If you are like most people, you probably take some form of vitamin or other dietary supplement. But should you? Is that supplement actually helping your heart or helping you to live longer? Or is it just a waste of money that you could be spending on a better tool for a healthier life – a yoga app subscription, a bicycle, fresh produce? Many people in the U.S. are spending hundreds of dollars per year on vitamins and other dietary supplements, even though the evidence of their benefit is flimsy.

A new and ambitious evaluation of 277 randomized controlled clinical trials has found that dietary supplements probably aren’t doing you any good, at least when it comes to how long you live and your risk of dying of heart problems. The review, published in the Annals of Internal Medicine by researchers at various institutions including West Virginia University, Johns Hopkins and the Mayo Clinic, also found that many supposedly heart-healthy diets have neutral effects on mortality and heart disease risk.

A man buying supplements in the local pharmacy.
You probably don’t need that multivitamin.

This new review of clinical trials investigating the impacts of dietary supplements comes on the heels of previous reviews that have come to similar conclusions. There is not good evidence that dietary supplements – things like multivitamins, B vitamins, vitamin E, vitamin C, omega-3 fatty acids – provide any protection against heart disease, cancer, cognitive decline with aging or other chronic diseases.

Randomized controlled clinical trials are studies that compare the effects of an intervention in one group of people, like taking a multivitamin or eating a diet low in saturated fats, to the same effects among a “control” group of people who don’t receive the intervention. In these studies, people are randomly put into the intervention or control group. The people in the trial often do not know what group they are in (for example, if they are taking a true supplement or a placebo), and the researchers or nutritionists interacting with these people are also often “blinded” to the group they are in. Randomized controlled clinical trials are the gold standard in determining whether a particular health intervention truly works or not.

The interventions evaluated in the 277 clinical trials included in this new review all involved a dietary supplement or a specific eating pattern. The supplements evaluated included antioxidants, beta-carotene, vitamin B complex, multivitamins, selenium, vitamin A, vitamin B3 or niacin, vitamin B6, vitamin C, vitamin E, vitamin D, calcium, calcium + vitamin D, folic acid, iron and omega-3 fatty acids. The dietary interventions included a Mediterranean diet, intake of reduced saturated fat, modified dietary fat, reduced dietary fat, reduced salt intake, increased omega-3 ALA intake and increased omega-6 fatty acid intake from nuts, seeds and oils. The effects of these interventions were evaluated by researchers conducting randomized controlled clinical trials for anywhere from 6 weeks to 140 weeks.

What researchers found when they reviewed and made an “evidence map” of all of these interventions might surprise you. Dr. Safi Khan at West Virginia University and colleagues found that, overwhelmingly, diet and dietary supplement interventions have little to no effect on the number of deaths from all causes or specifically from cardiovascular events (coronary heart disease, heart attack and stroke) in a given period of time. In other words, most dietary supplements are very unlikely to keep you alive for longer or reduce your risk of heart disease.

Khan and colleagues also found that the scientific evidence for any benefits or harms of dietary supplements is usually flimsy at best. In fact, the review shows that some common supplements, including those that contain calcium and vitamin D, can increase one’s risk of stroke. High levels of calcium and vitamin D from supplements may lead to negative changes to arteries and blood vessels. Other supplements that can be harmful in high doses supplied by vitamin pills include β-carotene, vitamin E, niacin and vitamin A. In previous reviews of clinical trials, antioxidants and niacin supplements have been found to negative impact mortality. Niacin can harmfully raise blood glucose (blood sugar) levels.

But there is some good news.

The review found that reduced salt intake (or a DASH diet – example menus here) significantly reduces the risk of all-cause mortality and cardiovascular mortality. Eating a low salt diet reduced mortality risk by about one tenth, across clinical trials evaluated in this review. It also reduced the risk of cardiovascular-related death by about one third among people with high blood pressure.

