Your health is what you eat: the role of nutrition in health

This Thought for Food from Professor and researcher in Health Economics at the University of Sao Paulo, Flavia Mori Sarti, focuses on the importance of healthy diets based on regular intake of fruit and vegetables to maintain health and prevent the onset of noncommunicable diseases (NCDs), alongside the potential impacts on health care costs.

In recent decades, advances in nutrition research have been showing the role of diet in promoting health and preventing diseases. A balanced food consumption pattern that includes diverse types of staples, fruits, vegetables, and protein sources provides the energy, macro- and micronutrients to support healthy lifestyles. The consumption of other bioactive compounds may also help prevent certain chronic NCDs such as type 2 diabetes, dyslipidemias, and cardiovascular diseases.

However, the food consumption patterns of many populations around the world have been changing away from more traditional patterns towards modern diets marked by excessive intake of industrialized foods with high content of sugar, trans-fats and salt. The nutrition transition refers to the process of substitution of foods in natura with industrialized foods in different populations. This is often accompanied by a decrease in physical activities during transport, work and leisure, and an increase in sedentary activities.

The importance of consuming fruits and vegetables

Agriculture remains one of the most important economic activities, generating employment and income for billions of individuals worldwide. There are approximately 250,000 edible plant species known; however, only around 120 species are cultivated for human consumption. In addition, 12 plants and five animal species are responsible for approximately 75% of world food. Yet, plant food sources represent the main source of energy and nutrients, and are the sole contributors to fiber intake in the human diet.

Many health authorities recommend food consumption patterns with increased consumption of fresh fruits and vegetables to ensure sufficient intake of fiber, micronutrients, trace elements and bioactive compounds, also known as phytochemicals.

Dietary guidelines referring to the daily intake of fresh fruits and vegetables seek to promote the supply of nutrients through healthy diets, optimizing body functions and maintaining an individual’s health. Considering variations in cultural habits, several countries and regions publish and update national dietary guidelines based on current nutrition knowledge adapted for their populations (for example, Australia, Brazil, European Union, India, Japan, New Zealand, and the United States).

Nutritional deficiencies, such as a lack of specific vitamins and minerals found at high concentrations in plants, may be prevented through inclusion of diverse fruits and vegetables in daily meals. There is significant evidence that the high consumption of fiber reduces cholesterol and reduces the risk of cardiovascular diseases, diabetes and certain types of cancer. In addition, research on the numerous bioactive compounds that have been identified in plant foods show their contribution to the reduction of risk of NCDs in diverse population groups.

However, not all fruits and vegetables are of equal benefit. The 5-a-day mantra, adopted by authorities in many countries to increase fruit and vegetable consumption, can give the impression that all forms of fruit and vegetables deliver equally positive health consequences. While increased fruit and vegetable consumption is linked to multiple positive health outcomes, it is important to acknowledge the varied nutritional contents of these foods.

For example, there has been much debate on whether fruit juices should count towards achieving intake targets. While fruit juices contain many important micronutrients, they are also a source of sugar while lacking fiber. In developed nations, dietary fruit and vegetable variety is poor, with starchy vegetables making a disproportionately high contribution to vegetable intakes. These foods deliver a high energy intake with low nutrient diversity compared to other vegetables, such as leafy greens. The most desirable increases in fruit and vegetable consumption would be those that deliver high concentrations of micronutrients and fiber without contributing to macronutrient excesses.

Diet-health nexus for reduction of health care costs

Although there is substantial evidence on the protective effects of healthy diets, the consumption of diverse fruits and vegetables in daily diets is usually lower than recommendations in many countries.

The World Health Organization recommendation regarding consumption of fruits and vegetables is to include at least 400 grams per capita per day in the diet. However, according to data from the Food and Agriculture Organization (FAO), only 101 out of 174 countries had sufficient food supply to achieve this recommendation in 2018. Accounting for food waste (approximately 15% to 30% of food supply, depending on the country), the proportion of countries that fulfill the WHO recommendation reduces to approximately 60 out of 174 countries.

On the other hand, 169 out of 174 countries had a food energy supply greater than 2,000 calories per capita per day. Even accounting for food waste, approximately 120 countries still provide excess daily calories for adult individuals with sedentary lifestyles.

Therefore, modern lifestyles lead to a higher prevalence of obesity and related morbidities in many countries. The recent Global Burden of Disease Study 2019 indicated the greatest recorded increase in populations’ exposure to obesity and diabetes was between 1990 and 2019, among other risk factors for early mortality linked with modifiable behaviors. Simultaneously, the low diversity in food consumption patterns provide low intakes of micronutrients and bioactive compounds, characterizing the double burden of diseases, marked by coexistence of undernutrition and obesity related to NCD.

In Brazil, direct costs due to outpatient and inpatient care for treatment of 14 overweight- and obesity-related diseases has been estimated to total US$ 2.1 billion per year between 2008 and 2010. Other estimates pointed to expenditures of approximately 3.45 billion reais (US$ 908 million), attributable to outpatient, inpatient and medication for treatment of hypertension, diabetes and obesity on the national health system in 2018.

A systematic review of literature showed estimates of substantial direct health care costs of obesity and related diseases in 17 studies from developed countries and 6 studies from developing countries. They found that the medical costs associated with obesity and its knock-on effects had been increasing across both the developed and developing world. A previous review indicated that obesity was responsible for approximately 0.7% to 2.8% national health care expenditures in developed and developing countries worldwide. Additionally, individuals diagnosed with obesity usually presented costs 30% higher in comparison with healthy weight individuals due to occurrence of obesity-related NCD.

Conclusion

The reversion of negative nutrition transition trends worldwide depends on changes at individual, social, and policy level: these include gradual modifications of dietary patterns towards greater inclusion of nutrient-dense fruits and vegetables; increased physical activity levels, particularly during transportation and leisure; regulation of food marketing directed at children; adoption of nutrition education strategies; and health promotion actions within primary health care.

The cost-effectiveness of numerous strategies targeting obesity among children, adolescents and adults was assessed through economic evaluation studies in Australia, showing higher effectiveness of actions focusing on lifestyle changes among younger individuals, especially tackling consumption of industrialized foods and beverages, promoting physical activity and encouraging regular consumption of nutritious foods. Primary health care strategies addressing healthy lifestyles through family-based visits and surgical interventions showed reasonable cost-effectiveness.

Besides reducing costs in national health systems, incremental changes in diet associated with adjustments in physical activity level may prevent the onset of diverse NCD and reduce early mortality in different population groups worldwide, thus prolonging healthy life years and maintaining quality of life of individuals. In sum, following dietary guidelines will be a win-win situation for individuals and governments.

The Thought for Food was written by Flavia Mori Sarti, professor and researcher in Health Economics from the University of Sao Paulo, Brazil.

Glossary

Photo courtesy of Flavia Mori Sarti.