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Cardiac diets – what does the science say?

Recent advancements in science and discoveries around how nutrition affects the health of the heart in both dogs and cats has driven the production of new therapeutic diets. Purina Institute recently released their findings that a nutrient blend appears to improve heart health in pets with chronic heart disease, and can even slow and prevent the development of the condition in at risk breeds.

I was speaking with a veterinary cardiologist recently, who nonchalantly mentioned ‘nutrition doesn’t really seem to help heart conditions much anyway’. I was left a little agape, nutrition is the cornerstone of health. Good nutrition doesn’t just improve health conditions – it stops them in their tracks. With so much research being done in this department with the FDA investigation into grain free diets and heart disease, and now the Purina Institute looking into how nutrition supports heart health, I think its a topic we should delve a little more into.

First off, how does nutrition affect the heart and heart function, and how can nutrition be used as a treatment and prevention of common heart conditions?

Nutrition and the heart

The heart is a muscular organ – it needs to be fed just like any other muscle in the body. However, the type of fuel it uses appears to be unique to other muscles in the body. Being under a continuous workload, the heart has a much higher resting energy metabolism than any other organ in the body and requires a huge range of nutrients to keep it pumping and its cells producing energy (known as ATP).

In the late 1980’s we discovered that a deficiency in an amino acid called taurine triggered the development of dilated cardiomyopathy in cats – this subsequently led to the inclusion of taurine in all cat foods being required by law and highlighted the importance of nutrition in the prevention, and treatment of heart disease in companion animals. For dogs, this amino acid is not a requirement as they are able to make taurine from other amino acids – cysteine and methionine. Beyond taurine, amino acids such as lysine and methionine are also vital in cardiac health; these amino acids help synthesise carnitine which helps transport long chain fatty acids to the mitochondria for ATP production.

But nutrition for heart health doesn’t just stop at amino acids; to keep the heart pumping, the organ requires energy in the form of ATP (adenosine triphosphate). It’s not just protein that provides energy to muscles, in fact the heart appears to source energy from a variety of different nutrients – recent research found that the heart actually primarily uses fatty acids as an energy source! What this means is that the mitochondria (energy-generating cells) in the heart uses fatty acids as a substrate to convert into ATP, the body’s useable energy source. This research also shows us that mitochondria is flexible in what it uses to convert to ATP and depending on the availability of nutrients in the diet, cardiac workload and altered metabolic conditions, the mitochondria may use ketones, glucose or branched chain amino acids instead.

Another vital nutrient that must be present in the diet is Vitamin E – this vitamin is always supplemented in pet food because there is no source in nature that can provide the levels that pets require in their diet, but did you know it also plays a role in heart health? When cells undergo metabolism, they produce Reactive Oxygen Species (ROS); these molecules can accumulate and cause oxidative stress in the body, damaging cells, DNA and proteins. When the mitochondria is dysfunctional or under stress, heart failure progresses. Vitamin E is an antioxidant and scavenges ROS to prevent oxidative stress, which in turn, protects the heart from harm and reduces the progression of heart failure.

Heart conditions and the role of diet

When we talk about heart disease, this is just a general term for a number of different conditions. So when we are thinking about what we can do nutritionally for our heart disease patients, we need to first think about what condition we are talking about as the nutritional factors of each condition is a little different. First up, what types of heart disease can affect our pets?

How do I choose a diet for my cardiac patient?

Source: Small Animal Clinical Nutrition, Chapter 36 – Cardiovascular Disease

For any cardiovascular disease, it’s important to ensure that all the above nutritional factors are met. There’s countless reasons a pet may be deficient in these factors; gastrointestinal issues, the inability to synthesise them effectively, poor intake and absorption, etc. So, before supplementing it is important to assess the pet’s diet and make any adjustments if it’s lacking. My golden rules for diets in patients with heart disease:

It’s always ideal to try and change the diet before supplementing individual nutrients, as per the Purina Institute research – it’s how the nutrients work together as a complex, rather than any one nutrient, so I strongly recommend changing to a cardiac diet where possible. If feeding grain free, I recommend to switch off this entirely as the evidence we currently have shows that a diet change can either partially or entirely reverse this form of heart disease. The above values give a guide if seeking a diet that will still work for heart disease but may not be a prescription diet for the pet’s condition.

Still confused about what to feed a heart disease patient? Read more in the Small Animal Clinical Nutrition textbook – Chapter 36 on Cardiovascular Disease. This textbook is always being updated to reflect the latest research we have on pet food and nutrition, so do check it out.

What are your golden rules when choosing a cardiac diet? Leave them in the comments below!


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