Search results: american journal of clinical nutrition

I like the special editions of the business newsletter, FoodNavigator USA.  This especially big one collects its recent articles on sodium reduction—a big issue these days.   These give a good idea of how food companies are dealing with pressures to lower their salt content.

It’s expensive, risky, and difficult, but manufacturers have made huge progress on sodium reduction in recent years. But how much further can they go, and where is the return on investment if consumers are at best indifferent to their efforts, or at worst downright suspicious?

This special edition explores the challenges of sodium reduction, and asks whether it’s falling down the food policy agenda in the US, but also provides examples of creative solutions that can help manufacturers reduce it without compromising on taste or functionality.

Is sodium reduction falling down the food policy agenda?  Four years ago sodium was public enemy #1. The Institute of Medicine (IOM) was calling for the FDA to modify the GRAS status of salt and slash the daily value for sodium to 1,500mg, and the food industry was on high alert. Today, sugar is the new bogeyman, and while sodium intakes remain stubbornly high, the FDA has yet to issue voluntary guidelines. So is sodium reduction falling down the food policy agenda?

AHA education campaign pressures food manufacturers to reduce sodium: The American Heart Association says its recently launched consumer education campaign encouraging Americans to “break up with excess salt” seeks to “build an army of passionate and willing supporters” to pressure food manufacturers to reduce sodium in packaged foods.

Advanced technology eases sodium reduction efforts: Advances in technology can help firms more quickly and easily reduce sodium in breads and grain-based packaged foods – a previously repetitive and expensive trial and error process, according to Janice Johnson, food applications leader in salt at Cargill.

Will proposals to mandate potassium labeling on the Nutrition Facts panel give potassium-chloride based sodiumreplacers a shot in the arm?  Some food manufacturers still worry that using potassium chloride to replace salt in their recipes might compromise their clean label credentials. But the FDA’s recent proposal to include potassium as one of the nutrients that must be listed on the Nutrition Facts panel is helping to change that mindset, says NuTek Salt.

Sodium reduction: has all the low-hanging fruit been plucked?  Food manufacturers are under increasing pressure to reduce sodium, but surveys suggest many shoppers are, well, not that bothered. So where does this leave firms plugging sodium reduction solutions?

Reformulation by stealth: Just 2% of new launches in salty snacks make overt sodium reduction claims: The vast majority of sodium reduction activity in the US food industry is now being conducted by ‘stealth’ in order to avoid alienating shoppers, according to Tate & Lyle.

Industry to FDA: Think again before setting category-by-category sodium reduction targets.  Two leading food industry associations have urged the Food and Drug Administration (FDA) not to set category-by-category limits for sodium amid rumors that the agency is planning to outline a new sodium reduction strategy this year.

Can seaweed become the ultimate salt replacer – and why hasn’t it yet?  Seaweed is well-researched, sustainable and effective, according to an expert. So what is stopping it from really taking off as a salt replacer?

Mandatory salt reduction could save more in healthcare costs: Study.  Mandatory salt reduction may save more in healthcare costs than the current voluntary system, say the authors of a study published in Value in Health.

Myth busting? High salt intake may not increase thirst:  It is commonly believed that consumption of salty foods increases thirst, and could be a reason for increased consumption of sugary soft drinks and alcoholic beverages. But just how true is this notion?

Are salt reduction efforts reflected in heart health?  Salt reduction efforts around the world are making progress – but how has lower salt consumption affected health?

Salt substitutes help reduce blood pressure.  Efforts to reduce consumer blood pressure and risk of hypertension by replacing normal salt with blends of potassium chloride, magnesium sulfate and less sodium chloride are working, but may be more effective in countries where the majority of salt comes from home cooking, according to a meta-analysis in the December American Journal of Clinical Nutrition.

‘Quiet’ salt reduction is vital – but gourmet salt growth may stifle industry efforts.  Salt replacer use is growing but low salt claims are not, as food companies favour a ‘quiet’ approach – but growth in gourmet table salts may threaten salt reduction efforts.

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When the FDA advisory came out a week or so ago, I started getting questions about whether it meant that women must eat fish during pregnancy and, if so, how much.

As I said in my previous post on the topic, if you like fish, of course eat it, otherwise I can’t think of any compelling reason why anyone has to eat fish.

I view the data on the dilemma caused by omega-3 fatty acids in fish (good) versus the content of methylmercury (bad) as still rather uncertain.  Dr. Malden Nesheim and I discussed this point in an editorial we wrote for the American Journal of Clinical Nutrition [reference 1 below].

