Natural Flea Control With Yeast

There are many options for natural flea control. While I always prefer natural methods to deter fleas, my experience with natural methods is that few of the treatments work on their own. Most require a “multi-modal” effort. This means that you have to attack the problem from all sides in order to have the most success. You must treat the environment (safely) while also improving the health and in particular skin health of the pet in order to have the greatest chances of success.

Today I share with you just one of the many ingredients to a successful flea deterrent strategy: Yeast.

Yeast is an old method with anecdotal evidence in repelling fleas and ticks. While the actual scientific evidence is lacking (only one study performed in the 1980s), adding yeast to the diet can help fill a valuable nutritional gap. Vitamins and minerals in processed dog food are often lacking. Nutrients are destroyed and degraded both during the high heat processing and with long storage times. For this reason, adding an additional source of B-vitamins to your pet’s diet in the form of yeast can be beneficial.

Yeast on its own may or may not be enough to repel insects. However, because of its added nutritional benefits, I believe it is an important component of a multi-modal flea and tick repelling strategy.

Let’s take a look!

There are two types of yeast that are commonly used as flea repellants: Nutritional Yeast and Brewers Yeast. Both are derived from a species of yeast called: Saccharomyces cerevisiae. Yeast contains multiple B-vitamins but in particular, Vitamin B1, which is also known as Thiamine, which is purported to repel fleas, ticks, mosquitos, and other common pests when ingested.

Some say that insects like fleas do not like the smell of Vitamin B1. Others say it is the yeast smell the insects do not like. However, in regards to the second point. In my experience as a veterinarian, dogs with yeast overgrowth on their skin still have problems with fleas, so I am not certain how much the yeast smell theory is true.

While Brewers Yeast and Nutritional Yeast are technically derived from the same type of yeast, they are not the same product. Let’s take a look at their differences:

Brewers Yeast For Natural Flea Control

Brewer’s yeast is used to brew beer. It is grown on malted barley or other grains. The dead yeast cells leftover from the brewing process can be consumed as a nutritional supplement but have a bitter taste. De-bittered Brewers yeast is available, although this reduces the amount of some of the nutrients in the product.

Brewer’s yeast is rich in B vitamins (B1, B2, B3, B5, B6, B7, and B9) and antioxidants. It promotes healthy skin, hair, eyes, and liver function in humans and pets. The high levels of B vitamins may reduce anxiety in dogs. It is also high in selenium, potassium, chromium, iron, zinc, and magnesium. These minerals are essential for a variety of cell and organ functions as well as overall good health. It’s important to note that brewer’s yeast does not contain B12, a necessary vitamin found in animal products, and sometimes added to nutritional yeast.

This yeast comes in an active (alive) and inactive (dead and dehydrated) forms. The active form can act as a probiotic and is sometimes used for diarrhea and irritable bowel syndrome in people. Studies in rats have shown it might counteract Clostridium Difficile overgrowth.

While the exact mechanism of keeping fleas away is not yet well known, it is believed that insects in general might be more attracted to pets with poor overall health. Brewers yeast has a high nutritional value as it is rich in B vitamins and minerals, which are essential for the overall health, metabolism, but also hair and skin structure. This nutrient fortification may repel fleas and ticks, or it may be the scent as some people believe.

All of that being said, One Study from 1983 found that adding Brewer’s yeast to the diet did not repel fleas. The study did find that dogs receiving active Brewer’s yeast had less fleas than those dogs that ate inactive Brewers Yeast.

Some have found that the combination of Brewer’s yeast with Garlic works better to repel fleas and ticks compared to brewers yeast alone. It is good to find a brand of tablet that also includes Omega-3s. Improving the quality of the coat will in itself help to keep insects away.  While it doesn’t work for every pet, brewers yeast combined with small amounts of garlic appears to help some dogs repel fleas and is a safe option to try for them. However, it must be given daily for maximum effectiveness.

If you are going to choose this option, it is best to find a commercial product so that you know you are giving safe amounts.

Side Effects

Side effects associated with brewers yeast are relatively rare. However, in large dogs, it should be administered with caution as it could increase the risk for fermentation and gas accumulation. Small dogs can, too, develop digestive disturbances. 

It is not recommended to give brewers yeast in animals that:

• Are immunocompromised

• Have preexistent digestive diseases

• Are prone to yeast infections (on skin and ears),

• Are allergic to yeast

• Receive anti-anxiety medication

Brewers’ yeast is high in calories. Thus, in obese pets, the caloric intake needs to be reduced according to the quantity and caloric content of brewers yeast added to the meal. 

If your pet becomes itchy after starting Brewers Yeast, discontinue the product. If your pet is already itchy from the fleas, and becomes more itchy when you start Brewers Yeast, this likely means your pet has a yeast allergy (not uncommon in animals). 

Recommended Dose: 1 teaspoon per 30lbs of body weight. Decrease or increase accordingly based on your pet’s weight. 

Nutritional Yeast For Natural Flea Control

Nutritional Yeast is specifically grown to be a nutritional supplement. This yeast is commonly grown on molasses made from sugar or sugar beets. Sugar beets are a GMO food. Look for non-GMO Nutritional yeast to avoid Nutritional yeast that is grown on sugar beets.

Nutritional Yeast is naturally high in B-vitamins and other minerals. The yeast is also a complete protein. It is a common supplement for vegans and vegetarians who may not get enough protein or B-vitamins on a plant-based diet. Nutritional Yeast is killed during the manufacturing process. It has a cheesy, nutty flavor. Many pet owners have found that cats in particular love the taste of Nutritional Yeast and it can be used to entice even picky eaters to consume their food.

Even though Nutritional Yeast naturally has some vitamin B in it, it is often not in high enough amounts to be used as a nutritional supplement. It also does not contain vitamin B12, a common nutrient missing in vegan and vegatarian diets. For this reason, Nutritional Yeast comes in two forms: fortified and non-fortified. In the fortified versions, vitamin B’s and primarily Vitamin B12 are added to the formula. When fortified, most Nutritional Yeast can become a good source of vitamin B12 and other B vitamins.

Just like Brewer’s yeast, it is unclear how or if Nutritional Yeast helps to repel fleas. However, it may be a combination of the high vitamin B1 content or something about the odor. Nutritional Yeast also helps improve the coat by adding additional sources of vitamins and nutrients that may be missing in the diet. So even if it doesn’t help repel fleas or only helps a little, it will be a nice boost of nutrients for your pet.

Side Effects

Just like with any yeast, Nutritional Yeast is not always recommended for pets with a predisposition to a skin yeast overgrowth – either in their ears, between their toes or on their skin in general. If you introduce Nutritional Yeast into the diet and your pet becomes more itchy, they may have a yeast allergy. Symptoms should go away once the Nutritional Yeast is discontinued. Some gastric side effects such as increased gas may occur. If this happens, discontinue the supplement.

Pro tip: Cats love the taste of nutritional yeast! Sprinkle on top of food to entice even the pickiest of eaters to gobble down their meals.

Recommended dose: 1 teaspoon per 30lbs of body weight. Decrease or increase accordingly based on your pet’s weight.