“The mechanism behind the benefit of reduced salt intake on death is most likely related to reduced blood pressure. Hypertension is a known risk factor for [cardiovascular disease], and scientific evidence exists of a direct relationship between dietary salt intake and blood pressure.” – Effects of Nutritional Supplements and Dietary Interventions on Cardiovascular Outcomes, Khan et al., 2019

There is a caveat to a low salt diet for heart health. Such diets may be particularly beneficial among people with salt-sensitive hypertension. Different people have different sensitivities to salt intake in terms of how much a given amount of salt causes their blood pressure to rise. For this reason, not all people with high blood pressure will see a significant reduction with reduced dietary salt intake.

African American Woman Seasoning Homemade Pizza
Cooking at home can help you control and moderate your salt intake. Making pizza or spaghetti? Look for lower sodium sauces and make your own pizza dough or garlic bread without salt! Spices you can use instead of salt include oregano, thyme, ginger, allspice, onion powder, garlic powder, pepper, curry and paprika!

Omega-3 fatty acid supplements also slightly reduced the risk of cardiovascular events including myocardial infarctions and coronary heart disease. However, Khan and colleagues rated the level of certainty of this evidence to be low. In other words, a physician practicing evidence-based medicine would be likely to look at this evidence and advise that you don’t need to be taking omega-3 fatty acid supplements, unless you really want to. Getting omega-3 fatty acids from your diet is probably just as good or better than spending your money on supplements.

Folic acid supplements also lowered the risk of stroke, but primarily among individuals in China where consumption of folate fortified foods such as pastas and cereals is not as common as in the US. Natural sources of folate include legumes like beans, chickpeas and lentils.

All other dietary supplements evaluated in the review had no measurable benefits on cardiovascular outcomes or overall mortality, including antioxidants, beta-carotene, vitamin B complex, multivitamins, selenium, vitamin A, vitamin B3 or niacin, vitamin B6, vitamin C, vitamin E, vitamin D and iron. 

Sidebar: Supplements of Vitamin C (an antioxidant) may be beneficial in situations where abnormal levels of oxidative stress are a concern, such in people exposed to cigarette smoke or when hypoxia (low oxygen supply) occurs as a complication during pregnancy. In general, vitamins and dietary supplements can be critical in treating specific deficiencies, but you should work with your physician to identify your nutrient needs as opposed to taking supplements “just because”.

Other dietary interventions evaluated in the review also had neutral impacts on cardiovascular risk and mortality. This may seem surprising for interventions such as the Mediterranean diet. In previous studies the Mediterranean diet has been shown to be somewhat effective in reducing cardiovascular disease risk, but these studies are often small and dietary interventions are notoriously difficult to conduct in clinical trials. They involve having people keep food diaries. People in these studies can always eat beyond the assigned intervention foods. These studies are also usually limited by relatively low research participant numbers and follow-up durations. 

Ultimately, we simply don’t have enough data from clinical trials to definitely say whether Mediterranean and low fat diets protect against death from heart disease and other chronic diseases. This doesn’t mean that certain aspects of these diets aren’t beneficial to your health.

Good sources of vitamins A, B, C, E, K include broccoli, sweet potatoes, orange, avocado, spinach, peppers, olive oil, dairy, beets, cucumber, beens.
Good sources of vitamins A, B, C, E, K include broccoli, sweet potatoes, orange, avocado, spinach, peppers, olive oil, dairy, beets, cucumber, beens.

So what CAN you do to improve your heart health?

A visit to your general practitioner and a blood test can reveal any vitamin or mineral deficiencies that you may need to take supplements for. But other than for a known deficiency, there is little health reason for most people to take dietary supplements. These supplements are at best ineffective and in some cases can harm your health.

Sidebar: There may be cases in which a given supplement doesn’t reduce your cardiovascular risk if you are otherwise healthy, but could provide some protection against progression into heart failure once you have already had a cardiovascular event such as a heart attack. More precision medicine research is needed to determine who benefits from a given dietary intervention when. As always, talk to your physician before taking a dietary supplement.

