Daniel Lubetzky

Jane Brody published a very sensible reality check about diet in yesterday’s New York Times. That it proved sensible was all but inevitable, as her column was clearly much informed by an interview with the eminently sensible, and extremely knowledgeable Dr. Frank Hu of Harvard, late of the Dietary Guidelines Advisory Committee, and newly elected to the National Academy of Medicine. I happily take this opportunity to offer my public congratulations to Dr. Hu for that last item, among the highest honors a biomedical professional can receive- and certainly very well deserved in this case.

As noted, Ms. Brody’s column was very sensible, telling us there are good and bad fats, good and bad carbohydrates. But with all due respect to her august journalistic pedigree, I think it fell slightly short of the mark by failing to go beyond macronutrients altogether. What Jane Brody meant to say, in other words, is what I was privileged to say jointly with Dr. Hu: wholesome foods in sensible combinations. Dr. Hu and I in in turn owe a debt of gratitude to Michael Pollan, who first threw down that gauntlet with: food, not too much, mostly plants.

Ms. Brody’s column rightly belies the currently prevalent, cacophonous nonsense about saturated fat. No, there is no evidence that eating more saturated fat is “good” for us, and certainly none that health (of people, let alone the planet) is promoted by eating more meat, butter, and cheese. As recipes go, that argument has been egregiously overcooked from the start.

Similarly, and obviously guided by Dr. Hu’s wisdom, she notes that it matters what we eat instead. This crucial consideration, so often ignored by those with dubious motives where a devotion to public health ought to be, was the subject of a recent paper in the Journal of the American College of Cardiology- which concluded on the basis of science precisely what sense would predict. Replace saturated fat calories (and the foods providing them) with sugar and refined starch calories, and health outcomes are comparably poor both times. Well, what else would one expect as an outcome of inventing more than one way to eat badly?

However, replace those saturated fat calories with either whole grains or unsaturated oils (and the foods that provide them, notably nuts, seeds, olives, avocados, and fish)- and health outcomes improve markedly. I am sure there must be something related to relativity or quantum physics in the mix here that I am overlooking, but as far as I can tell, this translates to: eat food that is good for you, and it will be good for you.

Yep, that’s the punch line, folks. Food that is good for us is good for us. And that’s what Jane Brody meant to say, and didn’t: it’s not about macronutrients at all; it’s about food. Eat wholesome foods, mostly plants, in sensible combinations – and the macronutrients, and micronutrients, and glycemic load, and all the rest- generally sort themselves out quite handily.

The evidence for this proposition is overwhelming. Dr. Hu and I have both had cause to look it over from altitude, in the service of independent review papers in the Lancet, and Annual Review of Public Health, respectively. Our confluent conclusions in those two unrelated projects are what prompted us to write together about “wholesome foods in sensible combinations” in the first place.

In my own case, even more evidence figured in the mix in the writing of the most recent edition of my nutrition textbook, spanning some 50 chapters, 750 pages, and approximately 10,000 scientific citations. There are admittedly excruciating details in that mix, but the gist condenses to: wholesome foods, mostly plants, in sensible combinations. And that was the very conclusion reached by the 2015 Dietary Guidelines Advisory Committee in an extensively referenced, 572 page report.

Finally, it’s just what one sees through the lens Dan Buettner has provided us to the Blue Zones of the world, those places where people live the longest and the best. Their diets vary considerably, but all vary on a common theme. You guessed it: wholesome foods, mostly plants, in sensible combinations. No Blue Zone is mostly runnin’ on donuts, any more than any Blue Zone is mostly runnin’ on meat, butter, and cheese. Rather, the emphasis is consistently where the evidence suggests it ought to be: on vegetables, fruits, whole grains, beans, lentils, nuts, and seeds.

Why not let Jane Brody have the last word? Because the last word really needs to be food, not nutrient. We have already demonstrated our nearly endless capacity to pervert almost any nutrient preoccupation into a public health boondoggle. A fixation on nutrients plays directly into the hands of industry elements that can design new inventories of junk food faster than most of us can say “monosodium glutamate.”

For decades, we have fixated on one nutrient at a time, and wound up with lipstick on a pig (willfully engineered to maximize our calorie intake, into the bargain!) for breakfast, lunch and dinner. Rather than renouncing the folly of subjugating foods and dietary patterns to mononutrient preoccupations, we have instead reacted with all the subtlety of a block of rock subject to Newtonian impulses: equal and opposite reactions. If saturated fat wasn’t the right scapegoat, let’s try carbohydrates; or sugar; or fructose; or gluten…

Let’s not. Let’s eat wholesome foods, mostly plants, in sensible combinations- and put an end to this era of fatuous fixations, and profits over public health. That’s what the evidence has long indicated. That’s what a massive, if as yet little known, consensus among the world’s leading experts favors. That’s just what the 2015 Dietary Guidelines Advisory Committee concluded.

And it is, I presume, what Ms. Brody meant to say.

Jane Brody Article: The Fats You Don’t Need to Fear, and the Carbs That You Do

The nutritional pickle so many Americans are now in is largely a result of “an oversimplification of dietary recommendations that created a fat phobia,” Dr. Frank B. Hu of the Harvard T. H. Chan School of Public Health told me.

Starting in the 1970s, when accumulating evidence from animal and human studies showed that a diet high in saturated fats and cholesterol was an important risk factor for cardiovascular disease, dietary guidelines urged people to eat less fat.

