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Wednesday, January 28, 2004
Thanks to the Food Industry, Your Diet May Be Killing You (Part 3: In the Name of Shelf Life)
I'm not even going to discuss the issue of food additives and preservatives, a thorny, hotly contested one. Instead, I want to talk about how food itself is handled and modified, mechanically or chemically, in order to increase its shelf life.
Our food distribution system frees us from the limitations of seasonal foods, so our diets can be varied in all seasons as never before, even if we live in temperate climates. We can eat asparagus and strawberries in December, zucchini and eggplant in March, fresh herbs any time.
In addition, we can be pretty sure that the packaged foods we buy are free from rancidity, molds, and other unpleasantness, thanks to the magic of chemistry and food processing.
So what's wrong with increasing shelf life and making foods easier to transport?
Let's start with the produce department. If you've ever grown your own vegetables, bought them from a farm stand, or had home-grown vegetables given to you, you might have noticed that they seem to keep much longer in the refrigerator than do the veggies you buy at the supermarket. They keep their color, texture, and glossiness longer, and they even taste better when you do eat them.
That's because the produce you buy in most supermarkets is already fairly old. I don't know how old, but figure that it had to be shipped from a farm to some centralized packing and distributing location, where it's sorted, wrapped, boxed, possibly waxed, and loaded to be shipped again, this time to the supermarket (although there may even be intermediate stops). It sits around in some warehouse until it's needed, or it sits at the supermarket until it's time to fill the racks, shelves, and coolers of the produce department. There it sits some more, until someone buys it. (Most supermarkets have contracts with produce suppliers that actually prohibit them from using locally grown produce: thus the sad sight, for example, of limp, browning summer squashes at the height of the harvest season.)
All this time, the nutrients are fading right out of the vegetables, especially Vitamin C and phytochemicals, those mysterious substances we're just beginning to learn about and which play important roles in maintaining the body's health. There's nothing "dangerous" about this, but you should be aware that you're not getting the maximum nutrients out of days-old produce. In fact, it's possible that frozen or even canned produce is a better bet when it comes to nutritional content, depending on the age of the comparable "fresh" produce.
Another effect of sending our food over long distances is that vegetable varieties have been bred to make them more resistant to the effects of transportation. So we get tomatoes that bounce when you drop them, zucchini that's flavorless and watery but resists bruising, and green beans that just don't pack the flavor of home-grown but keep their firmness and color longer. Last summer we grew an old Italian variety of zucchini and were pleasantly surprised by its superior flavor and texture. But if you want those attributes, you have to grow your own or buy locally.
In part 2 I discussed trans fats, which undergo a process that turns them from a liquid into a solid at room temperature. Trans fats don't turn rancid with time, as other fats do, which is why they are so heavily used by food processors. Too bad that that longer shelf life translates into big trouble for your heart, should you ingest much trans fat.
But trans fats aren't the only fatty acids to be changed by food processing. Today oils are generally "refined" during processing in order to give them a longer shelf life. Unfortunately, what's removed are the omega-3 fatty acids, which are very vulnerable to oxidation and rancidity. You've probably heard of omega-3, since it's now thought to play a significant role in reducing heart disease. Well, good luck coming by it these days ... especially if you're limiting your intake of fish due to concerns about heavy metal and other pollutants. Cold-pressed oils, such as walnut oil and cold-pressed canola, can provide some, but you may not be able to find these in your local supermarket. It's worth going to a health-food store for cold-pressed oils. About the only cold-pressed oil most supermarkets carry is extra-virgin olive oil.
The one plant oil high in omega-3 is flaxseed oil, with a whopping 57% of its content as omega-3 fatty acids. But guess what? A new, "improved" flaxseed oil, Linola, has recently hit the market. The "improvement" is an improvement in shelf life--and the omega-3 fatty acid has been reduced from 57% to 2%! Some improvement.
I use extra-virgin olive oil and need to find a health-food store where I can buy flaxseed oil (flaxseed oil can't be heated, so it's used as salad dressing, etc.). I also buy a brand of eggs that has a higher amount of omega-3 fatty acids due to the diet fed to the chickens. What a shame that we now have to search out a substance that was once plentiful in our diets!
[Next: grains and cereals]
Monday, January 26, 2004
Thanks to the Food Industry, Your Diet May Be Killing You (Part 2: Hidden Dangers)
These are really nasty.
They are two to four times as damaging as saturated fats and are thought to be responsible for up to 10% of deaths from heart disease.
And they're in so many processed foods, accounting for 4% of calories in North American diets. Why? Shelf life and ease of transportation. They also increase the melting point of fat--good for deep-frying, which explains their attractiveness to the fast-food industry--and permit high temperature cooking.
Trans fats are made when hydrogen latches on to some of the double-bonded carbons in a fat molecule, changing them into single bonds. Some of the remaining double bonds twist into a new, straightened shape, giving the fat different chemical and physical properties.