Here’s what the FDA advisory says:

Eat 8 to 12 ounces of a variety of fish each week from choices that are lower in mercury. The nutritional value of fish is important during growth and development before birth, in early infancy for breastfed infants, and in childhood… Fish contains important nutrients for developing fetuses, infants who are breastfed, and young children. Fish provides health benefits for the general public. Many people do not currently eat the recommended amount of fish.

This is a prescriptive statement telling pregnant women that they should eat fish.

I would argue that the data on which FDA based this prescription are limited, especially because the results of its scientific assessment are based mostly on theoretical models rather than empirical studies.

Here’s what makes me think some skepticism is warranted:

1. The effects of even low-level methylmercury exposure may be greater than discussed in the assessment [see reference 2], as the latest analysis from the Environmental Working Group explains.
2. The increase in young children’s IQ associated with fish-eating during pregnancy is low—-0.7 to a maximum of 3 IQ points.

As the FDA’s assessment report says:

On a population basis, average neurodevelopment in this country is estimated to benefit by nearly 0.7 of an IQ point (95% C.I. of 0.39 – 1.37 IQ points) from maternal consumption of commercial fish. For comparison purposes, the average population-level benefit for early age verbal development is equivalent in size to 1.02 of an IQ point (95% C.I. of 0.44 – 2.01 IQ size equivalence). For a sensitive endpoint as estimated by tests of later age verbal development, the average population-level benefit from fish consumption is estimated to be 1.41 verbal IQ points (0.91, 2.00). The assessment also estimates that a mean maximum improvement of about three IQ points is possible from fish consumption, depending on the types and amounts of fish consumed.

How significant is this?  And does the small benefit in childhood persist into adolescence or adulthood?

3. The economic question.  Fish are expensive.
4. The ecological questions.  Advice to increase fish consumption comes up against environmental realities—-overfishing, fish farming—-that make the recommendation impossibly unsustainable [reference 3].

• The levels of long-chain omega-3s in farmed fish depend on feeding them wild fish, an ecological problem on its own.
• Guidance about fish can’t be just nutritional; it has to take the economic and ecological impact of fish choices into consideration [reference 4].
• Current per capita fish consumption is about half the FDA recommended level, and half of that is shrimp.  Fortunately, shrimp don’t have much mercury (although the ones from Asia may have other contaminants), but they also don’t have much omega-3).

All of this suggests grounds for skepticism.  I think a better recommendation would leave more wiggle room to account for uncertainties.  Here’s how I would edit the FDA’s statement:

Pregnant women may eat up to 8 to 12 ounces of a variety of fish each week from choices that are lower in mercury.  Fish are useful sources of nutrients that may have value for growth and development before birth, in early infancy for breastfed infants, and in childhood, and may provide health benefits for the general public.  Other food sources also provide such benefits.

References

[1] Nesheim MC, Nestle M. Advice for fish consumption: challenging dilemmas. American Journal of Clinical Nutrition. 2014;99:973-974.

[2] Karagas MR, Choi AL, Oken E, Horvat M, Schoeny R, Kamai E, Cowell W, Grandjean P, Korrick S. Evidence on the human health effects of low-level methymercury  exposure. Environ Health Perspect. 2012; 120:799-806.

[3] Jenkins D, Sievenpiper JL, Pauli D, Sumaila UR, Kendall CWC  Are dietary recommendations for use of fish oils sustainable? Canadian Medical Association Journal 2009;180: 633-637.

[4] Oken E, Choi AL Karagas MR, Marien K, Rheinberger CM, Schoeny R, Sunderland E, Korrick S  Which fish should I eat? Perspectives influencing fish consumption choices. Environmental Health Perspectives 2012;120:790-798.

Mal Nesheim and I have an editorial in a recent issue of the American Journal of Clinical Nutrition: “Advice for fish consumption: challenging dilemmas.”

We commented on a research article evaluating blood mercury levels in adults eating seafood.

In it, we point out that

the 2010 Dietary Guidelines for Americans advise Americans to consume 8 ounces (227 g) of seafood per week to reach an average intake of 250 mg/d of the omega-3 fatty acids EPA and DHA.

This recommendation represents a substantial increase over current consumption amounts of ∼3.5 oz/wk. It is based on “moderate, consistent evidence” that the health benefits of increased seafood consumption outweigh the risks associated with methylmercury, a toxic contaminant of large predatory food fish (tilefish, shark, swordfish, king mackerel) and, to a lesser extent, albacore (white) tuna.

To avoid this toxin, the guidelines advise eating seafood typically found to be low in methylmercury, such as salmon, anchovies, sardines, and trout.

