What You Need to Know About GMOs

Woman shopping at a farmers market

Getty Images / Dalibor Despotovic

While some people are concerned about what to eat, others are more focused on where their food comes from and how it was grown. The collective interest in genetic modification, pesticide use, and organically-grown food has expanded, and with that comes the debate about the necessity and the safety of these farming practices.

What exactly does genetically modified food really mean, why is it done, and how does it intersect with pesticide use? A registered dietitian shares the latest science about genetically modified organisms (GMO), so you can make informed decisions about which foods to buy and eat.

What Does GMO Mean?

Genetically modified organisms (GMOs) are plants or animals in which the genetic material (DNA) has been altered in a way that would not occur naturally, either by mating or by natural recombination. It is also known as gene technology or genetic engineering.

The first GMO foods became available to Americans in the 1990s. Common GMO crops in America include corn, soybeans, and canola.

GMOs are a huge advance in science, which literally lets researchers select individual genes to be transferred from one organism into another, even between species that aren't related. Some people hear about GMO technology and are excited by the scientific research that allows for this type of DNA alteration, while others are frightened that DNA can be altered by science.

There's no right or wrong way to feel about GMOs, but it's a good idea to really understand why foods may be genetically modified before you form an opinion.

It's also important to note that GMO is not the same as hybridization or selective breeding, which are natural methods that farmers have used for thousands of years to yield crops with specific desirable traits, such as larger strawberries or corn in different hues. DNA is not altered in those cases.

Why Foods Are Genetically Modified

Researchers develop GMOs that offer an advantage to farmers or consumers. For example, if GMO crops produce a higher yield, the farmers generate more profits, and consumers get more food at a lower price.

Sometimes foods are genetically modified specifically to produce a greater nutritional benefit. One example is Golden Rice, GMO rice with 50 percent of the daily value for vitamin A, which is a common nutrient deficiency in the developing world.

Foods may also be modified to improve crop protection. That means the DNA of the crop is altered to ensure the crop can withstand disease, drought, or pests. This also means that the crop may be more tolerant to pesticides, so lower quantities of pesticides can be used.

Some of these advances can be achieved through non-engineered methods, but altering plants or animals through traditional breeding methods takes a long time, and the changes can't be precise or specific.

One benefit of GMOs is allowing researchers to change plants or animals in a more specific way and in a shorter amount of time. Of course, some opponents see this as a detriment rather than a benefit and worry about changing the DNA of foods, which could potentially trigger allergies or antibiotic resistance.

Why Supplements Are Genetically Modified

Supplements are made in factories using a blend of many ingredients, and some of the ingredients may be genetically modified. This may be done for usefulness, cost, or other practical reasons.

For example, vitamin D supplements may be made from lanolin, which is obtained from sheep's wool. Some sheep are genetically modified to produce more milk and wool, so the lanolin from those sheep would be considered GMO.  

Some supplement companies choose to ensure there are no GMO ingredients in any of their products. Both GMO and non-GMO supplements are available.

Common Concerns Regarding GMOs

Some people are concerned by the use of GMOs for human health and for the planet. Here are some reasons why:


There is some concern that transferring genes from common allergens (peanuts, fish, soy) into other foods could cause an allergic reaction in susceptible people. But transferring genes from common allergens is discouraged unless scientists can prove that the transferred gene is not allergenic. No allergic effects have been found relative to GM foods currently on the market.


Some GMO plants are bred to be resistant to insects, which reduces the use of pesticides. But many GMOs are engineered to survive direct application of pesticides, such as glyphosate (the primary ingredient in Roundup). Glyphosate was classified as a probable human carcinogen (with overexposure) by the International Agency for Research on Cancer.

Antibiotic-Resistant Gene Transfer

There is some general concern that antibiotic-resistant genes could be transferred into GMO foods, then into the human body. The probability of transfer is low (but not impossible).

