Ask the RD

by Sanna Delmonico, MS, RDN, CHE on Sep 29, 2016

Food for Thought

Question: Are purple and red carrots, purple cauliflower and other colorful varieties of vegetables nutritionally the same as the regular vegetables?

Answer: I was recently served a salad of thinly shaved ribbons of purple, red, orange and yellow carrots. It was beautiful, unique and delicious. I’m glad to see these colorful vegetables become more widely available, because it makes cooking and eating that much more interesting. Nutritionally, colorful varieties are both similar and different to the more usual options.

Vegetables get their color from brightly hued phytochemicals: orange carrots from beta-carotene, red tomatoes from lycopene, for example. Phytochemicals are biologically active compounds found in plants, including fruits, nuts, legumes, herbs, spices and whole grains. At least 5,000 phytochemicals have been identified. Many others are yet to be discovered, and much more research is needed before we fully understand their health benefits (Liu 2013). Think of phytochemicals as protective. Some are antioxidants, for example, protecting cells from damage. So while more colorful vegetable varieties contain nearly identical amounts of some nutrients like fiber, colorful phytochemicals do set them apart.

Compared with white varieties, purple cauliflower is higher in phytochemicals called anthocyanins, also responsible for the color of purple cabbage and blueberries (Bhandari & Kwak 2015). Likewise, purple carrots are higher in anthocyanins than orange carrots. Red carrots, which get their color from lycopene, have higher antioxidant activity than orange carrots (Leja et al. 2013). Vegetable color may impact health. In a small study, men who ate yellow and purple potatoes every day for 6 weeks showed decreased oxidative damage and inflammation (potential precursors of cancer and/or heart disease) compared with men who ate only white potatoes (Kaspar et al. 2011).

Is it time to give up those less colorful vegetables? Variety in the diet is always good, and we still have a lot to learn about the health benefits of individual phytochemicals and individual vegetables. Why not eat them all? Because they provide endless, gorgeous variations in the appearance and flavor of food, I recommend enjoying all the colors of the produce rainbow.

References

Bhandari, S.R., & Kwak, J.H. 2015. Chemical composition and antioxidant activity in different tissues of brassica vegetables. Molecules, 20, 1228–43.

Kaspar, K.L., et al. 2011. Pigmented potato consumption alters oxidative stress and inflammatory damage in men. Journal of Nutrition, 141, 108–11.

Leja, M., et al. 2013. The content of phenolic compounds and radical scavenging activity varies with carrot origin and root color. Plant Foods in Human Nutrition, 68, 163–70.

Liu, R. H. 2013. Health-promoting components of fruit and vegetables in the diet. Advances in Nutrition, 4, 3845–25.

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About the Author

Sanna Delmonico, MS, RDN, CHE

Sanna Delmonico, MS, RDN, CHE IDEA Author/Presenter

Sanna Delmonico, MS, RDN, CHE is a faculty member at The Culinary Institute of America at Greystone, in the Napa Valley, where she teaches food safety and nutrition.