Allergy Free Gardening

“Less than perfect-looking fruits and vegetables may be the healthiest choices.”

It has long been thought by many nutritionists that organic produce is superior to non-organic chiefly because the organic has an absence of pesticide residue. Some also feel that a well-tended organic soil will produce more essential nutrients, and that these will be taken up by the plants, rendering the organic produce a richer source of food.

Both of these reasons make considerable sense from a scientific point of view, as pesticides have indeed been strongly connected in many studies to significant statistical increases in allergy, asthma, cancer, obesity, and many other human and animal diseases. Likewise, produce that has more nutrients has also been shown to be of greater value in protecting health.

But new evidence, uncovered in the search for disease-fighting phyto-compounds, points to a strong link between actual insect damage on produce and an impressive increase in the production of health protective properties in the fruits and vegetables. This may add another new and important real value to organically produced fruits and vegetables.

When any plant is under attack by fungus, insects, or for that matter any external enemy, the plant produces numerous substances in an attempt to fight off its foe.

Cabbage plants, and all members of the cabbage family, produce varying amounts of a substance called glucobrassicin (GBS). Glucobrassicin has been shown in studies to have strong anti-tumor properties, and to especially effective against breast cancer.

Leaves from cabbage family members (cruciferous vegetables such as broccoli, kale, collards, mustard greens, cauliflower, turnips, etc.) when attacked, have been shown to produce seven times more glucobrassicin (GBS), compared to plants not attacked. This same phenomenon has now been demonstrated in numerous other species of plants, although each species of plants may produce its own selective protective substance.

For the cabbage plant under attack, the increase in GBS serves the plant itself because it increases the plant’s strength and helps to repel further attacks. For those of us who are lucky enough to be eating this kind of vegetable, the up to seven-fold increase in glucobrassicin means that we are getting much greater than normal amounts of a natural substance that has been shown to fight cancer and to aid in hormonal balance.

It would make sense to suggest then, that organically produced fruits and vegetables, which are not sprayed, may often be less perfect looking than chemically sprayed produce, because they may well have been exposed to more attack by natural pests…which would make them higher in food value from a human health perspective. I would suggest that a good deal of the typical perfect looking supermarket produce is, indeed not really perfect at all.

A rapidly growing number of studies have now consistently shown evidence of the health-promoting value of eating cruciferous vegetables. If one does an exhaustive examination of thousands of health-nutrition studies of the past decade, this, along with four other findings has been repeatedly affirmed.

In particular these are:

1. Strong health benefits from increased use of Omega-3 fatty acids.
2. Strong evidence of the protective benefits of regular exercise.
3. Overwhelming evidence of the high health value from eating blueberries.
4. Vitamin D supplements can lower rates of cancer, diabetes, allergies, and numerous other diseases.
5. Consistent evidence of the health benefits of eating cruciferous vegetables, especially the greenest ones, such as broccoli, Brussels sprouts, collards, mustards, and kale.

Another ingredient of cruciferous vegetables is Diindolylmethane, usually called simply, DIM. DIM has been shown to reduce the amount of “bad” estrogen, increase fat burning, and improve the muscle to fat ratio in the body.

Worth noting, too, about cruciferous vegetables is that high heat can destroy some of the phytonutrients, but that some of the nutrients require cooking for their greatest benefit. Many of the most important compounds in cruciferous vegetables are water-soluble, thus it is smart to save and use the water after cooking. It is advised that they be cooked in a covered pot, with a minimum of water, and that they not be cooked at too high a heat, nor for too long a period of time. “Greens” should still be green in color after they’re cooked.

Plant scientists experimenting with another cruciferous plant of ancient origin, woad, Isatis tinctoria L., have been spraying fertilized, and unfertilized plants with a solution of jasmonic acid, which induces leaf damage, much like damage from attack by insects. All of the injured plants more than doubled their amounts of GBS. Interesting too, is that by far the greatest increases were seen in the unfertilized plants. These were greenhouse-grown plants and the fertilizers were not organic. It would be interesting to see the same experiment done with organic fertilizers.

Nonetheless, what is clear is that actual physical, mechanical damage to the plants leaves resulted in plants that produced much higher levels of phyto-compounds that are protective of human health. How does this directly relate to organically produced fruits and vegetables?

I would surmise that actual physical damage to the crops from, in particular, small pestiferous insects, is indeed triggering high levels of GBS and other plant (and human) protective substances.

Before the popularity of organic gardening, the westernized world went through a prolonged period of “better living through chemicals.” During this time almost all fruit and vegetable crops were sprayed, resulting in a host of pesticide-related health problems, but also producing very perfect looking produce. Many decades ago, no doubt shoppers were happy just to be able to buy apples, pears, peaches, or cabbage at the store, and while no doubt they shopped for the most attractive purchases, it is likely they were completely used to buying produce with visual imperfections.

Today, most shoppers won’t touch an apple or a cabbage that has even the smallest evidence of any chewing or gnawing by insects. A tiny bird peck on a peach or plum will quickly get it rejected by almost all shoppers, and perhaps by those shopping for organic produce as well. This would seem to be a mistake.

It is worth noting too, that a plant’s environment can also have a profound impact on the amount of antioxidants, vitamins, and other phytonutrients. For example, wild blueberries from rugged, cold northern Minnesota may be more than twice as rich in life extending compounds such as resveratrol as blueberries from the pampered cultivated plants flourishing in Washington. Why is this?

The answer would seem to be related primarily to the sort of increase in phytonutrients we see in vegetable plants under attack. A tougher environment can produce a more valuable product.

Tom Ogren is the author of a great many published newspaper and magazine articles and is the author of five published books, including Allergy-free Gardening, from Ten Speed Press, Berkeley, California. Mr. Ogren lectures widely and does consulting on landscape plants and allergies for numerous organizations, including the American Lung Association, county asthma coalitions, schools, hospitals, and cities in the US and abroad. His work has been featured on HGTV, NBC, CNBC, CBS, and he has twice been a guest on NPR, National Public Radio. His website is: www.allergyfree-gardening.com