Healthy Food & Healthy Living by Dr. Ayala

What should Americans eat? The 2010 dietary guidelines

The advice on what to eat for optimal health is reevaluated and dispensed by the government every five years and we’ll be seeing new guidelines published later on this year.

The foundation for the guidelines is an independent, evidence-based report, prepared by the Dietary Guidelines Advisory Committee, which is comprised of independent experts—mostly academics in the fields of nutrition and health. The advisory committees have been giving, in essence, pretty much the same advice for the past thirty years: Eat less solid fats, salt, and added sugars and more fruits, vegetables, and whole grains. Move more. The devil’s in the details—wording, upper and lower limits for nutrients, emphasis on food groups—and this document is usually not received without debate by the food industry and other players.

Yet not much happens. Guidelines aside, obesity rates have continued to climb, and the fast- and processed-food diet is still the most prevalent food pattern observed by Americans.

The Dietary Guidelines Advisory Committee Report of 2010 issued its recommendation recently, the report is now open for comments, and following the public comment period the USDA and US Department of Health and Human Services will take in the comments—let’s hope politics won’t be thrown into the mix—and translate the Advisory Report into the 2010 Dietary Guidelines for Americans.
So what’s new in the 2010 Advisory Committee Report guidelines?

Cut Salt. By a lot.

The 2005 guidelines recommended a daily sodium upper limit of 2,300 mg sodium for the general adult population, and a 1,500 mg per day sodium limit for people with hypertension, African-Americans and older Americans. Since these latter groups comprise 70 percent of US adults, the new 2010 guidelines recommend 1,500 mg per sodium day upper-limit for the general population. It’s quite a challenge, given the vast amounts of salt processed foods contain, and the high levels of salt most people are accustomed to. Most Americans consume more than twice the 2,300 mg “old” upper-limit.

Food patterns: Plant centered patterns promote health, and vegetarian diets get the nod

The new report realizes that people eat food, not isolated nutrients, and counting grams of fats, servings of carbs and milligrams of salt isn’t a tempting lifestyle for most—who wants to walk around with reading glasses and a calculator? Many experts believe that total diet and food patterns are better guides to what we should be eating. The 2005 report mentioned two eating patterns recommended for their health benefits, the DASH (Dietary Approaches to Stop Hypertension) eating plan, and the USDA food guide eating plan—yet these two plans still resemble a diet recipe and not a dietary pattern—they’re still more about counting servings rather than providing food rules and a framework for a healthy diet.

The new proposed guidelines go further, and suggest two eating patterns proven to promote health: the Mediterranean-style and vegetarian-style diets. What these patterns have in common is emphasis on plant-foods. If the vegetarian style diet indeed gets an endorsement in the final guidelines this is going to be quite a shift—the guidelines and pyramids of past were big promoters of animal protein, and vegetarians and vegans seemed like poor step-kids living a life of compromise on inferior substitutions. (Full disclosure: I am a vegetarian, mainly for ethical reasons.)

Here’s the report’s recommended diet in a nutshell:

“Shift food intake patterns to a more plant-based diet that emphasizes vegetables, cooked dry beans and peas, fruits, whole grains, nuts, and seeds. In addition, increase the intake of seafood and fat-free and low-fat milk and milk products and consume only moderate amounts of lean meats, poultry, and eggs.
Significantly reduce intake of foods containing added sugars and solid fats because these dietary components contribute excess calories and few, if any, nutrients. In addition, reduce sodium intake and lower intake of refined grains, especially refined grains that are coupled with added sugar, solid fat, and sodium.”

I guess this is as close as we can get to spelling out how we should eat without offending any food industry. May I offer my interpretation in plain-speak?

There are many ways to eat healthy, all of which emphasize plenty of plant foods—fruits, vegetables, whole grains and such—and moderation in pretty much everything else. There’s one food pattern that clearly doesn’t work: the processed- junk- and fast-food diet tends to make people fat and unhealthy. Eat that stuff only on special occasions.

