"There's only one hard and fast rule in running: sometimes you have to run one hard and fast."

Saturday, January 24, 2009

Minnesota Fats

Sorry, this post's not about Jackie Gleason's role in The Hustler. I just needed a title. I've been considering starting another blog about diet and nutrition, but I worry about all the crazies it might attract. This is sort of what a post on it might look like. I'm thinking of calling it "I can't eat that!"

The skinny on fat
It was only a short time ago that all fat was considered good. During the depression of the 1930's, fat was at a premium as a source of calories and of taste. Then, all fat became bad. Then some fats became good again. I expect that soon there will be dozens of different ways to classify fats as good or bad and all of them will conflict.

First, let's start with the fact that your body can make fat, but there are some fatty acid components of some fats that it can't make. One class of these are omega-3 fatty acids and another omega-6. Your body can make all omega-3's from alpha-linoleic acid (ALA) and all omega-6's from linolenic acid, so there are only two fats your body needs to get from food.

Omega-6 fatty acids aren't talked about much, but are necessary for forming parts of some cell walls (especially in nerve cells) and the chemical messengers known as prostaglandins. The most concentrated source of linolenic acid is herring (and the obscure fish menhaden), but is present in small quantities in a variety of foods, especially whole grains. Soy, wheat germ, safflower oil, mustard and rapeseed [rapeseed got renamed canola, but canola oil processors insist that their oil comes from the canola bean, not rapeseed] are good sources. There is some omega-6 in all animal-based foods, but usually it's surrounded by saturated fat.

Saturated fat has become the one thing nutritionists all seem to agree one should avoid (as well as trans-fats, which come from chemically hydrogenating other fats; trans-fats can be argued to not even be food). Saturated fats are linked to heart and vascular diseases in several ways, one of which is related to increased amounts of serum cholesterol. Oddly, the high-fat Atkins diet was found not to increase cholesterol, but this was true only for those who were actually losing weight; when losing weight, saturated fat is turned into energy, rather than stored.

Omega-3 fatty acids are all the rage at the moment and most Americans could use more in their diet. The current recommendation is consumption of 1 gram (9 calories) of omega-3's each day. That's not much! Americans are buying fish oil and flax oil supplements in large quantities to get omega-3's, but it's easy to get enough with a decent diet. Some claim that fish oils, which contain EPA and DHA (eicosapentaenoic acid and docosahexaenoic acid) are better for one's health, but one's body can readily make these from ALA. These oils go rancid extremely fast, developing a "fishy" smell and sometimes cause fishy burps.

Good sources of omega-3's are herring, sardines, salmon, mackerel, trout, cod-liver oil, scallops, purslane (a green you're more likely to find growing in your lawn than in a store), flax, walnuts, squash, swiss chard, kale, dried beans, lamb, soy, canola oil and, if desperate, omega-3-enriched eggs. Evening primrose and borage are supposed to have omega-3's as well, but there's some argument about these. Flax seeds must be ground to be digestible and go rancid quickly.

One should limit saturated fat as much as possible and one only needs a small amount of omega-3's and omega-6's, which leaves other monounsaturated fats and polyunsaturated fats. Polyunsaturated fats have been found lately to be required in small quantities but can lead to health problems in very high quantities (more than 10% of one's calories); they can be found in almost all foods, but are highest in some nuts and seeds. A varied diet will inevitably contain all the polyunsaturated fats one needs; if not, one's body can make them from monounsaturated fats.

This leaves monounsaturated fatty acids (MUFA) for the majority of the fats one should eat. These are very high in nuts, seeds, avocados and olives. For cooking oils, olive and canola are highest in monounsaturated; canola is slightly higher, but olive oil has polyphenol antioxidants as well (if you really want to have the highest amount of antioxidants, one should get "propeller-expressed, cold-pressed, extra virgin olive oil"... or just eat olives, which have other nutrients, if more salt). Nuts, such as almonds, have the advantage over vegetable oils in being laden with vitamins and minerals. There's a current diet based upon MUFAs that includes chocolate; there's a lot of good to be said about chocolate, but it's a poor source of MUFAs.

On second thought, who needs another source of dietary information?

Addendum: other sources of omega-3's: canola oil, hemp oil, sea vegetables.


nwgdc said...

I'm not positive, but I'm pretty sure there is no "canola seed." "Canola" is a term coined by the makers and it has something to do with Canada and Oil, if my memory serves me correctly.

wildknits said...

Very interesting! Now, what type of herring???? Living with a commercial fisherman (Lake Superior herring- Coregonus artedii- otherwise known as cisco, tullibee, freshwater herring) my diet can be quite rich in herring ;->

I am curious about this - and all things dietary for personal and professional reasons. And there does not seem to be much information about the nutritional composition of herring out there.

wildknits said...

Found a list from the Mn Sea Grant that places Lake Herring on the "high N-3" (omega-3 fatty acid) list.

In another article they go on to say they are low in contaminant and available almost year round. Think of what that means for the fisherman: heading out into a Lake Superior storm to check the nets.

So, Steve - thanks for spurring me on to do some more research about the fish that graces my dining room table quite often!