The myth of superfoods

We are bombarded with messages about superfoods. Superfoods can be found on menus. Take kale. A few years ago kale was a boring vegetable that wasn't very popular because of its hard leaves and unattractive taste profile. Now it is labeled as a superfood and it has become very popular? Why? What makes "superfoods" so "super"??

Some of the most common or talked about superfoods include blueberries, spirulina (read here about the shocking reason why spirulina is called a superfood), quinoa and kale, but the list is long!! The term ‘superfood’ has no agreed definition. It is a marketing term and certainly not a scientific term. You will find the term in popular magazines, on the packaging of an expensive supplement or in an advertisement, but it does not exist in the medical literature. Superfoods is a buzzword that has gained a lot of traction in the general population. What is so special about these foods?


Special effects

Superfoods are generally described as having special healthful effects, such as ‘cholesterol lowering’, ‘cancer preventing’ or ‘performance enhancing’. Some of these claims may even have some evidence, as superfoods are generally foods that are high in certain nutrients, antioxidants, vitamins or minerals. Proponents of certain superfoods may take evidence – however suspect – of certain nutrients being healthful in some cases and linking that food to the possible health effect.


We generally link antioxidants to various health effects. The evidence is derived mostly from studies that show that a higher intake of fruits and vegetables produces a number of health benefits. Thus, we conclude antioxidants are good. If we now have a food that is high in a particular antioxidant, we may call this a superfood. There is nothing “super” about that food, other than it has a high concentration of certain antioxidants.


For example Montmorency cherries contain phytonutrients with antioxidant and anti-inflammatory properties. Does this make it a superfood? If we would only eat these cherries would this make us healthy? Certainly not… we would lack many other nutrients. Healthy nutrition is about having a mixed and balanced diet so that we get all of the nutrients we need from a wide variety of sources. If there was one food that would contain all these nutrients that would be a real "superfood". But such foods do not exist.


If there was one food that would contain all these nutrients that would be a real "superfood". But such foods do not exist.

Nutrient density

Superfoods are promoted because of their nutrient density, a rather general term describing how many or how much of various nutrients are found in the food. This could include any nutrient, such as protein, fibre, vitamins or minerals, and is a non-specific term. Nutrient dense foods can be useful for preventing deficiencies in certain nutrients, but in most cases, eating more than the amount required to stay healthy does not confer any benefits.


Superfoods may be high in one nutrient they are low in or even deficient in other nutrients. So why would it be a superfood? Wouldn’t a food be more of a superfood if it contained a large number of essential nutrients? Instead of a high concentration of one of them?

Kale wasn’t very popular till a clever marketing person called it a superfood… Kale is a superfood, rich in antioxidants, fiber, and vitamin A. But so are other green leafy vegetables….


Antioxidants

A large proportion of superfoods are marked as superfoods due to their antioxidant content, and though there is evidence for certain antioxidants having positive roles in health, they are not universally agreed upon as being beneficial in all scenarios. For example, studies show that supplementation with high doses of vitamins C and E – two vitamins with antioxidant properties – blunt the adaptations to an exercise training programs in participants. Therefore, antioxidants should not be considered universally beneficial.


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Effects on health

Studies in humans have been performed to investigate the effects of certain foods on certain markers of health. Most studies use extracts or concentrates of the foods in question, such as concentrated fruit juices, or pills containing the nutrient. This is usually to allow large enough amounts of the nutrient to be eaten, as eating the food itself might require unfeasible amounts. Many of these studies have shown small positive effects, while other show little to no effect. However, some studies have involved feeding people normal, manageable amounts of certain superfoods and observed improvements in markers of health. For example, one 6-month study involved feeding overweight and obese people a placebo or 1 cup of blueberries per day for 6 months. Eating 1 cup of blueberries improved a number of markers of cardiovascular health, including cholesterol. Another study found that eating a serving of dark chocolate every day for a month improved similar markers of cardiovascular health. However, other studies have shown no effect of such foods. On balance, the evidence suggests that there may be small benefits to eating specific superfoods in large, but achievable amounts. But would eating more fruit and vegetables in general not do the same thing? Or is the effect specific to this “superfood”?


On balance, the evidence suggests that there may be small benefits to eating specific superfoods in large, but achievable amounts. But would eating more fruit and vegetables in general not do the same thing? Or is the effect specific to this “superfood”?

Summary

One of the biggest problems with the term ‘superfood’ is that any whole, minimally processed food could be considered a ‘superfood’ by virtue of one or more of its properties, nutrients, or ingredients. Instead of focusing on a handful of possible superfoods, health and sporting performance are likely to be optimised through eating a wide variety of foods, including fruits and vegetables. Common dietary advice is to ‘eat the rainbow’, which encourages eating a variety of foods, especially fruits and vegetables. Different colours of foods are generally linked to different profiles of nutrients, and by eating all of these, the greatest variety of health benefits can be obtained. Where specific nutrients have been shown to benefit health or performance – such as nitrate from beetroot – it is generally most convenient to use supplements to achieve the normally very high intakes required to exert an effect.


References

  1. Hill J, Keane K, Quinlan R, Howatson G. Tart Cherry Supplementation and Recovery From Strenuous Exercise: A Systematic Review and Meta-Analysis. Int J Sport Nutr Exerc Metab. 31(2):154-67, 2021

  2. Ristow M, Zarse K, Oberbach A, Kloting N, Birringer M, Kienhtopf M, Stumfoll M, Kahn C, Bluher M. Antioxidants prevent health-promoting effects of physical exercise in humans. Proceedings of the National Academy of Sciences. 106(2):8665-70, 2009

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