On the weekend a story by lawyer David Gillespie was published in several newspapers promoting his new book titled ‘Toxic Oil’. I’ve also tracked down an extract from his book on the internet. Mr Gillespie’s theme is that the consumption of vegetable oils, especially oils rich in omega 6, is killing us.There are so many errors and misleading statements in these short extracts that I can’t say I am looking forward to reading the full book. Here is a taste.
Gillespie says: … the amount of omega 6 oil we consume has exploded … our average polyunsaturated fat intake is currently … 11 per cent of our total calorie intake – more than double what it was in 1996.
This is just plain wrong. Intake of polyunsaturated fat in Australia has never been anywhere near as high as 11 percent of daily calories and rather than ‘exploding’ it has been declining for three decades.
The evidence on this issue is available to all in the two National Nutrition Surveys in 1983 and 1995, two CSIRO surveys and the 2007 Children’s Nutrition and Physical Activity Survey. The overall picture is one of a steady decline in polyunsaturated fat intake from 1983 until the present. Page 17 of the latest survey report shows children’s intake of polyunsaturated fats to be just 4 percent of total calorie intake across both genders and all age groups, about a third of that claimed by Mr Gillespie. Children’s intake of polyunsaturated fat is little different from the mean intake of men and women of 4.5 percent of daily calories observed in the last survey of adults in 1995.
Where did Mr Gillespie get his figures from?
Gillespie says: Just 200 years ago, barely any of these diseases [diabetes, dementia, obesity, cancer and heart disease] existed …These diseases have raced from obscurity to epidemic proportions during a period when our health authorities have told us to replace animal fats with seed oil.
What Mr Gillespie fails to mention is that 200 years ago life expectancy was about 40 years of age and there was little opportunity for these chronic diseases to develop. The dietary change that so concerns Mr Gillespie has been associated with a doubling of life expectancy to over 80 years of age, but of course this is due to many factors. As the human body doesn’t last forever, old age is associated with increased risk for chronic disease.
Gillespie says: Vegetable’ oil makes you exceedingly vulnerable to cancer. Every mouthful of vegetable oil you consume takes you one step closer to a deadly (and irreversible) outcome.
Mr Gillespie had to go back to a study published in 1969 in order to find support for this tired old argument. He cites the Los Angeles Veterans Trial which was intended to test whether replacing dietary saturated fat with polyunsaturated fat would lower the risk for heart disease. Mr Gillespie states that “… there was a dramatic difference in cancer deaths between the two…” which he attributes to an adverse effect of omega 6 fats from seed oils.
Actually, there was no statistically significant difference in cancer deaths between the intervention and control groups in this study. And when the results of five similar studies, including the Los Angeles Veterans Trial, were combined again there was no statistically significant increase in cancer risk associated with high omega 6 intake.
Mr Gillespie then goes on to quote the findings of a cohort study that found higher breast cancer risk associated with the consumption of polyunsaturated fats. But that’s just one study. There have been many cohort studies into dietary fat and breast cancer and a pooled analysis of seven of the best studies was conducted in the mid-1990s. And the results? There was no suggestion that polyunsaturated fat increased the risk for breast cancer.
No recognised cancer authority anywhere in the world recommends the restriction of polyunsaturated fat for the prevention of cancer, not the Cancer Council, not the World Cancer Research Fund, no-one.
Gillespie on saturated fat, polyunsaturated fat and heart disease risk
Although Mr Gillespie rails against omega 6 fats he appears to be rather partial to saturated animal fats. He questions the accepted wisdom that replacing saturated fats in the diet with polyunsaturated fats lowers the risk for coronary heart disease, citing the ‘French Paradox’ and the ‘Israeli Paradox’ which contradict the argument. This is primitive scientific evidence.
The advice to replace saturated fats with polyunsaturated fats comes from consistent sets of evidence from different types of studies, including a meta-analysis of diet/blood lipid trials, a pooled analysis of 11 prospective cohort studies and a meta-analysis of randomised controlled trials.
Just about every authoritative nutrition organisation in the world agrees that replacing saturated fat with polyunsaturated fat lowers heart disease risk, including the World Health Organisation, the National Health & Medical Research Council (latest Australian Dietary Guidelines), the Heart Foundation, the Baker-IDI Heart and Diabetes Institute, the CSIRO, the American Heart Association and the Dietary Guidelines for Americans.
Gillespie says: I am a lawyer and the only relevant skill I bring to the table is an ability to gather, understand and synthesise evidence… Just like law, science should be all about the evidence.
Public health nutrition recommendations stand or fall on their evidence base. All of the above organisations carefully scrutinise scientific evidence and weave it into dietary recommendations. Their reputations rest on the quality of advice they provide.
What they don’t do is cherry-pick, selectively unearth old studies with atypical results, present these findings as amazing new insights and ignore more recent, better conducted studies that resolved key nutrition debates years ago.
Gillespie says: More recent research is starting to suggest that polyunsaturated fats and in particular the omega-6 fats in seed oils also lie behind the accelerating incidence of … macular degeneration
Two major studies into diet and macular degeneration have been conducted in Australia – the Melbourne Collaborative Cohort Study and the Blue Mountains Eye Study. The findings of both studies were similar:
• Neither study found that total polyunsaturated fat intake affected risk, or that butter or margarine consumption affected risk.
• In both studies it appeared that omega 3 fats from fish offered some protection.
In the Blue Mountains Eye Study the authors explored the idea that omega 6 fats may interfere with the beneficial action of omega 3 fats from fish. However, the statistical test for an interaction between the two was not significant.
Gillespie says: … trans fats are just the tip of the iceberg.
Part of Mr Gillespie’s concern about seed oils appears to be based on the misconception that all oils with high polyunsaturated fat content need to undergo hydrogenation and are therefore full of trans fats. He states “Because canola oil has fewer polyunsaturated fats than soybean oil, it doesn’t require as much hydrogenation and has about half the trans fats of soybean oil.” The truth is that canola oil and soybean oil on the supermarket shelves do not ‘require’ hydrogenation at all and neither contains appreciable amounts of trans fats.
Trans fat intakes are low in Australia and seed oils are certainly not the major source. The meat and dairy fats that Mr Gillespie appears to support contribute about three-quarters of the trans fat in the Australian diet.
Gillespie says: If you do what I suggest, you will be doing all the wrong things, according to our health authorities. You’ll be eating butter, drinking full-fat milk, chomping through bacon and eggs for breakfast and enjoying a meat pie for lunch.
Need I say more?
What Mr Gillespie doesn’t mention
In demonising polyunsaturated fats Mr Gillespie fails to mention one salient point: polyunsaturated fats are the only fats that are essential nutrients for humans. Although the body can make monounsaturated and saturated fats it must get polyunsaturated fats from food. The idea that the only essential fats in the diet are the ones that make us sick defies logic and commonsense, let alone the weight of scientific evidence.
Mr Gillespie has presented an alarmist thesis based on inaccurate data, unsound assumptions and rehashed theories from yesteryear. No authoritative nutrition organisation agrees with him.