Human sperm quality has been in a nosedive over the last half century. Now a new study proves exactly the same thing has been happening to dogs. And the likely cause is seed oils in their feed (for humans and dogs).
Last week a very strong study was released that showed consistently plummeting sperm quality in a large controlled dog breeding program. Quality dropped by 2.5% a year from 1988 to 1998 and then 1.2% a year from 2002 through to 2014. The reason for the improvement was that between 1999 and 2001, dogs that were not producing viable sperm were removed from the breeding program. Something you can do with dogs but potential fathers are a bit persnickety about.
These results are very close to those we already have in humans, the other omnivore that shares the diet and the living space of dogs. Similar rates of human sperm quality decline are now being reported in all Western countries (although alarmingly at a decline of 3% a year, Australia is at the high end).
Humans don’t normally eat dog food (well, I don’t), but there is one ingredient both dogs and humans eat now that neither ate before the early 20th century. And that’s seed oils.
Pick up your favourite packet of dog food and peer closely at the ingredients. Here’s a typical example (from Pedigree, one of the most popular dog foods on sale in Australia):
Cereals &/or cereal by-products, meat & meat by-products (poultry, beef &/or lamb), poultry palatant, beet pulp, salt, minerals, sunflower oil, vitamins, amino acid, antioxidants
The Cereal (husks and small cereal particles left over from milling as well as whole grains as filler) and Meat by-products (lungs, spleen, kidneys, brain, livers, blood, bone, fatty tissue, stomachs and intestines) are in dog food precisely because they are hard to sell to humans.
The ‘Palatant’ is flavouring to make it taste like food (and so the owner thinks it smells like food). If it weren’t there a dog wouldn’t eat it.
And Beet pulp is the fibre left over after they extract sugar from sugar beet plants. It makes dog poop firmer and this apparently pleases those who do the scooping.
Aside from the vitamins and minerals, there is only one ingredient in this ‘food’ that also appears in human food. In this brand it is sunflower oil but it often just described as vegetable oil.
These oils are not made from vegetables at all. Rather they come from seeds (like Canola or Rapeseed, Soybean, Sunflower, Safflower, Rice Bran and Grape). The dead give-away is often that they will make claims about the food containing ‘essential fatty acids’.
Omega-6 fat is the dominant fat in the ‘vegetable oils’ used in every processed food and in most dog foods. And there is ample evidence in both human and animal trials that omega-6 fats degrade sperm quality.
These Omega-6 based seed oils are the fat of choice for the processed food and the pet food industries because they are a lot cheaper than fats from animals and exotic fruits like olives, avocados and coconuts. As a result, human consumption of Omega-6 fats has at least tripled in the last century. We have no long term data on vegetable oil consumption by dogs. But it is not unreasonable to assume it is similar since, packaged dog food has only really been available since the end of the first World War and only the cheapest possible ingredients are used in most pet food.
While sperm quality is important to dog breeders (and humans who might want kids), I suspect it’s not of much concern to pet owners in general. Sperm quality is however an early warning for a much nastier set of diseases increasingly linked to consumption of these oils. Chief among these is cancer.
In humans we have high quality evidence that people fed these oils are twice as likely to suffer from cancer as people who are not. And there is strong evidence that as the amount of it in our food has accelerated, so too have the numbers of us affected by cancer.
Similarly, in dogs the rates of the most common cancers have tripled since the late sixties. Cancer is at terrifyingly high levels in most pets now, affecting 1 in 4 dogs. And those are just the ones we know about (because they are insured).
Dogs don’t get to choose not to eat seed oils. But their owners can. And surprisingly it is the extremely cheap brands that are often seed oil free. Woolworths Homebrand dry dog food, for example, uses ‘Animal Fat’ rather than seed oils. If you avoid dog foods which include seed oils you’ll give your best friend his best chance at avoiding cancer.