How Do We Know How Much?
His gaze was direct and almost a challenge as this athletic, business-suited yuppie uttered a demand before we had even sat down to our first nutrition counseling session. “Look, just tell me what I gotta eat and how much to get my cholesterol down by fifty points-fast.” I had never quite mastered the inscrutable “counselor” look: my overly expressive Italian face usually reflects my emotional response, which, in this case, ran the gamut of surprise at his fierce determination to more than a bit of annoyance at his obvious disdain for the complexity of making lasting nutritional changes. But in the next few seconds, I decided that I admired his faith in both nutrition science and a dietitian’s ability to deliver the goods. It also shows the public’s desire for specific recommendations and guidelines on a healthy diet.
Most members of generation X are too young to remember when there were only four basic food groups. That phrase harkens back to the days when junior high students, at least girls, were taught to cook and admonished to memorize the “Basic 4.” As the focus shifted from nutritional deficiency to excessive intake linked to chronic disease, however, new paradigms for recommendations became vital. The starting point for dietary recommendations, the Recommended Dietary Allowances (RDAs), have evolved, often contentiously, over the last half of this century. In fact, they are currently being updated and renamed Dietary Reference Intakes (DRIs).
The RDA have been and continue to be the best yardstick we have to evaluate dietary intake. Their objective is to suggest a level of intake for many essential nutrients that is as close to adequate as possible for as many people as possible. You can probably see the difficulty inherent in coming up with one number, say for vitamin A, that is appropriate for an entire nation! This is an unavoidable design flaw, and one that should be taken into account, but not one that should preclude confidence in and use of the RDA.
In addition to a yardstick for adequacy, we also need something that translates the latest scientific knowledge about nutrition and disease into understandable and usable guidelines. As research continued to accumulate, the government stepped up to the plate and issued the Dietary Guidelines for Americans. These seven simple recommendations have since been revised and expanded on, and have spurred other health organizations to develop their own dietary guidelines; we have recommendations from the American Heart Association, the American Cancer Society, and a few others for good measure. Contrary to some public opinion, dietary recommendations from the government and most health agencies seem to converge on similar themes.
DRIs and RDAs: How Do They Come Up with These Things?
Currently, the newly revised recommendations, DRIs, cover the following nutrients: calcium, phosphorus, fluoride, magnesium, vitamin D, and the B vitamins. The RDAs for the remaining essential nutrients will be updated in the next year or so and we still need to use the old RDA until the update is complete. So we’ll talk about both DRIs and RDAs, which you can consider almost one and the same.
The RDA for vitamins and the other essential nutrients are established by a subcommittee of the Food and Nutrition Board (FNB) of the National Research Council (NRC) and the National Academy of Sciences (NAS). The current DRIs are being updated by the Institute of Medicine. The NAS is a government agency, but the DRI committee, like the RDA committee before it, is made up of independent researchers representing various specialties in the field of nutrition. That’s important, not just because a lot of people don’t trust the government, but because the people who generate the RDA have broad expertise and experience and bring an unbiased view to the table.
The committee reviews the current information available from animal, human, and population studies and develops recommendations for nutrient intake. A recommendation is made for each nutrient in terms of the daily amount different groups of people need; the current DRI groups, which will cover all nutrients within the next few years, include:
- pregnant and lactating women (different age groups within each)
- infants: 0 to 6 months; 6 months to a year
- children: 1 to 3 years; 4 to 8; 9 to 13
- males: 14 to 18; 19 to 30; 31 to 50; 51 to 70; over 70
- females: 14 to 18; 19 to 30; 31 to 50; 51 to 70; over 70
The RDA for a nutrient includes what’s called a “margin of safety,” to account for individual human variation and differences in how well the body is able to absorb the nutrient from various food sources. Most experts believe that the RDAs, which are only applicable to healthy people, probably cover up to 95 percent of the American population. A small number of people will not get enough of a particular nutrient if they take in the RDA, and others will get more than they need.
