Category Archives: Featured Topics

Move over potatoes, make room for healthier school lunch

The U.S. Department of Agriculture (USDA) has come under fire from politicians and potato lobbyists over its proposal to cut back on French fries and potatoes in school lunch and offer broccoli and other vegetables instead. Yet its plan is based on sound science—and could help turn around this country’s obesity and diabetes epidemics.

The USDA’s proposal is a straightforward switch: Cap the amount of potatoes and other starchy vegetables that school lunch can serve at one cup per week—the equivalent of a medium baked potato—and promote a wider variety of vegetables, especially dark green and orange varieties, such as broccoli, spinach, and carrots. (1) The recommendation is part of a 76-page proposed overhaul of the nutrition standards in U.S. school meal programs, and the agency is on solid scientific footing: It’s following the recommendations from an expert panel at the Institute of Medicine (IOM), which spent a year reviewing research on children’s nutrient needs, as well as food choices that prevent obesity and chronic disease. (2)

Read more about the health benefits of vegetables and fruits.

U.S. children, on average, only eat about 40 percent of the government’s daily recommended vegetable intake—and 29 percent of that comes from potatoes, most of them fried. (2) Children are especially low in their intake of dark green vegetables, orange vegetables, and legumes (dried beans), getting less than 20 percent of the recommended intake.

By limiting starchy vegetables at lunch, and setting new requirements for dark green and orange vegetables, the IOM was trying to steer children’s diets in a healthier direction: “The committee anticipates that…with repeated exposures and high-quality food preparation, students will learn to value the vegetable items offered.” (2, p. 170) In other words, over time, kids will get used to eating broccoli, carrots, and other colorful vegetables—and may even start to like them.

Read more about Harvard’s new Healthy Eating Plate.

Read more about glycemic load.

Potatoes don’t count as a vegetable on Harvard’s new Healthy Eating Plate, and with good reason: They are very high in carbohydrate—in particular, the kind of carbohydrate that the body digests rapidly, causing blood sugar and insulin to surge and then dip. (The scientific term for this is that they have a high glycemic load.)  In the short term, this roller coaster-like effect on blood sugar and insulin can lead people to feel hungry again, soon after eating—and this, in turn, can lead to overeating. (3) Over the long term, diets high in potatoes and similarly rapidly-digested, high carbohydrate foods can contribute to obesity, diabetes, and heart disease. (49)

Potatoes do contain important nutrients—vitamin C, potassium, and vitamin B6, to name a few. But the potato is not the only source of these nutrients, nor is it the best: Cup for cup, for example, broccoli has nearly nine times as much vitamin C as a potato, and white beans have about double the potassium. Yet a cup of potatoes has a similar effect on blood sugar as a can of Coca Cola or a handful of jelly beans. (10) That’s a high metabolic price to pay for nutrients that children can easily get from other sources.

Potatoes seem to be a particular culprit for weight gain and diabetes. A recent study from Harvard School of Public Health that tracked the diet and lifestyle habits of 120,000 men and women for up to 20 years looked at how small food-choice changes contributed to weight gain over time. People who increased their consumption of French fries and baked or mashed potatoes gained more weight over time—an extra 3.4 and 1.3 pounds every four years, respectively. (6) People who decreased their intake of these foods gained less weight, as did people who increased their intake of other vegetables. A similar long-term study found that high potato and French fry intakes were linked to a greater risk of diabetes in women, and that replacing potatoes with whole grains could lower diabetes risk. (5)

For people who are lean and active, potatoes likely don’t exact such a severe metabolic toll. But one out of three children and two out of three adults in the U.S. are overweight or obese, and many do not get enough daily physical activity. That’s all the more reason to use potatoes sparingly in our meals, if at all.

“Eating more than two servings of potatoes a week may be okay for people who dig their own,” says Walter Willett, Professor of Epidemiology and Nutrition and chair of the Department of Nutrition at HSPH. “But today, few Americans get the amount of physical activity our ancestors did 80 years ago, and that means our metabolism responds poorly to high amounts of starch.”

Some politicians and potato lobbyists have raised concerns that replacing potatoes with a wider variety of vegetables would add $6.8 billion to the cost of school lunches over the next five years. (11) But that appears to be a short-sighted point of view: Obesity costs this country an estimated $152 billion a year in healthcare expenses, and those could rise to an estimated $319 billion by 2020. (12) That makes the cost of this school lunch upgrade seem like just a drop in the potato bucket.

References

1.U.S. Department of Agriculture. Nutrition Standards in the National School Lunch and School Breakfast Programs: A Proposed Rule by the Food and Nutrition Service on 01/13/2011. Federal Register. 2011;76:2494–2570.

