Nutritional support for cardiac patients: What the research says

Diet is just as essential for cardiac health as it is for cardiac recovery. Unfortunately, the nutritional deficiencies that lead to cardiovascular disease seldom resolve after a cardiac health event without sound nutritional guidance from a medical professional.

After a cardiac event, patients may need to reduce cholesterol intake or lose weight, among other dietary goals. The following is a snapshot of current research on supplements and whole foods that are beneficial for cardiac recovery. 

Iron

Iron deficiency can cause anemia, which can limit muscle function when oxygen levels drop. Low iron levels may also lead to activity intolerance and shortness of breath in patients. Unfortunately, this deficiency is perhaps more common than you would think. 

A 2022 study published in the Archives of Cardiovascular Diseases Supplements concluded that iron deficiency is “highly prevalent” in cardiac rehabilitation patients, especially in those who have undergone heart surgery or in those with heart failure. Among the 211 study participants, 39% were iron deficient. Among those in cardiac rehab following surgery, 61% were iron deficient, followed by 46% of patients with heart failure, and 31% of patients with coronary artery disease.

Methods of administration

Evidence supports iron supplementation during cardiac recovery—but the form of administration may be critical. Intravenous therapy may be more effective than oral supplementation.

According to a 2021 review published in ESC Heart Failure, oral iron therapy has not been studied extensively. Of the two studies that met inclusion criteria for the review, one study only had seven patients. That study concluded that oral iron supplementation did not lead to a higher peak oxygen consumption. In the other study, oral iron therapy showed no significant improvements.

By comparison, another study included in the review demonstrated that intravenous iron therapy was associated with self-reported quality of life improvements from patients, improved 6-minute walking distances, and “early reductions in calculated plasma volume status in weight.”

Myocardial infarction recovery

According to a 2019 review published in Pharmaceuticals there is evidence that myocardial infarction (MI) patients healed faster after starting iron supplementation 4 days after onset. Iron deficiency is also common in patients with pulmonary hypertension. When iron levels improved, these patients could walk for longer periods.

Patients looking to source iron from whole foods can turn to beans, lentils, spinach, tofu, prune juice, dried fruits, nuts, and broccoli.

Vitamin D

Vitamin D deficiency has been linked to cardiovascular disease. This hormone balances calcium and phosphate levels, improving cardiac function and strengthening cardiac tissue.

According to a 2018 review published in the International Journal of Preventive Medicine, evidence suggests a correlation between increased vitamin D intake and a decreased risk of thrombosis.

Low levels of vitamin D also increase the risk of hypertension and hyperlipidemia, which can lead to coronary artery disease (CAD) in some patients. Vitamin D has also been shown to increase the ejection fraction in heart failure patients. 

Food sources

Rich sources of vitamin D include trout, salmon, white mushrooms, sardines, and fortified nut beverages, such as almond and oat milk. If relying on supplements, patients should take vitamin D with food to enhance absorption. Research indicates that foods with some fat work best.

Recommended vitamin D levels vary by age, as well as the amount of natural sun exposure a person receives. This may be contingent on a patient’s geographic location. 

Coenzyme Q10

Coenzyme Q10 (CoQ10) is a mitochondrial molecule that facilitates energy production in human cells. Research has shown that many patients with cardiac conditions, such as cardiomyopathy, have low levels of CoQ10. 

A 2022 review published in the Asian Journal of Cardiology Research highlights some of the benefits of CoQ10 supplementation for cardiac patients. Examples include:

•  300 mg daily increased antioxidant activity and lowered inflammation levels in patients with CAD who were using statins.

• CAD patients significantly decreased total cholesterol and raised HDL-C levels in a meta-analysis involving eight trials. 

• CoQ10 lowered ventricular arrhythmias, boosted left ventricular function, and reduced total cardiac death in patients with post myocardial reperfusion.

• When administered within the first 3 days of MI, patients who received 120 mg of CoQ10 daily benefitted from its “rapid protective effects.”

Questions about supplementation

While the review highlights these proven benefits of CoQ10 for cardiac patients, “its use as a supplement, in the prevention and management of CHD, remains unclear.”

Patients who want dietary sources of CoQ10 can try oily fish, such as salmon and tuna, organ meats, such as liver, and whole grains.