Such advice, however, leads to at least 3 dilemmas. Eating more fish might raise methylmercury intake above safe amounts. Pressures to consume more fish might place impossible demands on an already threatened seafood supply. And the obvious solution—fish farming—raises concerns about what farmed fish are fed and how farmed fish affects the environment.

We urge the 2015 Dietary Guidelines committee to take all this into consideration when making recommendations about fish consumption: “We hope that its advice for seafood consumption will help a confused public resolve some of these dilemmas and make wise seafood choices.”

Wise seafood choices may be an oxymoron, alas.

A new diet study just out from the American Journal of Clinical Nutrition went to a lot of trouble to prove the obvious.  When it comes to weight loss, how much you eat matters more than the proportion of fat, carbohydrate, and protein in your foods.

Researchers at the Pennington Biomedical Research Center got volunteers to eat diets that were supposed to differ in proportions of fat (40% vs 20%), carbohydrates (35% vs. 65%), and protein (25% vs. 15%).

The results of the study are consistent with the findings from many previous studies:

• The major predictor for weight loss was adherence to the diet.
• People on all of the diets lost weight by six months, but regained some of it by two years.
• The study had a high drop-out rate (hence the importance of adherence).
• It was hard for people to stick to the diets, especially those at the extremes of one dietary component or another.

In my book with Malden Nesheim coming out on April 1, Why Calories Count: From Science to Politics, we review the previous studies of whether what you eat matters more to weight loss than how much you eat.

Some people find it easier to stick to diets that are higher in protein and fat.  I’m guessing that proponents of low-carbohydrate diets will argue that none of the diets in this particular study was really low in carbohydrate.

But studies show that people have a hard time adhering to diets that are very low in carbohydrate.  The low range in this study—35%—is at the lower end of acceptability for many people.

The bottom line: all diets work if you stick to them.

Order from your local independent bookstore or University of California Press or Barnes and Noble or Amazon.com.

Reviews, interviews, and commentary on Why Calories Count

2014

July 26   Review in Science Magazine

2013

September  Review in Health Affairs 2012;31 (9):2150-2151.

September 7 Radio interview with Dr. Don

August 15  Review in Frankfurter Allgemeine Zeitung by Thomas Weber (in German)

August 1  Review in the American Journal of Clinical Nutrition by Barbara Rolls

July 26  Interview with Tami O’Neill for EcoCentric blog

July 13  Interview with Donna Feldman on MyNetDiaryBlog

July 19   Interview about Why Calories Count with Nina Kahori Fallenbaum for Hyphen magazine: “Rice is Nice.”

June 6  KQED’s Forum (radio) Host: Spencer Michels

May 25 Video interview with Linda Watson on HuffPo.

May 21  Radio New Zealand

May 15 Radio interview with Susan Moran

May 14 TV Interview with Linda Watson on Cook for Good

May 9  Jenny Hutt radio

May 9  Candy Sagon on the AARP blog

May 4  Fort Worth Star-Telegram

May 2  Oprah.com

April 26 Review in Eat.Drink.Better

April 26  Susan Albers in the Huffington Post

April 24 Review on StarChildScience

April 20 Review in the Wall Street Journal

April 19  Interview with LifeScript

April 18 Review on The Black Sheep Dances.

April 17  The Page 99 Test and Campaign for the American Reader’s Page 99 of Why Calories Count.

April 16  A review in Serious Eats by Leah Douglas.

March 29: Times Higher Education (U.K.)

People should read this book. They should read it if they are obsessive weight-watchers or serial dieters, or just concerned about what their children eat. They should read it if they work in public health, the food industry, catering or education. And they should certainly read it if, like my colleague who reacted with horror to the title and the idea, they work to counter the “myth of obesity” and are supporters of the “health at any size” movement.

March 29: a blog from Finland (in Finnish)

March 28: Healthy Eating blog

March 26: Lisa Young’s portion teller blog

March 25: Miriam Morgan’s review in the San Francisco Chronicle

March 22: Eleanor West’s interview on Civil Eats.

March 21: Mark Bittman in the New York Times

March 20: Jane Brody in the New York Times

March 15: Nature magazine

Obesity has gone global — as has misinformation about nutrition and food. Nutrition scientists Marion Nestle and Malden Nesheim unscramble the confusion with a serving of science. They reveal how calories — those potent but ill-understood measures of heat energy — are really counted, why we need them, how we use them, how many we actually need and why it all sometimes goes so wrong. From ‘secret’ calories to food politics, malnourishment and calorie restriction for health, this is a feast for the mind.

