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Our heart is simply outstanding! Beating tirelessly to supply blood from the brain to the toes, we would literally be dead without the little guy. The health of the heart is so important.

We have long been told that increased intake of saturated fats is a no-no for heart health due to implications like coronary heart disease. But what about high intakes of sugar? Or the overconsumption of processed, packaged foods, so commonplace in our modern world?

Let’s take a look.

The pathogenesis of coronary heart disease

Coronary heart disease is when plaque builds up in your coronary arteries that supply blood to the heart, and correlated with high blood cholesterol. That plaque build-up is the well-known, and not-so-great, atherosclerosis.

Whilst a necessary part of the body’s defence system, inflammation that is running rampant because of dietary and lifestyle influences means bad news for heart health. In particular, the arteries can be damaged, and cholesterol is sent out to form plaques over the damaged area. However some types of cholesterol, when oxidised, contribute further to the arterial inflammation.

Of the various types of cholesterol, LDL is considered the bad cholesterol, although it is actually comprised of several forms of LDL – some worse than others. And it seems it may be the ratio of these LDL fractions that are correlated with cardiovascular issues such as blood vessel damage, as opposed to raised LDL as a whole.

Isn’t it about the fats?

Medicine has long considered high intake of saturated fat to be a contributor to increased cholesterol.7 As mentioned, high cholesterol has also been associated with the build up of arterial plaque build up, and therefore increased risk of coronary artery disease. So, low-fat eating has been promoted.

In fat’s place, the Western diet has trended toward our old mate sugar and refined, highly processed sources of carbohydrates. 1;7

The increased consumption of highly processed, shelf stable foods may be more a reflection of our super industrialised society rather than dietary recommendations.

It has been thought that to replicate the negative impact of high sugar intake on various cholesterol markers, one would need to eat 40% of daily calories as saturated fat! What?6 Granted, this stat is from decades ago. But just because it is old doesn’t mean we should completely disregard it.

Regardless, diets high in sugar have been found to increased levels of cholesterol levels, the not so helpful triglycerides, and LDL.4

On the subject of LDL, studies have shown that directly after consuming saturated fat, the nasty small-density LDL form decreases, and the helpful large LDL form increases.2 So yes, there may be an increase in LDL in the blood, but perhaps a helpful form predominates?

Science is still sorting out as to whether the large LDL form is protective, and it may be that raised LDL is not enough to suggest CHD risk.7 Whatever the impact of saturated fat, over many decades polyunsaturated fat has been seen as a preferred source of fat over saturated fats in reducing incidence of cardiovascular issues.

However, may we be focusing too much on fat in isolation? And is the replacement of higher fat intake with heavily processed foods, including excess refined sugars, the real nasty for our hearts?

Perhaps, it is the quality, source or type of saturated fat that incurs a physiological reaction seeing the body move into damage control. Perhaps the shift of a broader dietary pattern to that of more packaged foods has more of an impact than the isolated macronutrient of fat alone.

We eat food, not isolated nutrients

It is important to note that some diets high in saturated fat are high in sugar, and some sources of saturated fat can often be high sources of sugar.1

These foods are usually the junk food of an industrialised world, a pile of heavily processed, super refined ingredients.

Saturated fats are comprised of various forms of fatty acids, levels of which differ depending on the source. This can impact positive or negative health outcomes. For example, palmitate may raise LDL, but stearate and laurate can support positive total cholesterol to HDL ratio. 1;3

The issue with refined sugars is that we are consuming high amounts of the sweet stuff, but without its partners in nutritional crime, like fibre or antioxidants. This brings an abundance of oxidative stress, and inflammation. Hooray.

The results? Raised forms of detrimental cholesterol, and also increased incidence of cardio-metabolic issues, such as insulin resistance, raised uric acid, and impaired platelet function. 1

Fructose has a greater negative impact on cardio-metabolic factors than glucose. But that is often when delivered in high amounts as an isolated ingredient. It causes LDL particles to oxidise, and promotes formation of the sticky, icky, advanced glycation end products (AGE). Both are associated with formation of atherosclerosis. Not to mention the high consumption of fructose/soft drink contributing to non-alcoholic fatty liver disease, which has a powerful correlation to CHD.

Ultimately it has been found in recent years that a diet high in sugar results in a 3-fold increased risk of death by cardiovascular disease.5

Not all fats, or sugars, are created equal

Focusing on whole foods as opposed to individual nutrients will inadvertently reflect a healthy diet. Heavily processed, refined and added sugars, especially in excess, are a no-go. Similarly, we wouldn’t recommended high intake of heavily processed, refined oils, grains or any other food.

And whilst saturated fat is fine in a healthy diet, it needn’t predominate and we should enjoy other forms of fat such as monounsaturated and some polyunsaturated.

Much of what we eat can have synergistic or opposing effects on the body.

Eating the whole version of the food provides nutrients that can work together to best receive other nutrients, and it often tastes better! Think fibre and fruit slowing the release of simple sugars into the blood, or a tomato with a little olive oil that increases the absorption of fat-soluble phytonutrient lycopene. To absorb iron one needs vitamin C, therefore a common source of iron like red meat eaten with some greens will help boost absorption (and add some anti-oxidant protection to boot!).

Help your heart, and choose a diet high in whole foods and mostly plants, rather than a diet high in food from industrial plants.1

By Angela Johnson (BHSc Nut. Med.)

 

References:

  1. DiNicolantonio, JJ, Lucan, SC, & O’Keefe, JH 2016, ‘The Evidence for Saturated Fat and for Sugar Related to Coronary Heart Disease’, Progress in Cardiovascular Diseases, vol. 58, pp. 464-472.
  2. Dreon, DM, Fernstrom, HA, Campos, H, Blanche, P, Williams, PT, & Krauss, RM 1998, ‘Change in dietary saturated fat intake is correlated with change in mass of large low-density-lipoprotein particles in men’, The American Journal Of Clinical Nutrition, vol. 67, no. 5, pp. 828-836.
  3. Mensink, RP, Zock, PL, Kester, AM, & Katan, MB 2003, ‘Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials’, The American Journal Of Clinical Nutrition, vol. 77, no. 5, pp. 1146-1155.
  4. Te Morenga, LA, Howatson, AJ, Jones, RM, & Mann, J 2014, ‘Dietary sugars and cardiometabolic risk: systematic review and meta-analyses of randomized controlled trials of the effects on blood pressure and lipids’, American Journal of Clinical Nutrition, vol. 100, no. 1, pp. 65-79 15p
  5. Yang, Q, Zhang, Z, Gregg, EW, Flanders, WD, Merritt, R, & Hu, FB 2014, ‘Added sugar intake and cardiovascular diseases mortality among US adults’, JAMA Internal Medicine, vol. 174, no. 4, pp. 516-524.
  6. Yudkin, J & Comfort, A 1970, ‘Dietary Prevention Of Atherosclerosis’, The Lancet, vol 295, no. 7643, p.418
  7. Zelman, K 2011, ‘Practice Application: The Great Fat Debate: A Closer Look at the Controversy—Questioning the Validity of Age-Old Dietary Guidance’, Journal of the American Dietetic Association, vol. 111, pp. 655-658.