So where does that leave you? The best use of the RDA is to plan or evaluate diets for groups of people, such as in a nursing home or school. But as long as we recognize their limitations, it is reasonable to use the RDA to assess an individual’s diet. In fact, dietitians do it all the time; we just need to remember that while the RDA is our best estimate, that’s all it is.
Not all nutrients have an official RDA; some have other classifications. For example, the RDAs are not necessarily optimal intakes, but they aren’t minimum intakes, either. In other words, they are not set at a level to simply prevent a deficiency; they include an ample margin of safety. But for sodium, chloride, and potassium, an “Estimated Minimum Requirement” is set at a level which is the minimum you need with no margin of safety. Nutrients with an RDA under the 1989 RDA or the new DRI include protein and the vitamins and minerals.
If studies show that a nutrient is essential but the experts feel that there isn’t enough information to set an RDA, they suggest a range of intake with a special name. The 1989 RDA used the term Estimated Safe and Adequate Daily Dietary Intake (ESADDI). The nutrients still covered in this category include the trace minerals chromium, molybdenum, copper, and manganese. When the committee revises recommendations for these nutrients in the future, more research may provide solid evidence for establishing an RDA. The new DRI uses a similar category called Adequate Intake (AI), and has used that term for several nutrients which received updated recommendations.
The first RDAs were published in 1943, and the plan was to revise them every five years. In 1985, the RDAs were scheduled for revision, but because of scientific controversy, the update didn’t appear until 1989. The word controversy doesn’t do justice to the brouhaha which stormed across universities and research centers around the country, resulting in several lawsuits! The new DRls evolved from years of proposals and revisions for updating the RDAs and differ in two important ways. The first change is that the DRls represent one combined set of North American recommendations. Previously, Canadians had their own guidelines, similar to our RDAs. The second important change is that where the previous RDAs were designed to prevent deficiency, the new recommendations reflect current knowledge of nutrient amounts needed to promote optimal health and prevent chronic disease. The plan calls for revision of all nutrient recommendations in a seven-step process, by groups of nutrients. As mentioned, new numbers were recently issued for nutrients involved in bone health-calcium, magnesium, phosphorus, vitamin D, and fluoride, as well as the B vitamins.
The DRIs include different categories, just as the RDAs, to account for the more tenuous nature of the research for certain nutrients. In addition, they will continue to include the margin of safety, but with the DRI showing that value in the new AI category. The AI consists of the average intake that covers half the needs of those within a specific gender and age group. Another new category will address the increasing use of nutrient supplements and food fortification, by indicating the upper level of safety for some nutrients.
Estimated Average Requirement (EAR)
Intake that meets the needs of half the individuals in a specific group. This figure is used to develop new RDAs for some nutrients.
Recommended Dietary Allowance (RDA)
These values are derived from EARs. The RDAs are the EAR with an added amount that accounts for the variation in nutrient needs within life-stage groups (margin of safety). The RDAs will meet the need for almost all healthy individuals within a life-stage group.
Adequate Intakes (AI)
For many nutrients, the research data are not available to estimate an average nutrient requirement. For these nutrients, the DRls give an AI recommendation which appears adequate to sustain a desired indicator for health.
Tolerable Upper Intake Level (UL)
Widespread use of supplements and food fortification has prompted the NAS to include a value that represents the best estimates of maximum intakes that do not pose risks of adverse health effects in healthy individuals within a life-stage group.
One final note about the DRls/RDAs is that, in addition to specific nutrients, there is an RDA for daily energy or caloric intake. Because of the problem of obesity in this country, the energy RDA does not include a margin of safety. Instead, the RDAs are set at average levels for each age and gender group plus or minus 20 percent to account for either situations of higher need, as with increased physical activity, or periods of lower needs, such as occur in aging. What this means for you is that if you’re average for your age and gender, in body size and activity level, the energy RDA is probably close to your actual energy needs. The reference woman at age 19 to 24 is 5’5″ and weighs 128 pounds, while the reference man is 5’10”, weighing 160 pounds.
