World Health Day is a time when - as a nutritionist - I think about the links between nutrition and infection.
Current estimates suggest that 30 percent of global child mortality is directly or indirectly linked to malnutrition.
This is because infection and malnutrition are linked in a cyclical manner: malnutrition decreases immune function and increases risk of infection (e.g. vitamin A deficiency increases risk of diarrhea and respiratory tract infections) - while infection increases nutritional requirements and the risk of becoming malnourished (e.g. the malaria parasite destroys red blood cells and can result in iron deficiencies).
In poor communities that don't have clean drinking water, virtually every child can be infected with intestinal parasites and suffer from diarrhea, increasing their likelihood of being anemic and stunted.
Change in land use and forest cover has also been linked to changes in rates of malaria. In the Peruvian Amazon, areas high in deforestation had an eight times higher rate of mosquito bites than in sites with less deforestation.
This is because human-altered landscapes where water can pool (road ditches, mining pits, and areas of poor clearing) provide a fertile breeding ground for malaria-carrying mosquitoes. A study from Brazil showed that a 4.3 percent change in forest cover was associated with an almost 50 percent higher incidence of malaria.
Forests and trees are also an essential source of fuelwood. A paper by CIFOR staff explores how fuelwood scarcity may pose multiple risks to women's health: smoke from less-preferred fuelwood species can pose greater risks to respiratory track health. Also, women have less time to procure and prepare healthy food when they have to travel further to find fuelwood.
On the food security and nutrition side of the equation, wild foods obtained from forests and farmland with tree cover (such as fallows and agroforests) most often include fruits, vegetables and bushmeat: good sources of vitamin A and iron.
In Tanzania we found that children who had consumed wild foods from the forest had more diverse and nutritious diets.
Although wild foods contributed only two percent of the children's total calorie intake, they accounted for over 30 percent of vitamin A and almost 20 percent of iron that children had consumed per day (Powell et al. in press).
Bush meat plays an important role in diets of many people living in rural areas of developing countries. Bush meat is not only important as a source of protein, but also because it is a good source of iron and other micronutrients essential for health, growth and development (iron from meat is better absorbed than iron from plants).
A recent study from Madagascar found that without access to bushmeat, approximately 30 percent more children would suffer from anemia.
It is clear that we cannot overcome global malnutrition and micronutrient deficiencies without combined improvements to diet and reductions in infection rates.
This year, World Health Day focuses on high blood pressure, a disease that is strongly associated with diet and body weight. Forests may be able to help with high blood pressure too.
New work at CIFOR is currently looking at the role of forests in ensuring access to and consumption of adequate amounts of fruits and vegetables.
Increasing fruit and vegetable consumption not only improves intake of certain micronutrients such as vitamin A, but has also been associated with reduced blood pressure. Look for our new work on forests for food security and nutrition coming out soon!
CIFOR's research on forests and nutrition is part of the CGIAR Program on Forests, Trees and Agroforestry and is supported by the UK Department for International Development (DFID) and The Austrian Development Agency.