There is a lot of scientific evidence now that suggests that consuming most vitamins and minerals in the form of food (such as fruits and vegetables) is far superior to consuming them as supplements. Getting your vitamins and minerals from your food helps your body to better absorb these and also protects you against potentially harmful “megadoses” of particular compounds. Vitamin pills also don’t contain the dietary fiber known to be an important component of the health benefits of eating whole fruits and vegetables.

“If you don’t have a known deficiency, there is no reason that you should ‘top off’ your diet with more vitamins and minerals in the form of supplements, expecting them to improve your survival, because they do not,” Khan said.

If not taking supplements, what can you do to improve your heart and overall health? The most impactful steps you can take, based on the best available scientific evidence, are to:

  • Get more physical activity
  • Eat a balanced diet with plenty of fruits and vegetables
  • Reduce your salt intake if you have high blood pressure
  • Maintain a healthy weight
  • Stop smoking
  • Limit your alcohol intake

These are the lifestyle interventions Dr. Safi Khan pointed us to, not supplements, when we talked to him about his new review in Annals of Internal Medicine.

Couple having a snack after a run.
Exercise and balanced, plant-based nutrition are staples for heart health.

There is good evidence from observational studies – studies where people’s habits and health outcomes are observed but they are not randomly assigned to a specific intervention – that plant intake is protective against disease. Diets deficient in whole grains, fruits and vegetables appear to be particularly deadly, according to a 2019 systematic analysis of the health effects of dietary risks across 195 countries.

Sidebar: Get heart-healthy vitamins and minerals from your diet! Get folate from beef liver, legumes and cruciferous and green vegetables such as spinach and kale. If you consume alcohol at even a moderate level or are pregnant or wanting to get pregnant, you may need to get more folate into your diet. Get vitamin D from fatty fish, organ meats and dairy products. Get vitamin C from citrus fruits and broccoli. Get Omega-3 fatty acids from nuts and seeds such as flaxseeds as well as from seafood in moderation.

Regardless of any specific diet you might be on, you should try to incorporate a diversity of fruits, vegetables, nuts, seeds and whole grains into your diet to improve your health and prevent chronic disease. Systematic reviews of randomized controlled clinical trials reveal a positive relationship between fruit and vegetable intake and lowered diastolic blood pressure. People participating in clinical trials who receive nutrition-based advice and support in increasing their fruit and vegetable intake also have improved markers of cardiovascular health, such as lowered blood pressure. 

In a number of clinical trials, dietary fiber intake from plant foods such as fruits and vegetables also reduced cardiovascular disease risk factors including cholesterol levels and blood pressure.

Exercise is likely one of the most important factors in preventing cardiovascular disease and mortality. Exercise has similar benefits as established drug interventions, including statins and drugs that treat high blood pressure, in preventing coronary heart disease, preventing diabetes and treating stroke

Learn more about the types of exercise that improve heart health here and here. Cardio exercise, or activity that gets your heart beating at a faster pace than normal, is key to keeping your heart healthy.

Smoking is a major cause of cardiovascular disease as well as other diseases including cancer, and alcohol consumption can raise your blood pressure, lipid levels and other risk factors for heart disease. Taking steps to quit smoking, reduce your exposure to secondhand smoke and reduce your alcohol intake can radically reduce your risk of early death from a range of causes including heart disease.

Finally, maintaining a healthy weight through a dietary intervention that works best for you is key to preventing early death. Supplements won’t help you lose weight, but reducing your intake of processed foods, sugars, carbohydrates and saturated fats will. Intermittent fasting, or going some amount of time every day without consuming any calories, can also be as effective for weight loss as traditional dieting. Learn more and get started with fasting for weight loss here and here.

The Takeaway? Lose the supplements and multivitamins. Instead, spend your resources and time getting more movement and whole plant foods into your lifestyle, while limiting your salt intake, exposure to cigarette smoke and alcohol.