Go right now and take a look at the packaged foods on your shelves or in your refrigerator. If you see the words "partially hydrogenated vegetable oil" in the ingredients list, you've got a product with trans fats. Trans fats are in most margarines, baked goods, peanut butter (except natural peanut butter), crackers, cookies, breads, chips and snack foods, fast-food french fries, etc.
Like saturated fat, trans fat raises your bad cholesterol. It's worse for you than saturated fat, because in addition to raising your bad cholesterol (LDL, or low-density lipoprotein), it lowers the amount of good cholesterol (HDL, or high-density lipoprotein). In addition, trans fats increase the amount of triglycerides and lipoprotein (a) in the bloodstream. Higher levels of triglycerides and lipoprotein (a) have both been linked with heart disease. And if that weren't enough, trans fats appear to make platelets (important in blood clotting) stickier and more likely to form clots inside blood vessels in the heart, brain, and elsewhere.
So alarmed did the U.S. Food and Drug Administration become about trans fats that it is now requiring trans fats to be labeled on foods:
Food manufacturers have until Jan. 1, 2006, to list trans fat on the nutrition label. FDA estimates that by three years after that date, trans fat labeling will have prevented from 600 to 1,200 cases of coronary heart disease and 250 to 500 deaths each year.Until trans fats show up on the nutrition panel, look for partially hydrogenated vegetable oil in the ingredient list, and be aware of just what you're ingesting.
One of the things that most galls me when it comes to fats in food is the case of peanut butter. We've bought natural peanut butter for decades, and for good reason. Not only does it taste a helluva lot better, but it contains peanut oil, something in short (nonexistent) supply in Jif, Skippy, and other big sellers. Those peanut butter processors remove the peanut oil, which can be sold at a tidy profit, and replace it with trans fat--and, usually, sugar in the form of dextrose.
Thanks to the Food Industry, Your Diet May Be Killing You (Part 1: Food Pyramid Myths and How They Got There)
Americans eat a lot of potatoes--about 140 pounds per person yearly. Many of these are in the form of fast-food restaurant french fries; many are in the form of potato chips.
The USDA's Food Pyramid includes potatoes in the vegetable group, recommending 3 to 5 servings daily from this group. For a lot of people, potatoes make up one or more servings of those vegetables.
Problem? The potato should be considered a starch and included not with vegetables, but with carbohydrates-- refined flours, white rice, white bread, and pasta--as it is in the Healthy Eating Pyramid. Says Walter Willett in Eat, Drink, and Be Healthy:
The venerable baked potato increases levels of blood sugar and insulin more quickly and to higher levels than an equal amount of calories from pure table sugar. French fries as they are usually sold do much the same thing, while also typically packing an unhealthy wallop of trans fats.Potatoes, unlike other vegetables and fruits, don't contribute to decreased chances of heart attacks and strokes, cancers, or digestive problems.
And when you eat a potato, the carbohydrates are broken down into their sugar components. Glucose is rapidly absorbed into the bloodstream, and the rise in blood sugar is followed by a rise in insulin. The insulin helps cells soak up glucose, causing blood sugar levels to fall. Eating that potato causes a veritable flood of insulin to flow and that drives glucose levels too low. At that point your stomach and brain start sending out hunger signals.
Unfortunately, many Americans now have a resistance to insulin that keeps blood sugar at high levels for longer periods and forces the pancreas to produce extra insulin in order to get the glucose into cells. The insulin-making cells in the pancreas may wear out and eventually stop producing insulin.
For active, lean people, starches like that in potatoes aren't much of a problem. For sedentary and/or overweight people, however, a diet high in carbs is bad news.
The fast-food industry is a big one, and it's already taken some heat for the epidemic of obesity we're seeing in this country, especially among children. But the fast-food industry shows no sign of letting up, and french fries are a big proportion of the profits. Similarly, the snack food industry depends on variously flavored potato chips to keep its profits high.
Already the Idaho Potato Commission has become alarmed at the low-carb diets currently in fashion and is waging a national campaign to boost sales. Global french fry sales are down 5 %, and the industry isn't happy about it.
The potato industry has a lot invested in pushing potatoes as a healthy food. And, in fact, for active, lean people, potatoes are a healthy food. Active, lean people can handle carbs well, whereas sedentary folks leaning toward obese simply can't. And potatoes don't offer anything that can't be gotten elsewhere and with less chance of a spike in blood glucose levels.
As long as the USDA Food Pyramid calls potatoes a vegetable, people will feel comfortable counting their servings of potatoes toward the "5-a-Day" (servings of fruits and vegetables) health campaign. Yet those potatoes won't contribute the preventive measures of other veggies and fruits, plus they'll cause your glucose levels to spike and contribute to possible insulin resistance. That can make it hard for you to lose weight, not least because you'll feel hungry again not long after eating such starchy, easily digested substances.
You really need to consider five servings of fruits and vegetables per day as a starting point, and potatoes shouldn't be included. They belong in the "use sparingly" category of refined grains, starches, and sugars.
Sunday, January 25, 2004
Ah, the Impartial Newsmongers ...
Go. Read. Try not to despair.