Sunflower seeds and coconuts-- good for more than eating?

In the email Peter Lio sent me the other day, he mentioned that he is getting excited about the potential of two natural products: sunflower oil and coconut oil. He sent me references to two research papers on the topics.

Since sunflower and coconut oils are both edible, I imagine the risk of adverse effects (unless you're allergic to them) is pretty small. And they're oils, so that means they can work as emollients, and soften the skin and reduce transepidermal water loss. I'd like to know how they work in this dimension compared to commercial moisturizers-- does a lot rub off? (I have a problem with my clothes getting greasy) and how often do you have to apply them?

The most interesting thing is that these oils may have special properties; apparently coconut oil contains a fraction with antimicrobial activity, and in one study with a small number of patients, was shown to reduce Staph. aureus colonization.

Sunflower seed oil may be slightly more complex; or perhaps it's just that in the review paper I read, the authors covered a lot of research considering different aspects of sunflower seed oil. Let's call it SSO for short. The point of review's authors is that SSO is actually good for eczema treatment, but allow me to digress for a paragraph.

/Start digression The main component of SSO is the "essential" fatty acid linoleic acid. The authors point out that linoleic acid can be converted to arachidonic acid, a precursor of prostaglandin E2, which they say is a "known modulator of cutaneous inflammation." Indeed it IS a modulator-- PGE2 is a vasodilator and used clinically to induce erections and hasten birth. The review paper considers pediatric use, though, so let's assume those aren't going to be issues. (I'm just pointing out that you can't vaguely say "oh, this lipid turns into something that is INVOLVED in modulating inflammation," and expect me to rub it all over my skin when the compound concerned CAUSES inflammation.) /End digression

The lead author of the study works at Rady Children's Hospital at UCSD, home to a famous pediatric eczema center, so he's probably not a kook. Let's look at some positive aspects of SSO the authors highlight: a number of studies show that in a 2% formulation, SSO has anti-inflammatory properties equivalent to a "mid-potency topical steroid" and, when used in tandem with an actual steroid, can enable the same effective strength for 25% of the original steroid dosage.

This former grad student has some questions for the speaker.

• Steroids are related to cholesterol-- is anyone sure that SSO doesn't contain a certain percentage of "natural" steroid that is causing these effects? (And could have the same side effects as an "artificial" steroid?)
• Is there more than one active component? One or more of the major lipids, or some drug-like compound present at a small percentage?
• I'd like to see a breakdown of what's in that "2% sunflower oil distillate." The scientists seem to be mixing SSO with a bunch of lipids that are essentially the same thing as SSO, but also adding some nameless "phytosterols" and vitamin E.
• Who decided that 2% formulation was the ideal composition? And, most importantly, where's the dose dependence data? In drug trials, it's key to show that the magnitude of therapeutic effect increases as you increase the dosage of drug-- that indicates that it's the drug that's making it happen, and not something else you hadn't considered. I don't see any mention of dose dependence in this review.

OK, I've evidently developed a skeptical reaction, which I honestly didn't have to begin with. Sunflower seed oil-- I'm going to need some more evidence that there's anything behind the claims. It's not going to be anyone's miracle cure, but there's always the possibility that a natural product is hiding some magical ingredient.