DIET QUALITY AND HEALTH

Fri, August 02, 2019   |    Download PDF of this article

Dietary quality is an important determinant of weight gain and obesity, and a vast body of evidence shows that diet quality directly affects the risk of almost all important diseases independent of its effect on body weight. A previous report from the Centers for Disease Control and Prevention (CDC) suggested some reduction in obesity among young children, but the most recent data suggest that this was a statistical aberration, and the trends in obesity among adolescents and adults have continued upwards. The prevalence of obesity in adults has now reached 40 percent, and about 70 percent are overweight or obese. A recent projection based on historical weight trajectories predicted that 57 percent of today’s children will be obese by age 35. Although childhood obesity has appropriately received much attention, the health implications of weight gain among adults is also significant, as it accounts for about half of the excess obesity in the U.S. Weight gained by adults up to age55 strongly predicts poorer health after age 55, including rates of cardiovascular disease, type 2 diabetes, various cancers, reduced quality of life, and overall mortality after age 55.

The cohorts of children who experienced large increases in obesity in their early years are now being affected by the expected consequences. For example, rates of six obesity-related cancers are increasing among young adults. These increases in obesity are also contributing to the continuing decline over the past three years in U.S. life expectancy. These findings highlight the need to redouble our efforts to control weight gain among both children and adults, and that failure to do so will have increasingly serious personal and societal consequences. Encouragingly, the large differences in obesity rates within the U.S. and across countries indicate that this epidemic is not inevitable.

The quality of foods and beverages in our diets plays a major role in the cause, and potentially the prevention, of excess obesity. The past year represented one significant milestone, as the U.S.

Food and Drug Administration finally determined that partially hydrogenated fats no longer qualified as “generally regarded as safe,” or “GRAS.” This announcement effectively banned industrially produced trans fat in the U.S. Although by this time the large majority of trans fat had already been removed from the food supply, this was still an important development in terms of improving Americans’ diet quality.

DEFINING DIET QUALITY

The indicators of diet quality the Menus of Change initiative has used for tracking trends have been selected because they reproducibly predict risksof major diseases in multiple, large prospective studies. These indicators are discussed in more detail and with additional references on the Harvard T.H. Chan School of Public Health website, Nutrition Source. They are intakes of:

1. Vegetables (not including potatoes as they do not provide the same health benefits)

2. Whole Fruits

3. Whole Grains (especially more intact, or cut, versus milled whole grains, to replace refined grains and potatoes, which are both rapidly converted to glucose and absorbed, elevating blood sugar)

4. Nuts and Legumes, including soy-based foods

5. Fish

6. Plant Oils (rich in polyunsaturated and monounsaturated fats)

In practice, increasing polyunsaturated fat means using plant oils (i.e., liquid at room temperature) instead of butter, lard, or tropical oils (e.g., palm, palm kernel, and coconut oils) wherever possible. These plant oils also contain healthful monounsaturated fats. Because of widespread promotion of coconut oil as a health-promoting fat, the American Heart Association released a review of available evidence. This review emphasized the lack of evidence on long-term health consequences, but clear evidence suggested that coconut oil has adverse effects on blood cholesterol fractions when compared with liquid plant oils high in polyunsaturated fat. Limited use of butter or coconut oil when their special flavor is important is reasonable, but those options are best not used as a primary cooking fat.

7. Trans Fats (now eliminated)

8. Red and Processed Meat (to be substantially reduced)

9. Sugar-sweetened Beverages (to be substantially reduced)

10. Sodium (salt added in processing and cooking, to be substantially reduced)

Sodium reduction deserves special attention because it is the only indicator of diet quality that has been moving in the wrong direction. Unprocessed foods contain very little sodium, and foodservice operators (along with food manufacturers) play a major role in determining the amount of sodium consumed by the public.

Our indicators of diet quality do not includedairy foods as they are not essential and are not clearly related to risk of major health outcomes, including fractures. Consumption of cheese has been increasing dramatically over the last several decades in the U.S., becoming almost routine in salads and sandwiches. Cheese provides large amounts of sodium along with less healthy fats and many calories. Consuming smaller amounts of cheese and finding alternative ways to add flavor and variety to these foods—such as using nuts, nut butters, and seeds—are desirable.

Concerns have been raised that plastics or microplastics and synthetic endocrine disrupters in the environment are contributing to obesity, cancer, and other health risks. At this time we have little evidence on the long-term health consequences of these exposures, and we do not necessarily need an explanation for the obesity epidemic because it would be expected given the poor diet quality, general overconsumption of food, and low levels of physical activity in the U.S. population. Nevertheless, while research is ongoing, prudence supports limiting these exposures.

