Can an apple a day really keep the doctor away?

Posted Jul 13, 2017 | Blog Post

Is this true? Quotes such as this can be read worldwide throughout many nutrition magazines, networks and journals, but does the statement have any validity? The concept of nutritional degradation within produce has become a hot topic in the field of nutrition for the past 30 years, and it continues to be studied in various agricultural academic disciplines. The nutritional degradation of bananas in Zimbabwe or the economic and resource waste of spoiled cabbage in South Africa brings to light concrete examples of this phenomenon, but is switching our produce to organic and local the change we need to eat like our grandparents again?

Our History

Let’s start from the beginning. In 19th century North America, family farms were the norm and local and organically grown produce was the only food source readily accessible. For example, if a family in New York wanted vegetables for dinner they would go outside, pick, wash, and eat whatever was in their garden. Since then, times have changed and family farms have all but been eradicated. Yet the pleasure and utility we still see in growing our own vegetables in a garden continues to be sought after, even if it has become a hobby rather than a nutritional food demand.


Moving into the 20th century, family farms are now large industrialized complexes that gain a competitive advantage by specializing in one specific type of agricultural crop like wheat, corn or potatoes. These farms, year after year, tend to produce the same crop in the same region. This monocropping strategy has led to soil degradation and a loss of biodiversity in both crops being seeded and the native crops and plants in the area. When the soil degrades, there are fewer nutrients available within the soil to be uptaken by plants, and the extent of this degradation was seen in a study by Donald R. Davis et al..


This study, “Changes to USDA Food Competition for 43 Garden Plants,” examined 43 common garden plants including kale, lettuce, spinach, and strawberries between 1950 and 1999.They determined that there was a statistically significant decline in 6 out of the 12 nutrients they studied over these fifty years. Specifically, they saw that all the minerals they studied within the plants had a median average decrease of 16, 9 and 15 percent concentration for calcium, phosphorus and iron respectively. Furthermore, they saw two vitamins, riboflavin and ascorbic acid experience a median decrease of 38 and 15 percent respectively. Lastly, they determined that protein within the crops had a statistically significant decrease of 6 percent as well. They attributed some of these nutrient losses to global increased levels of CO2, which tend to decrease a plant’s ability to make protein at the trade-off of filtering more CO2. The rest however, they attributed to the theory of the dilution effect.

The Phenomenons

The dilution effect states that as crop yields increase due to fertilization, irrigation and other environmental means, there is a decrease in the concentration of minerals in plants. This is very concerning considering minerals in our diet are essential for bodily functions such as building strong bones, teeth, skin, hair, and nerve functions, yet, we need continuous increased crop yields to keep up with the growing food demand. However, if we were to grow produce organically and locally, could we sidestep soil degradation and therefore, retain these essential minerals in our vegetables while meeting food demand?


Like most things, the answer is complex and depends on the specific organic producer and the farming strategies they use. However, locally grown produce is important when it comes to decreasing post-harvest nutritional depletion and mechanical damage. A large portion of our fruits and vegetables in Ontario are grown in California and the US southern states, which means that by the time the produce reaches our grocery store shelves, it is already travelled 6000 km and is usually at least a week old.


Fruits and vegetables experience a phenomenon called respiration. In the same way that humans need air to breathe to gain energy (O2) and dispose of waste (CO2), fruits and vegetables continue to breathe even after they are picked off the stem. However, this respiration leads to the breakdown of stored organic materials because once the fruit or vegetable leaves the soil or the stem they were grown on, they are not able to gain back those nutrients they dispose of when breathing. The degradation of this organic material includes compounds such as carbohydrates, proteins and fats. These internal losses lead to a loss of food flavour, value and nutrient composition. Local produce fills this gap as it spends less time being transported to grocery shelves cutting down the time of respiration and nutritional value decay.


Going back to the quote at the start of this post, it may be a stretch to say that 1 orange in 1940 has the same nutritional content as 8 oranges today, however, the nutritional quality of our produce is decreasing. To counteract these issues, we need to find innovative sustainable solutions to grow our fruits and vegetables locally without extensive land use. One strategy that I have found to be very promising is vertical farming because it remedies a lot of the problems facing our earth’s depleting resources. Vertical farms are grown indoors and produce is grown high on shelves, therefore the impact on land use in almost negligible. Furthermore, these farms can be built in any climate, in both urban and rural areas and are local, require less transportation of produce, taste fresh, and arguably most importantly, are very environmentally friendly.


What are some of the innovative ways you’ve come across to eat locally? And if you haven’t, try out a farmer’s market this weekend and let me know if you taste a change in your produce! The industrial revolution may have put an end to family farms, but it doesn’t mean it has to end the nutritional value of our food.

Author: Bojana Radan

Photo Credit: Creative Commons, Lovely Organic Royal Gala Apples
Creative Commons, Blackwood Family Farm