13/11/2025
HOW TO CHOOSE A TUNA PRESERVE
In the photo below which I took in a nearby store, you see two different forms of tuna preserves in glass jars with olive oil. On the left (bright yellow) jar a more expensive organic higher quality less oxidised extra-virgen olive oil. The right one is cheaper, but contains possibly higher oxidised lower quality olive oil (paler colour).
Olive oil (rich in oleic acid) is emulsified by bile salts and broken down. These are absorbed by intestinal cells, and re-formed into triglycerides and repackaged into chylomicrons transporters that enter the lymphatic system and then enter the bloodstream. Enzymes on the blood vessel endothelium breakdown the chylomicron triglycerides releasing free oleic acid to:
1) Muscle tissues which oxidises them for energy.
2) Fat tissues which re-forms triglyceride for storage OR
3) Endothelial and immune cells incorporating them as membrane phospholipids.
If the olive oil you consume is lower quality (including other refined seed oils), there is a higher risk of post-prandial (hours after eating) oxidation and inflammatory responses which can raise cardiovascular risks longer-term, possibly even acutely with an underlying heart condition.
Conversely, a large body of research suggests that higher quality, high-polyphenol extra virgin olive oil also protects the cholesterol carriers in the blood from oxidation, known as low-density lipoproteins, and by doing so supports endothelial health and integrity, and meaningfully lowers heart disease risk over time.
A note about choosing tuna in a glass jar. By choosing a glass jar as opposed to canned, you considerably reduce exposure to epoxy resins which line the inside of the can, made with bisphenol A (BPA) and other deleterious compounds, endocrine disruptors strongly linked to poorer metabolic health, obesity, and higher risks of hormone-related cancers.
Keeping the tuna jars in a dark environment away from strong light or high temperatures also helps reduce oxidation of the oils. Once opened, it is best consumed quickly, or close the jar tightly to avoid oxygen uptake that can increase oxidation.
Take home message - quality matters! Paying that little bit extra for higher quality olive oil makes a cumulative difference for cardiovascular, metabolic, and endocrine health, so don't be a cheapskate! Just because you cant feel it, dosen't mean the benefits / risks are not happening.
Want to learn more about nutrition therapy to optimise your health? Get in touch for a consultation.
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