Selenium supplementation for dogs

[AlysonR]

Due to my own issues, selenium has suddenly jumped into focus as a possible culprit for all (but the first) of my dogs dying of cancer. Apparently there is less selenium in raw diets than commercial diets, though utilization may be higher: Selenium and Dogs: A Systematic Review

Has anyone looked into supplementing with selenium? It's a rather fussy process in humans, though supplementing with the form Se-Methyl L-Selenocysteine is very safe. Suggestions here? I don't know how to begin calculating how much (or little) selenium is in the raw diet I feed in the evenings, and my dogs do get commercially-prepared food in the mornings. But if they're gradually being depleted of selenium, it would explain why, at the age of 13 or so, they start developing tumors.

 

[GinnyW]

Personally I would find a deficiency fairly unlikely, in the dogs and also in well-nourished humans. The richest sources of selenium, and likely most bioavailable, seem to be in meats, fish, eggs, and that sort of food. The less processed the better assimilated, it seems, so a varied raw carnivorous diet should contain an appropriate amount. I do not use or trust any "prepared" diet, so cannot speak to their adequacy.

 

[AlysonR]

Selenium content would depend on what's in the soil where the animal grazed. My guess is that soils are becoming depleted. In any event, my own experience is that I was selenium deficient. Such a slowly building deficiency has a good profile for a rise in cancer risk later in life. And selenium is important in the prevention of cancer. Take a look at what Life Extension Foundation has to say about it -- good overview.

 

[aruna]

@Dr. Jeff do you have any thoughts?

 

[Dr. Jeff]

Has anyone looked into supplementing with selenium?

Not recently. I agree with Ginny that a dog eating a meat-based diet with organ meats, is unlikely to be physiologically predisposed to cancer.

Most plant-based diets for dogs (where the soil deficiency issue becomes more prevalent) are already supplemented with selenium.

As with any food or supplement, moderation is always key.

selenium concentration in soil has a smaller effect on selenium levels in animal products than in plant-based foods because animals maintain predictable tissue concentrations of selenium through homeostatic mechanisms.

From:

Office of Dietary Supplements - Selenium

Selenium overview for health professionals. Research health effects, dosing, sources, deficiency symptoms, side effects, and interactions here.

ods.od.nih.gov

Key results
All of the high‐quality randomised trials reported no effect of selenium on reducing overall risk of cancer or risk of particular cancers, including the most investigated outcome ‐ prostate cancer. Some trials unexpectedly suggested that selenium may increase risks of high‐grade prostate cancer, type 2 diabetes, and dermatological abnormalities.

Observational studies have yielded inconsistent evidence of a possible effect of selenium exposure on cancer risk, with no evidence of a dose‐response relation. When we pooled results of these studies, overall they suggested an inverse relation between cancer exposure and subsequent incidence of any cancer or some specific cancers, such as colon and prostate cancer. However, observational studies have major weaknesses. The selenium exposure status of participants could have been misclassified owing to limitations of the indicators of selenium exposure used, as well as to uncertainty regarding the particular selenium species contributing to overall exposure. In addition, unmeasured confounding from lifestyle or nutritional factors ‐ a major and well‐known source of bias in nutritional epidemiology studies of observational design ‐ could have been present. Therefore, the internal validity of these studies is limited.

Currently, the hypothesis that increasing selenium intake may reduce cancer risk is not supported by epidemiological evidence. Additional research is needed to assess whether selenium may affect the risk of cancer in individuals with specific genetic backgrounds or nutritional status, and to determine how the various chemical forms of selenium compounds may have different effects on cancer risk.

From:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6491296/