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Dietary supplements and heart health

From co-enzyme Q10 to plant sterols, can dietary supplements benefit your heart health? We explore the evidence.


Dietary supplements are taken along with food to boost intake of a particular substance, like a vitamin or mineral. They can be a pill, tablet, powder or liquid.

Some dietary supplements are advertised in a way that seems like they're good for your heart. But they're expensive to buy and there is not much evidence of how effective they really are.

If you're thinking about taking a dietary supplement to manage your cholesterol, blood pressure or risk of a heart attack or stroke, talk to your doctor first. It's important to ask them about:

  • how safe the supplement is
  • any effects it could have on medication you take
  • any side effects.

Types of supplements

There are lots of dietary supplements available at pharmacies, supermarkets and health stores. Some supplements contain a single ingredient however many contain a combination of ingredients (like fish oil and vitamin D). Often, they say they can improve your heart health.

Dietary supplements may be recommended in some situations. However, unless a health professional has recommended a specific supplement and dosage for you, we recommend eating a variety of heart-healthy foods to help look after your heart instead.

Plant sterols

There are low levels of plant sterols in fruits, vegetables, nuts, and cereals. Some foods like margarine have plant sterols added to them and you can also buy them as supplements.

Supplement names

Plant sterols are also known as plant phytosterols.


Eating foods that contain plant sterols as part of a balanced diet can help to reduce 'bad' cholesterol. Eating 2 grams of plant sterols everyday can help to lower cholesterol by around 9%1. If you've been prescribed medication to lower your cholesterol, like a statin, it's important that you continue to take your medication alongside taking plant sterols.

Eating foods with plant sterols added, or taking a supplement is only effective if you do it regularly.

Plant sterols may be best for people trying to lower their cholesterol. They should be taken as part of a heart-healthy diet with healthy fats, whole grains, vegetables, fruit, legumes, nuts and seeds.

Side effects

Plant sterols are generally safe for most healthy people.

If you have a health condition, talk to your doctor to see whether plant sterols are safe for you2.

Fish oil

Oily fish like mackerel, sardines and salmon are high in healthy fats called omega-3 fatty acids.

A fish oil supplement may be recommended if you don't eat enough/any fish and seafood, or if you don't get enough omega-3 fats from plant foods like chia seeds and walnuts.

A heart-healthy diet that includes two to three portions of fish (including oily fish) each week will give your body the omega-3 that it needs. You also get the benefits of protein and many other heart-healthy nutrients.


Fish oil is also known as omega-3. You may see the two most common types of omega-3 on the label: Docosahexaenoic acid (DHA) or Eicosapentaenoic acid (EPA).


There is a wide variety in the type and dosage of omega-3 supplements available. Some fish oil supplements may also contain a lot less omega-3 than what is claimed on the label3.

There is some evidence to suggest that eating more fish oil slightly lowers your risk of coronary heart disease4.

There is good evidence to show that a fish oil supplement (containing EPA and DHA) reduces triglycerides by about 15%4. This is good because triglycerides are a type of fat in your blood and having high triglyceride levels increases your risk of heart attack and stroke. The recommended level of triglyceride in your blood is less than 1.7mmol/L.

There's new evidence that a high dose fish oil supplement may benefit people with heart disease who take cholesterol lowering medication. A study has shown a 25% reduction in cardiovascular events, like a heart attack, when participants took the supplement twice daily when compared to a group who didn't5. However more research is needed before we can know if this is accurate.

Side effects

People taking blood thinning medications or anticoagulants such as aspirin or warfarin need to check with their doctor before taking fish oil supplements.

If you take fish oil supplements you may need to be careful about the food you eat. This is because taking a fish oil supplement, and regularly eating oily fish, could mean you get too much omega-3, which can have a blood thinning effect when taken in high doses.

Co-enzyme Q10

Coenzyme Q10 (CoQ10) is an antioxidant made by the body. It can also be bought as a supplement. Some studies show that heart disease is connected to a not having enough CoQ10. But it's hard to tell whether CoQ10 deficiency is the cause or result of heart disease.


Coenzyme Q10 is also known as CoQ10, vitamin Q10, Ubiquinone, and Ubidecarenone.


There's no evidence to show that CoQ10 lowers cholesterol and blood pressure6,7. Some evidence suggests that CoQ10 may be helpful for patients with heart failure but more research is needed8.

There is evidence that CoQ10 may help with the muscle-symptoms like muscle weakness, tiredness, and cramps that people can get from taking cholesterol-lowering medication, known as statins9.

Side effects

CoQ10 supplements seem to be generally safe. Side effects may include:

  • an upset stomach
  • headaches
  • feeling or being sick
  • a rash10.

Red yeast rice

Red yeast rice extract is grown on rice. It contains a natural version of a statin called lovastatin11. Statins are prescribed to lower the lipid levels and manage the level of cholesterol in your blood.

Red yeast rice supplements may help to lower 'bad' cholesterol. But how safe they are, and the side effects of the supplements is unknown. Most red yeast rice supplements also contain other ingredients. There is not much information about how these ingredients interact with each other and what side effects they may cause12.


Red yeast rice is also known as Monascus pupureas.

Side effects

Check with your doctor before taking this supplement. Lovastatin can cause muscle problems (known as myalgia), leading to your kidneys not working as well as they should. The risk of myalgia increases if you also take other medicines like itraconazole, ketoconazole, and other statins11.

Taking supplements

If you're thinking about taking a dietary supplement remember...

  • An overall heart-healthy diet with plenty of plant-based foods like vegetables, fruit, whole grains, legumes, nuts and seeds alongside fish and seafood will help look after your heart.
  • Dietary supplements are expensive. You may get more of a benefit from spending the money on heart-healthy foods like oily fish or nuts and seeds.
  • Not all supplements are safe. If you’re unsure about the safety of a supplement, talk to your doctor, pharmacist, or dietitian.
  • Dietary supplements may cause side effects, allergic reactions, or interact with other medications or supplements you might be taking. 
  • The way dietary supplements are made may not be standardised. Because of this, how well they work or any side effects they cause may differ among brands, or even within the same brand. 
  • The supplement you buy in health food stores or supermarkets may not be the same as the type used in research.

Read more about complementary therapies

7 foods to lower cholesterol

Lily Henderson, NZRD

Lily Henderson, NZRD

National Nutrition Advisor

I am passionate about improving the health of all Kiwis from young through to old. I have enjoyed working in nutrition in the UK, Australia and New Zealand.


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  2. Food Standards Australia and New Zealand (2016). Increased concentration of Plant Sterols in Breakfast Cereals. Supporting document 1 Risk assessment – Application A1134.
  3. Albert B et al (2015). Fish oil supplements in New Zealand are highly oxidised and do not meet label content of n-3 PUFA. Scientific Reports Journal; 5, 7928.
  4. Abdelhamid AS et al (2020). Omega‐3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database of Systematic Reviews, Issue 3.
  5. Bhatt DL et al (2019). Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia. New England Journal of Medicine. 3;380(1):11-22.
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