Why are some foods “good” and others “bad” for you?

Why are some foods (vegetables) considered good for you and other foods (donuts) considered bad for you?

Most of us know that vegetables contain vitamins, fiber, antioxidants, and phytochemicals that help give them their “good” label whereas donuts contain fat and sugar with very little nutritive value, which gives them their “bad” label.

Over the past 30+ years, we have continually been told that red meat and other animal based products such as baked goods, cheese, milk, margarine, and butter are “bad” for us because they contain saturated fat, which has been linked to the development of heart disease (1) and some cancers (2).

The American Heart Association (AHA) and numerous other professional organizations recommend consuming <7% of your calories as saturated fat to reduce the risk of developing heart disease. On average, Americans currently consume 11% of their calories from saturated fat (3) and heart disease continues to kill 610,000 Americans/year. Up to this point most people’s simplified frame of reference has been:

Saturated fat = bad.

Now to throw a wrench in your framework of ‘saturated fat = bad’ let me give you two examples.

1) Recently numerous large-scale studies and commentaries have suggested that saturated fat DOES NOT contribute to an increased risk of cardiovascular disease (4, 5).

2) Our pre-agricultural Paleolithic ancestors living greater than 10,000 years ago consumed, on average, 13.2% saturated fat (6) as part of their diets, and yet many of these populations had no signs of heart disease whatsoever (7)!

Cordain_2002_EJCN_Table_1_animal_food_5_versus_plant_foodFigure 1. Proportion of plant and animal food in hunter-gatherer diets (7).

There are several reasons why our Paleolithic ancestors, and for that matter, non-acculturated indigenous people living in our current time did not and do not respectively develop heart disease (7).  Our Paleolithic ancestors

1) relied heavily on fish and wild game for energy sources; thereby providing a greater number of mono- and polyunsaturated fatty acids to their diets.

2) obtained a tremendous amount of moderate intensity physical activity as reflected by their much greater aerobic capacities (see figures 2 & 3).

3) ate NO refined sugars or grains and instead survived on fruits, vegetables, nuts, seeds, and tubers when available.

Collectively, these behaviors worked to cancel out the Paleolithic people’s increased reliance on “the evil” saturated fat as a major energy source.

2 Aerobic_Capacities_for--__BAD___food_post

Figure 2: Comparison of hunter-gatherer and modern man aerobic fitness (8).

3 Aerobic Capacities_2

Figure 3: Aerobic Fitness of present day Hunter-Gather (Inuit) Males & Females compared to their Westernized offspring (Mod-males and females). The drastic reduction in aerobic fitness takes place within one generation (20 years) due to the adoption of a Westernized lifestyle (snowmobiles, outboard motors, other labor saving devices) (8).

Regardless of genetics or heritage, anyone who adopts the Westernized lifestyle, and with it a reduction in physical activity, an increase in sedentary behaviors, and an increase in caloric consumption will gain weight and become less healthy (9-12).

For example, in a classic study (12) researchers looked at heart attack rates in Japanese men living in Japan, Hawaii, and San Francisco. Men in San Francisco (the most Westernized of the three locations) had higher heart attack rates than men in Hawaii, and men in Hawaii had higher heart attack rates than men in Japan (least Westernized lifestyle). This study was able to show that lifestyle, and not genetics, was playing the predominant role in heart attack rates as each group of men was of Japanese ancestry and genetically quite similar.

Recently, the Paleolithic Diet (Paleo Diet) of our pre-agricultural ancestors has gained traction in the health & wellness community. The proponents of the Paleo diet provide its justification based upon the following logic:

Farming, and with it, the consumption of grain started ~10,000 years ago. The human body’s biology (genome) had been set during the previous ~2 million years of Homo evolution and was therefore not equipped or designed to consume grains and the other products that came along with agriculture and farming. Paleo dieters also avoid dairy and legumes but include meat, fruits, and vegetables, foods that our ancestors had SOME access to depending on geographic location and seasonality.

I am not for or against the Paleo diet; however, I do enjoy dairy, legumes, and grains and believe that they can be incorporated into your diet.

To me, the Paleo Diet is a good thing because it helps to make us more aware of all the overly processed carbohydrates (grains) that we consume on an all too often regular basis. However, like any diet, I am willing to bet that its effectiveness will decrease over time as the rigor with which we can adhere to the diet diminishes. When we first start a diet we are excited about it and strictly adhere to it.

