So, it turns out that Omega 3 fatty acids might influence heart rate because they inhibit myocyte voltage-gated sodium channels and prolong the relative refractory period…
What on earth is that supposed to mean?
We know that sometimes scrolling the internet can give you more questions than when you started with, so we’re going to take out the hard work for you.
The bottom line is that omega 3’s are particularly useful for heart health, but of course, we want to know why, so let’s take a look at what the evidence says.
First of all, let’s look at the function of the heart.
The heart is an organ that pumps blood throughout the body via the circulatory system, supplying oxygen and nutrients to the tissues and removing carbon dioxide and other wastes.
The heart circulates blood through two pathways: the pulmonary circuit and the systemic circuit.
In the pulmonary circuit, deoxygenated blood leaves the right ventricle of the heart via the pulmonary artery and then travels to the lungs, returning as oxygenated blood to the left atrium of the heart via the pulmonary vein.
In the systemic circuit, oxygenated blood leaves the body via the left ventricle to the aorta, and then enters the arteries and capillaries where it supplies the body's tissues with oxygen. Deoxygenated blood returns via veins to the venae cavae before re-entering the heart's right atrium.
The heart is a muscle, so it needs a fresh supply of oxygen and nutrients.
After the blood leaves the heart through the aortic valve, two sets of arteries bring oxygenated blood to the heart. The left coronary artery branches into the left anterior descending artery and the left circumflex artery. The right coronary artery branches out on the right side of the aorta. Blockage of any of these arteries can cause a heart attack, or damage to the muscle of the heart.
A heartbeat is produced by electrical pacemaker cells which cause the heart to contract. Calcium plays an important role here. Calcium enters the heart muscle cells during each heartbeat to contribute to the electrical signal to contract. In short, calcium produces contraction. A mismanagement of calcium is usually what contributes to heart rhythm disorders and abnormal calcium movement can directly impair contraction or relaxation, hindering the normal pump actions. This is when the heart, for want of a better word, becomes tired and can result in heart failure. But we also know there are genetic factors that also contribute to heart issues in our dogs.
Signs and Symptoms of Heart Issues in the Dog:
- Dry cough
- Shortness of breath
- Restlessness when sleeping
- Rapid weight loss
- Potbelly (caused by fluid build-up)
- Rapid tiring
- Fatigue
If you are concerned about your dog, then it is vital to seek Veterinary attention and advice
How Can Omega-3 Fatty Acids Support Heart Health
As we know, prevention is better than cure, so including beneficial foods in a dog’s diet can support their overall health, including heart function. If you dog has already been diagnosed with an existing health issue, then it’s important to discuss the addition of any new products or supplements alongside any medications with your Vet.
The 3 main omega-3 fatty acids that are beneficial for heart and cardiovascular health are α-linoleic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).
ALA is primarily found in plant-based foods such as olive, soybean, canola, walnut, and flaxseed oils (that we have in our Proflax Blends), and in walnuts and flaxseeds as well.
EPA and DHA are primarily found in marine-based foods like fatty fish such as tuna, salmon, mackerel, herring, trout, halibut, and cod.
How Omega-3 Fatty Acids May Affect the Heart:
- Lower triglyceride levels, increase HDL (ie, good cholesterol)
- Lower resting blood pressure
- Decrease platelet aggregation and prevent blockage of coronary artery
- Decrease risk of arrhythmias (abnormal heart rhythm)
- Increase compliance of arteries
- Decrease atherosclerosis
- Reduce inflammatory markers
There is evidence of rapid declines in coronary heart disease mortality with the consumption of oils rich in alpha-linolenic acid, such as flaxseed oil. https://pubmed.ncbi.nlm.nih.gov/17955332/
Studies have demonstrated a significant reduction in risk of sudden cardiac death in humans consuming the most linoleic acid. A diet rich in linoleic acid has been associated with a lower incidence of calcified coronary plaques along with a reduced risk of cardiovascular mortality, which subsequently lowers the all-cause mortality levels in humans. https://pubmed.ncbi.nlm.nih.gov/21076723/
In Humans, the Lyon Diet Heart Study is perhaps the most well-known, and it separated 605 myocardial infarction survivors into two groups, one group was placed on a low-fat diet, and the other on a Mediterranean diet including margarine enriched in linolenic acid (1.1 g/day). After a two-year follow-up, the incidence of cardiovascular disease, including cardiac mortality, decreased dramatically (73%) in the intervention group. This raised the possibility that the inclusion of linolenic acid in the diet can significantly improve cardiovascular health.
Whilst there are some key differences between humans and dogs, there is also evidence of the benefits in dogs too.
The point worth noting is there are known differences in plasma concentrations of fatty acids between breeds. For example, one study demonstrated higher plasma concentrations of γ‐linolenic acid in Boxers but lower concentrations of arachidonic acid and total omega‐6 fatty acids compared with Doberman pinschers. https://pubmed.ncbi.nlm.nih.gov/18241015/
Dogs with heart failure have been shown to have relative deficiencies in certain fatty acids and it is considered that as dogs have an increased capacity to use fat as energy, they can easily switch to allow fatty acids to become the major energy source in the adult heart. Without this fuel, the heart suffers.
Evidence has suggested that omega-3 supplementation has reduced the incidence of atrial fibrillation in dogs and as we know, atrial fibrillation is a heart condition that causes an irregular and abnormally fast heart rate. https://pubmed.ncbi.nlm.nih.gov/15262826/
There is also data which suggests omega-3 supplementation significantly affects survival rates in those dogs suffering with heart failure secondary to DCM. https://pubmed.ncbi.nlm.nih.gov/18466257/
It is thought that the effect of omega-3 is multifactorial, but they include significant effects on sodium, potassium, and calcium channels. It is also considered that omega-3’s reduce platelet aggregation, which mitigates risks of clots and therefore won’t impede blood flow to the heart. https://pubmed.ncbi.nlm.nih.gov/7983618/
The evidence is clear, omega-3 fatty acids can support cardiovascular health, but there is evidence for both plant-derived fatty acids and fish-derived fatty acids.
Balance is key – so opt for fatty fish in your dog’s meals, whether this is tinned or fresh mackerel and sardines, together with plant oils such as chia or flaxseed oil.
Written by Lisa Hannaby - Bsc. Psych. Hons, MSc Human Nutrition