I well remember all the hype surrounding the publication of the NACNE (National Advisory Committee on Nutrition Education) report in the early 1980s (1). The main thrust of this was that the national diet had deteriorated to such an extent that it was responsible for the relatively high level of chronic diseases, especially heart disease and certain cancers. Particular interest was generated because of allegations that the government of the day had attempted to suppress the document. Eventually The Lancet published the report. It presented quantitative recommendations for reductions in the consumption of fat, saturated fat, sugar and salt. It also recommended an increase in the intake of dietary fibre.
Despite the reluctance on the part of government, the official COMA (Committee on Medical Aspects of Food Policy) was instructed to review the evidence and effectively confirmed the NACNE recommendations. This was then endorsed as government policy. Subsequently the main emphasis was on the fat and the saturated fat in terms of the health promotion strategies and the response by the food industries.
COMA recommended that the saturated fat intake should be reduced from 20% of food energy to 15% as part of a strategy to reduce cardiovascular disease (2). This target was reached by 2000(3). In fact the National Food Survey shows that the intake of saturated fat has fallen from 56.7 g/day in 1969 to 29.2 g/day in 2000(4). What is very clear is that the predicted improvements in public health certainly have not materialised. The incidence of obesity has continued to increase. In men it has doubled since 1993, which is when detailed information was first collected (5). Even more worrying is that since 1994 the incidence of diabetes has more than doubled for both men and women (6).
The position in the UK is mirrored in the USA. In an article in the New York Times, published earlier this year , Gary Taubes provides valuable insight into the failing of nutrition which help to explain why there are fundamental flaws in the current approach to public health nutrition(7).
Taubes points out that over 600,000 scientific papers and articles have been published on these topics in the last 50 years. So why have we made so little progress? In his assessment , which I fully support, the conventional explanation is that:
“Type 2 diabetes is caused or exacerbated by obesity, and obesity is a complex, intractable disorder. The more we learn, the more we need to know.”
He goes on to suggest another possibility, which seems eminently sensible:
“The 600,000 articles — along with several tens of thousands of diet books — are the noise generated by a dysfunctional research establishment. Because the nutrition research community has failed to establish reliable, unambiguous knowledge about the environmental triggers of obesity and diabetes, it has opened the door to a diversity of opinions on the subject, of hypotheses about cause, cure and prevention, many of which cannot be refuted by the existing evidence. Everyone has a theory. The evidence doesn’t exist to say unequivocally who’s wrong.”
The necessary high quality research into human nutrition is expensive because it is so complex and investigations have to continue for a long time, if the results are to be valid. In the real world this is usually just not feasible even in countries such as the USA, which is relatively well off. The inevitable consequence is that the vast majority of researchers have adjusted their sights by accepting a lower standard of evidence than is required to reach conclusions that are genuinely worthwhile.
This means adopting various approaches include the following:
- Using laboratory animals to do experiments and then hoping the results can be extrapolated to humans which may or may not be true
- Conducting experiments for a relatively short period (in terms of the human lifespan) on a specific group of humans and then assuming they applicable for the entire lifetime. It is also very common for results obtained with middle-aged men to be applied to men and women of all ages.
- Making observational studies to find out the relationships between a particular disease and the consumption of selected foods. Once an association is established it is often assumed to demonstrate cause and effect even though there is no direct evidence that this is actually the case. Other possibilities which include another separate cause which affects both factors may be totally ignored
This situation is completely unacceptable but it seems to be the way things are done. While it is blindingly obvious to anyone who makes an objective analysis that present policies are not working. Indeed this is part of the problem and the fact remains that they continue to be implemented. Here in the UK the government persists with its Responsibility Deal which requires that the food industry takes steps to reduce even further the amount of saturated fat which is present in the typical British diet. The fact that substantial reductions have already been achieved while public health continues to deteriorate is shrugged off because it would mean that the politicians and the leading lights in the medical and public health professions would have to admit that that the original advice was wrong.
The reality is that although researchers would justify their approaches on the grounds that this is the best they can d. This simply is not good enough. Rigorous standards are essential if research dealing with human nutrition is to have any meaning. Hopefully ways can be found to obtain the requisite funding…… perhaps a small levy on the sales of food. If not, surely it is preferable to admit that we just do not know rather than effectively guessing what policies to adopt thereby running the risk of doing more harm than good!!
REFERENCES
- Ad hoc working party of National Advisory Committee on Nutrition Education(1983) . Proposals for nutritional guidelines for health education in Britain. . London: Health Education Council.
- Department of Health and Social Security (1984) “Diet and Cardiovascular Disease” London: HMSO
- http://webarchive.nationalarchives.gov.uk/20130103014432/http://www.defra.gov.uk/statistics/files/defra-stats-family-food-nfs-nfsexcan.xls
- http://webarchive.nationalarchives.gov.uk/20130103014432/http://www.defra.gov.uk/statistics/files/defra-stats-family-food-nfs-nutshist.xls
- Health Survey of England 2010 Adult Trend Tables
- Health Survey for England 2009
- Gary Taubes (2014). http://www.nytimes.com/2014/02/09/opinion/sunday/why-nutrition-is-so-confusing.html?_r=0