Throughout my career, I’ve seen many fads and crazy ideas, usually perpetuated by someone selling something. Some crazy theories also gain traction through ‘influencers’ while many people claim they ignore nutrition advice because experts ‘are always changing their advice’.
What amazes me is how much of what we were emphasising in the 1960s hasn’t changed. For example, we’re still trying to get Australians to eat more vegetables, more fruit, more wholegrains, more legumes and more dietary fibre. No change in that since the 1960s. We’ve also been urging people to go easy on junk foods and drinks – a tougher call these days because of the explosion of products!
The major changes in my 58 years as a nutritionist are the number of food products available and the way we shop. In the 1960s, most Australians had access to 600-800 foods, many only available in season. You worked out what you wanted and went to the shops, usually on foot, with a list and a basket. The modern one-stop supermarket now stocks around 30,000 of the 50-60,000 products the food industry has developed. You walk in, choose what grabs your eye from the vast array, fill a huge trolley and take bags of foods home in your car.
Sweetness and saltiness dominate the flavour profile. Many highly profitable processed products have as little ‘real’ food as possible, bulked up with sugars, starches, fats and various ingredients that you’d never find in any home kitchen. Check the ingredient list and nutrition information panel on food labels.
As research into human nutrition and modern health problems has expanded, there have been some refinements in our advice.
Eggs
One example concerns eggs. Egg yolk contains cholesterol and many people are confused about it. Cholesterol is a waxy fat that is part of all animal cells and plays a role in making some hormones. We need some cholesterol, but we don’t need to get it from foods because the body can easily make its own from certain types of saturated fats. Unfortunately, a diet rich in these saturated fats can increase blood cholesterol to unhealthy levels. Genetic factors mean that some people make too much cholesterol and this leads to fatty deposits building up in the arteries and dramatically increasing the risk of heart attacks.
So where do eggs fit in? When we developed Australia’s first Dietary Guidelines, we didn’t find evidence that modest consumption of eggs was a significant problem for most people. That meant our initial Guidelines (in 1981) and all subsequent revisions have simply included eggs in the food group that also features lean meats, poultry, fish, legumes, nuts and seeds.
However, the National Heart Foundation noted that Australians commonly combined eggs with sausages or fatty bacon – both sources of undesirable fatty acids – so they recommended restricting eggs.
At that time, blood tests usually only recorded the total level of cholesterol in the blood. Over the years, it became apparent that cholesterol in the blood exists in different forms and blood tests began to measure high density lipoprotein (HDL) and low density lipoprotein (LDL). LDL is the most dangerous – and the most common problem. Research is continuing on how beneficial HDL is, although it doesn’t undo the problems caused by high LDL.
Studies found that eggs consumed as part of a healthy diet and without lots of saturated fat had less effect on LDL cholesterol, so the Heart Foundation updated its recommendation for healthy people. For those with diabetes or high LDL cholesterol levels, they recommended limiting eggs to not more than 7 a week.
Fats
The topic of fats is another area where changes have occurred. Some fats are ‘good’ (in moderation); others are ‘bad’.
Trans fatty acids are particularly hazardous. Small quantities are found in meat and dairy products but most come when plant oils are hardened to a form that provides long shelf life and gives a crisp texture to snacks, biscuits and fried foods.
This process was previously used in making margarine spreads but complaints from nutritionists and the World Health Organisation forced companies to make changes. Major fast food companies also changed the way they processed fats, although many fast food products still contain way too many undesirable types of saturated fat. Researchers have found that some foods and a few spreads sold in outback stores still contain these fats. Without proper labelling, they’re ‘invisible’. Unfortunately, Australia only requires trans fat to be declared on a food label if the product has a nutrition claim about cholesterol, polyunsaturated, monounsaturated, or omega 3, omega 6 or omega 9 fatty acids. Along with many colleagues, I continue to lobby for better labelling.
‘Good’ fats contain unsaturated fatty acids. These include a small amount of omega 6 polyunsaturated fats and a particularly valuable type known as omega 3s. Small amounts of the latter are found in lamb but the major sources are seafood, linseeds, canola, hemp and some varieties of seaweed. Soy beans and walnuts also contribute some. Unfortunately, omega 3 fatty acids will oxidise and go ‘off’ rapidly. If that occurs with fish and other seafood, the nose provides an excellent warning. Seafood consumed fresh, frozen or canned is an excellent source of valuable omega 3 fatty acids.
Linseeds are rich in omega 3s, but as soon as the protective coating is removed, the fats oxidise and form compounds harmful to health. This happens so quickly that we don’t recommend linseed oil as a food. (Its rapid oxidation, however, makes it ideal to use in paints and coatings for timber.) It’s also important to eat linseeds whole as they go off rapidly when ground. Eaten as brown seeds, linseeds stick to the large intestine and feed ‘good’ bacteria.
Fresh canola oil is a healthy product, but it has a short shelf life and many people don’t detect when oxidation sets in (gives it a faint, almost fishy, smell). At that stage, throw it out. Mixing small amounts of fresh canola oil with butter in refrigerated spreads is safe.
Seaweeds are an exciting potential future source of omega 3 fats – and also an excellent source of many nutrients, especially iodine, as well as having some interesting antioxidants. (A topic for another column.)
Research about saturated fats has also shown that the food matrix surrounding them influences their effect. With dairy products, the fat in milk, yoghurt and cheese has different effects from butter. Same fat, different matrix. Again, a topic for a future column.
Unhealthy foods and drinks
In this area, the advice hasn’t changed, although the vast expansion of unhealthy foods is now a massive problem. Banning them won’t help, but keeping them for feasts, parties and special occasions would make a massive difference to the national girth. Sigh!
