Rosemary Stanton: Fat facts

LAST month Dr Aseem Malhotra, a cardiology registrar, wrote an opinion article in the BMJ claiming that advice to reduce cholesterol “has, paradoxically, increased our cardiovascular risks” and “saturated fat is not the major issue for cardiovascular disease”.

In the same week, ABC’s Catalyst program weighed into the argument, with claims that the world has been misled by the demonisation of saturated fat.

Catalyst, which aired the second part of the program last week, relied on the opinion of a journalist and four US experts — a nutritionist, two cardiologists and a physician — but failed to note that three of the experts market a range of “alternative” products via their websites (www.jonnybowden.com, www.drsinatra.com, www.proteinpower.com), including diet “aids” (with “slimming” claims), anti-ageing, “brain power” and detox supplements, plus a variety of bars, shakes, drinks and powders. One product even claims its citrus bergamot content will lower triglycerides, blood sugar and inflammatory LDL (low-density lipoprotein) cholesterol and raise HDL (high-density lipoprotein) cholesterol.

On the topic of saturated fat, both the BMJ article and Catalyst attack the published reports of Ancel Keys’ Seven Countries studies (12 000 men; 16 populations) on dietary patterns and coronary heart disease begun in the 1960s.

These and other studies reported a strong correlation between intake of saturated fat and serum cholesterol, which led to official guidelines recommending lean meats and low fat dairy products and fewer fried foods, cakes, biscuits and fatty snacks. Food companies responded by developing and marketing a range of fat-reduced products, such as cookies (often giant-sized), desserts, yoghurts, sweet and savoury snacks and confectionery. Most replaced some of the fat with sugar or highly refined starches.

In the US, intake of fat did not fall, but because the extra sugar and starch pushed energy intake up by 7% in men and 22% in women, the percentage of energy from fat fell slightly as the population grew fatter.

The Australian Dietary Guidelines have always specifically recommended limits to sugar and salt. Swapping one source of kilojoules (saturated fatty acids) for another (sugars and starches) is not likely to produce any great health breakthrough!

Malhotra quotes a couple of studies claiming total cholesterol is not a risk factor in a healthy population. Many other studies have found the opposite. A recent systematic Cochrane review concluded that reducing dietary saturated fat lowered the risk of cardiovascular events by 14% among more than 65 000 participants of whom 4585 had a cardiovascular event over a 2-year period. Benefits occurred in men but not in women. Such results are not dramatic, but they do not support Malhotra’s claim that “advice to remove saturated fat has increased our cardiovascular risks”.

In fact, it would not be possible to “remove” saturated fat since some is found in any food that contains fat. The real problem is that trying to reduce or calculate saturated fat intake suffers from a lack of specificity.

Foods contain a mixture of saturated, monounsaturated and polyunsaturated fatty acids. They also differ in many other nutritionally important ways. For example, a tablespoon of lard, 35 g of cheddar cheese, 35 g of white chocolate, a small 145 g piece of rump steak or 70 g of potato crisps all contain the same amount of saturated fat.

Monounsaturated fats are the dominant fats in foods as diverse as eggs, almonds, chicken nuggets, liquorice, peanut brittle and rolled oats.

With polyunsaturated fats, there is a need (often ignored) to distinguish between foods containing omega 3 and omega 6 polyunsaturates. Delve into the omega 3s and you find different actions of those from plants such as walnuts, canola and chia seeds and the longer chain omega 3s in seafood. The omega 6s also keep different company when liquid oils are made into spreads. Remember too that early studies about polyunsaturated fats related to spreads containing large quantities of the trans fat, elaidic acid.

Simply tallying the amount of any type of fat consumed is a totally inadequate way to judge any diet. Such issues influenced the NHMRC to seek evidence and give advice about foods rather than individual nutrients (www.eatforhealth.gov.au). It has also led to studies and evidence backing Mediterranean-style or healthy Japanese eating patterns — both shown to be healthy over many years and recommended by Ancel Keys.

And that’s the message to pass on to patients.
 

Dr Rosemary Stanton OAM is a leading Australian nutritionist.