Vitamin D is sometimes called the ‘sunshine vitamin’ because people produce it when their skin is exposed to sunlight. Despite this natural source, an estimated one billion people worldwide have vitamin D deficiency or insufficiency; this leads to weakened bones and may contribute to several other health problems.
People among all ethnic groups and all ages are affected. To address this health concern, vitamin D can be added to foods during production in a process called fortification.
Vitamin D Deficiencies In Various Populations
Vitamin D is essential for bone health because it helps people absorb calcium. With consistent vitamin D deficiency, children might develop rickets. This is characterised by soft and weak bones that cause fractures and deformities.
Vitamin D deficiency in adults contributes to osteoporosis, which is marked by weak and brittle bones. This often leads to broken bones, most commonly of the wrist, spine, and hip. Women of Caucasian and Asian descent are more prone to osteoporosis than other ethnic groups, according to the International Osteoporosis Foundation.
Research has also shown that vitamin D may improve muscle strength and reduce inflammation. It may also fight heart disease, high blood pressure, and cancer.
Reports of vitamin D deficiency and its consequences in Asia include the following:
- Preterm birth: A study of 1,103 women in northeast China found that severe preterm births were associated with maternal vitamin D deficiency. Similarly, a meta-analysis of 10 observational studies, which included 10,098 participants, found that pregnant women with vitamin D deficiency during pregnancy have an increased risk of preterm birth.
Anaemia: Studies in Korea have noted associations between vitamin D deficiency and iron deficiency. One such study found an indirectly proportional association in healthy female children and adolescents. Another study of Korean females ages 10 years or older found that depressed vitamin D levels increase the risk of iron deficiency anaemia.
Vitamin D deficiency can occur in climates with prolonged winters where people stay indoors most of the time. But deficiency can also occur in tropical climates as well. For example, in Singapore, a study of 114 participants found that about 42 percent were vitamin D deficient. In India, a study of 174 women found that 84 percent were vitamin D deficient.
In hot climates, people may limit their time outside to avoid the heat, or wear protective clothing or sunscreen when they are outside. In some sunny countries, the cultural expectations are for women to be completely covered when they are outside. All of these factors prevent people from creating vitamin D from exposure to sunshine.
Meeting Daily Intake Levels
Recommendations for how much vitamin D healthy people need every day vary by country. Generally, the recommended daily intake ranges from 400 international units (IU) for infants less than six months old to 800 IU for people over age 65 years. Higher amounts may be recommended for people in high risk groups or people with vitamin D deficiency.
Very few foods, such as certain kinds of fish, contain vitamin D naturally. However, it is unlikely that people would consume enough of those foods to meet their vitamin D requirements.
Consider that 100 g of canned tuna has 236 IU of vitamin D, and one egg yolk has about 20 IU of vitamin D naturally. Consuming 800 IU of vitamin D would require eating two servings of canned tuna and 16 eggs!
Consequently, some countries add vitamin D to other commonly consumed foods. In Canada, fortifying milk and margarine with vitamin D is mandatory. In the US, food manufacturers voluntarily fortify milk and some orange juice and breakfast cereals with vitamin D, while including vitamin D in infant formula is mandatory.
A report from the US Centers for Disease Control and Prevention in 2011 showed that in 2001–2006, two-thirds of the population had sufficient vitamin D levels, about one-fourth were at risk of vitamin D inadequacy, and eight percent were vitamin D deficient.
‘Smart’ Fortification: Targeting Common Foods
A consideration for any fortification program is whether the target audience consumes the food to be fortified. Fortifying milk is likely to benefit children, but adults, who usually drink less milk than children, may need vitamin D from another source.
In this case, it may be necessary to fortify multiple foods to reach the adults who need vitamin D to prevent osteoporosis and women who need vitamin D for healthy pregnancies.
Jordan, Kuwait, Oman, and Palestine fortify wheat flour with vitamin D, according to data from the Food Fortification Initiative (FFI). Two types of vitamin D are available: D3 and D2. Quentin Johnson, FFI technical coordinator, said D3 is usually used in flour fortification. D2 is derived from plants and may be preferred by vegetarians and others who follow dietary restrictions.
In a more novel approach, a manufacturer in Canada has developed a strain of baker’s yeast which adds vitamin D to bread during the baking process.
The amount of vitamin D to use in fortified products varies based on several factors, such as how much the population consumes the food to be fortified. In the US, milk is fortified with 100 IU of vitamin D per cup (236 ml) of milk. In Canada, milk is fortified with 35–40 IU per 100 ml of milk. Margarine in Canada is fortified with 530 IU or more per 100 g.
The abovementioned four countries that fortify wheat flour with vitamin D add 0.01 parts vitamin D per million parts flour, but these countries also have much higher wheat flour consumption than is typical of Asia. Modelling programs are available to estimate how much fortification of specific foods would contribute to the population’s nutrient intake.
Rice would seem to be a logical food to fortify throughout most of Asia since it is commonly consumed. Current rice fortification efforts include iron, folic acid and several other B vitamins, but not vitamin D, said Becky Tsang, FFI technical officer for Asia. For fortified rice to be accepted by consumers, it has to be nearly identical to non-fortified rice.
Also, to have a health impact, fortified rice must retain its nutrient value even if it is washed or soaked before cooking. Therefore, before rice is fortified with vitamin D, it would require more research to verify that adding vitamin D does not change the appearance or taste of rice, and that it will be stable throughout storage and cooking.
How Fortification Improves Health
Countries usually set standards for food fortification. Standards (also referred to as regulations or standards of identifies) describe the type of nutrient to be used in fortification and the levels of inclusion.
When fortification standards are set appropriately based on people’s customary food intakes, it is highly unlikely that any nutrient will be consumed in excess. Also, mandatory fortification of specific foods will allow government food safety authorities to check for fortification during routine inspections of food manufacturers.
Fortification is used around the world to improve the nutrient intake of populations. Salt is routinely fortified with iodine, and cooking oil is commonly fortified with vitamin A.
Wheat flour, maize flour, and rice are often fortified with iron and B vitamins such as folic acid, thiamin, and niacin. Riboflavin, another B vitamin, can be added to flour but not rice because it turns fortified kernels an unacceptable colour.
The nutrients added to these foods help prevent certain devastating birth defects, childhood blindness, and debilitating anaemia. With improved nutrition, children perform better in school and are more likely to resist infections, and pregnant women are less prone to maternal death.
Also, adults are more productive, leading to greater earning potential for the individual and economic progress for the country.
The World Health Organisation (WHO) notes that fortifying staple foods is “associated with significant reductions in the incidence of deficiency-related outcomes and improvements in the health status of populations.”
Fortification is a cost-effective way to address vitamin and mineral deficiencies among a population. Nutrients such as vitamin D can be added during the routine food production process. Successfully fortified foods are delivered through established distribution processes and should not require consumers to change their eating, shopping, or cooking habits.
As more evidence emerges on the number of people with vitamin D deficiency and the associated health problems, fortifying foods with vitamin D will likely become a more common solution.