In a quick Google search, there are lists of 10, 11, 25, and 52 superfoods that are the “best.” Here is the practical summary of them all: the best superfoods are whole foods.
This may be anti-climatic, but trying to suggest that certain types of whole foods are any more or less valuable than other types of whole foods is flawed for a variety of reasons. Generally, these lists are biased towards fruits and vegetables, but the concepts herein can apply to grains, beans, and to some degree protein sources like meat, eggs, and seafood.
The Micronutrient Sell
Many of these lists tout certain foods are high in specific vitamins or minerals (e.g., blueberries for vitamin C, kale for calcium). However, there are 13 essential vitamins and 15 essential minerals, so the first question you should ask is “what about the other 27 essential micronutrients?” (1,2). This also does not include considerations for essential macronutrients like amino acids in proteins and omega-3 fatty acids. The total number of “essential” nutrients (i.e., they must be obtained from the diet) is approximately 40 (3). So targeting one food because of a couple specific nutrients is not the complete picture.
Similarly, these articles often make health claims related to a specific organ or system; Vitamin A and eye health is a classic example. Vitamin A is necessary for “maintaining the integrity and function of all surface tissues” including the eye (4). But other nutrients like vitamin C and vitamin E are also needed (5). So, another question you should be asking is “what about the rest of me?” While everyone wants healthy eyes, the leading cause of death is heart disease suggesting that the focus on
healthy eating should be geared more toward the major cause of mortality than a specific organ (thankfully, whole foods are good for cardiovascular and eye health!).
The other consideration is the relevance of serving sizes. Kale and calcium is a good example. In 100 grams (g) of kale (raw), there are 254 milligrams (mg) of calcium. This is a good dose considering the Recommended Daily Allowance (RDA) for adults is 1,000 mg. However, 100g of kale covers a dinner plate. A serving size of leafy greens is usually 2 cups bringing down the per serving basis of calcium to 106 mg (6). Conversely, almonds have 76 mg of calcium per standard serving (28g/1 ounce). Yes, still less than kale, but it hopefully illustrates serving sizes are an important variable for assessing realistic nutrient intake.
The Phytochemical Sell
Phytochemicals are non-nutritive but bioactive, plant chemicals with health-protective properties (7). For example, some phytochemicals (glucosinolates) may be called “cancer-fighting compounds” because of their anti-cancer properties (8). However, phytochemicals include at least 5,000 different chemicals with other important functions and even functions not yet known (7). It would be foolish to limit one’s diversity of whole food material, simply because we have data about certain compounds.
There is also the issue of what a therapeutic dose of these phytochemicals looks like in terms of food quantity. As an example, resveratrol is a phytochemical in plants like red wine, grapes, and berries and may be protective of cardiovascular health (9). Where the clinical evidence shows effectiveness, resveratrol doses are on the order of 150 mg per day (9). The resveratrol concentration in red wine varies but ~5 mg per liter of wine is on the higher end (10). This suggests an impossible amount of daily wine (e.g., liters of wine!) is needed to reach a therapeutic dose.
Variety Works in the Long Haul
It is a nice idea that simplifying one’s diet to a short list of foods will lead to optimal health. However, highlighting a handful of nutrients incorrectly applies a reductionist approach to complex physiology. Yet, understanding the complex physiology is not necessary for application. Eating whole foods more often than not, and varying the diversity of those whole foods, is the level of complexity needed for optimal application.
Besides the nutrient diversity gained from varying one’s diet, another valuable aspect of variance is sustainability. Even if there were only 10 foods that led to optimal health, there is the very real problem that long-term adherence would be rather dismal. The diet is so monotonous that many would fail not long after they started. Therefore, even though romaine lettuce might not be as nutrient dense as kale, if it adds some variety (while also displacing poorer quality items), the end result is an overall win.
You can try and track all the micronutrients, phytochemicals, etc., to ensure your diet optimizes each one. It will be a rather painstaking process, however, and not necessarily put you in a better position than consistently eating a diet of varied whole, unprocessed food.
- United States National Library of Medicine (USNLM). (2015 Feb 9). Definitions of Health Terms: Minerals. MedlinePlus. Retrieved Dec 10, 2017, from: https://medlineplus.gov/definitions/mineralsdefinitions.html
- United States National Library of Medicine (USNLM). (2015 Apr 2). Vitamins. MedlinePlus. Retrieved Dec 10, 2017, from: https://medlineplus.gov/vitamins.html
- Ames, B.N. (2015). Moderate Deficiency of an Essential Vitamin or Mineral Accelerates Diseases of Aging. Retrieved Dec 10 2017, from: https://www.uncnri.org/wp-content/uploads/2015/05/Ames-NC-Kann.pdf
- Gilbert, C. (2013). What is vitamin A and why do we need it? Community Eye Health, 26(84), 65.
- McCusker, M.M., Durrani, K., Payette, M.J., & Suchecki, J. (2016). An eye on nutrition: The role of vitamins, essential fatty acids, and antioxidants in age-related macular degeneration, dry eye syndrome, and cataract. Clinics in Dermatology, 34(2), 276-285.
- United States Department of Agriculture (USDA). (2015). 2015-2020 Dietary Guidelines for Americans. Retrieved Aug 9, 2017, from: https://health.gov/dietaryguidelines/2015/
- Liu, R.H. (2013). Health-Promoting Components of Fruits and Vegetables in the Diet. Advances in Nutrition, 4, 384S-392S. doi:10.3945/an.112.003517
- Prakash, D., & Gupta, C. (2012). Glucosinolates: the phytochemicals of nutraceutical importance. Journal of Complementary & Integrative Medicine, 9, Article 13. doi: 10.1515/1553-3840.1611
- Zordoky, B.N.M., Robertson, I.A., & Dyck, J.R.B. (2015). Preclinical and clinical evidence for the role of resveratrol in the treatment of cardiovascular diseases. Biochimica et Biophysica Acta (BBA) – Molecular Basis of Disease, 1852(6), 1155-1177.
- Atanackovic, M., Petrovic, A., Jovic, S., Gojkovic-Bukarica, L., Bursac, M., & Cvejic, J. (2012). Influence of winemaking techniques on the resveratrol content, total phenolic content and antioxidant potential of red wines. Food Chemistry, 131, 513-518.