Wednesday, December 3, 2014

Looking Beyond Nutrients to the Whole Package


The appetite for nutrient focused healthy eating messages in the media is insatiable. In 2014 this has been highlighted by the abundance of messages such as ‘quit sugar’ and ‘cut carbohydrate’ in the media. But is demonizing single nutrients really the path to a healthy diet?

Traditionally nutrition research has focused on the effects of individual nutrients and health. While this approach has shed ample light on our understanding of the mechanisms by which nutrients and other bio-active food components act within the body, the messages generated from such research have often unintentionally complicated the concept of healthy eating.

As we eat foods not nutrients, healthy eating messages which focus solely on the presence or absence of an individual nutrient are of limited use. Such messages do not comprehend that nutrients never act on the body in isolation, but rather are packaged with many other nutrients within foods which act together to influence health. For example, whole grains contain more than 26 health promoting nutrients and bio-active components and increasingly studies are showing that single these components do not simply act alone to protect health, but rather in concert. This explains why the observed benefit of the whole food package of whole grains often exceeds that explained by the action of each nutrient.(1, 2)

In addition, a focus on a single nutrient in isolation also overlooks the impact of the food matrix (the structure of foods when consumed) and the overall the composition of the meal within a long term eating pattern. Each of which plays an important role on the impact of food on health.

Clearly nutrition is a very complex system and so focusing on a single nutrient in attempt to establish a healthy eating pattern is like trying to build a house with one tool. Constructing a healthy diet to reduce risk of disease across the lifespan requires a holistic, whole of diet approach as opposed to a reductionist nutrient focused solution. With advances in our understanding of the complexity of nutrition, health authorities and evidenced based practitioners have shifted the emphasis of dietary recommendations away from nutrients towards foods.

A focus on food was a key objective in the development of the 2013 Australians Dietary Guidelines. The Guidelines are designed not only to provide the nutrients essential for wellbeing but also to provide adequate amounts of the foods known to reduce the risk of chronic disease. Underpinned by a comprehensive review of over 55,000 studies, the Guidelines encourage Australians to consume a variety of nutritious, available, affordable and culturally appropriate foods from each of the five food groups: grains, mostly whole grain or high fibre; vegetables and legumes; fruits; lean meats, poultry, fish, eggs, nuts; and dairy.

In addition, with Australians waistlines increasing(3), the Guidelines also focus on promoting a healthy weight; for the average size person doing light physical activity, adhering to an eating pattern which reflects the Guidelines will result in a daily reduction in energy intake and should result in weight loss.

Despite the recent re-focus of public health nutrition to foods not nutrients, single nutrient messages are taking centre stage in the media. Many may argue that the intent of messages such as ‘quit sugar’ or ‘low carb’ is to serve public health and encourage Australians to limit energy dense, nutrient poor food choices (i.e. soft drinks, pastries, biscuits, cakes and processed take away foods). However, the blunt nature of a nutrient focused recommendation inevitably results in vocal advocates of such messages also taking aim at foods and food groups such as fruits, whole grains and legumes, calling for the exclusion of these foods from the diet. This is despite the fact these foods are backed by the scientific evidence of being linked with better health.

As a result, these nutrient focused messages fail to reflect the evidence of the relationship between food and health. For those not convinced, such recommendations also contradict evidence from Blue Zones, the populations around the world with the best health and longest lives, who enjoy mostly plant based diets which include whole fruits, whole grains and legumes – each of which appear on the banned list of the latest quit sugar and low carb fads.

Just as past reductionist advice to reduce fat failed to achieve its intended outcome of encouraging people to eat more naturally low fat plant foods available at the time, current and future nutrient focused messages will fail to address the complex relationship between diet and diet related disease risk. Nutrition science continues to increase our understanding of the relationship between the food we eat and health and more often than not studies are demonstrating that it is more about all the elements of foods acting together rather than a single nutrient.

References

  1. Fardet A. New Approaches to Studying the Potential Health Benefits of Cereals: From Reductionism to Holism. Cereal Foods World. 2014;59(5):224-9.
  2. Parker TL, Miller SA, Myers LE, Miguez FE, Engeseth NJ. Evaluation of synergistic antioxidant potential of complex mixtures using oxygen radical absorbance capacity (ORAC) and electron paramagnetic resonance (EPR). Journal of agricultural and food chemistry. 2010;58(1):209-17.
  3. AIHW. Australia's health 2014 Australia's health no. 14. Cat. no. AUS 181. Canberra: AIHW.2014. Available from: http://www.aihw.gov.au/australias-health/2014/