Monday, March 17, 2014

Two types of oil misunderstood: Canola and coconut

Oil Facts:
1. Canola oil is not considered harmful from a toxicological aspect. In fact it's quite healthy!
2. Coconut oil, on the other hand, is not so good for your health.

Information for those who want to read a little bit more:

Canola oil
- Produced from a cultivar of "rapeseed" which is with low erucic acid content (The mustard plant)
- Erucic acid, for those who are unfamiliar with it, is a naturally-occuring omega-9 fatty acid, with a chain length of 22 (denoted as C22:1 omega-9), has not been reported to be associated with human toxicity. It appears to be toxic to mice[1].
- Current cultivars of rapeseed contain only trace quantity of erucic acid (less than 0.1%).
- Other purported toxins in rapeseed includes glucoinolates, which are said to be goitrogens (resulting in a goitre, toxic to the thyroid gland). These are at very low levels in modern rapeseed plants, which contain less than 10 umol/g, compared with broccoli, a common plant containing glucoinolates in the order of 10 mmol/g (dry weight), a 1000x difference. If you can eat broccoli, glucoinolates in canola oil is probably OK.
- It is low in saturated fat, and contain a favorable profile of omega-6 and omega-3 fatty acids.
- It has a fairly high smoke point (204 C), which is about 10 degree higher than cooking (non-extra virgin) olive oil.

Coconut oil
- It contain 91% saturated fat, the highest of all natural oils (excluding those that are hydrogenated). Taking saturated fats *cannot* be very good for your health.
- It does contain a blend of medium chain fatty acids, some of which are good (and some of which are bad) for the heart. One should also note that the famous "heart-killer" BUTTER also contain some 10% of myristic acid, which are said to be a health-promoting component of coconut oil.
- Yes, it's probably healthier than butter, but probably less healthy than even the evil canola oil mentioned above.

Some general facts of oil-making
- Other than cold-pressed oil, most oil produced nowadays include a step of solvent extraction using organic solvents such as hexane, absolute alcohol, and so on. Hexane contamination in oil is usually insignificant. Hexane is probably the least of your worries in your daily diet if you asked me. The air you breath is probably more harmful than the hexane in oil if you live in Hong Kong, given the recent pm2.5 readings.

[1] Chocolate is toxic to dogs. There are a lot of stuff that are toxic to one species and not to other. If you look into your mice biology textbook, you will get to know that they do not digest vegetable fat as well as a lot of other animals.

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