Introduction to the double burden of malnutrition
In South America, many countries have seen different changes over the last decades. Some of these changes are the epidemiological transition, the demographic transition, and the nutritional transition. To start, the epidemiological transition is the transition from infectious diseases to non-communicable diseases. In other words, there is a higher prevalence of deaths from NCDs nowadays compared to infectious diseases (as it was in the past). The demographic transition is defined as the change in fertility and mortality, from high fertility and high mortality to low fertility and low mortality. The nutritional transition led to a change in diet and physical activity. Together with other factors, this last transition has resulted in an increase of the double burden of malnutrition in South America.
Definitions
Malnutrition is defined as both the nutritional deficiencies and excesses of macro-and micronutrients. The double burden of malnutrition (DBM) is characterized by the co-occurrence of undernutrition and overweight, obesity, or other diet-related non-communicable diseases (NCDs) throughout life. Undernutrition can be categorized into four groups: wasting, stunting, underweight, and deficiencies in vitamins and minerals. Wasting means that someone has a low weight for their height and stunting means that someone has a low height for their age. In general, wasting is the result of recent weight loss and stunting is the result of chronic undernutrition. Underweight in children means that the weight is low for the age. In adults, a Body Mass Index (BMI) below 18.5 is seen as underweight and a BMI below 16.5 as severe underweight. BMI is used to classify weight and it is the relation between weight and height. The formula is a person’s weight divided by the square of his height (kg/m2). Overweight and obesity are the result of an imbalance between energy intake and expenditure the other way around: too much energy consumed and too little energy used. In adults, a BMI above 25 is classified as overweight. A BMI above 30 is classified as obesity.
Types
The DBM can occur within individuals, households, or populations. For individuals, the DBM means that a patient is overweight but at the same time has a vitamin deficiency. It could also be the case that at one point in his or her life the person is undernourished and at another point in life the person is overweight. At the household level, it means that different members of the household have different types of malnutrition. At the population level, the double burden of malnutrition means that undernutrition and overweight, obesity, or NCDs are coexisting in the same community, region, or nation.
Causes
There are many different causes of the DBM and this also differs depending on which level is being looked at, i.e. individual, household, or population level. However, there are some overarching themes. The fact that children who are undernourished, have a higher chance of becoming overweight, developing obesity or diabetes later in life is due to ‘metabolic programming’, meaning that fat is more likely to accumulate if a child grew up with constrained child growth. A DBM within a household occurs mainly in middle-income countries that are in the middle of a rapid nutrition transition. The physical environment also has an influence on the DBM. According to the United Nations, more than 50% of the world’s population lived in urban areas in 2015. Urban areas have shown to have an impact on the behavior of its population. In urban areas, people spend less energy at home and at work. Furthermore, food is purchased on the streets or in a restaurant more often, which is likely to be over-processed. A person is influenced by media, education, peer pressure, and culture. In rural areas, stunting is more common due to child marriages. This is because of different reasons. One of the reasons is that these children do not continue their education. This also results in lower socioeconomic status, and thus the ability to financially take care of the children is lower resulting in stunting. Urban areas have a lower occurrence of child marriages, resulting in less stunting. However, urban children are less physically active during their free time. Lastly, the media advertises the consumption of processed foods.
Consequences
Malnutrition has many different consequences for the health of those affected. To name a few, if undernourished, someone is more easily affected by infectious diseases, and this can even lead to higher child mortality rates. On the other hand, undernourished children have an increased risk for NCDs later in life. Lastly, overweight and obesity are increasingly found to be underlying causes of NCDs.
The consequences of the double burden of malnutrition is a very interesting topic in itself that will be discussed in our next blog post!