The food environment: We all need to work together to improve it

The guidelines acknowledge that although personal food choices play a central role in the obesity epidemic, our food environment is also a key-player that needs to be addressed urgently:

“In order to reduce the obesity epidemic, actions must be taken to improve the food environment. Policy (local, state, and national) and private-sector efforts must be made to increase the availability of nutrient-dense foods for all Americans, especially for low-income Americans, through greater access to grocery stores, produce trucks, and farmers’ markets, and greater financial incentives to purchase and prepare healthy foods. The restaurant and food industries are encouraged to offer foods in appropriate portion sizes that are low in calories, added sugars, and solid fat. Local zoning policies should be considered to reduce fast food restaurant placement near schools.”

Is there hope for change?

Absolutely. I think the guidelines provide an evidence-based framework on which policies, action and choices need to be made. Although the advice is basically the same over many decades, there are more people listening, a first lady dedicated to the cause, a strong and growing crowd of people who care about this issue, and are eager for change, a health-care system threatening to collapse under the rising costs of obesity-related disease and a food movement rising.

I’m hopeful (as a matter of principle and as a way of life). Are you?

Dr. Ayala

Reposted as part of Food Renegate's Fight Back Fridays--go join the food fight!

Does our food trigger early puberty?

Despite the fact that girls don’t mature mentally any earlier, they are reaching puberty at ever younger ages. An article in The Sunday Times last week announced that girls now begin puberty at age 9. The article cites a Danish study, which looked at a sample of 1000 girls, and showed that breast development started on average at age 9 years and 10 months, a full year earlier than it did in a similar group studied 15 years earlier.

Entering puberty is cause for celebration and a good sign of reproductive and overall health. Yet the novelty of getting your periods wears off all too soon and many a girl/woman/mom has wondered what possible advantage is menstruating from such early an age, when none of us wish parenthood on teens.

Is early puberty a new phenomenon and yet another sign of our unhealthy lifestyle?

There’s been a dramatic fall in the age girls start puberty (the first sign of which is usually breast development, or in medical terms: thelarche) and start getting their periods (the medical term for which is menarche) in the 20th century. The age at which girls started getting their periods has been dropping by a few months every decade, and western European girls, who started menstruating on average at the age of 16-17 in the 1840’s are now getting their periods at around age 12-13. But as a matter of fact this trend has been leveling-off in the past 30 years.

So no, this is nothing new, and if anything the rate of advancing puberty has slowed down, at least in the US.

What affects earlier puberty

Nutrition:
The most significant factor affecting the age of puberty onset is nutrition. The single best predictor of the onset of a girl’s first period is her weight and there’s plenty of evidence suggesting that the nutritional state of a population accounts for most of the variation in the timing of puberty. It’s well established that obesity and extra calories initiate puberty sooner, while severe caloric restriction (as seen in girls with Anorexia Nervosa or in ballet dancers) delays puberty.

But it’s not just the calories: Certain foods and nutrients seem to affect puberty onset more than others. A new study in Public Health Nutrition followed more than 3000 British girls’ diets at age 3, 7 and 10 years of age, and correlated diets to age of onset of the girls’ first period.

They found that higher intake of meat and animal protein at age 3 and 7 correlated strongly with earlier periods (high meat intake at age 3 was defined as 8 portions a week or more, and 12 portions of meat a week or more at age 7). This finding was independent of the girls’ body weight, and the age at which their mothers menstruated. As expected, they also found that higher caloric intake overall correlated with early periods.

Discussing their findings, the authors, led by Imogen Rogers, suggest that diet in early and mid-childhood may affect the onset of puberty much more than the diet in later childhood, and conclude that higher intakes of meat and protein in childhood may promote earlier periods.

Genetics:
The onset of puberty is influenced by genetics, and there’s some correlation between a mother and her daughter’s age at puberty.

Contaminants:
There’s a reasonable concern that chemical contaminants and hormonal residues in the food chain and in our drinking water may affect puberty in humans. The Times’ article also suggests BPA is a suspect worth investigating. The mechanism seems plausible—hormonal residues and hormone-like chemicals can potentially affect the complex and finely tuned system that initiates puberty, and there are some animal experiments that support this notion.
It’s going to be quite difficult to prove or disprove that these contaminants are implicated in human puberty, but as always, prudency suggests that it’s not a very good idea to be exposed to or ingest contaminants with potential hormonal activity—that stuff definitely isn’t food.

