Heart health nutrition myths … BUSTED by science!

The internet is awash with mis-information on what we should and shouldn’t eat, and it's often in relation to heart health. This can be very difficult to navigate and unfortunately can often lead to unhealthy eating patterns, so here we focus on the most frequent offenders. We clarify the situation for each myth, based on the best scientific evidence available, and include practical, straight forward advice.

A low-fat diet is needed to lower cholesterol … Incorrect

We actually need fat in our diet for several important functions including a healthy immune system and good brain function. In fact, what is important is the type of fat we include rather than the proportion of total fat.

Dietary fats are not all metabolised in the body in the same way. Saturated fats, found in red and processed meats, dairy products, coconut milk and palm oil, as well as foods made from these such as cakes, biscuits and pastries, increase the amount of bad cholesterol (LDL) in the blood. This in turn increases the risk of cardiovascular diseases including chronic heart disease, stroke and vascular dementia. On the other hand, unsaturated fats, found in nuts, seeds, avocado, oily fish and cooking oils made from plants such as olive oil and rapeseed oil, have been found to decrease the blood levels of LDL and decrease the risk of cardiovascular disease.

The UK and international guidelines reflect this by recommending we limit intake of saturated fat to 10% of total energy intake which is approximately 20g for women and 30g for men, while keeping total fat intake to around a third of our total energy intake. Therefore, rather than reducing fat intake we should swap foods that are high in saturated fat for the healthier unsaturated fat. For example, instead of fatty meats like sausages or bacon opt for lean options such as chicken (with the skin removed) and fish. See lots more swap ideas for healthy fats.

(Hooper et al., 2020; Li et al., 2015; Scientific Advisory Committee on Nutrition, 2019)

Nuts are high in fat so should be avoided … Incorrect

Nuts certainly should not be avoided in your diet. In fact, the opposite is true, with the UK guidelines stating that nuts should be included as part of a healthy diet. This is based on many observational studies that show an association between eating nuts with a lower risk of cardiovascular disease, and also some intervention studies that show nut consumption actually causes LDL cholesterol reduction.

It is true that nuts have a high fat content, however most of this is the heart-healthy unsaturated fat, and some research shows that not all energy from nuts is absorbed by the body. Nuts are also a good source of micronutrients (manganese, potassium, iron, zinc, selenium, vitamin E and B vitamins) and are high in both protein and fibre, so overall a very healthy option. Walnuts are worthy of a special mention because in addition to heart health benefits, this type of nut is also one of the few good plant sources of the omega-3 fat essential in our diet for good heart and brain health.

A palm-sized portion of plain or roasted nuts make a healthy snack but try to avoid flavoured and seasoned nuts which include added oil, salt and sugar. Nuts also make a great addition to stir fries, salads and breakfast cereals.

Find recipe ideas containing nuts.

(Baer et al., 2016; Estruch et al., 2018; Guasch-Ferré et al., 2017; Ros, 2010; Schwingshackl et al., 2018)

Chocolate is a healthy option … Incorrect (sorry!)

There is certainly a lot of noise on the internet about this one, possibly because we all want chocolate to be a healthy ‘superfood’, but sadly this is not the case. It is true that cocoa seeds used to manufacture chocolate are high in antioxidants and there is some evidence that consuming high levels of these antioxidants are linked to heart health.

However most of the antioxidant content is removed during processing and very little remains in the chocolate we eat (you would get far more antioxidants from eating an apple). Chocolate is high in sugar and fat making it very calorific and far from being a healthy option. This does not mean chocolate should be excluded from a healthy diet but it is sensible to view it as a treat and eat it in moderation. One interesting study showed chocolate is more likely to improve your mood if it is eaten mindfully so the best advice for chocoholics is to have a couple of blocks of your favourite chocolate and REALLY enjoy it.

When choosing between the different types of chocolate it is worth knowing that dark chocolate made from 70% or more cocoa solids has the most antioxidant content and less sugar. Milk chocolate contains very few antioxidants and double the sugar, while white chocolate contains no cocoa solids so you will not get any antioxidant benefit from it.

Below are the calories, total fat, saturated fat, sugar and flavanol comparisons between 20g portions of different types of chocolate.

	Energy (kcals)	Saturated fat (g)	Total fat (g)	Free sugar (g)	*Antioxidant (flavanol) (mg)
Dark chocolate (60-69% cocoa) /20g	117	5.0	8.4	5.2	34
Milk chocolate/ 20g	108	3.7	6.2	11.2	14
White chocolate / 20g	107	3.7	6.5	11.1	0

*For comparison a medium sized apple contains 184mg flavanol

Eggs should be avoided … Incorrect

There is a lot of confusion around whether eggs can be part of a healthy diet, which stems from the fact that egg yolks contain cholesterol. Dietary cholesterol is found in animal foods such as whole milk dairy products, egg yolk, meats, poultry and some shellfish, and while it does raise blood cholesterol levels, its effect is usually modest.

Foods high in saturated fat have a more significant effect on blood cholesterol so it is much more important to limit the amount of saturated fat in the diet. Eggs are low in saturated fat and have many other nutritional benefits so, for the general healthy population, they can be included as part of a heart-healthy diet.

For certain groups of people however the recommendation for eggs is slightly different. For those with Familial Hypercholesterolaemia (FH), high blood cholesterol levels and those who are at high risk or have cardiovascular disease, we recommend limiting intake to 3-4 eggs a week.