2. Institute of Medicine. School Meals: Building Blocks for Healthy Children. Washington, D.C.: National Academies Press; 2009.

3. Abete I, Astrup A, Martinez JA, Thorsdottir I, Zulet MA. Obesity and the metabolic syndrome: role of different dietary macronutrient distribution patterns and specific nutritional components on weight loss and maintenance. Nutr Rev. 2010;68:214-31.

4. Halton TL, Willett WC, Liu S, et al. Low-carbohydrate-diet score and the risk of coronary heart disease in women. N Engl J Med. 2006;355:1991-2002.

5. Halton TL, Willett WC, Liu S, Manson JE, Stampfer MJ, Hu FB. Potato and french fry consumption and risk of type 2 diabetes in women. Am J Clin Nutr. 2006;83:284-90.

6. Mozaffarian D, Hao T, Rimm EB, Willett WC, Hu FB. Changes in diet and lifestyle and long-term weight gain in women and men. N Engl J Med. 2011;364:2392-404.

7. Barclay AW, Petocz P, McMillan-Price J, et al. Glycemic index, glycemic load, and chronic disease risk–a meta-analysis of observational studies. Am J Clin Nutr. 2008;87:627-37.

8. Beulens JW, de Bruijne LM, Stolk RP, et al. High dietary glycemic load and glycemic index increase risk of cardiovascular disease among middle-aged women: a population-based follow-up study. J Am Coll Cardiol. 2007;50:14-21.

9. Chiu CJ, Liu S, Willett WC, et al. Informing food choices and health outcomes by use of the dietary glycemic index. Nutr Rev. 2011;69:231-42.

10. The University of Sydney. Glycemic Index Database. Accessed October 8, 2011.

11. Huang, J. USDA wants to limit potatoes in school lunches. National Public Radio. October 5, 2011.

12. Dor AF, Langwith C, Tan E. A heavy burden: The individual costs of being overweight and obese in the United States. The George Washington University School of Public Health and Health Services Department of Health Policy, 2010.

It’s time for the salt feud to fade

One of the longest-running feuds in modern nutrition science revolves around a simple question: Will reducing salt intake save lives?salt-spillled-new

Fifty years ago, when the science of salt was just beginning to develop, the controversy was understandable, appropriate, and even helpful. It forced researchers on both sides to scrutinize and improve their work and research methods. A provocative, controversial article in Science magazine by journalist Gary Taubes, called “The (political) science of salt,” lays out both positions, though Taubes blatantly sided with the camp backing the idea that reducing salt would have little effect on health. (1) Keep in mind that some of the pro-salt ideas were fueled by the Salt Institute, a trade association that continues to fight restrictions on salt with the same tenacity and arguments that the tobacco industry has used to fight restrictions on smoking. (2) In the past, the position of the Salt Institute has been allied with that of large food companies and the National Restaurant Association, but more recently, the NRA has been working with its members to pro-actively address the challenge of reducing sodium levels in food.

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Food rating systems: A not-so-smart choice

shopping-cart-small-2

When rushing through the supermarket, who has time to pore over Nutrition Facts labels and compare ingredient lists?

That’s why more than a dozen rating systems have been established to help shoppers identify healthful products. (1) Some, like the Guiding Stars program in Hannaford supermarkets, put rating information on food shelf tags below various products. (2) Others, like the controversial (and now on-hold) Smart Choices Program, put jazzy labels on the front of packages. (3) The problem with these programs is that they use varied, and sometimes dubious, rating systems.

Take Smart Choices as an example. Started by the country’s top food companies (ConAgra, Kellogg’s, Kraft Foods, Pepsico, Unilever, and others), the program gave its seal of approval to foods that meet certain standards. Products could not exceed defined thresholds for fats (saturated, trans, total), sodium, cholesterol and added sugars, and were required to include calcium, fiber, or certain vitamins. (4) Under these guidelines, Apple Jacks, Cocoa Krispies, Cocoa Puffs, Corn Pops, Froot Loops, and Keebler Cookie Crunch—which all have 12 grams of sugar—got the same Smart Choices check mark as Cheerios (which has 1 gram of sugar).

“In principle, the Smart Choices seal could have been very useful for identifying foods that meet a high nutritional standard,” says Dr. Walter C. Willett, chair of the Harvard School of Public Heath Department of Nutrition. “However, the program’s standard was so low that even horrendous junk foods could qualify.”

