Important findings from nutrition research in the last few years has turned 20 years of dietary advice for heart disease and weight loss on its head. The new findings have been difficult to digest by many who are have been trained to think a certain way – that carbohydrate is GOOD and saturated fat is BAD. In this blog post, I hope to dispel some of the outdated recommendations for heart disease that are still very common and discuss some recent guidelines that are backed up by strong research and being endorsed by health organisations around the world as we speak.
The latest evidence from a Meta Analysis (1) tells us that the risks for coronary heart disease associated with saturated fat and carbohydrate are the same. In other words, if you take carbohydrate (for eg. rice) and exchange half the calories for saturated fat (for eg. as in cake), there is no detriment or benefit. This isn’t saying that cake is better than we thought; it’s that rice is worse.
In fact, it is particularly challenging to accept based on the evidence that high GI carbohydrate may actually lead to greater coronary risk than saturated fat. (2)
This is not to say that saturated fat is not a problematic nutrient. It most definitely is. What needs to happen is that saturated fat in the diet should be replaced by unsaturated fats, not carbohydrate. Unsaturated fats, especially polyunsaturated fats, have been shown in numerous studies to lower LDL cholesterol and increase HDL. As a consequence, healthy diets should be moderate in fat, not low in fat.
But how do we know which carbohydrate foods to cut out and which to keep?
Not all carbohydrates are created equal. Two things that will affect the quality of carbohydrates are its GI and its nutrient density. Low GI carbohydrates are digested slowly and released slowly into the blood stream allowing insulin to do its work steadily. High GI foods (where the carbohydrate is broken down very quickly causing a huge spike in the bloodstream) will require large amounts of insulin to clear up. It is therefore best to choose low GI carbohydrates are whenever possible.
Another factor that will determine which carbohydrates we need to choose is its nutrient density. Nutrient density is important because at the end of the day, the fundamental nutritional role of food is to provide the body with essential nutrients.
Both nutrient density and glycaemic index are important criteria to determine whether or not the carbohydrate is a ‘good’ one. Both of these were used in a new model published a few months ago in the journal of Nutrition and dietetics to assess the quality of carbohydrate-rich foods. (For detailed information on the new model and recommendations, please go here: http://scepticalnutritionist.com.au/?p=369)
The model brought to light some surprising issues while confirming some familiar trends. To simplify the results, I separated them into two distinct groups, those of high quality and those of poor quality.
Carbohydrate foods of high nutritional quality – have more often
- Legumes (eg. kidney beans, soya beans, baked beans, split peas)
- Milk (skim milk better than full fat or flavoured milk)
- Yoghurts (low fat yoghurt better than the full fat alternatives)
- Vegetables (carrots, peas were better than starchy vegetables like potato)
- Fruits (top rated fruits include orange, nectarine, mango, banana and peach)
- Cereals like All bran, special K and sustain
Carbohydrate foods with very poor nutritional quality – have only sometimes/in small amounts
- White rice
- Sugary drinks (cordial, soft drinks, even apple juice!)
- Chocolate (like mars and snickers)
So how will this new model translate into how we eat on a day to day basis? It really comes down to these guidelines:
1) Decrease saturated fat intake.
Ways to do this include choosing reduced fat dairy like skim and low fat milk. When cooking meats, make sure you trim the fat. Replace butter with soft, plant based margarines.
2) Decrease carbohydrate intake
Cut out the unnecessary carbs found in the limit list. They have very poor nutrition and are simply empty calories. If you are someone who has a lot of rice, choose the rice variety with the lowest GI, basmati rice, and have LESS of it. 1/2 – 1 cup of cooked rice is plenty.
3) Replace what you have cut back on by having more unsaturated fats.
Add unsaturated oils (such as canola, sun flower or olive oil) when cooking. Add olive oil to salads and when baking or roasting. Have a small handful of nuts everyday. Choose more fish, especially fatty fish like salmon and tuna. For a good list of unsaturated fats, go here:
Do keep in mind that the goal is to REPLACE the saturated fats with the unsaturated, not to go overboard on oils.
In conclusion, strong evidence suggests that such a diet that is MODERATE in fat, LOW in carbohydrate, and moderate-high in protein would assist in improving your lipid profile, preventing chronic diseases like CHD and diabetes, assist in good sugar control and no doubt an ideal way to go for weight loss.
1) Mozaffarian D. Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials.
2) Jakobsen MU et al. Intake of carbohydrates compared with intake of saturated fatty acids and risk of myocardial infarction: importance of the glycemic index. Am J Clin Nutr. 2010 Jun;91(6):1764-8.)