The Dietary Guidelines: Can We All Agree?
The Dietary Guidelines first appeared on the scene back in 1980. The purpose was to help Americans make food choices that would prevent poor diets which research began linking to chronic diseases. These nutrition recommendations were a joint effort of two government agencies, the U.S. Departments of Agriculture and Health and Human Services (USDA, USDHHS). Since their inception, they’ve been both applauded and panned, but the guidelines have endured to be revised most recently in 1995.
The latest guidelines appear to be a bit more relaxed, cutting Americans some slack on previously frowned-on food ingredients such as sugar and salt. This left some nutrition advocates jeering. But in the words of one USDHHS official, the new Dietary Guidelines promote “moderation over marathons” and suggest that Americans consider realistically attainable health and dietary goals.
The U.S. Dietary Guidelines for Americans
- Eat a variety of foods.
- Balance the food you eat with physical activity. Maintain or improve your weight.
- Choose a diet with plenty of grain products, vegetables, and fruits.
- Choose a diet low in fat, saturated fat, and cholesterol.
- Choose a diet moderate in sugars.
- Choose a diet moderate in salt and sodium.
- If you drink alcoholic beverages, do so in moderation.
The major changes in the evolution of the Dietary Guidelines involve an emphasis on the benefit of vegetarian diets, which is included in the text for the first guideline, the more realistic focus on weight maintenance rather than attainment of ideal weight, and a more positive wording for the guidelines on salt and sugar. Another change came not in the wording of the guideline concerning alcohol, but in the accompanying text, which points to recent studies that tout the possible benefits of moderate alcohol consumption. Also in the text of the publication is another reference to recent research promoting the importance of folic acid for pregnant women.
The revised Dietary Guidelines evoked this less-than-positive characterization of the government’s role from one nutrition advocate: “It’s laissez-faire or do-nothing behavior. Guidelines should tell people what’s the best possible diet and urge them to move in that direction. These don’t.”
Others, however, have commented more positively on specific aspects of the guidelines which emphasize the importance of physical activity in weight maintenance. The new guidelines recommend that Americans engage in thirty minutes of moderate physical activity every day, providing examples such as gardening, housework, or brisk walking. The rationale for this guideline follows the general tenor which stresses a more realistic approach rather than ideal goals.
While the new Dietary Guidelines for Americans may be too moderate for everyone, the USDHHS secretary’s summarizing comments may be welcomed by consumers who’ve been overburdened with stringent preaching: “We Americans should eat a wide variety of foods, balance diet with physical activity, and use good judgment in our consumption of sugar, salt, and alcohol.”
Food Labeling: Putting the Guidelines to Use
Pick up a package of fudge cookies and you’ll get more information than you probably want to know: the label will probably tell you that if you eat two servings, you’ll use up your fat allotment for the entire day! If you’re like most people, you’ll eat the cookies anyway, but at least you’re informed. That didn’t used to be the case. Prior to 1993, the food labeling laws hadn’t kept pace with nutrition research.
Just as the RDAs had centered on adequacy and preventing nutrient deficiency, so too did the food label. You’d have information on riboflavin, thiamin, and a host of other nutrients that aren’t the problem of the average American, but not a word on saturated fat and salt. In addition, manufacturers. didn’t have to include nutrition information unless they made a product claim. Under prodding from Congress, the Food and Drug Administration (FDA) came up with a new food label, Nutrition Facts. The FDA fixed most of the problems with the old labels, especially by mandating that virtually all food products had to include nutrition information. The exceptions include raw, single ingredient foods, fresh fruits, vegetables, and raw fish, which have voluntary nutrition information at the grocery store shelf.
It’s worth taking a close look at Nutrition Facts, because you can use it to make decisions about the products you buy and how to integrate them into a healthy diet. The food label highlights key nutrients, especially those linked to prevention of chronic disease, including vitamins such as C and A. The nutrient amounts in your cookies show up as percentages of what you should eat in one day, called Daily Values.