Although health advice focused on saturated fats from high-fat animal foods, many people generalized the advice to mean all fats, choosing in their stead a panoply of reduced-fat and fat-free foods rich in carbohydrates, from crackers to sweetened yogurts. They especially increased their consumption of two kinds of carbohydrates, refined starches and sugars, that have helped to spawn the current epidemic of obesity and Type 2 diabetes.

Experts now realize that efforts to correct past dietary sins that made heart disease and stroke runaway killers have caused the pendulum to swing too far in the wrong direction.

“The mistake made in earlier dietary guidelines was an emphasis on low-fat without emphasizing the quality of carbohydrates, creating the impression that all fats are bad and all carbs are good,” Dr. Hu, a professor of nutrition and epidemiology, said. “It’s really important to distinguish between healthy fats and bad fats, healthy carbs and bad carbs.”

He explained that saturated fat, found in fatty animal foods like meats and dairy products, raises blood levels of cholesterol and is not healthy, “but olive oil is important — it’s beneficial for cardiovascular health and body weight.” Olive oil, like canola, avocado and nut oils, is monounsaturated, and while it has as many calories as meat and dairy fat, it does not raise serum cholesterol or foster fat-clogging deposits in blood vessels.

“We have to get out of the fat phobia mind-set,” Dr. Hu stressed, adding that we also have to abandon the idea that all complex carbohydrates are good.

Sugars are simple carbohydrates and starches are complex carbohydrates; all are ultimately broken down into glucose, the body fuel that circulates in blood. Sugars are digested rapidly, quickly raising blood glucose, but most starches take longer to digest.

Important exceptions are refined carbohydrates, like white bread and white rice. Starchy foods with highly processed grains that have been stripped of dietary fiber act more like sugar in the body. They are rapidly digested and absorbed, raising blood levels of glucose and prompting the secretion of insulin to process it. When consumed in excess of the body’s need for immediate and stored energy, refined carbs and sugars can result in insulin resistance and contribute to fatty liver disease.

Alas, potatoes, the nation’s most popular vegetable, act like sugars and refined carbohydrates. They have what is called a high glycemic index, the ability to raise blood glucose rapidly. Potatoes, Dr. Hu explained, are made of long chains of glucose easily digested by enzymes in the mouth and stomach, and the fat in French fries slows the process only slightly.

The concept of a glycemic index, proposed in 1981 by David Jenkins and his colleagues in The American Journal of Clinical Nutrition, has since been validated repeatedly and is now accepted as a good way to distinguish between the kinds of carbohydrates that are health-promoting or at least neutral and those that have negative health effects.

In 2002, Dr. David S. Ludwig, a pediatrician, endocrinologist and nutrition researcher at Boston Children’s Hospital and professor at the Harvard T. H. Chan School of Public Health, published a comprehensive review of how glycemic index influences human physiology, clearly demonstrating its importance to preventing and treating obesity, diabetes and cardiovascular disease. Had Americans and their physicians heeded it then, we might have been largely spared the fix we’re now in.

The index was developed by testing the glucose response to a standard amount of carbohydrate against a reference food, either pure glucose (index number 100) or white bread (71). High-glycemic foods like baked Russet potatoes (111), white baguette (95), cornflakes (93), white rice (89), pretzels (83), instant oatmeal (83), rice cakes (82), Gatorade (78) and French fries (75) induce higher blood glucose levels than ordinary white bread and are best consumed infrequently and in small quantities.

At the other end of the glycemic spectrum, oatmeal (55), pasta (46 for spaghetti, 32 for fettuccine), apples (39), carrots (35), skim milk (32), black beans (30), lentils (29), prunes (29), barley (28), chickpeas (10), grapefruit (25), peanuts (7) and hummus (6) have a smaller effect on blood glucose, and green vegetables like broccoli have too little an effect to be measured.

Closely related to the glycemic index is the glycemic load. While the glycemic index measures how quickly a particular food raises blood sugar, the glycemic load takes portion sizes into account. Hence a food like watermelon, with a high glycemic index, has a low glycemic load, since much of the fruit is water.

High-glycemic foods are a particular problem for people trying to control their weight. The amount of insulin released to lower blood glucose can overshoot the mark and result in a rapid return of hunger. A low-glycemic food, on the other hand, has no such effect. And those that are rich in wholesome fats, like peanuts or avocado, can actually delay the return of hunger, though the calories can add up quickly if consumed to excess.

“The glycemic index and glycemic load of the average diet in the United States appear to have risen in recent years because of increases in carbohydrate consumption and changes in food-processing technology,” Dr. Ludwig wrote in 2002. The pattern persisted in the decade that followed, and can largely explain the rise in overweight and obesity among Americans of all ages.

In addition, chronic consumption of meals with a high-glycemic effect can induce insulin resistance, the hallmark of Type 2 diabetes, and an excess of free fatty acids in the blood, resulting in fatty liver disease. The prevalence of both these disorders has risen in recent years, and both can lead to chronic inflammation, a promoter of cardiovascular disease.

Dr. Hu said that when he was growing up in China, most people were physically active and thus able to handle the glycemic load of large amounts of white rice consumed. “Now, however, the Chinese have become more sedentary but still consume large amounts of white rice, and both obesity and diabetes are on the rise,” he said.