Colorful compounds in fall leaves are also in edible foods that support a healthy diet.
These red, orange, and yellow pigments are called carotenoids. There are over 600 carotenoids found in nature and about 50 carotenoids in the human diet. The most widely recognized carotenoid is beta-carotene.
Carotenoids are essential for photosynthesis in plants. Thus, life might not exist without them!
The most abundant carotenoids in our food are:
- Beta-carotene
- Alpha-carotene
- Beta-cryptoxanthin
- Lutein
- Zeaxanthin
- Lycopene
Health Benefits
We can reap numerous health benefits from edible plants that contain carotenoids.
Carotenoids have antioxidant properties, help reduce inflammation, and aid the immune system. They also help cells communicate with each other.
Several carotenoids are converted to vitamin A in the body. Vitamin A is an essential nutrient required for normal eyesight, growth and development, and other critical functions.
Thousands of studies provide evidence of health benefits attributed to carotenoids, including:
- Reducing the risk of illness1,2
- Supporting eye health1,2 including lowering the risk of AMD3
- Protecting skin from sunburn4,5
- Lessening premature aging of the skin6
- Reducing the risk of many cancers, including breast and prostate cancer1,2
- Supporting bone health7,8
- Increasing breast milk concentrations of carotenoids and vitamin A9,10 providing nutrients to babies
Rich sources of carotenoids
Foods rich in carotenoids include many red, orange, and yellow fruits and veggies and dark leafy greens such as:
- mandarin oranges, oranges, OJ
- tomatoes
- mangoes
- pumpkin
- red sweet peppers
- orange sweet potatoes
- kale, spinach, collard greens
- black beans
Food vs. Supplements
Too much vitamin A, such as in high-dose supplements with greater than 100% of the recommended daily amount, can be harmful.
Caution is also advised with high-dose beta-carotene supplements. Several studies have shown an increased risk of cancer with high-dose beta-carotene supplements in some people (e.g., smokers).
However, foods rich in provitamin A carotenoids (beta-carotene, beta-cryptoxanthin) are one of the safest ways to consume vitamin A.1,11
Thus, it is important to focus on obtaining nutrients from food.
Fresh vs. Canned or Frozen
The amount of carotenoids in food can vary dramatically depending on cultivar, growing conditions, and other factors.
Carotenoids can break down with light, heat, and oxygen. Thus, fresh off the plant has the highest potential for larger concentrations.
However, many variables are involved in our global food system, including transport and storage times and conditions. Thus, sometimes canned, frozen, or juiced products have higher nutrients than fresh.
Buying a mixture of produce – fresh, canned, juiced, frozen – can help to increase the amount of carotenoids consumed.
Purchasing more locally grown, in-season produce and buying canned or frozen off-season produce (or produce you are not going to eat right away) may also maximize the available carotenoids in purchased foods.
Don’t forget to eat the produce you buy. Good intentions are not enough to have a healthy diet!
Produce is also the most wasted and contributes significantly to landfill space and greenhouse gas emissions.
Cooking and Prep
Carotenoid concentrations in foods tend to decline with higher temperatures, longer processing time, and oxygen exposure.
On the other hand, cooking can often soften the food matrix allowing more carotenoids to release.
For example, tomatoes rich in lycopene often have higher measured amounts after light cooking. Dark leafy greens release more beta-carotene when chopped or lightly cooked than when eaten raw.
Thus, the best way to prepare food is the one that encourages you to consume more colorful plants. It’s better to have some than none!
Make your diet colorful
With so many health benefits, it’s no wonder nature has so many carotenoids! From the pink feathers in flamingos to the colorful leaves in the fall, carotenoids are everywhere.
Let the fall colors be a reminder to include these natural colors in your diet and to eat well!
Dedication – Much gratitude to Dr. Betty J Burri for her mentorship during my studies of carotenoids and their nutrition and health benefits at the University of CA, Davis. Her enthusiasm for understanding these beautiful compounds has been an inspiration.
References
1. Carotenoids, In: Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Institute of Medicine. The National Academies Press, Washington, DC. 2000.
2. Carotenoids. Linus Pauling Institute. Oregon State University. http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/carotenoids
3. Johnson. Nutr Clin Care. 2005;5(2)56-65.
4. Lee et al. Proc Soc Exp Biol Med. 2000; 223:170-174.
5. Stahl et al. Am J Clin Nutr. 2012; 96:1179-1184S.
6. Terao et al. J Clin Biochem Nutr. 2011;48(1):57-62.
7. Yamaguchi. J Health Sci. 2008; 54(4):356-369.
8. Liang et al. Molecules. 2012; 17:7093-7102.
9. Turner et al. Am J Clin Nutr. 2013; 98:1200-8.
10. Canfield et al. Eur J Nutr. 2001; 40:30-8.
11. Vitamin A, In: Dietary Reference Intakes. Institute of Medicine. The National Academies Press, Washington, DC. 2006.
Content presented here, although created by US Registered Dietitians and PhD-level Nutritional Biologists, is for informational purposes only and is not intended to be medical advice. Consult your health care provider before using any supplements or making dietary changes.