Daily Values, in turn, consist of two sources which don’t show up on the label, Reference Daily Intakes (RDIs) and Daily Reference Values (DRVs), but it’s important to know what they represent. RDIs are the old u.s. RDAs which used an even older source, the 1968 RDAs. The DRVs are specific recommendations for nutrients which didn’t have an RDA, highlighting those linked to disease, either positively or negatively: fat, saturated fat, salt, fiber, sugars, and others.
These are the nutrients which manufacturers must include on the label; they were selected because of current health issues:
- total calories
- calories from fat
- total fat
- saturated fat
- total carbohydrate
- dietary fiber
- vitamin A
- vitamin C
If a claim is made on the label about other nutrients not on the mandatory list, such as potassium or monounsaturated fat, the manufacturer must provide the information. In addition, if the product contains a nutrient either by fortification or enrichment, it must include that information.
One of the main gripes from critics is the fact that the DRV s are based on a daily intake of 2,000 calories. This is obviously a compromise, since caloric needs vary greatly from one group of the population to another. However, one of the reasons for settling on 2,000 is that increasing the energy level would increase the fat allowance, possibly encouraging higher fat intakes.
Nutrition Facts shows standardized serving sizes for various types of products for the first time. In past years, the manufacturer decided on what serving size to base the nutrient analysis. This led to what appeared to some consumers as a slightly deceptive practice, when, for example, a serving size of cereal equaled one-fourth of a cup. It was true that there were only 5 grams of fat in a serving, but most people would tend to eat four times that amount, thus acquiring a hefty 20 grams of fat at almost a third of the daily allotment.
The FDA has also restricted the use of product health claims for a list of seven nutrient/disease relationships. The claim must also be worded in such a way as to accurately reflect the relationship between the nutrient, the,disease, and the nutrient’s relative importance in the total diet. The approved relationships include:
- calcium and osteoporosis
- fat and cancer
- saturated fat and cholesterol and heart disease
- fiber-containing fruits, vegetables, and grain products and cancer
- fiber-containing fruits, vegetables, and grain products and heart disease
- sodium and hypertension
- fruits and vegetables and cancer
Food Guide Pyramid: A Practical Guide to Putting It All Together
The story began rather innocuously in 1988 when the USDA began development and testing of a graphic tool for use in communicating the messages of the Dietary Guidelines for Americans. But what followed seemed more like the shootout at the O.K. Corral than anything else. After the smoke had cleared, a pyramid loomed on the American horizon with the battle lines still drawn.
Some bystanders wondered what all the fuss was about since government agencies had been issuing dietary recommendations for years, beginning with the RDAs and culminating in the revised Dietary Guidelines for Americans. After all, the triangular figure with suggested serving sizes and attractive clips of foods seemed innocent enough. But it was the very shape of the image and the message it projected that sent trade industry groups to the battlefront. The intent of the pyramid was to emphasize certain food groups, such as grain products and fruits and vegetables, while deemphasizing other groups, such as meat and dairy products, and conveying a sense of what proportions the groups should represent in one’s diet.
The USDA stated that a graphic image was needed to reinforce the messages of the Dietary Guidelines. The Dietary Guidelines call for increased consumption of complex carbohydrates and reduced intake of fats, saturated fats, cholesterol, sugar, and salt. Because animal sources contain predominantly saturated fat and cholesterol, these foods are deemphasized in a diet based on the guidelines.
In response, industry groups marketing these foods cited the availability and promotion of newer low-fat versions of old American staples, such as extralean ground round and nonfat dairy products. They pointed to the nutrient density of these products and challenged their position on the new pyramid, which had placed animal-derived foods directly below the fats and sweets group at the tip of the structure. The message of the pyramid is that grain products such as bread, cereal, and rice should form the bulk of the diet, accounting for most of the calories provided. Next are the fruits and vegetables, providing key vitamins and minerals. Toward the top are the foods which should be eaten more reservedly-the meat and dairy group. At the very top are the fats and sweets, with the admonition “to be used sparingly.”
