If your job was to sell products rich in saturated fat, current nutrition guidelines and policies would be a real impediment. So what would you do?
In the 1980s, human rights lawyer Geoffrey Robertson became a media personality hosting a television series dealing with ‘Hypotheticals’. He would outline a hypothetical situation and then invite prominent citizens to play imagined roles of the key players addressing various aspects of the situation, thereby exposing the various interests at play.
Let’s play ‘Hypotheticals’. I’ll be the moderator. You can play the role of the food company Chief Executive, Public Relations Guru or Ethicist.
As governments struggle to address the rising prevalence of obesity and other chronic diseases there have been increasing calls for taxation on selected foods as a means of improving the quality of national diets. Last year Denmark introduced the world’s first ‘fat tax’, but in an abrupt turnaround the much maligned tax has been repealed. What went wrong?
Targeted taxation of foods
The rationale for targeted taxation of foods to improve health draws on the fundamental economic principle that the demand for any good is related to its price. If the price goes up, the demand goes down, and vice versa. Hence the demand for goods is said to be ‘elastic’. Viewed through this prism, addressing diet-related chronic disease becomes straightforward – use the tax system to increase the price of junk foods and lower the price of healthier foods. Too easy.
Following consultation with stakeholders, the draft Australian Dietary Guidelines have been further refined, with some improvements in relation to cereal fibre, trans fats and added sugar. Even the mess around saturated fats has been tidied up a bit, but is it enough?
The first post on The Sceptical Nutritionist highlighted several problems with the draft Australian Dietary Guidelines and these have been discussed in detail in recent months. Encouragingly, some of the issues appear to have been addressed during the consultation period. The clues come in a draft appendix to the Australian Dietary Guidelines that was recently released for consultation, which includes the latest version of the key Dietary Guidelines statements.
More emphasis on cereal fibre
There is now greater emphasis on cereal fibre. The previous statement that recommended cereal foods should be ‘mostly wholegrains’ has been changed to ‘mostly wholegrain and/or high cereal fibre varieties’. This is consistent with the science as many of the studies used to support the wholegrains recommendation used high fibre foods, suggesting that recommending high fibre cereal foods was equally valid.
An important new dietary trial has produced challenging results. And there is more to come.
A decade ago two similar studies were undertaken in Finland and the United States to test whether type 2 diabetes could be prevented by diet and lifestyle. In both studies, overweight subjects with pre-diabetes were placed on low fat, weight reduction diets and exercise programs. Amazingly, the results of the two studies were exactly the same: the interventions lowered the incidence of diabetes by 58% over three years. The key drivers of the benefit were considered to be weight loss and increased physical activity.
One issue that these trials did not explore in any depth was the role of diet quality in diabetes prevention i.e. was the ‘low fat’ aspect of the diets relevant? The recent results of the PREDIMED trial provide some tantalising insights.
A current affairs program broadcast last week posed the question: ‘Is low fat milk unhealthy?’ And then followed up with ‘For more than two decades we’ve been encouraged to go low fat or even no fat when it comes to milk, but stunning new results may change all that.’ Really? What are these stunning new results?
Whenever new scientific findings are announced via current affairs programs on television my scepticism antennae start to twitch. It’s a safe assumption that a public relations firm has been engaged to push the story through to the general public. Let’s look at the science behind it.
The trigger for the program was a review published in the European Journal of Nutrition exploring possible links between the consumption of high fat dairy foods and risk for cardiovascular disease and obesity. This is one of a series of reviews of epidemiological evidence relating to dairy foods published over the last few years.
Trans fats are bad news for heart health but what should we do about them? Should we give them top billing in the new Dietary Guidelines, demand trans fats be declared in nutrition information panels on food labels, or regulate them in some other way? Hang on … haven’t we already dealt with trans fats?
All fats in our diet are made of substances called fatty acids. Although there are hundreds of them, fatty acids can be grouped into three broad classes – saturated, monounsaturated and polyunsaturated. By far the majority of mono- and polyunsaturated fatty acids have a characteristic ‘bent’ shape, which the scientists call cis. However, a small proportion of unsaturated fatty acids are ‘straight’ and this trans shape gives them different physical properties, more like saturated fats. Fats with a high proportion of trans fats (or saturated fats) tend to be solid, not liquid like oils rich in cis fatty acids.
High fat, calorie-rich foods have long been thought to be fattening and policymakers continue to recommend their restriction in order to prevent obesity. However, scientific support for this advice has fallen away. The latest research suggests that identifying foods that promote future weight gain is much more challenging than previously thought, with carbohydrate quality playing a central role.
Traditional dietary advice for preventing obesity has revolved around eating less calorie-rich food. In the 1980s and 1990s the best way of achieving this was thought to be by limiting total fat intake and this became the core strategy for the prevention of obesity. It made good sense as gram-for-gram fat contains more calories that protein or carbohydrate – lower fat foods are lower calorie foods. By the turn of the century, dietary advice for obesity prevention evolved to limiting intake of ‘energy dense’ (calorie dense) foods. This was a small change in emphasis as the key drivers of energy density are fat and water content.
Lowering the fat content or energy density of the diet as a means of preventing obesity makes so much sense to nutritionists and dietitians that it is seldom challenged but the unfortunate reality is that these recommendations can no longer be supported scientifically.
Limiting saturated fat intake has been recommended for decades as a way of lowering the risk for coronary heart disease. However, this recommendation needs to be revised following recent findings that saturated fat and carbohydrate confer the same risk for heart disease. Now the best advice is to replace saturated fat with unsaturated fat.
In the beginning: the Seven Countries Study
The Seven Countries Study shaped the thinking of a generation of nutritionists. In this famous study the diets in fifteen cohorts of subjects in seven countries were examined and the risk for various diseases was estimated over time. The most compelling finding was the positive association between dietary saturated fat and the risk for coronary heart disease – the lower the intake of saturated fat, the lower the risk for heart disease.