The U.S. Food and Drug Administration (FDA) put the Smart Choices program on notice in August 2009 with a letter that it would be concerned if any front-of-package labeling system “used criteria that were not stringent enough to protect consumers against misleading claims; were inconsistent with the Dietary Guidelines for Americans; or had the effect of encouraging consumers to choose highly processed foods and refined grains instead of fruits, vegetables, and whole grains.” (5)

In late October 2009, the FDA announced it was establishing an independent panel to propose standards that companies must follow if they want to put nutrition guides or labels on the front of packages. (6) Soon after that, Smart Choices announced that it would “voluntarily postpone active operations and not encourage wider use of the logo,” (7) and news reports say that the program’s key founding companies have agreed to phase out the logo from their products. (810)

Until the FDA’s proposed standards come along, it’s a good idea to make your own smart choices by reading Nutrition Facts labels and ingredient lists instead of relying on those that may be as interested in a company’s health as yours.

References

1. Nutrition rating systems: a comparison. Fooducate Blog. Last updated September 2009. Accessed November 2, 2009.

2. Hannaford Bros. What is Guiding Stars? Hannaford.com. Accessed November 2, 2009.

3. Smart Choices Program. Guiding food choices. SmartChoicesProgram.com. Accessed November 2, 2009.

4. Smart Choices Program. Which foods get into the Smart Choices Program? SmartChoicesProgram.com. Accessed November 2, 2009.

5. U.S. Food and Drug Administration. Letter to the Smart Choices program. FDA.gov. Last updated August 19, 2009. Accessed November 2, 2009.

6. U.S. Food and Drug Administration. Background information on point of purchase labeling. FDA.gov. Last updated October 21, 2009. Accessed November 2, 2009.

7. Smart Choices Program. Press release: Smart Choices Program postpones active operations. SmartChoicesProgram.com. Last updated October 23, 2009. Accessed November 2, 2009.

8. Neumann W. Food label program to suspend operations. The New York Times: October 24, 2009, B1

9. Kraft Foods chooses to phase out ‘Smart Choices’ label. ChicagoTribune.com. Last updated October 29, 2009. Accessed November 2, 2009.

10. Eight food manufacturers agree to drop Smart Choices logo. LegalNewsLine.com. Last updated October 29, 2009. Accessed November 2, 2009.

Taxing soda to slow the obesity epidemic

Adding a penny per ounce tax to sugar-sweetened beverages could slow the growth of obesity in the U.S.—and could raise billions of dollars for obesity prevention and soda-cans-mediumother health programs, according to a new analysis by seven public health experts in The New England Journal of Medicine.(1)

Overweight-and obesity-related medical costs in the U.S. total an estimated $147 billion a year—nearly 10 percent of all health care spending—and sugary drinks are a major contributor to the nation’s obesity epidemic. (2-4)

A penny-per-ounce excise tax would likely spur consumers to cut their sugary drink calorie consumption, potentially by 8 to 10 percent—enough to promote weight loss and lower the risk of sugary drink-related chronic diseases—and could raise nearly $15 billion per year, the authors write. Levying an excise tax directly on beverage manufacturers—rather than a sales tax on consumers—would likely be the most efficient way to collect the tax and lead to the greatest effect on consumption because consumers would see this as a higher price. A tax on the sugar content of beverages would also give manufacturers an incentive to cut down the sugar content of drinks.

How much money could a tax on sugary drinks raise in your state? Try the soda tax revenue calculator at the Rudd Center for Food Policy and Obesity website.

Find out how much sugar is in soft drinks, iced tea, sports drink, juices, and other beverages.

References

1. Brownell KD, Farley T,Willett WC, Popkin BM, Chaloupka FJ, Thompson JW, Ludwig DS. The public healthand economic benefits of taxing sugar-sweetened beverages. The New England Journal of Medicine. 2009.

2. Finkelstein EA, Trogdon JG, Cohen JW, Dietz W. Annual medical spending attributable to obesity: payer- and service-specific estimates. Health Affairs (Millwood). 2009; July 29 (Epub ahead of print).

3. Malik VS, Schulze MB, Hu FB. Intake of sugar-sweetened beverages and weight gain: asystematic review. American Journal of Clinical Nutrition. 2006; 84:274-288.

4. Vartanian LR, Schwartz MB, Brownell KD. Effects of soft drink consumption on nutrition and health: a systematic review and meta-analysis. American Journal of Public Health. 2007; 97:667-675.

Excess Weight Is Not Good for You

A Closer Look at Obesity, Health Risks, and Mortality

 

scale-tape-home Writing in the November 7, 2007, Journal of the American Medical Association, federal researchers concluded that being overweight isn’t associated with the chances of dying from heart disease or cancer. (1) Even more surprisingly, they found that overweight may be associated with lower risks of dying from emphysema, infections, injuries, Alzheimer’s disease, and a potpourri of other diseases not related to cardiovascular disease or cancer. Obesity was associated with excess deaths from cardiovascular disease, diabetes, and kidney disease, but not cancer. With nearly two-thirds of Americans considered as being overweight, studies like this one seem to offer reassurance that carrying extra pounds isn’t so bad.

