Dietary patterns are major element of nutrition security
Availability of and access to sufficient and healthy food is often considered the foundation of nutrition security. Ultimately, however, it is the use and utilisation of this food that is decisive for our health and well-being. In other words, consumption is a major element of nutrition security.
We eat on average more than 80,000 meals during our lifetime. Without any conscious effort, this habit ensures that our body functions well: The nutrients make sure that body components can be made, that our body has sufficient fuel and that it can defend itself against diseases. Knowledge about which nutrients and other food substances we need, and in what quantities, is provided by human nutrition science. This discipline is rooted in several other scientific domains, including biology, biochemistry and physiology, and more recently also studies at the cellular level such as molecular biology, genomics and genetics.
This latest development has introduced a new scientific field, which we now call nutrigenomics. The nutrition science started off about 100 years ago with the discovery of several vitamins. These compounds are vital, and lack of them causes deficiency diseases. Interestingly, we are now not only worried about deficiencies and undernutrition but even more about overnutrition. The excessive intake of energy, sugars, fats and salt was recently found to be an important determinant of various diseases.
Our obesity epidemic and chronic diseases which occur with ageing such as cancer, cardiovascular disease and diabetes mellitus are associated with overnutrition. In addition, high intakes of, for example, fat-soluble vitamins can be toxic. Good nutrition, therefore, means optimal nutrition – not too little intakes but also not too many – by a balanced diet.
Excessive intake of energy, sugars, fats and salt was recently found to be an important determinant of various diseases
Quackery
But what is a balanced diet? Everybody who reads a ladies magazine, or is an active sports person, is aware of the various components, guidelines and advice related to nutrition. Unfortunately, the media often reports as many fables as facts, even descending into outright quackery. This situation is confusing to many people for two main reasons. Firstly, as eating is a habit we all do, the results of even the smallest studies are of interest to a large group of consumers and health-conscious people. Secondly, nutrition and health is a difficult field to study compared, say, to medication research. Nutrition is dealing with many components eaten at the same time, while pharma usually deals with one specific component at a time. Furthermore, the health effects of single dietary com pounds are generally subtle and often only become clear in the long term.
This makes controlled dietary trials difficult. Edith Feskens, professor of nutrition and the metabolic syndrome, and her team therefore need to rely to a large extent on observational studies. An example is cohorts of participants in which we examine dietary habits, and then follow them for at least 10 years to see what diseases develop. A drawback of this approach is that dietary habits are correlated with other habits (for instance, coffee drinkers tend to drink more alcohol and smoke more) and thus these other habits, which we call confounders, need to be accounted for in statistical analyses. But the risk of residual confounding always remains as we cannot measure all relevant health habits. And the dietary assessment, and assessment of the other relevant habits, is not easy. Do you remember what you had for dinner yesterday? How many grams of rice, pasta or potatoes? Cooked with how much salt? Did you have meat, how much and which kind? And do you remember your mid-afternoon snack?
EetMeetWeet
In 2011 Fesken's group started with a unique observational study in Wageningen and the surrounding towns. Joining forces with all chair groups of the Division of Human Nutrition at Wageningen UR, the goal is to tackle the difficulties in nutrition sciences from three angles: Improve the methodology for dietary assessment, gain insight into the human body with imaging techniques, and use functional tests, biochemical markers and nutrigenomics to obtain more insight into the health status of individuals. The study is called in Dutch ‘EetMeetWeet’ (eating, measuring and knowing). Wageningen UR collaborates with the municipal health services as well as the local hospital, Gelderse Vallei in Ede.
It is a rewarding effort as both very much appreciate the cooperation and everyone recognises the added value. About 2000 men and women aged between 20 and 70 years are participating in the study by providing extensive information on dietary intake and eating habits, completing health questionnaires and providing blood and urine samples. Height, weight and waist circumference are measured to indicate the presence of overweight or abdominal obesity. A body scan gives information on the overall percentage of body fat and of bone mineral density, an important indicator of osteoporosis.
Vascular function is measured, as arterial stiffness is a risk factor for subsequent cardiovascular disease. A cognition test is also taken as we suspect that specific dietary factors such as -vitamins and certain fatty acids affect mental functioning. All participants are asked to return to the university for similar measurements after one and two years in order to study the natural history of diet and health. Many interesting scientific questions can be answered by this data collection. For example, questions on dietary habits are also included: Where do you eat, at what time, with whom? How fast do you eat? How mindful are you of what you are eating? These are important determinants of overeating, such as mindlessly snacking in front of the TV. Adding this information to the detailed nutrient intakes gives us a better view of the dietary patterns that give rise to obesity and its metabolic consequences
Subtle effects
Dietary patterns are the new kids on the block in this field. People choose foods and eat them in certain combinations; they do not go to the supermarket to buy folic acid or potassium. We are increasingly realising that the subtle effect of each nutrient can play a role and may add up, or counteract, the potential beneficial effect of another. An example of this are whole grain foods, which may be healthy as long as they do not contain too many simple sugars. We know that dietary fibre enhances intestinal passage and prohibits constipation, and may have other beneficial metabolic effects. On the other hand, fibres contain phytates, which inhibit the uptake of minerals such as iron and zinc. We know that this prohibiting effect is less than the beneficial effect, so whole grains are generally regarded as healthy. But this example also shows that it is really impossible, and even dangerous, to label foods as healthy or non-healthy. It is really about the amount and variation of intake. You won’t get very far by consuming cucumbers alone.