By any measure, the vitamin supplement industry is booming. Estimates put vitamin sales around $12 billion annually. According to a 2013 Gallop poll, more than half of Americans take vitamin supplements. Vitamin use is even higher in older Americans, with 68% of those over 65 years old regularly taking a vitamin supplement. More women (54%) take vitamins than men (46%). A 2017 study found that 54% of adults older than 60 took at least one vitamin supplement, while 29% took four or more supplements. With more than 90,000 vitamin products available to choose from, is there evidence to recommend vitamin supplementation? Does taking a vitamin lower the risk for heart disease? Let’s look at the data for some specific vitamins.
First there are the B vitamins, whose story is closely tied to homocysteine. In the late 1960’s and early 1970’s it was observed that patients with high levels of homocysteine in the blood tended to develop blockage in their heart arteries at an early age. This began the homocysteine theory of atherosclerosis. Homocysteine is an amino acid (one of the building blocks of protein) and is metabolized using folic acid (a B vitamin) and vitamin B12. Patients with high levels of homocsyteine in the blood can have a genetic defect, but two thirds are due to deficiency of folic acid, vitamin B6 and vitamin B12. Giving folic acid supplementation decreases the level of homocysteine. It seemed plausible that giving vitamin supplementation with folic acid would reduce homocysteine levels and decrease heart artery blockages. However well done studies showed that giving folic acid did reduce homocysteine levels but this did not translate into lower risk for heart attack, stroke and cardiac death. It is now felt that homocysteine rises as a consequence of a vascular event, rather than as a cause of the event and that vitamin B supplementation doesn’t reduce cardiovascular risk.
Next up are the antioxidant vitamins, C and E. Foods rich in antioxidants, such as fruits and vegetables, are known to protect against heart disease. Does supplementation with the antioxidant vitamins, C and E, provide the same heart protection? To test this theory, the British Heart Protection study gave vitamin C and vitamin E to patients at high risk for cardiac death. They found that there was no benefit of vitamin C or E in reducing heart attack, heart death or cancer. The Women’s Health Study followed nearly 40,000 healthy women for 10 years to see if supplementation with vitamin E would reduce cardiac events. Vitamin E did not decrease the risk for heart attack, stroke or death. Lastly, vitamin E was given to patients with known heart artery disease to see if it reduced cardiac events. Once again there was no difference in heart attack, stroke or death. In fact, congestive heart failure occurred more often in patients taking vitamin E, showing that excess vitamin E may be harmful. Because of this, cardiologists have stopped prescribing vitamin E.
Next at bat is vitamin D. Vitamin D has been most extensively studied in bone disease, especially osteoporosis, but there is a strong association between vitamin D deficiency and cardiovascular disease. Studies of hundreds of thousands of patients, followed for more than 20 years, have shown an association between vitamin D deficiency and hypertension, diabetes, high cholesterol and heart disease. Unfortunately, supplementation with vitamin D is not effective in lowering blood pressure, is not useful as a treatment for diabetes and doesn’t significantly change the cholesterol blood panel. It is possible that vitamin D deficiency is a result of cardiovascular disease, rather than a cause of it. The jury is out on vitamin D treatment in heart disease, as some studies show a small reduction in heart deaths, while others show no benefit. The reason for the discrepancy is that most studies looked at vitamin D’s effect on the bones, the heart events were secondary. In addition, these studies tended to involve older patients and patients who already had established heart disease. Studies specifically looking at vitamin D supplementation and heart disease are ongoing, with results due in the coming years. Despite this, it is well established that patients with chronic kidney disease benefit from vitamin D therapy. In this population vitamin D reduces blood pressure and heart deaths.
It seems that supplementation with B vitamins, vitamin C and vitamin E have struck out with heart disease while vitamin D is still in play. The US Preventive Services Task Force, a group of independent physicians, agrees. They reviewed all of the data on vitamin supplements and could not recommend them for heart protection. This appears to be a common phenomenon with supplements in general. Whenever humans try to capture the good ingredients found in food and produce a pill, the pill comes up short in terms of benefit. In the case of vitamins, there may be a couple of reasons for this. Perhaps it is not the vitamin that is beneficial, but some other substance. For example, fruits and vegetables are high in fiber, vitamin supplements are not. In addition, the body carefully regulates its use of vitamins. The body uses what it needs and any excess is excreted in the urine. The typical American diet, for all of its faults, provides plenty of essential vitamins and minerals. Many of our foods are fortified, for example, milk with vitamin D, and flour with B vitamins. Any excess supplementation just isn’t being used.
Appropriate vitamin intake is essential for overall health. In addition, there are many clinical situations where vitamin supplementation is indicated and useful (such as nutritional deficiencies). However, for heart protection eat fresh and natural foods, especially fruits, vegetables, whole grains, and seafood. Don’t expect vitamin supplements or a daily multivitamin to reduce the risk for heart disease.