Actually, the pyramid is not an American invention, having first appeared in Sweden in the mid-1980s and later in Australia in 1987. Both of these countries used the figure to convey their very similar versions of dietary guidelines. Critics had complained that the shape of the pyramid would confuse people because the top of something is usually the best. In the case of the “Eating Right Pyramid,” as it was later coined, in the top position were the foods to avoid. Some educators proposed that the pyramid be inverted to avoid this confusion. However, the USDA reported having conducted exhaustive testing and evaluation of the graphic with individuals and focus groups, much the same as marketing experts do in the business world. They stated that there were no significant findings related to shape inversion.
Although the pyramid has many supporters, some groups still are not convinced that it can be effective and not misrepresent certain foods. The unveiling took longer than expected, more because of objections from the food industry than efforts to test and polish the pyramid. Some critics have come up with their own pyramids: the Mediterranean Diet Pyramid, the Asian Pyramid, the Vegetarian Pyramid, and the Oldways Pyramid, which is based on plant foods. The USDA Center for Nutrition Policy and Promotion recently issued informational fact sheets outlining the differences between its pyramid and new ones on the scene in an effort to resolve consumer confusion. It pointed to its chief advantages over its competitors-broader choices of foods and specific suggestions for number of servings from each group.
One of the long-term goals for the pyramid is widespread recognition among American consumers, and a recent survey showed that awareness increased from 58 to 67 percent of Americans within the past few years. Countless nutrition educators, those working with groups from children to the elderly, have found it to be a fun and effective teaching tool in imparting the nutrition and health recommendations of the Dietary Guidelines for Americans.
To find out if your diet stacks up to the pyramid, you need to know how many calories you should be taking in. For this, you’ll need to fill in the form at the end of this section. At the end of the chapter, you’ll need to review your diet record sheets to evaluate your current intake compared to the recommendations in this chapter.
No one is sure how much someone should weigh to promote health, since being either too thin or too fat are both associated with health risk.
Other Dietary Recommendations
The government isn’t the only group to issue nutrition recommendations; a host of public and private agencies have thrown their hats into the ring. We’ll look at diet guides from a private agency, the American Heart Association, and a joint effort, the 5-a-Day program.
American Heart Association Recommendations
The American Heart Association (AHA) recently released updated guidelines for Americans in its battle to prevent cardiovascular disease (CVD), diseases of the heart and blood vessels such as heart attack, high blood pressure, and stroke. The new guidelines build on previous recommendations, especially the Dietary Guidelines for Americans.
The AHA points out in the preamble to its guidelines that although its focus is the prevention of CVD, the recommendations are consistent with those issued for the prevention and treatment of other major killers such as some forms of cancer, kidney disease, and diabetes. The recommendations are geared toward reducing well established risk factors for CVD, which include:
- the elimination of cigarette smoking
- appropriate levels of caloric intake and physical activity to prevent obesity and reduce weight in those who are overweight (especially abdominal or upper body fat)
- consumption of 30 percent or less of the day’s total calories from fat
- consumption of 8 to 10 percent of total calories from saturated fatty acids
- consumption of up to 10 percent of total calories from polyun saturated fatty acids
- consumption of 15 percent of total calories from monounsaturated fatty acids
- consumption of less than 300 mg per day of cholesterol
- consumption of no more than 2,400 mg per day of sodium
- consumption of 55 to 60 percent of calories as complex carbohydrates
- consumption of alcohol (those for whom alcohol is not contraindicated) should not exceed two drinks, or 1 to 2 ounces of ethanol, per day
What was that old-fashioned saying about an apple a day? It may have been closer to the mark than we thought, but in this case, more is better! As nutritionists have recommended shifting away from the traditional basic food groups approach to a healthy diet, various suggestions on which foods and how much have been proposed. When the Pyramid was introduced last year, amid much opposition, along with it came the 5-a-Day program focusing on fruits and vegetables. Consumers had heard a multitude of information on the benefits of increasing their consumption of these foods, but the number seems to have gotten lost in the shuffle.