4 Dietary_Adherence_by_Diet_Type--Dansinger_Figure updated

Figure 4. Adherence to diet type decreases over time (13).


5 Weight_Loss_over_Time_Dansinger_Figure updated

Figure 5. The amount of weight lost during dieting decreases over time and is directly related to dietary adherence (13) (as seen in Figure 4).

In any drastic dietary intervention that we undertake our rigor and intensity decreases over time and so does our weight loss/health (for more information please see “Why All Diets are Created Equal”).

One could say, okay, so it seems like the key to a healthy diet is avoiding processed foods. I would say that in general this is a good rule to follow but as we have previously discussed in “6 Nutrition Myths Debunked”, not all processed food can be considered “bad” food or junk food and some processed food contributes key nutrients to the American diet that we otherwise would not get.

When we dissect an American’s diet between the years 2003 and 2008 on the basis of the 2010 Dietary Guidelines for Americans (14), we see that processed foods contributed

55% of dietary fiber

48% of calcium

43% of potassium

34% of vitamin D

64% of iron

65% of folate

46% of vitamin B-12

As consumers, we have an urge to know what components of a food are that makes it healthy: what is it that distinguishes a “good” food from a “bad” food? Scientists have been able to identify some of the pieces of the puzzle (antioxidants, fibers, phytonutrients) but we’re certainly missing the vast majority of the puzzle.

Either out of complete ignorance or the willingness to set ethics aside to make a quick buck, the supplement industry has attempted (through marketing) to capitalize on the few things we know about what makes a healthy food healthy and have attempted to create a shortcut for you to meet your nutrient demands without having to eat a healthy diet. All you have to do is take a few pills! Or do you?

6 Macpherson_H_2013_AJCN_Multivitamin_Use_and_Mortality

Figure 6. Collection of studies on the use of multivitamin multimineral (MVMM) supplementation and mortality (15).

The author of the multivitamin multimineral supplementation study presented above concludes that…“the current study provides the highest level of evidence to indicate that MVMM supplementation has no significant effect on the risk of all-cause mortality, mortality of vascular etiology, or mortality due to cancer.”  In other words, multivitamins do not work for their intended purpose.  Individual antioxidant supplements prove to be no better (Figure 7).

7 Bjelakovic_2013_JAMA_Antioxidants_and_Mortality

Figure 7. Antioxidant supplements are not associated with lower all-cause mortality. Beta carotene, vitamin E, and higher doses of vitamin A may be associated with higher all-cause mortality (16).

Okay, so the Paleo diet probably isn’t sustainable over the long term, not all processed foods are “bad” foods, it’s probably a waste of money and perhaps even harmful to supplement with antioxidants. So what should we be doing?

MOVE MORE AND EAT LESS! Oh, I know that people get viscerally upset by this advice and like to say that healthy living is much more complicated and that this simplified advice doesn’t do anything for them. The only thing that probably upsets people more is saying that a calorie is a calorie. But I digress.

Even if you move just a little more throughout your day and eat just a little bit less (or try to eat more fruits and vegetables) you will be so much healthier. For more on this topic please see my NEROI post.

8 Wen_CP_2011_Minimum_Amount_of_Physical_Activity

Figure 8. Daily physical activity duration and mortality reduction (17). Walking just 15 minutes/day decreases your risk of premature death by a whopping 14%!

The bottom line is that, despite our best efforts, we still do not know what is in fruits and vegetables that make them so healthy for us. For a comprehensive and truly awesome analysis of how little we know about why fruits and vegetables are good for us, please read Thomas Campbell’s book “Whole: Rethinking the Science of Nutrition”. Don’t worry the book isn’t crazy technical but it is crazy good and should be required reading for anyone in the health & wellness field.

Eating more than 4 fruit and vegetable servings/day greatly reduces your risk of premature mortality. You don’t have to go shake, smoothie, and juicing crazy to reap the benefits of fruits and vegetables. Eating “superfoods” or greater than 5 servings of fruits and vegetables/day really doesn’t provide you with any additional health benefits. If you are a juicer or smoothie king/queen, good for you but outside of your moral high ground you’re probably not going to live any longer than someone consuming 4 servings of produce the conventional way.

9 Wang_X_2014_Diminishing_Retuns_of_Fruit_and_Vegetable_Consumption

Figure 9. Fruit and vegetable consumption/day and risk of premature death (18). The best ROI is eating 4 servings of fruits and vegetables/day.

