s Shredded Wheat (91) over General Mills’ Cheerios (37) because it has more fiber and less sodium.

“The reality is that consumers eat processed food,” she says. “They buy cereal. They buy salty snacks. We want to help them make the most of these choices from a nutritional standpoint.”

For his part, Fuhrman says that although ANDI does score processed foods, the ratings system is best used for whole foods — which are the foods he’d like to see us all eat more of. Even when processed foods are fortified, he notes, they simply do not have the full spectrum of micronutrients that whole foods contain. Also, because the full value of all nutrients can’t be properly weighted, “some fortified foods may get better scores than they really deserve.”

NuVal’s algorithm, Maggi says, takes fortification into account. Fortified vitamins and minerals are capped in the rating formula, while naturally occurring nutrients are not. “If you look at Total cereal, you don’t get credit in the score for all of those [added] vitamins,” she says.

Big Fat Confusion

Another place both NuVal and ANDI invite confusion is in their assessment of fats. NuVal’s scoring system gives walnuts, which are high in polyunsaturated fats, more credit (82 out of 100) than ANDI does because, as Maggi puts it, NuVal has stayed abreast of the changing views on nutrients that have an impact on disease, such as cholesterol.

“Not all fats are the same,” she says. “Trans fat is closely related to heart disease, which is a serious, expensive and prevalent problem. Dietary cholesterol, on the other hand, is not as closely related to heart disease. So it’s not as weighted.”

Both systems, however, have a bias against saturated fats, which have long been wrongly blamed as a primary factor in high cholesterol and heart disease, and which are now thought to be critical to many biochemical functions.

Both ANDI and NuVal assign higher scores to skim or fat-free milk compared with whole milk, for example. NuVal relegates saturated fats to the same category as trans fats in its formula — which explains not only the lower ratings for full-fat dairy but also why fresh coconut rates so low (24). Fresh coconut fares even worse in the ANDI system, scoring a paltry 10.

Although saturated fat has long been demonized as one of the main reasons people gain weight and fall prey to heart disease, the scientific evidence for this view has never been strong. An article published last year in the American Journal of Clinical Nutrition looked at 21 studies involving about 350,000 people and found no significant link between saturated fat in the diet and heart disease. Increasingly, processed sugars and carbs appear to be more important factors. (Read “Heart News.”)

Far From Perfect

Fuhrman readily admits that ANDI “is not a perfect system.” For example, Fuhrman says veggies like mushrooms (135) and onions (50) should be rated much higher given their powerful anticancer properties. Yet, like NuVal, ANDI had to base its ratings on what is in the government database, and the government does not currently measure the anticancer properties of mushrooms and onions.

Accordingly, says Fuhrman, choosing only those foods with the highest nutrient-density score is not the only key to an ideal diet. Filling up your shopping cart exclusively with ANDI’s (or NuVal’s) top-ranked goods would probably leave you short on healthy fats, for example, as well as a little low on variety.

Still, by comparing the ratings of foods in particular categories, a smart shopper can come away with a sense of which foods deliver the most nutritional bang for the buck, and that might encourage consumers to try vegetables and fruits they might otherwise pass by.

When you’re in the produce section at your local Whole Foods Market looking at fruits, for instance, you’ll see from the ANDI ratings that apples (72) are rated higher than bananas (30) but not as highly rated as blueberries (130) or strawberries (212). That just might make you toss some berries in your basket.

Above all, Fuhrman says, he simply wants shoppers to see how powerful ➺ green vegetables are. “I want people to think, ‘I should make a green vegetable every night for dinner.’”

NuVal’s Maggi wants to help folks make better choices in every aisle. “If you’re looking for a canned vegetable as a side dish, then you can trade up from Del Monte canned green beans [59] to Del Monte canned spinach [76],” says Maggi. “Overall, the message of guidance is a good one.”
Even Kathie Swift sees systems like ANDI and NuVal as a step in the right direction. She notes that while she and other nutrition experts are debating the finer points of various food-rating programs, “the average person is still eating total crap.”  The ratings systems are useful as an on-ramp to better eating, she says: “Let’s get you started here and then move you up.”

is a Minneapolis writer.

Leave a Comment

Subscribe to our Newsletters

Newsletter Signup
Weekly Newsletter
Special Promotions