I’ve always pictured my role primarily as providing the latest science, but you can’t understand all the new discoveries without a good foundation. The Dietary Guidelines for Americans has a chapter on food components to reduce. But, when they say things like “reduce intake of solid fats (major sources of saturated and trans fatty acids),” what does that mean in terms of which foods to cut down on?
Similarly, there’s a chapter on nutrients we should increase our intake of, so-called “shortfall nutrients.” But, when they say we need more magnesium, for example, what does that mean in terms of actual food? There’s no magnesium aisle in the grocery store. In my video What Are the Healthiest Foods? I analyze 20 different types of foods to see, based on the federal guideline criteria, which are the healthiest and which are the least healthy. There are a lot of fascinating charts in the video, so I encourage you to check it out.
To give a better idea of which foods to eat and which ones to avoid, in the video I use traffic-light labeling, so imagine that a green light means to “go ahead and eat,” yellow or amber means “caution,” and red tells you to “stop and think before you put that in your mouth.” Note these don’t correspond to the more comprehensive Traffic Light designations I detail in my book How Not to Die. When considering what foods in our diet may contribute most of the added sugars we consume, as one would suspect, sweets and sodas are red-light foods, but there are often surprising levels of extra sugar even in savory snack foods, like Ritz crackers. So, what are the top five offenders? Soda contributes 36.6% of the added sugars we consume, with grain-based desserts like donuts contributing 11.7%, Kool-Aid-type beverages contributing 11.5%, dairy desserts including ice cream contributing 6.4%, and candy contributing 6.2%.
What about caloric density? Surveying which foods contain the most calories per serving, oils join desserts and processed snack foods as the worst, though eggs, meat (including fish and poultry), nuts, seeds, and soda can’t be considered low-calorie. The top five sources of calories in the American diet are basically desserts, which contribute 6.4% of our total calories, bread, which contributes 6.0%, chicken, which contributes 5.6%, soda and other sweetened beverages, which contribute 5.3%, and pizza, which contributes 4.5%.
Which foods contain the most cholesterol? Eggs, fish, chicken, and red meat all earn the red light, while desserts, dairy, and other meats earn the yellow. Which foods contribute the highest percentages of cholesterol intake to the American diet? Number one by far is eggs (24.6%), with chicken coming in second (12.5%), beef third (11.0%), cheese fourth (4.2%), and pork fifth (3.9%).
As for saturated fat, desserts, dairy, and snack foods are all designated as red light, with eggs, chicken, fish, and red meat getting the yellow light. Most of the saturated fat in the American diet comes from cheese (8.5%), pizza (5.9%), grain-based desserts (5.8%), dairy desserts (5.6%), and chicken (5.5%).
Salt levels are highest in lunch meat and snack foods, which both get a red light. But, Americans get most of their sodium from bread (7.3%), chicken (6.8%), pizza (6.3%), pasta (5.1%), and lunch meat (4.5%).
Trans fats are present in many foods—naturally or artificially added or created. Snack foods earn red-light levels, while oils, animal products, and animal-derived products get yellow lights. The primary contributors of trans fat in the American diet are cakes, cookies, crackers, pies, doughnuts, and other grain-based processed foods (40%), followed by animal products (21%), margarine (17%), French fries (8%), and chips and microwave popcorn (5%).
Now, to the nutrients. If you fast-forward to the 3:00 minute mark of my What Are the Healthiest Foods? video, you can see which foods are the best sources of such nutrients as calcium, fiber, magnesium, potassium, and vitamins A, C, D, E, and K. Foods in the chart with a green designation are a high source of a particular nutrient, while pale green designees are a medium source and white entries are a poor source. Since the body’s food currency is in calories, not grams or food weight, nutrient density by calorie is a better way of making assessments. Our body monitors how much energy we eat, not how much weight (of food) we eat. We only have about 2,000 calories in the calorie bank to spend every day; so, to maximize our nutrient purchase, we want to eat the most nutrient-dense foods.
To look for trends in nutrient density by calorie, we can rank the foods in the chart from best to worst, which you can see at the 3:47 minute mark of the video.
The clear winners are unprocessed, unrefined, plant-derived foods, including vegetables, herbs and spices, fruit, mushrooms, legumes, whole grains, and nuts and seeds. In general, these foods lack the disease-promoting components we want to avoid and, as the Dietary Guidelines Committee states, “These foods contain not only the essential vitamins and minerals…but also hundreds of naturally-occurring phytonutrients…that may protect against cancer, heart disease, osteoporosis, and other chronic health conditions.” So, these foods also contain hundreds of phytonutrients found in whole plant foods that are largely missing from processed and animal-derived foods. Additionally, the lack of disease-preventing compounds may be compounded by the presence of disease-promoting compounds.
So this is why people eating more plant-based tend to end up eating a more nutrient-dense dietary pattern, closer to the federal dietary recommendations. The more plant-based we get, apparently, the better.
For more information on the best diet to maximize nutrient intake while minimizing the intake of harmful food components, check out my video What Is the Healthiest Diet?. How low should one try to push their intake of some of the food components to avoid? See Trans Fat, Saturated Fat, and Cholesterol: Tolerable Upper Intake of Zero, How Much Added Sugar Is Too Much?, and, for sodium, High Blood Pressure May Be a Choice. Surprised that trans fats weren’t limited to partially hydrogenated junk? Check out Trans Fat in Meat and Dairy.
And for an overview on why I do this work to publish the latest in health and nutrition, see my introductory series.
Michael Greger, M.D.
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