The term “superfood” is continuing to explode in marketing and media. Magazine headlines and food advertisements touting the latest superfood can be so pervasive that consumers may become confused or overwhelmed. While the label superfood is abused by some, due to a lack of regulation and formal definition of the term, there are many foods that rightly deserve this classification. To help increase the quality of your diet, the following article outlines how you can critically evaluate the scientific evidence behind the superfood claims.
While some broadly define superfoods as foods rich in nutrients like vitamins, minerals, and fiber, most add that the food must also promote a specific aspect of health. The health promotion facet of the definition is key. Although nutrient quantity is a potential indicator of health, nutrient quality and bioavailability, which can vary from food to food, also influence the healthpromoting capacity of a food. Beware of superfood claims based solely on the amount of a particular nutrient within a food. In determining superfoods, focus on studies that strongly link consumption of foods that produce positive health benefits. There are four broad categories of studies that are often used to investigate the healthpromoting properties of a food.
- Placebo controlled experiments – study subjects are split into two or more groups, one receiving the food with potential health promoting properties and the other receiving a placebo (a similar food that is not likely to provide strong health benefits). Neither group should know if they are receiving the beneficial food or the placebo. While this type of study is the most authoritative, they are often difficult to perform on whole foods due to the difficulty in finding a suitable placebo. Some resort to using an extract or encapsulated form of the food. If an extract is used, check to see how much of the whole food would be required to achieve the same results. Some experiments use doses that would not be possible through whole food intake. A study on chocolate is a good example of quality placebo controlled research. While the 2 bars of chocolate used in the experiment, providing nearly 450 calories together, are at the upper limits of plausible inclusion in the diet, the cardiovascular benefits of this dose was validated in an experiment using a placebo chocolate with low flavonol content.
- Epidemiological studies – a population with a desired health outcome is compared against another population without the desired health outcome to determine how their diets and lifestyles differ. While this type of study offers great preliminary evidence, it is generally not considered strong evidence until a placebo controlled experiment has been performed. Differences between two populations are often great and it is usually impossible to state with 100% assurance that one particular difference is the cause of the health benefit. Some foods are difficult to investigate in a placebo controlled experiment, however, because lifelong intake may be required to obtain a desired health outcome. Soy is a good example of quality epidemiological evidence. Numerous studies have documented the improved health in Asian populations with high soy intake compared with other populations that don’t have high soy intake.
- Ethnobotany – this is a science investigating the traditional use of foods by various populations. Again, this is typically regarded as preliminary until validated through placebo controlled studies and is generally of lesser scientific weight than epidemiological studies. It can provide meaningful insights into potential benefits of foods, nonetheless, and guide future scientific studies. Interest in the cardiovascular benefits of cocoa began when it was noted that the Kuna Indians of Panama had extremely an extremely low incidence of cardiovascular, attributed to their large dietary intake of cocoa. Maca is an example of a food that has received significant media attention due to its use traditionally by Peruvians to enhance vitality.
- Animal and in vitro – studies done on animals or on isolated cells. This is generally the lowest level of scientific evidence and should never be viewed as conclusive until it has been validated through human experiments. These studies offer advantages over human studies because they can be investigated in highly controlled environments with animals that have shorter lifespans to provide faster results. These studies can be highly effective at investigating how a particular food may provide benefits and help support evidence found in epidemiological or ethnobotanical studies. Animal and in vitro studies, however, commonly use doses that far exceed any that are possible within humans. Additionally, the food being studied may not function the same way in humans due to differences in physiology or limitations in getting the desired compound to the right part of the body. Studies on the ORAC value of berries is a good example of in vitro experiments that suggest a potential benefit.
As you seek to include more superfoods in your diet, remember that there is overwhelming scientific evidence in favor of the health-promoting properties of a varied diet, rich in common vegetables and fruits. While focusing on adding specific superfoods to your diet can be a great way to unleash the health-promoting properties of food, it won’t make up for a poor diet, and should not compromise dietary variety. To maximize your health, eat a “superdiet” rich in vegetables, fruits, whole grains, healthy fats, and quality protein, and incorporate those superfoods that have robust scientific evidence supporting their effectiveness.
By Ron Beckstrom, MS, RD, HFS
This article is for nutrition information purposes only and does not constitute medical advice. Always seek the advice of a qualified health provider with any health concerns you may have. The information in this article is not intended to promote any specific product, or for the prevention or treatment of any disease.