Midttun and colleagues have quantified baseline blood vitamin levels for several populations using standard methods. These measures provide a useful tool to guide medical practice, make recommendations for vitamin intake and determine disease risk.
Blood vitamin concentrations are frequently used to assess health status, but there are no clear standards for optimum blood vitamin concentrations. Studies that determine blood vitamin concentrations are often performed in different labs using different methods, so they are not comparable. Vitamin deficiencies can be detrimental to health and are linked to the risk of cancer and other diseases, and so it is important to have adequate standards.
Midttun and colleagues published a paper in the American Journal of Clinical Nutrition in which they assessed blood concentrations for vitamin B-2 (riboflavin), vitamin D (phosphate), vitamin B-9 (folate), vitamin B-12, vitamin A (retinol), and vitamin E in individuals from the United States, Norway, Sweden, Finland, Australia, China, and Singapore. The researchers used blood samples collected between 1974 and 2010 from 5314 healthy participants, along with information on smoking status and multivitamin supplement use. Blood vitamin levels were measured using several types of mass spectrometry, a method which measures the weight of purified chemical substances. The researchers also used microbiological methods to measure the levels of folate and B-12 specifically.
Individuals from the United States and Australia had the highest B-vitamin levels whereas individuals from Norway, Sweden, Finland, and Australia had the highest levels of fat-soluble vitamins (vitamins A, D, and E). Individuals from the United States also had the highest levels of folate and riboflavin. Individuals with high vitamin intake from multivitamin supplements or fortified foods tended to have higher blood levels of all vitamins compared to individuals who did not take multivitamin supplements. About 16.1% of the sample was deficient in vitamin B-6 and 9.1% was deficient in vitamin D, although this proportion varied by population. Cultural practices such as avoiding sun exposure may be responsible for low vitamin D levels in Asian regions in particular.
These results will be useful for developing baseline expectations of blood vitamin levels in different populations and for making recommendations for supplementation. However, the use of multivitamin supplements by individuals from outside of the United States is not well-recorded, and the use of single vitamin supplements is not recorded for the majority of the individuals. These kinds of supplementation may confound some of the results. Further, although some populations were not exposed to fortified foods or drinking water, others were. The samples were collected over a long time period, complicating this problem.
Written By: C.I. Villamil