Is early puberty a health issue?

Earlier periods are associated with an increased risk of breast cancer. Less established is the correlation between early periods and ovarian cancer and heart disease. On the other hand, early periods may protect against osteoporosis.

No less important are the social issues related to early puberty: It’s never easy to be a teenager; being different and precocious at that tender age is even harder. And I must say, earlier puberty makes a severe mismatch worse. The human reproductive system seems to kick-in once it figures out there are enough nutrients stored to support a pregnancy—too bad it has no gauge for mental maturity, as, at least in general, girls’ judgment, mental development and independence seem too ripen a full decade after their bodies do.

Can we influence the age of puberty? The most modifiable and proven factor affecting puberty onset is weight. Preventing obesity and eating a balanced, plant-rich diet is a good recipe for overall health anyway—if it also prevents early puberty that would perhaps be an extra bonus.

Dr. Ayala

Reposted as part of Food Renegate's Fight Back Fridays--go join the food fight!

Childhood obesity: How can 15% of kids be above the 95th percentile?

A friend of mine said she has a dumb obesity-related question for me: How can 15 percent of kids be above the 95th percentile?

Let me explain.

My friend’s girls—like most kids nowadays—are monitored for obesity as part of their health screening at school. My friend looked at the screening results—in which BMI is expressed as percentile for age and gender (more on that below)—gave some thought to the definitions of overweight and obesity, and realized that the math just doesn’t make sense. We’re hearing time and time again that obesity has reached epidemic proportions, and that a third of our kids are overweight, half of these obese. Yet, if overweight in kids is defined as having a BMI above the 85th percentile how can a third of US kids be classified as overweight? If obesity in kids is defined as having a BMI above the 95th percentile how can 15 percent of the kids be obese? There can only be 5 percent above the 95th percentile, right?

It’s not a dumb question at all, so I’d like to devote this post to some really basic concepts in the diagnosis of childhood obesity, and solve this question for those of you wondering if—as in the imaginary Lake Wobegon of Prairie Home Companion fame—all kids can be above average.

BMI for kids: What is it and why bother with BMI percentiles

Body Mass Index (BMI) is a number calculated from a child's weight and height (weight in kilograms divided by height in meters squared). BMI is a useful and easy screening tool for body fatness for most kids—it doesn’t measure body fat directly but studies have shown that BMI correlates quite well with body fat in most people.

In adults BMI on its own can assess obesity—we consider an adult (man or woman) with a BMI above 25 to be overweight, and above 30 to be obese—yet in kids a BMI on its own tells us very little. For example: A BMI of 21—a healthy weight for an adult—is indicative of obesity in a 6 year-old boy, would categorize a 10-year-old boy as overweight, but would put a 16 year-old well within the range of a healthy weight.

Why isn’t kids’ BMI on its own informative? Kid’s body shape and composition change with age. The amount of body fat, muscle and bone transform dramatically with age, and the amount of body fat differs quite greatly between boys and girls. That’s why pediatricians use BMI-for-age charts (see image), in which they plot your kids’ BMI comparing it to kids of the same age and gender.

The BMI percentile allows medical professionals to categorize kids’ weight: A BMI below the 5th percentile indicates underweight. BMI percentiles between the 5th and 85th percentile are considered healthy weight. BMI percentiles between the 85th and 95th percentile are overweight and BMI above the 95th percentile indicates obesity.

Who decides what’s a normal weight?

To establish a percentile chart you’d need a reference population. As we all know weight (unlike other body characteristics such as eye color, blood-type or even height) changes remarkably as a population changes its diet and activity level. Indeed, our kids’ weights as a collective have shifted dramatically in the past 30 years.

Therefore, in establishing the BMI-for-age charts the reference population is the kids of the past—mostly of the 60’s and 70’s, before the obesity epidemic started. There are several charts used around the world, each developed referencing a different population, but they all carry an historic picture of past generations, when childhood obesity was much less prevalent. When you get your kids’ BMI-for-age he’s not compared to the kids of today, but rather to what experts feel is a “normal” population.

And that explains how 15 percent of kids can plot above the 95th percentile—they’re plotted compared to BMIs of kids before the obesity epidemic began in full force.

