Food and food ingredients from genetically engineered plants are now widely present in the U.S. food supply. As of 2012, the USDA reported 88% of corn, 93% of soybeans, and 94% of cotton produced in the U.S. is genetically engineered. Initially, genetically modified foods were meant to increase crop yields, reduce pesticide use, and address world hunger. Controversial gene silencing, also known as RNA interference (RNAi), was recently introduced with FDA approval for two new crops: apples that resist browning and potatoes that produce less acrylamide.

When genes are silenced their expression is reduced. Gene regulation by definition is said to drive the process of cellular differentiation and lead to the creation of different types of cells with distinct gene expression profiles, which in turn produce specific proteins with the same genome sequence. Gene expression is regulated by a wide range of mechanisms that increase or decrease the production of specific proteins or RNA. Although research has reported some positive findings with regard to gene regulation, the research findings also warn of harmful side effects and the toxicity of the gene silencing treatments developed to address infectious diseases and neurodegenerative disorders. Some scientists view the introduction of such methodologies as a large-scale, unpredictable experiment involving human health and the environment.

Non-Browning Arctic Apple Introduced to U.S. Market
Earlier this year, British Columbia-based Okanagan Specialty Fruits (OSF) announced the introduction of genetically engineered Arctic Granny Smith and Arctic Golden Delicious apples into the U.S. market. As the result of a $41 million merger, OSF was acquired by Intrexon, a Maryland-based synthetic biology company with interests in the genetically engineered salmon and livestock industry.

Despite strong, ongoing protests from the British Columbia Fruit Growers Association (BCFGA) and various anti-biotechnology consumer and industry groups both in Canada and the U.S., OSF is currently planting as many trees as possible in the U.S. with the intention to apply gene silencing to improve other varieties of apples. OSF scientists also seek to genetically engineer peaches, pears and cherries to make them scab and fire blight resistant, resist browning and improve dwarfing and canopy shape. In response to OSF targeting the largest apple producing states (Washington, Michigan and New York) surveyed growers, manufacturers and consumers have been asserting that no one wants a non-browning apple.

Demand for non-browning apples comes from the food service sector of the industry, which desires long shelf life for food products. However, silencing fruit browning creates the risk that apples will still rot without consumers and manufacturers being able to tell whether or not the produce is fresh, suggesting potential food safety issues. Lemon juice and other natural methods to inhibit browning have been suggested as alternatives.

Okanagan’s U.S. grown apples are expected to make it to the market in late 2016 and gene silenced apples could make their way into nutraceuticals, supplements and functional ingredients in the coming year. For this reason, extra attention to sourcing and supply chain verification may be required for manufacturers wishing to avoid GM apple ingredients. Products exported to global markets could also be negatively impacted by the widespread introduction of gene silenced apples and apple ingredients due to the growing number of countries that have banned GMOs.

Although there are strong assertions from OSF that its Arctic brand will be clearly marketed and sold under the Arctic label to allow manufacturers and consumers to make informed purchasing decisions, Canada’s British Columbia Fruit Growers Association is advising buyers to avoid all U.S. Granny Smith and Golden Delicious apples if they want to be certain they are not consuming GMO apples. The U.S. Apple Association added its non-support for the apples, commenting that it had not heard customers calling for a non-browning GE apple and noting that costs to the industry in the form of labeling and marketing efforts necessary to differentiate conventional vs. GE apples would detract from the commercial benefit of growing the non-browning apples. Overwhelming numbers of surveyed health conscious consumers (more than 90%) are now reporting they do not favor GE foods and that mandatory labeling of all GMO foods and ingredients is needed.

Hazards of Gene Silencing
According to the Center for Food Safety, Okanagen Specialty Foods did not analyze the impact that suppressing fruit browning with novel RNAs may have on the rest of the gene family in the tree or whether there are off-target impacts on other genes.

CFS scientists explained that “the USDA should hold off on deregulating RNAi-engineered crops until they have gotten a grip on the latest research in this area. Unlike earlier cut-and-splice techniques used on DNA, the new techniques, called RNA interference or RNAi, are based on the manipulation of RNA molecules in order to dial back the expression of or ‘silence’ genes.”

“The Arctic Apple has been engineered to reduce polyphenol oxidase (PPO) enzymes responsible for browning in apple flesh after bruising. However, these enzymes are also found throughout the tree, where impacts of the engineering were not determined. In addition, recent studies show that interference that targets one gene might unpredictably turn off or turn down unrelated genes. In other plants, PPO genes are known to bolster pest and stress resistance. As a result, non-browning apple trees might be more vulnerable to disease and require more pesticides than conventional apples. Okanagan did not analyze PPO gene functions in apples other than browning in the fruit. Nor did it attempt to determine whether the Arctic has inadvertently silenced genes outside the PPO family.”

Polyphenols for Good Health
Digestive enzymes are catalysts that facilitate important metabolic changes and support the bioavailability of nutrients in foods. Food is broken down into nutrients, which in turn produce energy and repair the body’s physical structure and functions. Enzymes that cause browning in fruit may in fact be key in supporting healthy bodily function and reducing digestive stress. Consumers looking for preventive healthcare, healthy aging and optimal sports performance have been turning to enzymes to supplement their nutritional regime.

Apples turn brown because of a reaction between polyphenol oxidase enzymes and oxygen. When the apple is cut or bitten into, oxygen activates the enzyme and creates melanin, which causes the brown color. When polyphenol enzymes are silenced, melanin is not produced and the apple does not turn brown. Non-browning apples, which turn off the polyphenol enzymes, may lack an essential component necessary to produce the health-promoting benefits desired with apple ingredient use.

Apple consumption has been correlated with positive effects for obesity, heart disease, stroke, diabetes and neurological diseases. Dried apple peel powder has been associated with improved joint function and antioxidant protection. Research studies support apple consumption as a viable all-natural intervention to lower cholesterol, with researchers crediting the presence of polyphenols as the causative factor. Extensive research has also credited polyphenol enzymes in preventing intestinal polyps and colon cancer, lowering blood glucose and preventing glycation damage, reducing symptoms of seasonal allergies, boosting immunity and fighting infection. These are the same enzymes that are being silenced in the newly engineered Arctic Apple, pointing to concerns about the unwanted effects of gene alteration.

Silencing useful enzymes may prohibit positive health benefits and inhibit the effectiveness, potency and synergistic effects of nutraceuticals, natural supplements and functional ingredients. Researchers also offer a word of caution with regard to gene silencing as it impacts melanin production in the human body, since health practitioners acknowledge melanin is an important physiological component. Inhibiting melanin production could affect skin color, hair color, eyesight and overall good health.

There is no current guarantee that the two new gene silenced apple varieties are safe for human health or the environment. Opponents of the apples would like to see an immediate halt to the introduction of the trees into the U.S. food chain. Cross-contamination issues for both conventional and organic apples may be likely.

Apples are a widely used ingredient in foods, supplements, nutraceuticals, infant foods, personal care products and cosmetics. The gene-silenced Arctic could find its way into fruit powders, fruit granules, fruit juice concentrates, and specifically apple fiber powder, apple flakes, apple pectin and pectin powder, and apple skin powder. For manufacturers and formulators wishing to protect the effectiveness of their products as well as the organic standard to meet strong consumer demands to avoid GMOs, a word of caution is prudent. The implications for health challenging GE contamination throughout the supply chain are widespread.