Overall, evidence accumulated over the last several decades strongly supports plant-forward food choices, meaning a style of cooking and eating that emphasizes and celebrates, but is not limited to, plant-based foods—including fruits and vegetables (produce); whole grains; beans, legumes (pulses), and soy foods; nuts and seeds; plant oils; and herbs and spices— and that reflectsevidence-basedprinciples of health and sustainability. This pattern was examined directly in a recent analysis using a

plant-based dietary index that gives one pointfor each serving of healthy plant-based foods, and a negative point for each serving of animal- sourced foods. Among more than 200,000 men and women followed for up to 26 years, a higher plant-based score was linearly related to lower risk of coronary heart disease, consistent with earlier findings for type 2 diabetes.

The findings from the large study on plant-based diets are consistent with a recent meta-analysis in which replacement of red meat with healthy plant protein sources—such as nuts, legumes, and soy foods—improved blood cholesterol fractions. The recent EAT-Lancet Commission report used three different approaches to evaluate the expected outcomes of adopting a healthy, plant-forward eating pattern. The report found that a shift to this flexitarian diet globally could potentially prevent approximately 11 million premature deaths per year. Furthermore, this shift is particularly needed in countries such as the United States, given the vast room for improvement in average dietary quality. Of the 190 countries evaluated, those in the Mediterranean region and Southeast Asia had the highest dietary quality scores, while the U.S. was in the middle range, scoring close to 50 on a scale of 100.

The foodservice industry is offering and promoting an ever greater array of healthier menu options and strategies in response to more health- and sustainability-conscious consumers who are interested in plant-forward eating. As discussed in the Portion Size and Caloric Intake issue brief (page 32), the calorie menu labeling legislation that went into effect in May 2018 has driven some restaurants to reformulate dishesand reconsider portion sizes, but there is still considerable room for improved nutritional quality of meals and the use of “stealth health” tactics to nudge consumer choices.

Chefs are also driving change when it comes to improving meals for children, both in schools and in restaurants. While the USDA issued revisions to existing policies that allowed for some flexibility

in the application of school nutrition standards, many schools are committed to staying with the original standards, and school meals still meet much higher nutrition standards than restaurant meals. The School Nutrition Association’s State of School Nutrition 2018 report highlights significant participation by schools nationwide in a variety of initiatives to promote healthier food choices. For example: of responding districts, 68 percent offer salad bars, 56 percent offer vegetarian meals, 14 percent offer vegan meal options, 60 percent offer locally sourced fruits and vegetables, 48 percent have implemented farm-to-schoolinitiatives, and 18 percent have chef partnerships (with an additional 20 percent considering or planning on doing this). The majority of these percentages have increased from the 2016 survey. All public schools in New York City will also adopt Meatless Mondays starting this fall, following a successful pilot program.

Many restaurants have been working on upgrading the nutritional quality of their kids’ menu both through voluntary industry efforts such as the Kids LiveWell program and through the emergence of state law mandates. A recent Tufts University study found that, while the quick service restaurants it evaluated increased the number of healthier sides and beverages on their children’s menus from 2004 to 2015, still fewer than 20 percent of meal bundles include those healthier items by default.

California recently addressed this issue with the passage of SB 1192, which requires all restaurants (including independent and chain operations) to make the default beverage in its children’s meals water, sparkling water, flavored water, unflavored milk, or a nondairy milk alternative. Policies and regulation across the country will vary, however, and with weakened federal leadership on this topic, voluntary industry efforts are critical for both public health and business impact.

Chefs are also stepping off the line to engage adults and kids in the educational process about food production and preparation. This movement is being supported by the Teaching Kitchen Collaborative, which has grown from 26 organizations in 2016 to 41 organizations across 16 states and three countries in 2019. Working with a local organization offering such classes— or helping to start them—is a relatively simple way through which chefs and operators can help improve the health of their community thanks to their skills. That can also include demonstrating healthier dishes in schools as a way to make students want to eat them when they are offered at the cafeteria.

In foodservice operations, including school foodservice, chefs can most effectively improve the diet quality of their customers by adopting healthier practices themselves. Beyond adding craveable plant-forward dishes to their menu, this means reducing the amount of red meat they serve, relying on herbs and spices rather than solely on salt for flavor, and cooking with healthier fats. Those strategies can be as explicit or implicit as they’d like, depending on their clientele, but must be part of their menu design.

