Sterols – The ‘Bargers’ in Olive Oil
admin | April 11, 2011My twin sister Cris is a ‘barger’. We all know one. You know – the person that always walks behind you, but as soon as a door is even slightly ajar, they seem to somehow be able to push their way through in front of you – usually achieving a bit of unwanted physical contact in the process. They’re so common I’ve often wonder why Sienfeld didn’t make an episode as a trilogy to their famous ‘high talkers’ and ‘low talkers’ episodes.
Plant sterols (or phytosterols), including those found in olive oil, are the ‘bargers’ in the context of cardiac health. Let me explain. The sterols that you find in olive oil are chemically very similar to cholesterol (which as its name suggests is also a sterol). They both have the same basic structure (that’s why they are all classed as sterols), but olive oil phytosterols have a few extra atoms attached to them as side chains hanging off the basic sterol structure. As it turns out, this similarity between cholesterol and phytosterols can ultimately work in our favour. This is how. Membranes in our body act like doormen. They allow the essential things that our body needs to function to pass from one place to another while at the same time restricting others. Some membranes allow cholesterol to pass through, but as it turns out, the phytosterols found in olive oil ‘barge’ in front of cholesterol when it tries to enter the open membrane doorway. And as they are chemically similar the ‘doorman’ lets them right through. By barging in, the phytosterols restrict the entry of unwanted cholesterol into the bloodstream. And lucky for us, those little side chains of atoms on the olive oil sterol make the world of difference when it comes to cardiovascular health.
The intake of phytosterols has been known to lower cholesterol adsorption for nearly 50 years. Phytosterols are now being artificially added to an increasing variety of foodstuffs – even ice-cream! However the most commonly encountered food fortified with phytosterols is margarine. When enough plant sterols from other sources are added to them they are often marketed as “lowering cholesterol absorption” or the like. (Incidentally all sterols are very fat soluble and completely insoluble in water. This is why phytosterols are always added to foods that have a high fat content).
The respected Australian Heart Foundation has an official position with respect to plant sterols. They say: ”Studies indicate that incorporating plant sterols into the diet may be an effective method of lowering total and LDL-cholesterol levels. By consuming plant sterols daily, adults may lower their LDL-cholesterol levels by around 10% depending on the age of the person. A reduced blood cholesterol level is associated with a reduced risk of CHD and stroke”.
The US FDA has also approved this statement regarding plant sterols: “Foods containing at least 0.4 gram per serving of plant sterols, eaten twice a day with meals for a daily total intake of at least 0.8 gram, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.”
So you can either stuff yourself with expensive ‘Frankenmarg’, eat fortified ice-cream (doesn’t sound right does it!), or you can make extra virgin olive oil a part of a balanced daily diet. The usual western diet contains around 0.2 to 0.3 g/day of plant sterols. A litre of extra virgin olive contains between 1 and 2 grams of phytosterols, so unless you glug olive oil like the average Greek (or are Greek), you can’t just rely on EVOO to get your daily hit of phyto’s- but it’s a start. Whole grain cereals and bread made from them are excellent sources, as are (wait for it – the not too phyto) shellfish. Nature does work in strange ways sometimes.
But if you like the idea of getting some phytosterols into you via the olive oil route, here are some things you might like to know.
EVOO sterol fact sheet
Major sterols (with approximate %’s):
ß-sitosterol (82%)
delta-5-avenasterol (10%)
campesterol (3-4%).
Total amount:
0.8g – 2.5g/kg, with an average of 1.5g/kg
Health benefits:
Lowers cholesterol absorption.
Other:
Total sterol content is dependent on variety.
Arbequina > Barnea > Frantoio=Corregiolla=Leccino=Manzanillo=Picual>Pendolino>Koroneiki
(Mailer 2007)
Some reports also suggest that olive oils from warmer climates contain more sterols than those from cooler climates.
Useful Reading
Kritchevsky and Chen (2005) Phytosterols—health benefits and potential concerns: a review. Nutrition Research 25, 413–428
Piironen et al. (2000) Plant sterols: biosynthesis, biological function and their importance to human nutrition. Journal of the Science of Food and Agriculture 80, 939-966.
Mailer (2007) The natural chemistry of Australian olive oil. RIRDC Report 06/132