February 1: The Scientist

Nutritional science guru Marion Nestle’s new book, Why Calories Count, seeks to crack open the inscrutable nature of the calorie. Think of the book, cowritten with Cornell University nutritionist and biochemist Malden Nesheim, as a diner’s elemental guide to eating. Nestle and Nesheim deconstruct the calorie—the bane of many a belly in the developed and developing worlds—to its barest components as a humble unit of work or heat before reassembling it and discussing its implications for disease, obesity, politics, and modern marketing.

From the strict chemical definition of a calorie to the 25-year quest by the Center for Science in the Public Interest to require nutritional labels, including calories, on alcoholic beverages, Why Calories Count weaves scientific and social tales into a rich portrait of the American diet and the laws that have shaped it.

By thoroughly burrowing into the meaning and impacts of calories, the authors intend to bestow a more relaxed yet active state of mind upon the reader. “Get organized. Eat less. Move more. Get political,” they suggest. Sounds like the most succinct diet book ever written.

Excerpts from other reviews

From Kirkus Reviews: A strong, rigorous overview of the calorie, its regulation and the politics behind food labeling and marketing.

From Library Journal (see the Barnes and Noble website): Neither a diet nor a weight-loss book, this scholarly, seriously researched work assists readers in evaluating diet claims, formulating strategies to lose, gain, or maintain weight, and learning how to make healthy food choices….and—what will probably be of most interest to the general reader—the role of big business in creating calorie-laden food and why it’s less politically controversial to recommend exercising than cutting back on calories.  

Summary

Calories—too few or too many—are the source of health problems affecting billions of people in today’s globalized world. Although calories are essential to human health and survival, they cannot be seen, smelled, or tasted. They are also hard to understand.

This book explains in clear and accessible language what calories are and how they work, both biologically and politically.   It takes readers through issues fundamental to understanding diet and food, weight gain, loss, and obesity, and sorts through the misinformation put forth by food manufacturers and diet program promoters.

Nestle and Nesheim explain the political stakes and show how federal and corporate policies have come together to create an “eat more” environment and give readers the information needed to interpret food labels, evaluate diet claims, and understand evidence as presented in popular media.

Their concluding advice: Get organized. Eat less. Eat better. Move more. Get political.

Blurbs for Why Calories Count:

“We need to understand what ‘empty calories’ are, so that we can feed our children food that is truly nourishing. On this topic, there is no better teacher than Marion Nestle, who writes with meticulousness, clarity and grace.”  —Alice Waters, author of The Art of Simple Food

“If you want to understand what’s wrong with our eating habits, you must understand the central role that calories play.  Nestle and Nesheim are two of the America’s finest nutritionists–and this book explains, clearly and succinctly, why calories count.  It is essential reading not only for people interested in food policy, but for everyone who wants to eat well and be well.” —Eric Schlosser, author of Fast Food Nation

“This superbly well-researched and scientifically sound book makes it clear how today’s food environment often overrides physiological regulatory controls of body weight. Why Calories Count is essential reading for anyone who wants to understand why so much about food choice lies in the hands of food marketers whose goal is to sell more products, not necessarily in the interests of public health.”  —Dr. David Kessler, author of The End of Overeating

“Thank god authorities like Nestle and Nesheim have teamed up to give us an epic view of a calorie: what it is, where it came from, what it means, how and why we count them. Thank god they’ve managed to decode nutritional science into a commonsense language we can all understand.  And thank god they’ve put calories in their place in a wider cultural and political context to help us think meaningfully about the food our lives depend upon.  I’m grateful.”  —Betty Fussell, author of Raising Steaks

“Calories. We all talk about them—many are even obsessed with them—but what do we really know about them? Not much. Marion Nestle and Malden Nesheim’s latest book changes all that, pulling back the curtain on calories and helping us understand them in a whole new light. You’ll never look at a 100-calorie pack of corporate cookies the same way again.” —Anna Lappé, author of Diet for a Hot Planet

 

Scientific debates about the role of sodium in high blood pressure go on and on.  Committees of scientists reviewing the research invariably conclude that people would be healthier if they ate less salt (salt is sodium chloride).  The 2010 Dietary Guidelines Advisory Committee is only the most recent group to urge population-wide reductions in sodium intake.

The Institute of Medicine has just issued a new report on reducing sodium.  Its Report in Brief gives a quick summary

As its primary strategy for sodium reduction, the committee recommends that the FDA set mandatory national standards for the sodium content in foods…beginning the process of reducing excess sodium in processed foods and menu items to a safer level. It is important that the reduction in sodium content of foods be carried out gradually…Evidence shows that a decrease in sodium can be accomplished successfully without affecting consumer enjoyment of food products if it is done in a stepwise process that systematically and gradually lowers sodium levels across the food supply.