Is a statistical norm a good indicator of health?

Why do we insist on seeing the weight of the past as the norm, and not accept our new dimensions as the new “normal”?

Obesity isn’t merely a statistical description of the extreme upper end of a bell curve. Obesity is a health issue, and we have plenty of evidence showing that kids with excessive body weight have higher blood pressure, higher cholesterol, are at risk of early onset of many diseases—heart disease, type 2 diabetes, some types of cancer, obstructive sleep apnea to name a few—and overall have a shorter life span.

Unfortunately, when it comes to weight and BMI too many kids are above average. Looking at population surveys over time, we see that kids’ weights, as a whole, have shifted up, and that kids are generally more than 10 pounds heavier than kids 30 years ago.

We all want a healthy future for our kids—that’s why we need to get childhood obesity under control.

Dr. Ayala

Reposted as part of Food Renegate's Fight Back Fridays--go join the food fight!

The TV ad diet and your health

What would you eat if your food choices were based on TV ads? A new study in the June issue of the Journal of the American Dietetic Association looking at the nutritional content of foods advertized on prime-time and kids’-time TV suggests you’d be eating a very imbalanced diet, rich in (guess what?) sugar fat and salt.

The authors, led by Michael Mink, PhD, analyzed ads placed in 84 hours of prime-time and 12 hours of Saturday morning (cartoon-time) broadcast in the four major US networks (ABC, CBS, Fox and NBC). Each advertized food item was then analyzed for nutritional content.
Here’s what they found:

• Of 3,584 total ads 614 (or 17 percent) were for foods. There were 3 food ads for every 30 minutes of broadcast

• A 2000 calorie diet consisting entirely of advertized foods would contain 25 times the recommended daily intake of sugar, and 20 times the recommended daily intake of fat

• During the 96 TV hours observed there were 116 public service announcements—none addressed nutritional education

• The hypothetical TV ad diet oversupplies the same nutrients Americans are known to consume too much of: protein (lots of meat), sodium, fat, saturated fat, and cholesterol

Do TV ads influence food choices?

Americans are exposed to TV for almost 7 hours a day, and food and beverage related TV ad spending was $11.26 billion in 2004. To put this sum in perspective: The federal budget for the 5-A-Day program (promoting fruits and veggies) was just $4.85 million and the entire US Department of Agriculture (USDA) nutrition education budget was $268 million for the same year. I’m sure food and beverage makers see proven results for their mass spending—otherwise they wouldn’t be incurring these costs.

Ads do affect our consumption habits, and are especially effective on the very young. Most toddlers can’t tell programming and advertising apart and many toddlers have been known to sing the tunes and repeat the message after being exposed to some ads just once, and to remain loyal to a brand forever.

Suggestions for a healthier advertizing environment

The authors have a few recommendations:

• Consumer education: Let the public know that food advertizing has a bias for foods that provide a whole day’s worth of sugar and fat in a single serving

• Food industry education and collaboration: Let food makers know they’re promoting nutritionally imbalanced foods (Does anyone actually believe they aren’t aware of that?)

• Public media strategies: Air more public service announcements to balance the nutrition message

• Regulation: Require nutritional warnings for imbalanced foods similar to those mandated on direct-to-consumer drug ads

I’d like to add a few suggestions of my own:

• Teach your kids how to apply critical thinking skills to the ads they see: here’s a Federal Trade Commission website with some great tools and fun games that may help

• Turn the TV off: Sorry, I know some say we’re in the midst of a new golden age of TV, and there are some very good programs to watch, but I truly believe that watching much less TV is a health promoting bit of advice, especially if you have kids at home. The 1 to 2 hours of quality programming per day upper limit suggested by the American Academy of Pediatrics seems indulgent enough

On the up side: I watched the French Open men's finals yesterday, and during these not necessarily representative few hours on NBC, food ads were scarce and Rafael Nadal drank water and ate a few bites of banana at critical points in the match (Nadal is well known for his banana habits)—overall a viewing session with a balanced health message.

I assume the researchers are still recovering from the 96-hour TV overload.

Dr. Ayala
Reposted as part of Food Renegate's Fight Back Fridays--go join the food fight!