PALEO AND KETOGENIC DIETS: HEALTHY? UNHEALTHY? IT DEPENDS?

High among current popular weight loss diets are those that severely restrict carbohydrates, including Paleo, ketogenic, Atkins, and other variants. There are some good reasons for their attractiveness.

Carbohydrates are not essential nutrients, and most of the carbohydrates in modern diets are refined sources of starch, sugar, and foods that have been bred for high carbohydrate content like industrial corn and potatoes in the U.S. These foods have low nutritional value and the high amounts of rapidly metabolized carbohydrates make weight control difficult and contribute to risks of diabetes and heart disease. Some of these diets, such as the Paleo diet, also exclude additives like salt and other preservatives, which can be desirable. Also, a ketogenic state has been useful for treating some medical conditions, such as some types of seizures.

However, the restrictive nature of these diets, some of which exclude dairy foods and whole grains, can potentially result in low intakes of desirable or essential nutrients. Most importantly, the health implications of restricting carbohydrates depend heavily onthe foods that replace those calories. Many of these diets emphasizehigh consumption of red meat—which has been related to higher risk of many negative health outcomes when compared to most other major protein sources—and dairy fat or coconut oil, which are highly saturated and not optimal sources of fat for routine use. Importantly, most studies of these diets have been for one year or less and we don’t have data on their long-term health effects. Further, the environmental consequences of high consumption of red meat and animal-based foods are major, and such diets are not sustainable if widely adopted.

That said, if a low carbohydrate eating pattern is desired, this ispossible with primarily plant-sourced foods, or even a vegan diet, by using nuts, seeds, soy foods, and some legumes as the main protein sources, unsaturated plant oils, generous amounts of non-starchy vegetables, and possibly modest amounts of intact whole grains. Sucha diet can be healthy and environmentally sustainable. For further details, see https://www.hsph.harvard.edu/nutritionsource/healthy- weight/diet-reviews/paleo-diet/.

PALEO AND KETOGENIC DIETS: HEALTHY? UNHEALTHY? IT DEPENDS?

High among current popular weight loss diets are those that severely restrict carbohydrates, including Paleo, ketogenic, Atkins, and other variants. There are some good reasons for their attractiveness.

Carbohydrates are not essential nutrients, and most of the carbohydrates in modern diets are refined sources of starch, sugar, and foods that have been bred for high carbohydrate content like industrial corn and potatoes in the U.S. These foods have low nutritional value and the high amounts of rapidly metabolized carbohydrates make weight control difficult and contribute to risks of diabetes and heart disease. Some of these diets, such as the Paleo diet, also exclude additives like salt and other preservatives, which can be desirable. Also, a ketogenic state has been useful for treating some medical conditions, such as some types of seizures.

However, the restrictive nature of these diets, some of which exclude dairy foods and whole grains, can potentially result in low intakes of desirable or essential nutrients. Most importantly, the health implications of restricting carbohydrates depend heavily on the foods that replace those calories. Many of these diets emphasizehigh consumption of red meat—which has been related to higher risk of many negative health outcomes when compared to most other major protein sources—and dairy fat or coconut oil, which are highly saturated and not optimal sources of fat for routine use. Importantly,

most studies of these diets have been for one year or less and we don’t have data on their long-term health effects. Further, the environmental consequences of high consumption of red meat andanimal-based foods are major, and such diets are not sustainable if widely adopted.

That said, if a low carbohydrate eating pattern is desired, this ispossible with primarily plant-sourced foods, or even a vegan diet, by using nuts, seeds, soy foods, and some legumes as the main protein sources, unsaturated plant oils, generous amounts of non-starchy vegetables, and possibly modest amounts of intact whole grains. Such a diet can be healthy and environmentally sustainable. For further details, see https://www.hsph.harvard.edu/nutritionsource/healthy- weight/diet-reviews/paleo-diet/.

Score: 3.5

The foodservice industry is increasing its range of healthier plant-forward menu options in response to more health-conscious consumers. Chefs are also driving change in meals for children, both in school and in restaurants, though more work needs to be done in improving nutritional quality of meals and food literacy among children through hands-on cooking.

IN SUMMARY:

  • Diet quality in the U.S. remains low and is helping to fuel an unrelenting epidemic of overweight and obesity.
  • In general, healthy plant-forward diets will provide improved health and well-being.
  • The foodservice industry as a whole is offering more nutritionally balanced and plant-forward menu items; chefsalsoplay an increasingly important role in influencing childhood nutrition through improving school food and kids meals and offering hands-on food education.