A report by the Centers for Disease Control and Prevention (CDC) finds that overall, the U.S. population has good levels of folate, vitamin A, and D, but some groups need to add more vitamin D rich foods, iodine, and iron to their diets.
The Second National Report on Biochemical indicators of Diet and Nutrition was released today. The Division of Laboratory Sciences at the National Center for Environmental health conducted lab analyses from 58 biochemical indicators for participants in the CDC’s National Health and Nutrition Examination Survey. The data covers the years 1999 through 2006, with emphasis on the last three years.
The report measures six nutrient biochemical indicators:
- Water-soluble vitamins, such as the B complex and vitamin C.
- Fat-soluble vitamins and nutrients, such as vitamins A and D.
- Trace elements, such as iodine and iron.
- Isoflavones and lignans, which are phytochemicals.
- Vitamin B6, or pyridoxine.
- Vitamin C.
- Fatty acids such as linoleic acid.
- Iron status.
These reports are used to help policy makers make decisions about the nutrition status of special population groups, and assess the effectiveness of public health efforts. They are also used to generate hypotheses for future nutrition studies.
The Risks of Dietary Deficiencies
There are some dietary deficiencies that are well studied, such as lack of vitamin C, which causes scurvy, and lack of thiamine or vitamin B1, which causes beriberi. But less than optimal levels of nutrient intake can increase the risk of other health problems, such as cancer, heart disease, eye diseases, and osteoporosis.
Scientists are discovering new micronutrients all the time. These nutrients are not included in the Dietary Reference Intake numbers provided by the government. That’s why it’s important to consume whole foods to get the best nutrition, rather than relying on a less than optimal diet and nutritional supplements.
Study Results
Overall, the prevalence of nutritional deficiencies hasn’t changed much from the year 1999.
- Folate or folic acid.
Folate deficiency in pregnant women can cause neural-tube birth defects such as spina bifida. Folate is also a key nutrient for heart health, since it may lower homocysteine levels, and it may protect against cancer. One significant finding in the report is that folate, or vitamin B9, levels rose after the USDA mandated folic acid fortification of cereal grain products in 1998. Folate deficiency among the general public is now less than 1%. In fact, after 1998 blood folate levels increased by 50% across all groups. - Vitamin D.
Vitamin D deficiency is a problem across all populations. This vitamin is critical for bone health and to protect against cancer and type 2 diabetes. It’s naturally found in only a few foods, such as egg yolks, liver, and fatty fish, and is added to milk and orange juice. The report found that non-Hispanic blacks had the highest prevalence of vitamin D deficiency, while at the same time they had better bone health, greater bone density, and fewer fractures than other ethnic groups. Further research is needed to explain this discrepancy. The levels of vitamin D in the blood decreased as age increased. - Fatty acids.
Fatty acids are essential to heart health. Human beings can manufacture all but two of these nutrients: the essential fatty acids linoleic and alpha-linolenic acid. The report found that younger adults had lower levels of fatty acids. No ethnic pattern was found. Scientists are currently studying the question of whether lowering dietary intake of saturated fatty acids reduces the risk of heart disease. - Iron.
Iron deficiency can cause anemia, problems in pregnancy, and reduced physical capacity. A new iron marker called serum soluble transferring receptor (sTfR) was used to check iron levels. The levels of sTfR increase after iron stores are depleted. The report found that Mexican-American children and non-Hispanic black women had the lowest body iron balances. The report also found that children had the highest sTfR levels, meaning the lowest iron stores. Children and women of childbearing age are at risk for iron deficiency, but men are at risk for excess iron. Excess iron can cause cirrhosis or liver cancer, as well as arrhythmia or heart failure and joint damage. - Iodine.
This trace element is a component of thyroid hormones. Iodine deficiency is the most preventable cause of mental retardation in the world. Iodine deficiency disorders also include hypothyroidism and goiter. The report found that women of childbearing age in the United States have almost insufficient iodine levels. Some salts are fortified with iodine, but that is not mandatory in the U.S. The iodine intake of the U.S. population in general is adequate, but women aged 20 to 39 have levels bordering on insufficient. - Acrylamide.
This is not a nutrient, but a chemical classified as “reasonably anticipated to be a human carcinogen”. Acrylamide is formed when starchy foods are cooked with dry heat, such as frying, grilling, or baking. The foods that form acrylamide include potato chips, snacks, crackers, and coffee. Lifelong exposure to this chemical is a concern. It’s measured as acrylamide hemoglobin adduct levels. The report found that hemoglobin adduct levels were detectable in nearly all of the blood samples. There was no consistent pattern across age, gender, or ethnic groups, but children had higher glycidamide-to-acrylamide hemoglobin adduct ratios compared to teens and adults. Further study is needed.
The CDC stressed that these findings do not indicate that people consume healthy and balanced diets. This report offers a “limited but generally favorable review of the nation’s nutrition status.”
