Why is the Mediterranean diet good for our immune system? With special recipe: Spinach and Ricotta Ravioli with EVOO and Sage Sauce
The Mediterranean diet, possibly the healthiest diet around, has countless health benefits. Many of these involve the functioning of our immune system. You may think of the immune system as warding off colds, flus and infections and this is one of the important jobs along with many others, including managing inflammation and chronic disease (1). There is no one or even just a few foods to magically keep our immune system strong. We know many nutrients are needed for an optimally functioning immune system which is where the overall diet, such as the Mediterranean Style of eating, plays an important role (1).
What is the Mediterranean Diet?
The Mediterranean diet is a nutrition model that varies between countries and regions, but is characterized by an abundance of quality extra virgin olive oil, together with plenty of plant foods such as fruits, vegetables, legumes, cereals, nuts and seeds, moderate amounts of seafood, yoghurt, cheese, poultry and eggs and a low consumption of red and processed meats and foods rich in sugar, with moderate drinking of wine, mainly red wine enjoyed with meals. It is a diet fairly high in fat, around 40-50% of energy intake, mainly from monounsaturated fatty acids from olive oil. (2) (3) (4).
The Mediterranean Diet, the Immune System and Chronic Disease
Patterns of eating such as that of the Mediterranean diet are well researched and known for reducing the risk of many non -communicable chronic diseases (e.g. cardiovascular, rheumatoid arthritis, type 2 diabetes) that have chronic systemic inflammation as a key underlying feature (1), with some studies looking specifically at the benefits of daily EVOO (5).
Research has shown diets in contrast to the Mediterranean style diet, that are high in refined starches, sugars and poor quality fats, low in fruits, vegetables and wholegrains and low in omega 3 fatty acids, may increase the risk of chronic disease due to activation of the innate immune system, (the first line of defensive against non specific pathogens). This is likely to cause excessive production of cytokines (small secreted proteins that signal between cells of the immune system), that cause inflammation (proinflammatory), and a reduction in anti-inflammatory cytokines. (6). It seems the Mediterranean style diet helps keep the chronic systemic inflammation in control.
Vitamins and Minerals needed to support a strong immune system
There are many vitamins and minerals needed for our immune system, including vitamin A, C and E all abundant in the fresh fruits and vegetables of the Mediterranean diet. It is common knowledge that fresh fruit is a good source of vitamin C and red or orange coloured fruits and vegetables vitamin A, but where do you find vitamin E? In the Mediterranean diet vitamin E is found particularly in nuts and EVOO. Vitamin E, (like vitamin A and C also are), is a strong antioxidant and has a signaling role important in the immune system. (7).
The Mediterranean Diet, Gut Health and the Immune System
Around 70% of the body’s immune (8) cells are found in the gut. A healthy interaction between our immune system and the gut microbiota is crucial for the maintenance of our body’s homeostasis and health. There are many aspects of the Mediterranean style of eating that support our gut health.
Polyphenols role in immune health
A diet rich in fruit and vegetables such as that of the Mediterranean diet, is rich in many antioxidants including one important group of compounds that display antioxidant behavior; polyphenols. (1)
Where are polyphenols found?
Dietary phenols are found in plants; including fruits, vegetables, herbs, spices, extra virgin olive oil, cereals, tea, nuts, seeds, some grains, legumes and wine. These foods are typical of the Mediterranean diet, making it a diet rich in phenolic compounds. (9)
What do polyphenols do?
Polyphenols are known to have an important role in our immune system via regulation of inflammation (1). The bioavailability of dietary phenols compared to micro and macronutrients are fairly low with only 5-10% estimated to be absorbed in the small intestine with the rest passing to the large intestine where the microbiota metabolise them into smaller particles that can be absorbed. This is where the health benefits begin. These metabolites reach other tissues in the body signalling immune cells in different organs. This signalling can include anti-inflammatory effects which could be one of the ways polyphenols reduce the risk of chronic disease. (1)
The phenolic compounds in EVOO have been found to be very bioavailable. Oleuropein is a polyphenol found in EVOO and has been shown to have anti-inflammatory, antimicrobial and antiviral properties. (10)
Polyphenols may also help modulate the balance of gut microbiota by stimulating growth of good gut bacteria and reducing pathogenic ones benefiting the health of the gut lining. This reduces the risk of pathogens we don’t want entering from crossing into the blood stream.
