In a double-blind study of patients with chronic heart failure, supplementation with the fatty acids present in fish oil for an average of four years resulted in a small but statistically significant decrease in the number of patients who died or were hospitalized for cardiovascular reasons. The treatment consisted of 850 to 882 mg per day of a mixture of eicosapentaenoic acid and docosahexaenoic acid (as their ethyl esters).¹ In another double-blind trial, supplementation with eicosapentaenoic acid and docosahexaenoic acid improved heart function and decreased the number of hospitalizations in patients with heart failure due to dilated cardiomyopathy.²

Clinical trials have shown that standardized extracts made from the leaves and flowers of hawthorn are effective in helping people with early-stage CHF.^3,4,5 Hawthorn extracts appear to increase blood flow to the heart, increase the strength of heart contractions, reduce resistance to blood flow in the extremities, and act as an antioxidant.^6,7,8 In a large preliminary trial, people with mild to moderate CHF were given 300 mg of hawthorn flower and leaf extract (standardized to contain 2.2% flavonoids) three times a day for two months.⁹ Symptoms of CHF—including heart palpitations, chest pressure, and swelling in the extremities—decreased throughout the trial during the use of hawthorn. The efficacy of hawthorn for the treatment of CHF has been confirmed in a double-blind trial.¹⁰

Hawthorn extracts are available in capsules or tablets standardized to either total flavonoid content (usually 2.2%) or oligomeric procyanidins (usually 18.75%). Doctors who work with herbal medicine often suggest 80–300 mg two to three times per day. Hawthorn berry products that are not standardized may be weaker, and the recommended amount is typically 4 to 6 grams per day for the whole herb, or 4–5 ml of the tincture three times per day.

People with CHF have insufficient oxygenation of the heart, which can damage the heart muscle. Such damage may be reduced by taking L-carnitine supplements.¹¹ L-carnitine is a natural substance made from the amino acidslysine and methionine. Levels of L-carnitine are low in people with CHF;¹² therefore, many doctors recommend that those with CHF take 500 mg of L-carnitine two to three times per day.

Most L-carnitine/CHF research has used a modified form of the supplement called propionyl-L-carnitine (PC). In one double-blind trial, people using 500 mg of PC per day had a 26% increase in exercise capacity after six months.¹³ In double-blind research, other indices of heart function have also improved after taking 1 gram of PC twice per day.¹⁴ It remains unclear whether propionyl-L-carnitine has unique advantages over L-carnitine, as limited research in animals and humans has also shown very promising effects of the more common L-carnitine.¹⁵

Magnesium deficiency frequently occurs in people with CHF, and such a deficiency may lead to heart arrhythmias. Magnesium supplements have reduced the risk of these arrhythmias.¹⁶ People with CHF are often given drugs that deplete both magnesium and potassium; a deficiency of either of these minerals may lead to an arrhythmia.¹⁷ Many doctors suggest magnesium supplements of 300 mg per day.

Taurine, an amino acid, helps increase the force and effectiveness of heart-muscle contractions. Research (some double-blind) has shown that taurine helps people with CHF.^18,19,20,21 Most doctors suggest taking 2 grams three times per day.

The body needs arginine, another amino acid, to make nitric oxide, which increases blood flow. This process is impaired in people with CHF. Arginine supplementation (5.6–12.6 grams per day) has been used successfully in double-blind trials to treat CHF.²²A double-blind trial has also found that arginine supplementation (5 grams three times daily) improves kidney function in people with CHF.²³

A small clinical trial found that supplementation with a bark extract of arjun (Terminalia arjuna) improved heart function as well as lung congestion in patients with severe CHF.²⁴ Patients in the study took 500 mg of arjun extract three times per day and began to exhibit significant improvement in heart function within two weeks; improvement continued over the course of approximately two years. The herb extract used in this study was concentrated but not standardized for any particular constituent. Commercial preparations are sometimes standardized to contain 1% arjunolic acid. Larger clinical trials are needed to confirm the results of this small study.

Berberine is used in Asia to treat congestive heart failure. In a double-blind trial, supplementation with berberine (300 to 500 mg, four times per day) for eight weeks significantly improved heart function and exercise capacity and reduced the frequency of arrhythmias in people with congestive heart failure.²⁵

As is true for several other heart conditions, coenzyme Q10 (CoQ10) has been reported to help people with congestive heart failure,^26,27 sometimes dramatically.²⁸ Positive effects have been confirmed in double-blind research²⁹ and in an overall analysis of eight controlled trials.³⁰ However, some double-blind trials have reported modest³¹ or no improvement^32,33,34 in exercise capacity or overall quality of life. Most CoQ10 research used 90–200 mg per day. The beneficial effects of CoQ10 may not be seen until after several months of treatment. In one preliminary trial, treatment with ubiquinol (the chemically reduced form of CoQ10) was beneficial for people with severe heart failure, after the standard form of CoQ10 had been ineffective.³⁵ Discontinuation of CoQ10 supplementation in people with congestive heart failure has resulted in severe relapses and should only be attempted under the supervision of a doctor.²⁶

Magnesium deficiency frequently occurs in people with CHF, and such a deficiency may lead to heart arrhythmias. Magnesium supplements have reduced the risk of these arrhythmias.³⁶ People with CHF are often given drugs that deplete both magnesium and potassium; a deficiency of either of these minerals may lead to an arrhythmia.³⁷ Many doctors suggest magnesium supplements of 300 mg per day.

Whole fruit and fruit and vegetable juice, which are high in potassium, are also recommended by some doctors. One study showed that elderly men who consumed food prepared with potassium-enriched salt (containing about half potassium chloride and half sodium chloride) had a 70% reduction in deaths due to heart failure and a significant reduction in medical costs for cardiovascular disease, when compared with men who continued to use regular salt.³⁸ While increasing potassium intake can be beneficial for heart patients, this dietary change should be discussed with a healthcare provider, because several drugs given to people with CHF may actually cause retention of potassium, making dietary potassium, even from fruit, dangerous.

Coleus contains forskolin, a substance that may help dilate blood vessels and improve the forcefulness with which the heart pumps blood.⁴¹ Recent clinical trials indicate that forskolin improves heart function in people with congestive heart failure and cardiomyopathy.^42,43 A preliminary trial found that forskolin reduced blood pressure and improved heart function in people with cardiomyopathy. These trials have used intravenous infusions of isolated forskolin. It is unknown whether oral coleus extracts would have the same effect. While many doctors expert in herbal medicine would recommend 200–600 mg per day of a coleus extract containing 10% forskolin, these amounts are extrapolations and have yet to be confirmed by direct clinical research.