The CDC's Division of Laboratory Sciences in the National Center for Environmental Health collected data from participants in CDC's National Health and Nutrition Examination Survey, by taking blood and urine samples. The data covers the years 1999-2006, with a focus on more recent figures from 2003 to 2006. Although the report is positive, it points out that it doesn't mean people are eating balanced and healthy diets.
As Christopher Portier, Ph.D., director of CDC's National Center for Environmental Health clarifies :
"These findings are a snapshot of our nation's overall nutrition status ... Measurements of blood and urine levels of these nutrients are critical because they show us whether the sum of nutrient intakes from foods and vitamin supplements is too low, too high, or sufficient."
As far as deficiencies go, the report makes note that problems vary according to age, gender and ethnicity, and gives an example of vitamin D deficiency that can be higher than thirty percent for non Hispanic blacks.
In all, the CDC's Second Nutrition Report collected information from blood and urine reference levels for 58 biochemical indicators. This was more than double the number of indicators used in its first report, published in 2008. It was the first-time data for iron deficiency was collected, and 24 healthy and unhealthy fatty acids were also looked at.
Folic Acid / Folate
There is good news in regards to folate, part of the vitamin B group, that is also responsible for iron absorption. A campaign that some people probably remember, was begun in 1998 to increase folate levels, that are particularly recommended for women of childbearing age. Low folate levels can lead to anemia. Breakfast cereal manufacturers have especially made a marketing issue from enriching their products with folate or vitamin B9 as it's also known. The vitamin is rich in foods such as broccoli, peas and Brussel sprouts, also in meat, eggs and dairy foods.
Since folate enrichment began in 1998, deficiency levels have dropped to less than one percent, while folate blood levels in all ethnic groups are now 50% higher. Before enrichment began, more than 12 percent of women of childbearing age were deficient in the vitamin. Folate is particularly important during growth periods where cells are dividing rapidly, such as during childhood or pregnancy. Folate (also known as Folic acid) has been shown to prevent birth defects, including problems with the babies spine and brain, including spina bifida. Whilst there is some concern that elevating folate levels may serve to mask vitamin B12 deficiency, it's clearly a good thing if the general population, especially potential mothers, have good level of the vitamin.
Vitamin D which is essential for good bone development, was seen to have the highest deficiency in non Hispanic blacks. Vitamin D is derived by the body in part by sunlight contact on the skin, so those with a darker complexion may need more supplements. However, it's not clear why only non Hispanic blacks show the greatest problems. Mexican-Americans had a 12 percent deficiency while non-Hispanic whites came in at only three percent.
Vitamin D has also been shown to protect against cancer and type 2 diabetes, as well as improve muscle strength.
Iodine levels were not seen as particularly encouraging, especially in younger women aged 20 to 39 years. This entire group had levels only marginally above deficient. The young women group had the lowest levels amongst women overall. Iodine is important because it provides the raw materials for hormones made by the thyroid that regulate growth and development. Iodine deficiency can cause mental retardation, hypothyroidism, goiter, cretinism, and varying degrees of other growth and developmental abnormalities. The breast tissue has a similar system for iodine absorption as the thyroid, thus competes for available iodine, and this is seen as part of the reason that pubertal girls tend of show deficiencies in the mineral at a rate some six times higher than boys of the same age.
For the first time, the report included details on Iron levels. Iron deficiency rates were higher in Mexican-American children 1 to 5 years (11 percent) and in non-Hispanic black (16 percent) and Mexican-American women (13 percent) of childbearing age (12 to 49 years), when compared to other race/ethnic groups. The new iron marker measurements will help scientists better interpret iron status in individuals, especially in persons with chronic disease that include inflammation, as well as certain cancers.
The report provides first-time data on blood levels of fatty acids in the U.S. population. These include heart healthy polyunsaturated fatty acids, as well as saturated fatty acids, that increase risk of heart disease. The report found heart healthy polyunsaturated fatty acid levels in plasma differ by race/ethnicity. These first-time measurements provide a baseline that will allow CDC to track fatty acid levels over time, which will evaluate our nation's progress toward heart healthy diets.
The CDC championed its report as a detailed biochemical assessment of the nutrition status of the US population. They say that the series of reports provide information specific to population groups defined by age, gender, and race/ethnicity to show how these factors affect nutrition status in the United States. The agency also says that it plans further analysis of the data to identify socio-economic trends, as well as lifestyle factors that might affect blood and urine vitamin and mineral levels. They also plan to continue their assessment of the nation's nutritional wellbeing in future reports.
More information is available on the
Written by Rupert Shepherd