Statement of

Dean DellaPenna, Ph.D.
Associate Professor
Department of Biochemistry
University of Nevada, Reno
Before the Senate Committee on Agriculture, Nutrition and Forestry
October 6, 1999

Thank you Mr. Chairman for the invitation to appear today before the Committee. My name is Dean DellaPenna. I am a Plant Biologist in the Department of Biochemistry at the University of Nevada at Reno. My research is focused on understanding, at a very basic level how compounds of nutritional importance to humans are made in plants. The message I hope you will take from my testimony is that we are now in a position to use molecular technologies to modify the nutritional composition of plant foods and that this approach holds great promise for helping to rectify longstanding nutritional deficiencies plaguing the developing and developed worlds.

Humans require a diverse, well balanced diet containing a complex mixture of nutrients in order to maintain optimal health. Plants are critical components of our dietary food chain in that they can synthesize and provide almost all necessary macro- and micronutrients. Macronutrients are the sugars, fats and proteins that make up the bulk of our foodstuff. Micronutrients are organic or inorganic compounds that are present in much smaller amounts, but are nonetheless required for good health. The micronutrients deemed essential in our diet are the familiar seventeen minerals and thirteen vitamins and it is these compounds in plants that I wish to focus upon this morning.

When we talk about vitamins and minerals in our diet we can think about two levels: the Recommended Daily Allowance or RDA and levels in excess of the RDA that are associated with additional beneficial or therapeutic effects. RDAs are the minimum recommended intake needed to alleviate nutrient deficiency, and are somewhat misleading, as they are not the levels needed for optimal health. Indeed, the intake of specific vitamins and minerals in excess of their RDA can significantly reduce the risk of certain cancers, cardiovascular diseases, and chronic degenerative diseases associated with aging. Some vitamins, minerals, their RDAs, and health benefits at higher levels are listed on my first poster.

As I said earlier, plant foods can, in theory, provide almost all the micronutrients essential for human nutrition, however, in practice, most plant foods (especially staple food crops) do not contain the full complement of vitamins or minerals in sufficiently concentrated amounts to even meet the RDA. As a result, fortifying the food supply with micronutrients has been a routine and necessary part of food production for several decades. Fortification has been only partially successful and severe nutritional problems still persist worldwide. All told, over 30% of the world's population suffer from one or more severe micronutrient deficiency with women, children and the elderly particularly at risk. Even in industrialized nations, micronutrient deficiencies are surprisingly common due to poor eating habits. As examples, in the US, 80% of teenage women obtain less than their RDA for iron, 50% of the population get less than their RDA for calcium and 30% of the population obtain less than their RDA for Vitamin E. These nutritional deficiencies occur in all sectors of the US population and the long-term consequences to health care costs, longevity and quality of life are staggering.

One way to ensure an adequate dietary intake of essential micronutrients would be to manipulate their levels in plant foods. Until recently such work had been hindered by the difficulty in isolating genes for vitamin synthesis in plants, however, the advent of genomics during the past 5 years has provided new routes for such work. One aspect of genomics is the complete sequencing of an organism's entire genome (its DNA blue print). Presently, the genomes of over 50 bacteria, one fungus and one nematode are available and the first plant genomes will be completed in the next few years. The information obtained from these genomes allows one to more clearly see the fabric of life within and between organisms, including vitamin biosynthetic pathways. What this means is that genes for vitamin synthesis from simple organisms like bacteria and fungi can be used to rapidly identify vitamin biosynthetic genes in more complex organisms like plants. In the past years my laboratory has developed and applied this approach, which we call Nutritional Genomics, to dissect and manipulate the synthesis of Vitamin E in plants. I would like to close by summarizing this work, but stress that the approach can be applied to other vitamins that are limiting in our diet.

Vitamin E is the most important fat-soluble antioxidant in our diet; cannot be synthesize by humans and must be obtained from plant sources in our diet. As indicated on my second poster, the Vitamin E RDA is 12-15 IU but higher dietary levels decrease the risk of several diseases. Unfortunately, obtaining even the RDA for vitamin E from the average diet is a real challenge; obtaining higher therapeutic levels is virtually impossible. The reason for this is that the major vitamin E sources in our diets, plant oils, contain vitamin E precursors that are 10 to 50 times less active than the most active form of the vitamin, alpha-tocopherol. Indeed, soy and corn oils contain 90% and 60%, respectively, of their potential vitamin E as these low activity precursors. Using Nutritional Genomics we have isolated a gene that can convert the lower activity precursors to the highest activity Vitamin E compound, alpha-tocopherol. With this technology we have increased the vitamin E content of Arabidopsis seed oil nearly 10-fold and are now working with industry to move the technology to agricultural crops such as soybean, maize and canola.

What this means in real life to the average diet is shown on my final poster. Eating 50 grams of soybean oil a day provides 12 I.U. of Vitamin E, the RDA for women (the RDA for men is 15 IU). Eating the same amount of oil engineered with our tocopherol genes provides 100 IU. In controlled studies, 100 IU taken as a supplement reduced the risk of coronary heart disease 40-50% and the risk of certain cancers up to 70%. Applying this technology to agricultural crops would virtually eliminate Vitamin E deficiency in this country as the RDA would be obtained by as little as 7 grams or 1.5 teaspoons of soybean oil (a low fat diet by any measure). A normal diet with 50 gm of engineered oil would significantly decrease the risk of heart disease and some cancers in the population, the two major causes of death in this country.

In conclusion, we are entering an era of Agricultural Biotechnology that will finally allow us to address longstanding nutritional deficiencies in the food supply, deficiencies that until now could only be partially addressed by fortification. The ability to manipulate plant nutritional content heralds an exciting new era and has the potential to directly benefit the farmer, consumer and overall health of the nation. Thank you again for your kind invitation to speak to this committee.