But wait!  Hypertension rates have been increasing for years without any change in sodium excretion, says a report in FoodNavigator.com.  The report refers to new study in this month’s American Journal of Clinical Nutrition reviewing trends in sodium excretion from 1957 to 2003.

Sodium excretion, a precise reflection of intake, say Adam Bernstein and Walter Willett of the Harvard School of Public Health, has not changed in the last half century, despite rising rates of high blood pressure.   Instead, they suggest that rising rates of obesity might be the cause.

The accompanying editorial, by David McCarron and his colleagues, takes the argument even further as can be seen just from its title: “Science trumps politics: urinary sodium data challenge US dietary sodium guideline.^”

The editorial says that this new study provides:

plausible, scientific evidence of a “normal” range of dietary sodium intake in humans that is consistent with our understanding of the established physiology of sodium regulation in humans. This scientific evidence, not political expediency, should be the foundation of future government policies….Guidance for sodium intake should target specific populations for whom a lower sodium intake is possibly beneficial. Such an approach would avoid broad proscriptive guidelines for the general population for whom the safety and efficacy are not yet defined.

Is this review likely to change the Dietary Guidelines due out later this year?  The Advisory Committee was convinced that the preponderance of evidence favors the importance of sodium as a causative agent in high blood pressure.

Because so much is at stake for the processed food industry, this argument is not likely to be resolved quickly.  Stay tuned.

Despite recent publications finding no correlation between intake of saturated fat and coronary heart disease (CHD) – see, for example, the recent meta-analysis in the American Journal of Clinical Nutrition – the debates over the role of saturated fat continue.

In that same issue of the Journal, another study says that reducing saturated fat only works if you replace it with something better.  If you replace saturated fat with carbohydrates, the effects on heart disease will be worse.

The fat story is not simple (in What to Eat, I explain the biochemistry of food fats in the chapter on fats and oils and in an appendix).  The main reason for the complexity is that different kinds of fats do not occur separately in foods.

Without exception, food fats are mixtures of  three kinds of fatty acids: saturated (no double bonds and solid at room temperature), monounsaturated (one double bond), and polyunsaturated (two or more double bonds and liquid at room temperature).  Food fats just differ in proportions of the three kinds.

Meat, dairy, and egg fats generally are more saturated.  Plant fats and oils are generally more unsaturated.

How to make sense of the saturated fat story? An expert panel from WHO and FAO just produced a new review of the evidence.  The panel evaluated CHD morbidity and mortality data from epidemiological studies and controlled clinical trials.  It found:

• Convincing evidence that replacing saturated fat with polyunsaturated decreases the risk of CHD.
• Probable evidence that replacing saturated fat with largely refined carbohydrates (starch and sugar) has no benefit and even may increase the risk of CHD.
• Insufficient evidence relating to the effect on the risk of CHD of replacing saturated fat with monounsaturated fats or whole grain carbohydrates, but a trend suggesting that these might decrease CHD risk.
• Possible positive relationship between saturated fat and increased risk of diabetes.
• Insufficient evidence for establishing any relationship of saturated fat with cancer.

The panel’s recommendations:  (1) Replace saturated fat with polyunsaturated fats (omega-3 and omega-6) in the diet, and (2) Limit saturated fat to 10% of daily calories or less.

Translation: Eat less animal fat and replace it with vegetable fats.

Historical note: These are precisely the same recommendations that have been standard in the U.S. for at least fifty years.  This was good advice in the late 1950s.  It is still good advice.

UPDATE, March 22,2011:  Another major review has just come to precisely the same conclusions, this one from an international expert panel.  It also suggests areas for future research.  See American Journal of Clinical Nutrition 2011;93:684-88.

Recent news reports encouraged me to take a quick look at the January 2010 American Journal of Clinical Nutrition where investigators have attempted to identify the proportion of human obesity accounted for by genetic variation.  Their conclusion: probably no more than 1% (we used to think it was 5%).  I don’t know why anyone would be surprised.  Obesity rates rose sharply in the early 1980s, with no possibility for so rapid a change in the genetic composition of the population.

I don’t think we need complicated genetic explanations for obesity.  We have so much evidence that people started consuming more calories at about that time and are continuing to do so.  Why more calories?  Portion sizes got bigger, and – hard as it may be to believe – larger portions have more calories!

In a commentary on the study, Claude Bouchard puts it this way:

The obesity epidemic we are facing today unfolded over the past few decades and can clearly not be explained by changes in the frequency of risk alleles. It is more likely due to a changing social and physical environment that encourages consumption and discourages expenditure of energy, behaviors that are poorly compatible with the genome that we have inherited.

Hence: eat less, move more!  And have an active weekend!