There’s just one small problem with this study: Its conclusions are almost certain to be wrong. Serious flaws with the study led to an underestimation of the impact of obesity; furthermore, its findings are inconsistent with many other larger studies conducted over the past 20 years.

The researchers, from the Centers for Disease Control and Prevention (CDC), derived estimates for the risk of dying from various diseases using three National Health and Nutrition Examination Surveys (NHANES) of about 37,000 Americans conducted between 1971 and 1975, 1976 and 1980, and 1988 and 1994. They then applied these estimates to deaths recorded in the United States in 2004, the last year for which full data are available, to come up with a determination of the number of deaths associated with being underweight, overweight, or obese, all compared with normal weight. (1) These categories refer to various ranges of body mass index (BMI), a measure that combines weight and height. Normal weight corresponds to a BMI between 18.5 and 24.9. Underweight is a BMI below 18.5, overweight is between 25.0 and 29.9, obesity is 30 to 34.9, and severe obesity is over 35.

In these analyses, being underweight wasn’t associated with the chances of dying from cardiovascular disease or cancer, but was associated with an increased risk of dying from other causes. Being overweight was not associated with the risk of dying from cardiovascular disease or cancer, but was associated with an increased risk of dying from diabetes or kidney disease and a reduced risk of dying from other causes. Obesity was associated with an increased risk of dying from cardiovascular disease, but not cancer or other causes.

The biggest flaw in this report is that the NHANES studies are simply too small to account for biases that often pose problems in studies of deaths and causes of death. One is reverse causation—low body weight often results from chronic disease, rather than being a cause of chronic disease. People with BMIs below 25 are a mix of healthy individuals and those who have lost weight due to a disease that may or may not have been diagnosed. The other is smoking—leaner people are more likely to smoke than their heavier counterparts. When reverse causation and the adverse effects of smoking aren’t fully accounted for, death rates among lean individuals will be inflated and those among overweight and obese individuals will be diminished. A careful critique of using the NHANES data to estimate mortality demonstrated that adequately “correcting for statistical biases and using higher ideal-weight categories increased the estimate of excess deaths attributable to obesity by approximately 400 percent and changed the negative estimate for overweight to a large positive estimate.” (2)

The CDC study isn’t even news. Findings from larger studies that have better accounted for reverse causation and smoking clearly show that increasing weight increases the risks of dying from cardiovascular disease, cancer, and other causes. More than 20 years ago, a study published by the American Cancer Society that included a million men and women documented the impact of excess weight on dying from cancer after accounting for smoking. (3) In 1999, researchers following a different million-person cohort for 14 years restricted their analyses to initially healthy nonsmokers. The risk of death from all causes, cardiovascular disease, cancer, or other diseases increased as BMI increased above the healthiest range of 23.5 to 24.9 in men and 22.0 to 23.4 in women. (4) A similar association between weight and mortality was observed in the Nurses’ Health Study (5) and a prospective study of more than 500,000 older men and women in a National Institutes of Health/AARP study. (6)

Interestingly, another report in the same issue of the Journal of the American Medical Association demonstrated that obesity is increasing the disabilities among older people, interfering with the ability to do simple, everyday activities such as climb the stairs, bend over, lift a bag of groceries, or walk around the block. (7)

The CDC study notwithstanding, the overwhelming weight of the evidence suggests that one way to stay healthy and live longer is to do what you can to keep your weight in the healthy range, and especially to minimize any upward creep in your weight or waistline during adulthood.

References

1. Flegal KM, Graubard BI, Williamson DF, Gail MH. Cause-specific excess deaths associated with underweight, overweight, and obesity. JAMA. 2007; 298:2028–37.

2. Greenberg JA. Correcting biases in estimates of mortality attributable to obesity. Obesity (Silver Spring). 2006; 14:2071–79.

3. Garfinkel L. Overweight and mortality. Cancer. 1986; 58:1826–29.

4. Calle EE, Thun MJ, Petrelli JM, Rodriguez C, Heath CW, Jr. Body mass index and mortality in a prospective cohort of U.S. adults. N Engl J Med. 1999; 341:1097–105.

5. Manson JE, Willett WC, Stampfer MJ, et al. Body weight and mortality among women. N Engl J Med. 1995; 333:677–85.

6. Adams KF, Schatzkin A, Harris TB, et al. Overweight, obesity, and mortality in a large prospective cohort of persons 50 to 71 years old. N Engl J Med. 2006; 355:763–78.

7. Alley DE, Chang VW. The changing relationship of obesity and disability, 1988–2004. JAMA. 2007; 298:2020–27.