Contamination of Other Crops

Genes from GM plants can cross over into non-GMO or organic crops, which is known as outcrossing. Some people are concerned about this unmanageable spread, and how it will affect soil, wild plants, the environment, and other crops.

How GMOs Are Regulated for Safety

In 1992, the Food and Drug Administration (FDA) stated that foods from GMO plants must meet the same requirements and safety standards as foods derived from traditionally bred plants.

The FDA, Environmental Protection Agency (EPA), and U.S. Department of Agriculture (USDA) work together to regulate GMOs. They monitor the impact of GMOs on human health and on the environment.

The safety of GMOs is monitored through the Plant Biotechnology Consultation Program. In this program, the GMO plant developer submits food safety assessment data, which is evaluated by the FDA. However, it's important to note that this program is voluntary, which means that GMO plant developers are not technically required to submit safety data to the FDA (but the FDA says that most do).

Can a GMO Be Certified Organic?

By definition, a food or supplement that is labeled as organic cannot be grown from GMO seeds or contain any genetically modified ingredients.

The USDA says "the use of genetic engineering, or genetically modified organisms (GMOs), is prohibited in organic products." If you are looking for non-GMO foods, you can buy foods that are labeled non-GMO or organic.

A Word From Verywell

Genetic modification is high-level science that can help increase food yield while lowering food prices, but some people are not convinced that it's a good idea. Since GMO foods have only been around since the 1990s, there is some concern that there are not enough studies on their long-term safety.

For now, the FDA, USDA, and EPA deem them as safe, and GMO foods (especially corn, soy, and canola) are widely available to consumers. If you don't want to eat GMO foods, you can choose items that carry a non-GMO or USDA organic label.

Frequently Asked Questions

  • What is the biggest issue people have with GMOs?

    Some people are concerned that GMOs may negatively impact human health or planetary health. Specific concerns include the use of genes that are potential allergens; the use of glyphosate, a potential carcinogen; and the contamination of non-GMO crops.

  • Do we need GMOs to feed the population?

    One of the benefits of GMOs is that they can increase crop yield, so there's more food to feed the world's population.

  • Do GMOs harm the environment?

    In some cases, GMO crops allow for fewer pesticides, which is positive for the environment. But GMO technology has also led to the creation of herbicide-tolerant weeds, which require more pesticides to be used, which is negative for the environment. Weighing these, it's important to note that the net effect globally indicates that GM crops have reduced the overall use of pesticides. GMO crops are also associated with a reduction in greenhouse gas emissions.

  • What are the pros and cons of GMOs?

    PROS: GMO crops may help reduce pesticide use and increase crop yield, and some GMO crops are engineered to be more nutritious.

    CONS: It's a new science, and there are no long-term (50-year) studies on safety. There are also concerns about allergens, outcrossing, and transferring antibiotic-resistant genes into foods.

11 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. World Health Organization. Food, Genetically Modified.

  2. Food and Drug Administration. Science and History of GMOs and Other Food Modification Processes.

  3. Food and Drug Administration. GMO Crops, Animal Food, and Beyond.

  4. Proceedings of the National Academy of Sciences. Allow Golden Rice to save lives.

  5. National Institutes of Health Office of Dietary Supplements. Vitamin D.

  6. Kalds P, Zhou S, Cai B, et al. Sheep and goat genome engineering: from random transgenesis to the crispr era. Front Genet. 2019;0. doi:10.3389/fgene.2019.00750.

  7. Food and Drug Administration. Agricultural Biotechnology.

  8. World Health Organization. International Agency for the Research on Cancer. IARC Monograph on Glyphosate.

  9. FDA. How GMOs are regulated for food and plant safety in the United States.

  10. USDA. Organic 101: Can GMOs be used in organic products?

  11. Montana State University. The environmental impact of genetically modified crops.

By Cara Rosenbloom, RD
 Cara Rosenbloom RD is a dietitian, journalist, book author, and the founder of Words to Eat By, a nutrition communications company in Toronto, ON.