Many of the health benefits of the Mediterranean diet are attributed to extra virgin olive oil and it’s monounsaturated fat content, however many of the antioxidant and anti-inflammatory benefits seem to be related to these very important phenolic compounds. (11)
The Mediterranean Diet, Prebiotics and the Immune System
Feeding of good gut bacteria is very important for a healthy immune system. Polyphenols act as food for the gut bacteria, when they are metabolised and so do other components of plant food called prebiotic fibre. A prebiotic is a type of fibre that must pass through the gastrointestinal tract undigested and stimulate the growth and/or activity of certain ‘good’ bacteria in the large intestine. (12).
Prebiotics are particularly high in certain plant foods such as:
- Legumes, chickpeas, lentils, kidney beans
- Vegetables such as garlic, onion, fennel bulb, leek and asparagus
- Fruit such as watermelon, nectarines, apples, pears
- Grains such as pasta, cous cous, oats, barley
- Nuts such as cashews and pistachios.
Many of these foods are regulars of the Mediterranean style of eating. (13)
Resistant starch is another type of prebiotic fibre. It is formed when we cook and cool pasta, potato and rice. Some of the fibre becomes indigestible and passes to the large intestines where the gut bacteria ferment it like they do other prebiotic fibres. A good reason not to throw away your left overs.
As the gut bacteria, ‘eat’ the prebiotic fibre they ferment it producing short chain fatty acids (SCFA) such as butyrate. This is the major source of energy for the colon, helping keep the gut lining healthy and preventing pathogens from invading. The SCFA also signal the immune system around the body as they pass through into the blood stream.
To support your immune system a Mediterranean style diet rich in plant foods and EVOO, that will provide vitamins, minerals, polyphenols and prebiotic fibre is key. This will support the body to not only ward off pathogens but will help to reduce chronic systemic inflammation involved in non -communicable disease.
In any style of the Mediterranean diet EVOO is used liberally in cooking of these plant foods; drizzling over vegetables, salads, legumes and grains to not only add nutrients but to increase absorption of nutrients and to most importantly enhance flavour. After all it is the flavour that is what makes the Mediterranean Diet most appealing and sustainable for the long term.
Spinach and Ricotta Ravioli with EVOO and Sage Sauce
3 cups ricotta cheese
1 cup grated Parmesan cheese (finely grated)
1 large egg
1/2 teaspoon salt
1/2 teaspoon ground black pepper
175 grams of frozen chopped spinach
1 pack of 50 Gyoza dumpling wrappings
1/2 tablespoon garlic infused extra virgin olive oil
80ml extra virgin olive oil
2 tablespoons butter
60 grams almonds (roughly chopped, or any nut of your choice)
2 tablespoons fresh sage leaves
½ a lemon squeezed, juice
Parmesan cheese (Extra, grated)
Mix the ricotta cheese, spinach, egg, grated Parmesan, garlic infused Extra virgin olive oil, salt and pepper together in a large mixing bowl and mix until combined.
Take one Gyoza wrapper and place a teaspoon or so of ricotta mixture in the middle. Brush the edges with water. Fold over to form a parcel and press the edges to seal so you have a half circle shape.
Continue with the remaining wrappers and filling. Place the ravioli on a tray lined with baking paper so they don’t stick and separate layers if placing on top of each other with baking paper to avoid sticking together.
Bring a large saucepan of water to the boil adding a touch of salt. Add in the ravioli and cook for around 6minutes. The ravioli will float to the top.
While waiting for the water to boil add the extra virgin olive oil and butter into a medium heated pan and cook until the butter starts to brown. Add in the sage leaves. Cook until the sage leaves are almost crispy. Add in the lemon juice and remove from the heat.
When the ravioli are cooked, use a slotted spoon and place them into the pan covering with the sage sauce. Sprinkle with extra parmesan cheese if desired.
Serve on warm plates with a side of green salad or vegetables.