General Health - The nutrition status of the nation and folic acid fortification of food
The most recent National Diet and Nutrition Survey (NDNS) has just been published. It is funded by the Department of Health and is carried out by a consortium of three organisations; the National Centre for Social Research (NatCen), MRC Human Nutrition Research (HNR) and the University College London Medical School.
The survey covers all four countries of the UK and is designed to be representative of the nutritional status of the UK population. This latest survey was carried out between February 2008 and June 2009 and involved 1,131 participants aged from 1.5 years upwards. It is based on a four-day food survey and, in each case, included two weekend days. This is important to note, as intake of food can change at the weekends, with typically more alcohol and takeaways being consumed on Fridays and Saturdays. Sunday provided a higher meat and vegetable intake for all age groups, most likely due to Sunday lunch. Vitamin and mineral levels are taken from food only and do not include any supplements. They are measured against the UK Reference Nutrient Intake.
The key findings of the survey include(1)
Consumption of cereals, which includes pasta, rice and pizza, is higher than seen previously.
White bread is still the major type of bread consumed by adults.
Consumption of meat is up.
Intake of saturated fat, trans fats and sugar is still too high at 12.8% and 12.5% of energy intake respectively instead of the recommended 11%.
Two-thirds of men and women are still not getting their ‘five a day’.
Fibre intake is low, with most people averaging 14g a day, with the recommended level being 18g.
Consumption of oily fish remains below the recommended one portion per week.
Iron intakes are low, particulary among teenage girls and women.
Intake of minerals particularly iron, magnesium, potassium and selenium fell below the RNI for 11 to 18 year olds.
Zinc, calcium and iodine fell below the RNI in girls aged between 11 and 18 years old.
Selenium levels fell below the RNI in older children and adults.
These results show that, although slightly better than in previous years, there are still many causes for concern in our nation’s eating habits and nutritional status.
The poor state of our nation’s health again brings up the thorny issue of food fortification. The Food Standards Agency is certainly considering mandatory fortification of bread or flour with folic acid to reduce the incidence of neural tube defects(2). The Scientific Advisory Committee on Nutrition (SACN), an independent scientific committee that advises the Government on nutrition, estimated that there are between 700 and 900 pregnancies affected by neural tube defects each year in the UK and are recommending fortification to reduce these numbers. Recent research has also highlighted the importance of B vitamins for brain function(3), and given the results of the latest NDNS, the answer to our nation’s poor nutritional status, could be the fortification of foods?
In the past, food fortification has been extremely successful in reducing nutritional deficiencies, such as iodide, to prevent goiter, and thiamine, to prevent beriberi(4), but today, the Government faces different problems when considering fortification. Deficiencies are now often limited to a subset of the population and the appropriate dosage of the nutrient needs to be found, so it that is effective and not toxic. Large dosages of certain nutrients may cause harm, e.g. vitamin A and perhaps folic acid.
After the United States and Canada began fortification with folic acid in 1996 and 1997, respectively, their incidences of colorectal cancers have been significantly increasing year by year(5), leading researchers to suggest that folic acid supplementation may lead to colorectal neoplasia(6), which has since meant new guidelines on folic acid supplementation being issued. In a recent study undertaken in Chile, it was suggested that there had been an increase in colorectal cancer rates since the country began fortifying wheat flour with folic acid in the year 2000(7). It would appear that reported cases of colon cancer increased by 162% in people aged 45 to 64 and by 190% in people aged 65 to 79. However, it should be remembered that B12 deficiency may be masked and exaggerated by folic acid supplementation. This has been a criticism of single-nutrient fortification for decades. Recent data from the US National Health and Nutrition Examination Survey indicates that the function of B12 deteriorates as serum folate status increases in people who are deficient in B12. People with low B12 and high folate concentrations are also at particularly high risk of memory impairment and anaemia(8).
In a study entitled Is folic acid good for everyone?, published in a 2008 issue of the American Journal of Clinical Nutrition, researchers noted that high blood concentrations of folic acid may be related to decreased natural killer cell cytotoxicity and reduced response to antifolate drugs used against malaria, rheumatoid arthritis, psoriasis and cancer. In the elderly, a combination of high folate levels and low vitamin B12 status may be associated with an increased risk of cognitive impairment and anaemia and, in pregnant women, with an increased risk of insulin resistance and obesity in their children. The team also commented that folate has a dual effect on cancer, protecting against cancer initiation but facilitating progression and growth of preneoplastic cells and subclinical cancers, which are common in the population. The researchers therefore conclude that fortification could be harmful for some people(9).
Food fortification is not a simple answer. It does not take into consideration the needs and variability of the population, and it takes no account of the complex interactions between nutrients, or even the well-recognised relationship of folate and B12. There is also a concern that if people think their white bread is giving them all the nutrients they need, where is the incentive to seek out a healthy diet, or even recognise that they need balanced nutrition?
Many supplement companies, in light of this research, have taken the decision to reduce the amount of folic acid in everyday supplements, such as multivitamins and minerals, but still provide it in specific combinations for people who will benefit, such as pregnant women and those wishing to support brain and heart function, which allows an appropriate supplement programme to be formulated with individual needs in mind.
1. Food Standards Agency. National Diet and Nutrition Survey. [Online]. Available at: http://www.food.gov.uk/science/dietarysurveys/ndnsdocuments.
2. Food Standards Agency. Folic acid fortification. [Online]. Available at: http://www.food.gov.uk/healthiereating/folicfortification.
3. PlosOne. Homocysteine-Lowering by B Vitamins Slows the Rate of Accelerated Brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial [Online]. Available at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.001224. [Accessed 21st September 2010].
4. Refsum H and Smith AD. Are we ready for mandatory fortification with vitamin B12? American Journal of Clinical Nutrition (2008) 88(2):253-254.
5. Mason JB, Dickstein A, Jacques PF, Haggarty P, Selhub J, Dallal G et al. A temporal association between folic acid fortification and an increase in colorectal cancer rates may be illuminating important biological principles: a hypothesis. Journal of American Cancer Epidemiology Biomarkers and Prevention. (2007) Jul;16(7):1325-9.
6. Cole BF, Baron JA, Sandler RS, Haile RW, Ahnen DJ, Bresalier RS et al. Folic acid for the prevention of colorectal adenomas: a randomized clinical trial: Journal of the American Medical Association (2007) 297:2351-2359.
7. European Journal of Gastroenterology & Hepatology. Folic Acid Fortification May Be Linked To Increased Colon Cancer Risk [Online]. Available at; www.medicalnewstoday.com.
8. Morris MS, Jacques PF, Rosenberg IH and Selhub J. Folate and vitamin B12 status in relation to anemia macrocytosis and cognitive impairment in older Americans in the age of folic acid fortification. American Journal of Clinical Nutrition (2007) 85(1): 193-200.
9. Smith AD, Kim YI, Refsum H. Is folic acid good for everyone? American Journal of Clinical Nutrition (2008) Mar;87(3):517-33.