Fermented foods and beverages are becoming increasingly popular. You can now find kombucha on tap in bars, sourdough bread in cafes and more varieties of yoghurt, sauerkraut and kimchi in your local supermarket.
But what are the heart health benefits and should you be including them in your diet?
Fermented foods have been part of the human diet for centuries, and were initially produced as a way to preserve foods, improve flavour and eliminate food toxins. Today, more people are turning to these foods for their potential health benefits 1, 2.
What are fermented foods?
Fermented foods are foods and beverages that have undergone controlled microbial growth and fermentation 1. Fermentation is an anaerobic process in which microorganisms like yeast and bacteria break down food components (e.g. sugars such as glucose) into other products (e.g. organic acids, gases or alcohol). This gives fermented foods their unique and desirable taste, aroma, texture and appearance.
There are thousands of different types of fermented foods, including:
- cultured milk and yoghurt
- wine
- beer
- cider
- tempeh
- miso
- kimchi
- sauerkraut
- fermented sausage.
Tempeh is made from fermented soy beans.
Sourdough bread is made from fermented dough.
Most foods can be fermented from whole foods like vegetables, fruits, cereals, dairy, meat, fish, eggs, legumes, nuts and seeds. While these foods are nutritious in their original form, through fermentation, they have the potential to carry additional health benefits – especially when they contain probiotics and prebiotics.
What are probiotics?
Many people know probiotics as ‘good’ or ‘friendly’ bacteria for the gut, with Lactobacillus and Bifidobacterium being the most well-known. Probiotics are live microorganisms or bacteria that provide a health benefit to the human body 4, 5.
Experts believe that most strains from commonly studied species, such as Lactobacillus and Bifidobacterium, benefit the gut by creating a more favourable gut environment 4. They also agreed that probiotics support a healthy immune system, however, some strains may be more effective than others.
Several other benefits such as supporting organ health (e.g. lungs, reproductive, skin) and mood are promising, but there is not enough evidence to say that all probiotics have these effects 4.
Many fermented foods contain probiotics because they are added or they naturally occur in the food. For example, Lactobacilli is a probiotic strain that is commonly found in yoghurt and naturally lives on the surface of some foods such as vegetables and fruit. This means that not all fermented foods contain probiotics, especially many commercially produced foods that are pasteurized, which kills any bacteria (along with their associated health benefits).
Yoghurt is made from fermented milk
What are prebiotics?
Prebiotics are food ingredients that the microorganisms in your body (e.g. gut bacteria) use or ‘feed’ on to grow and live, leading to health benefits 6. The most reported and researched prebiotics to have documented health benefits in humans are the non-digestible oligosaccharides fructans and galactans. 6.
Good sources of these include:
- asparagus
- garlic
- onions
- wheat
- chicory
- Jerusalem artichokes
- tomato
- barley
- honey
- rye
- milk (human and cow’s milk).
However, most fruits and vegetables, and legumes contain some type of prebiotic 7. As with probiotics, prebiotics have primarily been associated with improving the gut environment 6.
Garlic, onion, asparagus and leeks are examples of prebiotic foods.
What are the benefits of fermented foods?
Fermented foods have historically been valued for their improved shelf life and unique taste, aroma, texture and appearance. They also allow us to consume otherwise inedible foods. For example, table olives must be fermented in order to remove their bitter-tasting phenolic compounds.
Many health benefits have been associated with fermented foods, including reduced risk of cardiovascular disease, high blood pressure, diabetes, obesity and inflammation. They have also been linked to better weight management, better mood and brain activity, increased bone health and
better recovery after exercise 1, 3. When looking at heart health, probiotics may help to decrease total and low-density lipoprotein (LDL) cholesterol however the evidence for this is still very limited 8.
One explanation for all of these effects is the production of bioactive peptides, vitamins and other compounds produced by the microorganisms involved in fermentation and have key roles in the body, such as blood health, nerve function and immunity.
It’s important to remember that these health benefits are likely dependent on the type of fermented food and microorganisms involved. For example, yoghurt consumption has been associated with reduced risk of type 2 diabetes 9-11, while fermented milk that contains Lactobacillus helveticus has been associated with reduced muscle soreness 12.
Kombucha is made from fermented green or black tea.
How can I eat more fermented foods?
Although fermented foods may sound fancy, the practice of fermentation is actually simple and affordable. It only requires a few ingredients and when done at home, can save you a lot of money, while adding variety, new flavours and interesting textures to your diet. Vegetables such as cabbage, beetroot, radish, turnip and carrots are some of the easiest foods to ferment at home, as the bacteria living on the surface does the fermenting for you.
Try making your own sauerkraut, kimchi and pickled seasonal vegetables, including prebiotic-rich foods such as onion and garlic to add flavour and extra health benefits.
This is a great way to experience the benefits of fermented foods while including more vegetables in your diet.
Despite fermented foods being nutritious foods, there is no single food that improves our heart health – it is our overall diet.
Fermented foods are best eaten in the context of a heart-healthy eating pattern that emphasises vegetables, fruit, whole grains in place of refined grains, legumes, nuts, seeds and oily fish.
Kimchi is made from fermented cabbage.
Jeanette Rapson, NZRD
Cooking Curriculum Project Coordinator
I am currently completing my PhD research at Massey University on vegetables as first foods for babies.
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8. Cho, Y.A., Effect of Probiotics on Blood Lipis Concentrations: A meta-analysis of randomized controlled trials. Medicine, 2015. 94(43):e1714
9. Chen, M., et al., Dairy consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis. BMC medicine, 2014. 12(1):215.
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10. Soedamah-Muthu, S.S., et al., Consumption of dairy products and associations with incident diabetes, CHD and mortality in the Whitehall II study. British Journal of Nutrition, 2013. 109(4):718-726.
11. Iwasa, M., et al., Fermented milk improves glucose metabolism in exercise-induced muscle damage in young healthy men. Nutrition journal, 2013. 12(1):83.