Fortification means adding micronutrients to food during processing. For example, calcium and vitamin D are often added to orange juice, or folic acid to rice and pasta. Biofortification is similar, but the goal is to grow crops that start with more nutients, rather than adding them later.

Biofortified crops are grown and eaten by over 20 million people. They range from staples like corn and cassava, to others like broccoli and bananas. Many more are in development.

rice, corn, wheat, cassava, potato

The world’s staple crops include wheat, cassava, rice, and corn. They provide a good source of calories, but contain few vitamins or minerals.

Carotenoids and Public Health

world map of vitamin a deficiency

Percent of children under 5 years with vitamin A deficiency. Based on the World Health Organization Global Database (2009).

Many biofortifcation efforts focus on carotenoids. Carotenoids give flowers, fruits, and vegetables an orange color. They are also important for people. When we eat carotenoid-containing foods, our bodies convert the carotenoids into vitamin A.

Vitamin A is vital for the health of our eyes and immune system. It is also needed for normal function of our heart, lungs, and kidneys.

Many people around the world are vitamin A deficient. This includes about 250 million young children, and many pregnant women. Lack of vitamin A can be life-threatening because it is needed to fight infections. Vitamin A deficiency is also the leading cause of preventable childhood blindness. Biofortified crops, especially those grown in areas where vitamin A deficiency is high, have the potential to help.

Methods of Carotenoid Biofortification

For biofortification to work, it is important that researchers understand how plants make carotenoids. We know a lot about carotenoids, not just from crop research, but also from studying flower color. For example, from flowers we understand how plants make, store, and break down carotenoids. We also know about the genetics controlling these processes. Applying this knowledge leads to better crops.

Biofortification is done using traditional breeding and/or genetic modification.

Traditional Breeding

Traditional breeding involves many generations of crossing plants together, then selecting offspring with the desired trait. Levels of the carotenoid beta-carotene were increased by traditional breeding in corn and cassava.

Sometimes traditional breeding is not an option. For example, it has not worked to increase beta-carotene in rice, potatoes, or wheat. For traditional breeding to work, nutrient levels in the starting crop need to vary. Some crop plants are very hard to breed. Others may not start out with a specific nutrient.

Transgenic Technology and Gene Editing

Molecular apporaches to biofortification complement traditional breeding. Transgenic techniques move a beneficial gene from one species to another. Gene editing re-writes an existing gene to change its function.

The exact approach may be different, but outcome of the genetic change usually fits one of the categories below. Combining strategies often results in the biggest impact

  • Make more carotenoids. Transgenic technology can give plants new carotenoid-building machinery. Other genetic changes increase the amount of carotenoid-building machinery a plant already has. Some genes code for proteins that decrease the level of carotenoids made. Turning these genes off or down results in more carotenoids.
  • Increase carotenoid storage. Carotenoids accumulate in special organelles called chromoplasts. Genetic changes cause plants to make more or bigger chromoplasts.
  • Slow carotenoid breakdown. Genetic modifications increase compounds that stabilize carotenoids. They can also decrease the production of proteins that breakdown carotenoids.

Whether made through traditional breeding or molecular approaches, each new crop needs to be carefully evaluated. It is important that biofortified crops work in the real world to improve nutrition. High levels of nutrients are important, but they need to be in a form the body can digest and absorb. It is also important to consider if farmers will grow the new variety, and if consumers will eat it.

Related Content:

To learn more about the traditional and molecular techniques that are discussed Crop Improvement Methods.
For molecular approaches to work, it’s important to understand the genetics behind a trait. Learn more about how plants make carotenoids in the Genetics of Flower Color.

some orange flowers, including monkeyflowers

Researchers in Dr. Yaowu Yuan’s lab at the University of Connecticut use monkeyflowers to learn about carotenoid pigments.

Many Vegetables

Nearly every plant grown for food today has been improved through traditional breeding, molecular approaches, or both.

Carotenoids in Egg Yolks

Egg yolks get their color from carotenoids. The color varies, depending on the type and amount of carotenoids in a hen's diet. A hen that eats carotenoid-rich carrots and tomatoes will lay eggs with dark orange yolks. Hens that get carotenoids from greens and yellow cornmeal lay eggs with yellow yolks. Egg yolks can even be nearly colorless if a hen has a diet low in carotenoids.

Eggs are a good source of carotenoids for many people. There are lipids in egg yolks that make it easier for the body to absorb and use carotenoids, which are fat-soluble.

cracked egg


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