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Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Soil Depletion and Nutrients in Your Dog

Updated: January 14th, 2019

Trace minerals and elements have not gotten the attention they deserve for our pets’ health.

For example, zinc, selenium and magnesium are all critically important for dogs fighting cancer for many reasons, among them immunity and resistance to drug reactions.

One of the reasons this may be problematic is that many ill dogs have low levels of trace minerals.  To make matters worse, testing can be difficult as these nutrients are not stored in the blood, making blood testing not very accurate.

The problem is that the soil that crops are grown in, which are used for food, is gradually becoming depleted of minerals due to repeat farming of the same plots of land over time.  This is because it is uncommon for farmers to test the soil frequently enough to replace all of the missing nutrients. Sometimes excessive fertilization of some nutrients leads to an imbalance and crowds out absorption of other needed nutrients for the plant.

Another factor is that the source of many mineral like magnesium is from decaying organic material on the surface of the soil, which is not common in agriculture today.  Finally, the plants themselves are now designed to be high yield, and tend to need larger amounts of these minerals and nutrients in the soil.

Here is a chart showing how the nutritional value of some foods has dropped over time:

Table 2. Mineral Content of Selected Produce 1963 vs. 1999 – (mg/100g sample)
Percent Water
1963 1999 1963 1999 1963 1999 1963 1999
Apples, raw, with skin 7 7 8 5 110 115 84.8 83.9
Beans, snap, green, raw 56 37 32 25 243 209 90.1 90.2
Broccoli, raw 103 48 24 25 382 325 89.1 90.6
Carrots, raw 37 27 23 15 341 323 88.2 87.7
Lettuce, iceberg, raw 20 19 11 9 175 158 95.5 95.8
Oranges, raw 41 40 11 10 200 181 86.0 86.7
Peaches, raw 9 5 10 7 202 197 89.1 87.6
Peas, green, raw 26 25 35 33 316 244 78.0 78.8
Strawberries, raw 21 14 12 10 164 166 89.9 91.5
Tomatoes, red 13 5 14 11 244 222 93.5 93.7


It is true that pet foods are supplemented with necessary nutrients to help insure they get what they need. The problem however is that animals who are ill,  in many cases including cancer require further support to due imbalances and deficiencies.

The take home message here is that it is important for a dog with cancer to take a multivitamin, as stated in the GuideApocaps contains a boost of both magnesium and zinc. Everpup is a good supplement containing an large array of beneficial nutrients as dogs age.


Dr D




Leave a Comment

  1. Melissa on October 26, 2012 at 4:12 pm

    Thanks for this post. It answered my question about administering a multivitamin to Duncan. Today, by the way, he started to eat an apple and a persimmon for the first time in about 7 months. (He was always a big fruit eater). His energy is still up. I have started him on green tea as well as continuing the the ApoCaps and trying to get as many cruciferous veggies onto his plate. My question is, have ApoCaps ever been tried on humans? Is there anything in them that contraindicates human intake?

  2. Marianne on October 18, 2012 at 2:27 am

    Why do my dogs eat dirt when they go outside and what are they telling me they need added to their diets?

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