Nutritional Supplements and Cardiovascular Health

Do dietary supplements marketed for the promotion of cardiovascular health protect against heart disease?

Cardiovascular disease (CVD) is considered to be the leading cause of death in the United States. The most prevalent form of CVD in the United States is coronary heart disease, which often manifests as myocardial infarction.¹ In 2009, an estimated 785,000 Americans had a new coronary attack, of whom about 470,000 will have a recurrent attack. It is also estimated that every 25 seconds an American will have a coronary event, and that approximately 1 individual every minute will die from a coronary event.^1,2

Currently, there are a host of nutritional supplements marketed for the promotion of cardiovascular health and protection against CVD. The most common ingredients marketed for promotion of cardiovascular health include omega fatty acids, plant sterols, coenzyme Q10 (CoQ10), and garlic.

Omega Fatty Acids

A variety of available dietary supplements available specifically formulated for cardiovascular health contain omega-3 fatty acids alone or in conjunction with omega- 6 fatty acids. Omega-6 and omega-3 fatty acids (found in fattier fish such as tuna, mackerel, and salmon), are polyunsaturated fatty acids (PUFAs) and may have health benefits when consumed in the recommended amounts, especially when used to replace saturated fats or trans fats in the diet.³ Omega-6 and omega-3 PUFAs play a crucial role in heart and brain function and in normal growth and development.³ PUFAs are essential fats that the body needs but cannot produce, so they must be obtained through dietary means or supplements.³

The preferred option is the consumption of omega-3 fatty acids through dietary means. Many patients may elect to use omega-3 dietary supplements, however, due to their convenience or an individual’s inability to consume enough omega-3 fatty acids through diet alone. Patients with existing medical conditions and those taking any medications should always discuss the use of these supplements with their primary health care provider prior to use.

Common adverse effects associated with the use of omega-3 supplements include acid reflux/heartburn/indigestion, nausea, diarrhea, and increased burping. ^4-6 Gastrointestinal side effects can be minimized if fish oils are taken with meals and if doses are started low and gradually increased.^4-6

Various drug interactions have been associated with the use of omega-3 supplements, including aspirin, anticoagulants, antiplatelet agents, and some herbal supplements. ^4-6 In addition, caution should be exercised by patients with diabetes, because these supplements may slightly lower blood glucose.^4-6 Furthermore, pharmacists should remind patients that ingesting more than 3 g of omega-3 fatty acids in supplement form should be done only under a physician’s care, because high intake may result in excessive bleeding or worsen heart rhythm in individuals with arrhythmias.^2,5,6 Patients should be reminded that prolonged use of fish oil supplements may also cause vitamin E deficiency. For this reason, vitamin E is added to many fish oil products.⁴

Plant Sterol Products

Studies have investigated the benefits of plant sterols (phytosterols), naturally occurring plant-based ingredients that have been proved to lower low-density lipoprotein (LDL) cholesterol levels, thus possibly decreasing the risk of CVD.^7-9 Some common plant sterols include beta sitosterol, campesterol, and stigmasterol. ^8,9 Sitostanol, which is a saturated derivative of sitosterol, is the most common plant stanol.⁸ Plant sterols and stanols are chemically related and structurally similar to cholesterol. They have been shown to decrease total and LDL cholesterol by decreasing both dietary and biliary cholesterol absorption via the displacement of cholesterol from the micelles, thus resulting in a decreased solubility of cholesterol in the intestine.^8,10 Plant sterols are often added to margarine spread products and are available in a few supplements.

Although there have been few adverse effects reported regarding either the short-term or long-term consumption of plant stanol/sterol ester—containing fats, there has been some concern regarding decreased levels of plasma alpha plus beta carotene, a-tocopherol, and/or lycopene due to the consumption of foods containing both stanol esters and sterol esters.¹¹ Further investigation is needed to establish the long-term safety of recommended doses of stanols and sterols.^8,11

Coenzyme Q10

CoQ10 is found in every human cell, with the greatest concentrations in the mitochondria of the heart, liver, pancreas, and kidneys.⁶ It has been used in various supplements as a treatment for cardiovascular conditions such as heart failure, cardiomyopathy, and hypertension. ⁶ Dosages range from 100 mg to 200 mg daily.

The most common adverse effects of CoQ10 include nausea, gastrointestinal distress, anorexia, headache, dizziness, and irritability.^6,12 Patients taking warfarin should discuss the use of these supplements with their health care provider prior to using them, because the structure of CoQ10 is similar to the synthetic form of vitamin K (menaquinone) and may possess some procoagulant effects comparable with vitamin K.⁶ CoQ10 may also interact with some chemotherapeutic agents and certain antihypertensive agents.¹² The use of CoQ10 is also contraindicated in both pregnant and lactating women due to lack of clinical information regarding the safety of its use in these patient populations.⁶

CoQ10 supplements have become a popular treatment for managing the adverse effects, such as myopathy, of statin drugs.¹³ In general, CoQ10 is well tolerated and no serious adverse effects have been reported.¹³ More research is needed to determine whether CoQ10 is useful and effective for the treatment and prevention of statin myopathy.^6,13

Garlic

Garlic supplements have been used for the treatment of hyperlipidemia, hypertension, and other medical conditions, such as type 2 diabetes, as well as for the prevention of various cancers.⁶ Results from both animal studies and in vitro studies report that garlic possesses hypotensive, hypolipidemic, and antiplatelet properties.⁶

The most common adverse effects include nausea, vomiting, and heartburn and these adverse effects occur mostly at high doses. Body odor and halitosis are common complaints among consumers using these supplements, but odorless formulations are available. Due to antithrombotic effects, these supplements should be discontinued for at least 7 to 10 days before having any surgical procedure.⁶ Because of potential bleeding risks, patients taking warfarin, other platelet-active agents, or ginkgo supplements should be advised to consult their primary health care provider prior to using garlic supplements.⁶

Studies have reported that the use of garlic supplements may also decrease the concentrations of the agent saquinavir by an estimated 50%; therefore, the use of garlic supplements and certain agents, such as those to treat HIV, should typically be avoided.⁶ Some research shows that garlic can reduce blood pressure in individuals with hypertension by as much as 7% or 8%.14 Other studies report promising, modest, short-term effects of garlic supplements on lipid and antithrombotic factors, but more research is needed.^6,9

Conclusion

Prior to taking any of these supplements, patients, especially those currently taking medications for other medical conditions, should check with their primary health care providers to ascertain the appropriateness of using these products to avoid possible contraindications or drug interactions.

Patients should be advised that these products are not to be used as a replacement for prescription antihyperlipidemic agents. Patients with hyperlipidemia or those with risk factors for CVD should be encouraged to consult their primary health care providers for medical evaluation and treatment. Patients should also be reminded that a healthy diet and lifestyle that includes exercise and lifestyle modifications (eg, low-fat, low-cholesterol, high-fiber diet; smoking cessation; limited use of alcohol) are the best defense against CVD. There is no substitute for a healthy diet and lifestyle. PT

Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.