I wish we could quantify why some foods are “good” for you and others are “bad” for you but it just isn’t that easy. Any given food or nutrient is potentially bad for you or good for you. Potassium can be used as part of a lethal injection for death row inmates, too much vitamin A can severely damage your liver, even drinking too much water can kill you (please see my post on “Everything You Eat Will Kill You”).

It would be great if we could make a magic pill but it just doesn’t work that way. Instead, find ways to incorporate fruits and vegetables into your diet. If you are having trouble doing this, find someone to help you with this. I’m not a fan of just telling people what to do, find someone to SHOW you how to do it.

If we look at one food in isolation away from the rest of the diet we can find a way to call that food a “good” food or a “bad” food. But really, there is no such thing as a “good” food or a “bad” food. There are “good” diets and “bad” diets but not “good” foods or “bad” foods.

In the end we don’t really know what makes a “good” food good or a “bad” food bad. What we do know is that no single food can ruin your overall diet. If you eat 10 “good” foods and 1 “bad” food, your overall diet is going to be pretty dang good. I don’t know the components of a food that makes it “good” or “bad” but I do know that vegetables, fruits, lean meats, nuts, legumes, and whole grains are “good” for us regardless of what the nutrient components are. Epidemiological evidence tells us so.

Todd M. Weber PhD, MS, RD


  1. Steinberg D. Thematic review series: the pathogenesis of atherosclerosis. An interpretive history of the cholesterol controversy: part II: the early evidence linking hypercholesterolemia to coronary disease in humans. Journal of lipid research. 2005;46(2):179-190.
  2. Rohrmann S, Overvad K, Bueno-de-Mesquita HB, et al. Meat consumption and mortality–results from the European Prospective Investigation into Cancer and Nutrition. BMC medicine. 2013;11:63.
  3. Lin BH, Guthrie, J. Nutritional quality of food prepared at home and away from home, 1977-2008. Economic Information Bulletin No. (EIB-105) 24 pp, December 2012.
  4. Chowdhury R, Warnakula S, Kunutsor S, et al. Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis. Annals of internal medicine. 2014;160(6):398-406.
  5. Lawrence GD. Dietary fats and health: dietary recommendations in the context of scientific evidence. Advances in nutrition. 2013;4(3):294-302.
  6. Meskin S, Bidlack W, Randolph R. Phytochemicals: nutrient-gene interactions. Taylor & Francis, February 22, 2006.
  7. Cordain L, Eaton SB, Miller JB, Mann N, Hill K. The paradoxical nature of hunter-gatherer diets: meat-based, yet non-atherogenic. European journal of clinical nutrition. 2002;56 Suppl 1:S42-52.
  8. Cordain L, Gotshall RW, Eaton SB, Eaton SB, 3rd. Physical activity, energy expenditure and fitness: an evolutionary perspective. International journal of sports medicine. 1998;19(5):328-335.
  9. Kato H, Tillotson J, Nichaman MZ, Rhoads GG, Hamilton HB. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California. American journal of epidemiology. 1973;97(6):372-385.
  10. Luke A, Guo X, Adeyemo AA, et al. Heritability of obesity-related traits among Nigerians, Jamaicans and US black people. International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity. 2001;25(7):1034-1041.
  11. Ravussin E. Metabolic differences and the development of obesity. Metabolism: clinical and experimental. 1995;44(9 Suppl 3):12-14.
  12. Robertson TL, Kato H, Gordon T, et al. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California. Coronary heart disease risk factors in Japan and Hawaii. The American journal of cardiology. 1977;39(2):244-249.
  13. Dansinger ML, Gleason JA, Griffith JL, Selker HP, Schaefer EJ. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA : the journal of the American Medical Association. 2005;293(1):43-53.
  14. Weaver CM, Dwyer J, Fulgoni VL, 3rd, et al. Processed foods: contributions to nutrition. The American journal of clinical nutrition. 2014;99(6):1525-1542.
  15. Macpherson H, Pipingas A, Pase MP. Multivitamin-multimineral supplementation and mortality: a meta-analysis of randomized controlled trials. The American journal of clinical nutrition. 2013;97(2):437-444.
  16. Bjelakovic G, Nikolova D, Gluud C. Antioxidant supplements to prevent mortality. JAMA : the journal of the American Medical Association. 2013;310(11):1178-1179.
  17. Wen CP, Wai JP, Tsai MK, et al. Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. Lancet. 2011;378(9798):1244-1253.
  18. Wang X, Ouyang Y, Liu J, et al. Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies. Bmj. 2014;349:g4490.

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