NZ Herald article: Switch that sandwich filling (from butter to margarine)

This article was published in the New Zealand Herald today. Here is my very quick response

Switch that sandwich filling: study

“Replacing the cheese in New Zealanders’ sandwiches with sesame seed paste could help to cut the nation’s rate of heart disease by 10 per cent, a new analysis indicates.”

The Otago University researchers calculate, based on overseas studies involving more than 300,000 people, that a one-in-10 reduction in New Zealand’s high rate of heart attacks and related heart disease could be achieved by replacing some of the bad fat in our diet with good fat.

But simply decreasing the bad fat was not linked to reduced rates of heart attack or stroke in the US and European research.

Many of our favoured foods – such as butter, cream, cheese, bacon, fatty lamb chops, coconut cream and potato crisps – are high in saturated fat. It can boost the amount of bad cholesterol in the blood, which can harm the arteries supplying oxygen to the heart muscle.

Conversely foods rich in poly-unsaturated fat can reduce the level of bad cholesterol in the blood and also have other beneficial effects on health. Good sources include sunflower, safflower and canola oils, walnuts, sesame seeds, fresh salmon, and tuna canned in oil. Some margarines are good sources too, but also contain a significant amount of saturated fat.”

Of note a quote from a sister article in Stuff, Fat tax would add $1 to butter, showing how tenuous this association is:

“While the meta-analyses used in the study found benefits from replacing saturated fats with polyunsaturated fats, they did not find any significant association between saturated fat intake alone and cardiovascular disease. Replacing saturated fat with carbohydrates also did not reduce the risk of coronary events.

-It is useful to note here that polyunsaturated fat is linked with reduced cholesterol, this does not mean that polyunsaturated fat reduces the risk of heart disease. The Israeli Jews who have a very high consumption of the fats we are recommended to eat paradoxically have a high rate of heart disease Diet and disease–the Israeli paradox: possible dangers of a high omega-6 polyunsaturated fatty acid diet.

The abstract:

“Israel has one of the highest dietary polyunsaturated/saturated fat ratios in the world; the consumption of omega-6 polyunsaturated fatty acids (PUFA) is about 8% higher than in the USA, and 10-12% higher than in most European countries. In fact, Israeli Jews may be regarded as a population-based dietary experiment of the effect of a high omega-6 PUFA diet, a diet that until recently was widely recommended. Despite such national habits, there is paradoxically a high prevalence of cardiovascular diseases, hypertension, non-insulin-dependent diabetes mellitus and obesity-all diseases that are associated with hyperinsulinemia (HI) and insulin resistance (IR), and grouped together as the insulin resistance syndrome or syndrome X. There is also an increased cancer incidence and mortality rate, especially in women, compared with western countries. Studies suggest that high omega-6 linoleic acid consumption might aggravate HI and IR, in addition to being a substrate for lipid peroxidation and free radical formation. Thus, rather than being beneficial, high omega-6 PUFA diets may have some long-term side effects, within the cluster of hyperinsulinemia, atherosclerosis and tumorigenesis.”

-Many of the studies may not distinguish between Omega 6 polyunsaturated fat and Omega 3 saturated fat (clinically shown to reduce the risk of heart disease)

-Many of the studies used in the meta-analyis may be flawed, for example when a study from Sydney was re-evaluated using missing data and modern analysis techniques, the reverse was true:

“Study raises questions about dietary fats and heart disease guidance” http://group.bmj.com/group/media/latest-news/study-raises-questions-about-dietary-fats-and-heart-disease-guidance

 Excerpts:

 “The results show that the omega-6 linoleic acid group had a higher risk of death from all causes, as well as from cardiovascular disease and coronary heart disease, compared with the control group.

The authors then used the new data to update an earlier meta-analysis (a review of all the evidence). This also showed no evidence of benefit, and suggested a possible increased risk of cardiovascular disease, emphasizing the need to rethink mechanisms linking diet to heart disease.

The researchers conclude that recovery of these missing data “has filled a critical gap in the published literature archive” and that these findings “could have important implications for worldwide dietary advice to substitute omega-6 linoleic acid (or polyunsaturated fatty acids in general) for saturated fatty acids.”

In an accompanying editorial, Professor Philip Calder from the University of Southampton says the new analysis of these old data “provides important information about the impact of high intakes of omega 6 PUFAs, in particular linoleic acid, on cardiovascular mortality at a time when there is considerable debate on this question.”

Calder says the findings argue against the “saturated fat bad, omega 6 PUFA good” dogma and suggest that the American Heart Association guidelines on omega-6 PUFAs may be misguided. They also “underscore the need to properly align dietary advice and recommendations with the scientific evidence base.””

On the other hand refined carbohydrates appear to pose a greater risk for heart disease (I personally think a sugar tax is far more appropriate – unlike fat which has nutrients beyond the pure fat content, like vit A, E and K in butter – sugar is devoid of any nutrients and does not add anything but harm to our diet) “Are refined carbohydrates worse than saturated fat?”

http://ajcn.nutrition.org/content/91/6/1541.full :

“In this era of widespread obesity and insulin resistance, the time has come to shift the focus of the diet-heart paradigm away from restricted fat intake and toward reduced consumption of refined carbohydrates.”