REFERENCES – THE 3 CLASSES OF FOOD

What was our process for rating food groups?

We began by identifying 13 food categories, allowing us to group all potential foods into clear, non-overlapping areas. From there, we selected seven representative foods for each category, with the exception of eggs, as Americans typically only consume chicken eggs. Once we assigned seven foods to each of the 13 categories, we normalized the nutrient composition of each food to a 2,000-calorie intake. This means we evaluated how much of each nutrient a person would get if they consumed 2,000 calories’ worth of that food. 

That was done to show numbers large enough to showcase each food class’s nutrient profiles and patterns which translates to high %’s. While no one would rely on a single food for their entire daily calorie intake, examining the nutrients in 2,000 calories of one food allows for meaningful, health-based comparisons.

Nutrients are often compared by weight, such as per 100 grams of food, but we believe comparing nutrient content by calories provides a better guide to healthy eating. After all, everyone has a certain number of calories to “spend” daily on the nutrients that keep them healthy and fueled. 

In other words, individuals have a daily caloric “budget.” This budget represents the calories they need to consume to maintain their energy levels and overall health. The point is that it’s important to “spend” those calories wisely by choosing foods rich in essential nutrients rather than just focusing on calorie quantity. In other words, the focus should be on getting the most nutrition (vitamins, minerals, etc.) for the calories consumed, ensuring that what you eat supports health and vitality rather than just meeting calorie needs.

To calculate the individual nutrient scores:

1) We calculated the amount of nutrients a person would get from eating 2,000 calories of each of the 85 foods

2) We averaged the 28 nutrients individually by category

3) We took these nutrient averages and compared them to a real-life health standard, and in most cases, the Dietary Reference Intakes that have been established as public health guidelines in the area of nutrition and

4) We turned this comparison into a percentage. Thus, every nutrient in a food category had a score. We averaged each food category’s 28 nutrient scores together to calculate the total scores. Since lesser amounts of cholesterol, saturated fat, and sodium are healthier, we subtracted their scores when we averaged them with the other nutrients instead of adding them.

What was our process for rating food groups?

We used the Dietary Reference Intakes (DRIs) as established by the National Academy of Sciences for a 19-30 year-old sedentary woman whenever possible. The six specific publications we used in this context were:

References

We used the Dietary Reference Intakes (DRIs) the National Academy of Sciences established for a 19-30-year-old sedentary woman whenever possible. The six specific publications we used in this context were:

References

  • Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. The National Academies. 2002/2005.
  • Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. The National Academies. 2004.
  • Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride. The National Academies. 1997.
  • Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. The National Academies. 1998.
  • Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. The National Academies. 2000.
  • Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. The National Academies. 2001.

DRIs were not available for saturated fat or cholesterol, so we used the widely recognized recommendations for a 2,000-calorie diet established in the USDA Dietary Guidelines for Americans, 2005.

References

  • U.S. Department of Health and Human Services and U.S. Department of Agriculture. Dietary Guidelines for Americans, 2005. 6th Edition, Washington, DC: U.S. Government Printing Office, January 2005.

Since neither DRIs nor USDA Dietary Guidelines were available for monounsaturated fat, we used the American Heart Association’s recommendation as referenced below:

References

  • Krauss RM, Deckelbaum RJ, Ernst N, et al. Dietary guidelines for healthy American adults. A statement for health professionals from the Nutrition Committee, American Heart Association. Circulation. 1996 Oct 1;94(7):1795-800.

Since there was no established public health guideline for flavonoid intake, we used the following research articles to estimate the average American intake at 175mg per day.

References

  • Gu L, Kelm MA, Hammerstone JF, et al. Concentrations of proanthocyanidins in common foods and estimations of normal consumption. J Nutr. 2004 Mar;134(3):613-7.
  • Manach C, Scalbert A, Morand C, et al. Polyphenols: food sources and bioavailability. Am J Clin Nutr. 2004 May;79(5):77-47.

How did we determine the amount of nutrients in each food?

Most of our nutrient amounts were derived from the USDA’s National Nutrient Database, Standard Reference, Release 18. A dash (-) in our food chart indicates no available data. The additional sources we used for the flavonoid content of foods are listed below. Since animals cannot synthesize flavonoids, we limited our analysis of food flavonoids to plant foods.

References

  • U.S. Department of Agriculture, Agricultural Research Service. USDA National Nutrient Database for Standard Reference, Release 18. 2005.
  • Nutrient Data Laboratory, Beltsville Human Nutrition Research Center. U.S. Department of Agriculture, Agricultural Research Service. USDA Database for the Flavonoid Content of Selected Foods. March 2003.
  • Nutrient Data Laboratory, Beltsville Human Nutrition Research Center. U.S. Department of Agriculture, Agricultural Research Service. USDA Database for the Proanthocyanidin Content of Selected Foods. August 2004.
  • USDA-Iowa State University Database on the Isoflavone Content of Foods. 1999.
  • Azevedo L, Gomes JC, Stringheta PC, et al. Black bean (Phaseolus vulgaris L.) as a protective agent against DNA damage in mice. Food Chem Toxicol. 2003 Dec;41(12):1671-6.
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