Fish oil

Fish oil is rich in the omega-3 polyunsaturated fatty acids EPA and DHA. According to the Asian Journal of Cardiology Research review, fish oils have demonstrated efficacy in reducing angina, fatal and non-fatal MI, and sudden cardiac death. 

One study included in the review estimated that fish oil led to a 14% to 15% risk reduction for populations at high risk of coronary heart disease. Doses of 2 to 4 g daily of EPA and DHA have also been shown to reduce triglyceride levels and slow atherosclerosis, plaque formation, and coronary artery calcification.

MI recovery

When taken in appropriate doses, fish oil has also been shown to decrease the risk of heart failure. A 2021 Nutrients review highlighted one study that investigated the effects of 4 g of omega-3 administered daily for 6 months. Study participants received the supplement for 6 months following MI. Fish oil led to a “reduction in adverse left ventricular remodeling, non-infarct myocardial fibrosis and serum biomarkers of systemic inflammation beyond the current guideline-based standard of care.” 

The review also highlights an Italian study in which 7,000 heart failure patients received 1 g of omega-3 fatty acids daily. Researchers found that ejection fractions lowered in 91% of participants over 3.9 years.

In addition to fish oil and krill oil supplements, omega-3 fatty acids can be sourced from nuts and seeds, plant oils, and some fortified foods. 

Mediterranean diet

No diet is perfect, but the Mediterranean diet checks many boxes for recovering cardiac patients, or those concerned about their cardiovascular health. For example, a 2019 Circulation Research review was unequivocal in its findings, concluding that “there is a large, strong, plausible, and consistent body of available prospective evidence to support the benefits of the MedDiet on cardiovascular health.” 

After combing through existing studies, researchers selected 45 for inclusion in their meta analysis. They called the evidence substantiating the Mediterranean diet’s cardiac benefits “large, strong, and consistent,” noting that it leads to reduced rates of coronary heart disease, ischemic stroke, and total CVD.

Combating CVD

A 2017 review published in the Journal of Cardiovascular Medicine reached similar conclusions, calling the diet “a reliable weapon against CVD progression.” Specifically, the diet improves endothelial function, arterial stiffness, and cardiac remodeling, reducing peripheral artery disease, coronary artery disease, and heart failure. The antioxidant-rich diet can also lead to improvements in patients with atrial fibrillation, one highlighted study concluded. 

You’ll recognize some of the whole foods comprising the Mediterranean diet from elsewhere in this article. The diet relies on the following staples: 

• Whole grains

• Vegetables

• Legumes

• Fruits

• Nuts

• Seeds

• Herbs and spices

• Olive oil

• Fatty fish (mackerel, herring, sardines, albacore tuna, and salmon)

• Wine (in moderation)

Patients interested in the Mediterranean diet can begin by basing meals around whole grains, beans, and vegetables, eating fish twice weekly, swapping out butter with olive oil, and eating fresh fruit for dessert.

Sources

1. Agarwal, S. Impact of diet on cardiovascular diseases: Coronary artery disease Part II: Micronutrients and supplements. Asian Journal of Cardiology Research. 2022;6(1):13-29

2. Bronzato S, Durante A. Dietary supplements and cardiovascular diseases. International Journal of Preventive Medicine. 2017;9(1):80.

3. Elagizi A, Lavie CJ, O’Keefe E, Marshall K, O’Keefe JH, Milani RV. An update on omega-3 polyunsaturated fatty acids and cardiovascular health. Nutrients. 2021;13(1):204.

4. Lakhal-Littleton S. Iron deficiency as a therapeutic target in cardiovascular disease. Pharmaceuticals (Basel). 2019;12(3):125.

5. Loncar G, Obradovic D, Thiele H, Haehling S von, Lainscak M. Iron deficiency in heart failure. ESC Heart Failure. 2021;8(4):2368-2379.

6. Martínez-González MA, Gea A, Ruiz-Canela M. The mediterranean diet and cardiovascular health. Circulation Research. 2019;124(5):779-798.

7. Mattioli A Palmiero P Manfrini O & et al. Mediterranean diet impact on cardiovascular disease: A narrative review. Journal of Cardiovascular Medicine: 2017; 925-935.

8. Prevalence of iron deficiency in cardiac rehabilitation. Archives of Cardiovascular Diseases Supplements. 2022;14(1):105.