(Re-Posted from February 2010). Happy Ground Hog Day! It’s snowing today, but we’ve had a recent thaw here in Chicago (we’d actually been able to see the grass/ground recently). That sight of green got me thinking about seeds and gardening. (It’s actually time to start thinking about planting seeds indoors already!). Last month’s newsletter was about Community Supported Agriculture (CSA). Some of you asked the question, is local produce really better for you?
To answer this question, I went to many resources, all of which I’ve listed below. The overall answer? Maybe. The good news is that the factors that determine whether or not local produce is better for you can be controlled to a large extent by the local farmer or you in your own garden. These factors include general soil health, when you pick things, how much sun the garden gets (garden placement), what goodies you put into the soil—“soil amendments” and what baddies you can avoid—pesticides, herbicides, etc. I’ve also included two additional articles for those of you that are really interested in digging into the details (ha! no pun intended).
For the home gardener, here are my Top Three Reasons Why Growing Your Own Food Can Offer Better Nutrition:
1. You control the quality of your soil. The nutritional quality of produce depends on the quality of the soil and other factors including light, temperature, rainfall, season, location, altitude, crop maturity and crop variety (1). Soil quality involves a delicate balance of bacteria, fungi, humic acids (making up nearly 50% of the weight of humus which makes natural soil rich, dark and spongy), minerals and clay (which is able to hold water molecules between its layers, swelling to accommodate increasing amounts from rain or irrigation) (2). In other words, if you are growing a garden –or purchasing local produce– from soil that is no good, you are really no better off (or worse!) than the average produce that sits around in the grocery bins for ages. The key is in the soil—it all starts there*.
*Are you worried about lead in your soil? You should check levels before you start planting. Here are two labs that I have used personally:
2. You (and your kids) can eat your produce upon harvest, maximizing nutrients. The best time to eat a tomato or any yummy fruit or vegetable is right as it is picked, nice and ripe. And what is more fun!
– produce sold in the store has a harvest-to-eating lag time of days, weeks or even months! (8-10 days for highly perishable fruits such as berries and 8-10 weeks for less perishable produce such as squash, pumpkins, and grapes).
– Storage times dramatically affect the amount of nutrients found in produce. Spinach kept at 39 degrees F retained only 53% of its folate after eight days (3). Vitamin C losses in vegetables stored at 4 degrees C for seven days range from 15% for green peas to 77% for green beans (4).
So if you are encouraging your kids to eat veggies because you want them to get all the nutrients and vitamins, keep in mind how much more bang for your bite you will get out of really fresh produce. Knowing how much nutrient loss varies for things your kids eat is useful. My son loves to eat frozen peas (great, since they don’t use lose a lot of their vitamins in storage), but I’m happy that we grow other crops in our garden during the summer to make sure that we eat plenty of fresh veggies.
3. You can avoid pesticides and have your own “organic” produce.
– Various studies have demonstrated that organically grown produce is more nutritious than conventionally grown.
-Higher levels of cancer-fighting antioxidants were found in organically grown strawberries (19% higher) and marionberries (50% higher) (5).
-Organic peach samples showed a highly significant increase in polyphenols (mg equivalents of tannic acid/100 g fresh sample) compared with conventional peaches (6).
-Significantly higher levels of quercetin (30%), kaempferol (17%) and ascorbic acid (26%) were found in organically grown Burbank tomatoes vs. conventionally grown (7).
-As much as 40% more antioxidants were found in organically grown vegetables through a four-year study in Newcastle, England (8). The above suggests that if your local produce is organic, it is better for you. You can also buy organic produce from a CSA, a farmers market, or in the grocery store.
There is no doubt that organic produce is often more expensive than regular produce. So start by transitioning to organic over time and begin by replacing the “dirty dozen” in your shopping cart (from conventionally grown to organic):
(Determined by the Environmental Working Group)- for more information click here: http://www.foodnews.org/fulllist.php
(Buy These Organic)
3. Sweet Bell Peppers
Are there items in the produce section that shouldn’t cause as much concern? These are the “least dirty dozen”:
(Lowest in Pesticides)
3. Sweet Corn (frozen)
6. Sweet Peas (frozen)
Additional articles to peruse:
Is Local Produce More Nutritious? http://nefoodguide.cce.cornell.edu/files/all/local_produce.pdf
Maximizing the Nutritional Value of Fruits and Vegetables
Have fun eating your fruits and vegetables—remember, 5 a day!
(1) Diet and Nutrition, A Holistic Approach. Rudolph Ballentine, M.D. Chapter 2: Nutrition and the Soil. pp 23-38.
(2) Is Local produce more nutritious? Cornell Cooperative Extension. http://nefoodguide.cce.cornell.edu/files/all/local_produce.pdf
(3) “Storage time and temperature effects nutrients in spinach.” Penn State’s College of Agricultural Sciences and the Department of Food Science. March 18, 2005, Journal of Food Science, vol 69, no. 9.
(4) “Maximizing the Nutritional Value of Fruits and Vegetables”. Diane Barrett, PHD. Center for Excellence in Fruit and Vegetable Quality, University of California, Davis. http://fruitvegquality.ucdavis.edu/publications/MaxFoodVegApril%202006.pdf
(5) “Comparison of the Total Phenolic and Ascorbic Acid Content of Freeze-Dried and Air-Dried Marionberry, Strawberry, and Corn Grown Using Conventional, Organic, and Sustainable Agricultural Practices.” Agricultural Food Chemistry, 2/26/2003;51(5):1237-41
(6) “Polyphenoloxidase activity and polyphenol levels in organically and conventionally grown peach.” (Prunus persica L., cv. Regina bianca) and pear (Pyrus communis L., cv. Williams). Instituto Nazionale di Ricerca per gli Alimenti e la Nutrizione, V. Ardeatina, 546—00178, Rome, Italy. 2 August 2000.
(7) “Three-Year Comparison of the Content of Antioxidant Microconstituents and Several Quality Characteristics in Organic and Conventionally Managed Tomatoes and Bell Peppers.” Alexander W. Chassy, Linh Bui, Erica N. C. Renaud, Mark Van Horn, and Alyson E. Mitchell. J. Agric. Food Chem., 2006, 54 (21), pp 8244–8252.
(8) “Organic food ‘better than ordinary produce.” Lucy Cockcroft. UK Telegraph. 29 Oct 2007. (Based on the findings of the Newcastle study, Prof Carlo Leifert).
Disclaimer: This column is for information only, and no part of its contents should be construed as medical advice, diagnosis, recommendation or endorsement by the author. You should always ask your physician for his or her recommendation before starting any new health-related activity.