The 5-a-Day program was developed in 1988 by the California Department of Health Services. The targets included retail, media, and government agencies to spread the message about the healthfulness of eating fruits and vegetables. The program proved highly successful, with more than 1,800 retail operations, agencies, and industry groups participating. At just about the same time, evidence began to mount connecting high fruit and vegetable intake to a reduced risk for several diseases. More recently, the National Cancer Institute has borrowed the California theme and promoted the 5-a-Day program as part of a national health promotion focused on reducing the risk of cancer and heart disease.
Several key national authorities, such as the National Academy of Sciences, the U.S. Department of Health and Human Services, and the USDA, have recommended that people should eat at least five servings of fruits and vegetables daily. In fact, the Dietary Guidelines for Healthy Americans actually recommend up to nine daily servings. The basis for these recommendations is the burgeoning number of epidemiologic studies which suggest that people who eat greater amounts of fruits and vegetables, in particular those which are high in the antioxidant nutrients vitamin C and beta-carotene, have a lower risk for the two major killers in the United States, cancer and heart disease.
Other researchers have been quick to point out that there are a myriad of compounds in fruits and vegetables besides vitamin C and beta-carotene which may be wholly or partially responsible for the risk reduction. Some of these include the other carotenoids: alphacarotene, lutein, lycopene, and beta-cryptoxanthin. Additionally, fiber has been suspected of offering protection against these diseases based on several population studies. And the compounds known as indoles and dithiolthiones, from the cruciferous vegetables, such as broccoli, cauliflower, and brussels sprouts, have piqued the interest of cancer researchers in recent years.
The results of a recent study of almost 87,000 nurses point to why scientists have had difficulty in identifying a single compound which is responsible for possible protective effects. Researchers analyzed the food intake of subjects and found that those who ate five or more servings of carrots a week were 68 percent less likely to have a stroke than those who ate one serving a month at most. Apparently spinach conferred protection as well, although not to the extent that carrots did. While both carrots and spinach are high in beta-carotene, they also contain other carotenoids and fiber. In addition, other compounds in the vegetables, as yet undiscovered, could be in,volved in risk reduction.
The studies to date have been somewhat conflicting, with most showing reduced cancer and heart disease risk in populations with high fruit and vegetable intake, but with others not supporting this conclusion. In addition, some scientists believe that the levels needed of the antioxidant nutrients and other protective compounds to significantly lower disease risk can only be achieved with nutrient supplements. Data from one recent study support this view. Subjects had a significant reduction in risk for heart disease only when supplementing their diet with vitamin E, with dietary intake exerting no significant effects.
Failure to pinpoint the exact protective compound is the reason for encouraging an increase in fruit and vegetable consumption with the 5-a-Day campaign. In addition, most of the studies so far which have shown reduced risk for chronic disease were based on analysis of dietary intake of fruits and vegetables. However, the recommendations seem to fall on deaf ears, with a recent survey reporting fully 77 percent of Americans falling short and only 8 percent achieving the goal. Perhaps more alarming is the low percentage of Americans who are aware of the recommendation for fruit and vegetable daily intake: 34 percent thought it was one serving, 32 percent thought two servings, and 25 percent thought three to four servings.
The National Cancer Institute and other health organizations are hoping to increase awareness of the 5-a-Day recommendation. At this point, it isn’t clear why Americans haven’t taken to this simple advice, but the experts will keep plugging away at this worthwhile goal.
Let’s Take a Closer Look at Your Diet
Now it’s time to see how your diet stacks up against all of the recommendation we’ve just considered . It is important to remember that even a three-day intake record is not truly representative of the foods you eat over a longer period of time; but at least it’s a start we’ll use a quiz format in this chapter and upcoming ones to compare the average of your three-day intake to the various recommendation.