For more about eggs and cholesterol

(Scientific Advisory Committee on Nutrition, 2019)

Butter is better for you than margarine … Incorrect

Butter is manufactured by churning cream and removing the butter milk and as a result it is very high in total fat and saturated fat (approximately 82% and 52% respectively). This means that one teaspoon of butter contains 4.7g saturated fat which is a large proportion of the maximum daily quantity recommended by Public Health England of 20g for women and 30g for men. It is also very calorific with one tablespoon containing 110 Kcals of energy.

Margarine, also known as fat spread, is a processed food recommended as a heart healthy alternative to butter because it is made from vegetable oils such as rapeseed, olive and sunflower oil, containing the healthier unsaturated fats. They have been vilified on the internet partially because of the way they are manufactured but also because of the incorrect thinking that saturated fat is healthy. Some spreads provide additional heart benefits as their ingredients include plant stanols and sterols which can lower LDL cholesterol if eaten in the correct quantities.

So, while butter can be enjoyed in moderation as part of a healthy balanced diet it is not true that it is better for you than margarine due to its high saturated fat content.

(Scientific Advisory Committee on Nutrition, 2019)

Coconut oil is healthy … Incorrect

Coconut oil has been hyped on the internet as a healthy option and there are even suggestions that it can aid weight loss because it contains what are known as ‘medium chain triglycerides’ (MCT). However, although studies have shown that fats made up entirely of MCT increase good cholesterol, coconut oil contains just 15% MCT which means it is unlikely to provide the same benefits. More importantly coconut oil is made up almost entirely of the unhealthy saturated fat. To be precise it contains a whopping 92% saturated fat which is more than any other edible fat, including butter which contains 52% saturated fat. As such it is likely to cause similar heart health issues as any other high saturated fat food.

Coconut oil does have a lovely flavour and is excellent in Thai style curries but it is best to use it sparingly.

(Lockyer & Stanner, 2016)

Check the source of the information

Unfortunately, there are plenty more nutrition myths around, so when scrolling through social media sites or reading the news, make sure you check out the source of the information and don’t take it seriously unless it is clearly backed by strong scientific evidence. All national guidelines are based on reviews by leading academics in the field of all relevant research, so if you are in any doubt check out Public Health England or NHS site.

References

Baer, D. J., Gebauer, S. K., & Novotny, J. A. (2016). Walnuts consumed by healthy adults provide less available energy than predicted by the atwater factors. Journal of Nutrition, 146(1), 9–13. https://doi.org/10.3945/jn.115.217372

Billingsley, H. E., & Carbone, S. (2018). The antioxidant potential of the Mediterranean diet in patients at high cardiovascular risk: An in-depth review of the PREDIMED. In Nutrition and Diabetes (Vol. 8, Issue 1). Nature Publishing Group. https://doi.org/10.1038/s41387-018-0025-1

Department of Health. (1991). Dietary reference values for food energy and nutrients in the United Kingdom. HMSO. https://doi.org/Report on Health and Social Subjects 41

Estruch, R. et al. (2018). Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. New England Journal of Medicine, 378(25), e34. https://doi.org/10.1056/NEJMoa1800389

Guasch-Ferré, M. et al. (2017). Nut Consumption and Risk of Cardiovascular Disease.

Hooper, L., Martin, N., Jimoh, O. F., Kirk, C., Foster, E., & Abdelhamid, A. S. (2020). Reduction in saturated fat intake for cardiovascular disease. Cochrane Database of Systematic Reviews, 8. https://doi.org/10.1002/14651858.CD011737.pub3

Katz, D. L., Doughty, K., & Ali, A. (2011). Cocoa and chocolate in human health and disease. In Antioxidants and Redox Signaling (Vol. 15, Issue 10, pp. 2779–2811). https://doi.org/10.1089/ars.2010.3697

Li, Y., Hruby, A., Bernstein, A. M., Ley, S. H., Rimm, E. B., Willett, W. C., & Frank, B. (2015). Saturated Fat as Compared With Unsaturated Fats and Sources of Carbohydrates in Relation to Risk of Coronary Heart Disease: A Prospective Cohort Study. J Am Coll Cardiol, 66(14), 1538–1548. https://doi.org/10.1002/geot.201400068

Lockyer, S., & Stanner, S. (2016). Coconut oil - a nutty idea? Nutrition Bulletin, 41(1), 42–54. https://doi.org/10.1111/nbu.12188

Meier, B. P., Noll, S. W., & Molokwu, O. J. (2017). The sweet life: The effect of mindful chocolate consumption on mood. Appetite, 108, 21–27. https://doi.org/10.1016/j.appet.2016.09.018

Ros, E. (2010). Health benefits of nut consumption. Nutrients, 2(7), 652–682. https://doi.org/10.3390/nu2070652

Schwingshackl, L., Hoffmann, G., Iqbal, K., Schwedhelm, C., & Boeing, H. (2018). Food groups and intermediate disease markers: A systematic review and network meta-analysis of randomized trials. In American Journal of Clinical Nutrition (Vol. 108, Issue 3, pp. 576–586). Oxford University Press. https://doi.org/10.1093/ajcn/nqy151

Scientific Advisory Committee on Nutrition. (2019). Saturated fats and health. 443. https://www.gov.uk/government/publications/saturated-fats-and-health-sacn-report

Veronese, N. et al. (2019). Is chocolate consumption associated with health outcomes? An umbrella review of systematic reviews and meta-analyses. Clinical Nutrition, 38(3), 1101–1108. https://doi.org/10.1016/j.clnu.2018.05.019