Vitamins and Supplements — The Benefits of “Food First” | Dana-Farber Cancer Institute

For more information, recipes, and nutrition tips, and to watch more videos on Eating Well During Cancer, visit

Vitamins and supplements are a big area of conversation, controversy, and research. When considering ways to ensure that you are getting the nutrients you need for optimal health, Dana-Farber nutrition specialist Stacy Kennedy explains why it’s important to think about the benefits of “food first.”


I’m Stacy Kennedy, a nutrition specialist for Dana-Farber Cancer Institute in Boston. Welcome to Eating Well During Cancer. Today I’d like to talk with you about vitamins and supplements—what’s OK, what might be beneficial, and what should you avoid.

Vitamins and supplements are a big area of conversation, controversy, and research right now. But before we get into details around vitamin pills, I’d like to take a step back and think about the benefits of food first. A lot of research on vitamins and supplements comes out of data looking at what people were eating in their diet. We know that people who eat a variety of plant-based foods can gain a variety of important health-promoting nutrients that we call ‘phytonutrients.’

It’s really important to think about eating by the rainbow. Getting some red fruits and vegetables, what makes a tomato red is an antioxidant called ‘lycopene’ that’s going through a lot of research to see its potential role or benefit in prostate cancer. We have orange. What makes a carrot orange or a sweet potato have that vibrant, bright, orange hue is another antioxidant in the same family called ‘betacarotene.’ We also have yellow, like mango and banana. We know that green vegetables have a variety of important nutrients. Don’t forget about blue or purple—that anthocyanin that makes the blueberry blue is an antioxidant that can benefit our immune system as well. Then there’s also the white family, which is often overlooked—things like garlic and onions, which contain an important phytonutrient called ‘allium.’ There’s also ginger.

Many of these examples of antioxidants or phytonutrients also come in pill form, but what we want to do is take a look at food first. An as example of why this is important, let’s think about that betacarotene that we talked about in the carrot. Many years ago, there was a research study that found that people who ate more betacarotene-rich foods, like carrots, had lower rates of developing lung cancer. However, when people were given betacarotene supplement, the researchers actually had to stop the study early, because they found that the participants who were current or former smokers taking the active betacarotene were actually at risk for developing lung cancer—the total opposite effect of what we were hoping for in that type of study. We know now that high-dose antioxidant supplements during certain types of cancer treatment can actually reduce the effectiveness of that cancer treatment.

However, don’t give up your blueberries yet—getting antioxidants from foods doesn’t cause that same concern. The body knows how much to absorb and what nutrients your specific body needs at that current moment in time. So, eating as many blueberries as you want during cancer treatment is not going to be detrimental, like taking a high-dose antioxidant supplement could.

That doesn’t mean that all supplements are not healthy. It’s important to think about a supplement as just that—a supplement to your diet. For example. omega-3 fatty acids are an essential fat that we have to eat, and they play a role in many things—everything from helping to reduce inflammation to having a healthy brain and healthy mind and cognition. There’s a variety of benefits. We get omega-3 fats from certain types of fish, but we can also get them from things like walnuts. Some people may choose to take a supplement, but you always want to run that by your doctor or your nutritionist first. Look to get those nutrients from your foods first.

Now, some supplements might be necessary. For example, when you’re going through treatment, you may have low blood levels of certain nutrients, like magnesium, and in that case, you might need to take a supplement. Vitamin D is another example of a supplement that might be important to take. Vitamin D deficiency is very common, but it’s a blood test, so your doctor can check that out for you, and you can speak with your doctor and your nutritionist.

Hopefully you’ve learned that eating foods first is the best approach to getting your vitamins, and as far as supplements go, check and see—it’s always important to ask questions. For more information and recipes for great, nutrient-rich foods, and tips on what vitamins you may want to choose or avoid, check out our website or download our app. On behalf of Dana-Farber Cancer Institute, I’m Stacy Kennedy.

You May Also Like