Fun Fact - Oils and Digestion

The previous article described the three classes of macronutrients: proteins, carbohydrates, and fats. This article focuses on fats. As you recall, an oil or fat molecule consists of three chains connected to a glycerol backbone, like three long floppy pages of a book connected at the spine. each chain, on its own, is called a fatty acid, because one end is acidic, and when that acidic end joins with a glycerol backbone the result is a fat molecule. As you might expect, the property of the oil is determined by the property of the three fatty acids that comprise it. Long chains produce a higher melting point, thus the substance is a solid at room temperature. Solids are sometimes referred to as animal fats, while liquids, with shorter chains, are vegetable oils. But there is another variable. Saturated chains also have a higher melting point. Unsaturated chains, with double bonds between some of the carbon atoms, have a lower melting point. Vegetable oils are often unsaturated, with double bonds in the chains, thus they remain a liquid at room temperature. In summary, the fat on your steak has longer chains, and is probably saturated, while the oil in your frying pan has shorter chains, and is probably monounsaturate (one double bond), or polyunsaturate (many double bonds).

Butter is somewhat unique, in that it behaves like animal fat and vegetable oil at the same time. It is solid at room temperature, but just barely. You can melt it with the heat of your hand. Two thirds of its chains are saturated, and one third are unsaturated. Some chains are short, and some are long. One chain is unusually short, just 4 carbons long. This is the shortest chain of all the fats and oils. It gives butter its unique flavor, but it also contributes to the horrible smell and taste of rancid butter, as it separates from glycerol and is once again free butyric acid. In fact this acid is called butyric acid because it comes from butter.


Other 4 chain molecules follow this nomenclature. Butane, for instance, is the simplest 4 carbon chain, C4H10, with hydrogens all around. It is normally a gas at room temperature, but under modest pressure, just a couple of atmospheres, it becomes a liquid, and serves as fuel for your cigarette lighter. Replace H with OH at the end of butane and get butanol. replace two more hydrogens with double bond oxygen to get back to butyric acid. Put a methyl group on the third carbon to build 3 methyl butyric acid, a component of body odor. Thus the 4 chain molecules all inherit their names from butter, with butyric acid leading the way. Since butter is somewhat atypical, there are, perhaps, three classes of triglycerides: animal fats, vegetable oils, and butter.

Oils can be difficult to digest, but I didn't know that 30 years ago. If I had, our lives would have been so much easier!

The story began around 1980, when my future wife Wendy, in her late teens, could eat anything she liked. Then, as she moved into her twenties, she experienced episodes of uncontrollable diarrhea. these were infrequent, so rare in fact that she would attribute each occurrence to the flu, or something that just didn't agree with her, or some other random variable. She called in sick that day, because she could not leave the house. The next day was usually better. Sometimes her disorder was in remission for months, then she might have three bad days in a week. It was quite a mystery.

I married Wendy in 1991, and joined the investigative team. I wrote down everything she ate, and documented her reactions, but I couldn't see the pattern. After Beth was born in 1993, her disorder exploded into debilitating proportions. Wendy could barely leave the house, and when she did venture out, it was just a trip to the grocery store or some other essential errand. She memorized the locations of all the public bathrooms, and used them often. Unfortunately she had Beth with her (when I was at work), and carrying a babe in arms definitely slowed her down. Not trying to be graphic here, but sometimes she didn't make it. Today, with hindsight, we know why she had so much trouble after Beth was born, but we had no clue at the time. Beth had terrible colic, sometimes crying from 6 AM to 11 PM. It was unrelenting, and we were both sleep deprived. I'm not talking about a month of colic; she started the day she was born, and it lasted for 7 months. There was no time to cook, so we ate fast food, and take out, and box meals like Kraft Mac&Cheese and Hamburger Helper. The change in diet explains everything, now, but when Beth was crying non-stop, well, in the words of Paul Simon, "It's a wonder I can think at all."

No, I didn't try to go it alone. I'm not that macho / stupid. We went to doctors, and they were baffled as well. After many tests, they called it Irritable Bowel Syndrome, or IBS for short. That's just a name for her symptoms, and not much more. It certainly doesn't tell us what is wrong or how to fix it.

When Beth's colic finally abated, we started cooking again, and Wendy's condition improved, but only slightly. It was still worse than it was before our marriage. I continued to keep a log, but there was no pattern. Finally, when Beth was walking and talking, I realized my colossal mistake. On a bad day, Wendy always ran for the bathroom 20 minutes after eating, so I was trying to correlate what she ate with her symptoms 20 minutes later. Despite the compelling temporal connection, she was actually reacting to the previous meal, or even yesterday's fare. It takes hours for food to travel through the alimentary canal, sometimes the better part of a day. If the problem is intestinal, it won't be caused by something that is still in your stomach. Duh! Years of analysis wasted. Time to clear the slate and start again.

We moved to Michigan, and saw another suite of doctors, who were also stymied. I continued to look for patterns, but I was looking at specific foods, or food groups, or additives. I react to corn, my mother reacts to eggplant, my friend reacts to red#40 - that's where my head was at. I should have been looking at macronutrients, oils in particular. I didn't know.

In the mid 90's a new tool came on the scene, the Internet. I discovered a book, Eating for IBS, by Heather Van Vorous. Her research has helped millions around the world, maybe it would help Wendy - but it didn't seem to fit. Eggs and dairy are bad news, according to Heather, probably the worst foods you can eat - but these items were both on Wendy's safe list. After three bad days in a row, when we were depressed and discouraged, we would often whip up a homemade ham and cheese omelet with onion and green pepper, and follow that up with a bowl of ice cream for dessert. Delicious, and safe - she would feel better in the morning. That didn't look like Heather's guidelines at all, so I set her book aside for almost a year, and that was a mistake. When I looked at oils again, I realized Heather was right, if you turn her chart upside down. Wendy can eat dairy fat, which usually causes the most trouble for IBS sufferrers. Next is animal fat, which Wendy can have in moderation. finally, vegetable oils, which Heather allows in moderation, spell disaster for Wendy. She shouldn't eat anything containing soy oil, and yet that's all we ate during Beth's colicky phase. After 15 years of suffering, we finally had the formula: each meal should have at least 4 grams of fiber, at most 3 grams of vegetable oil, and at most 6 grams of animal fat. Yes, Wendy is an atypical case, but she does have something in common with millions of other IBS sufferers; she needs to understand and manage her macronutrients, especially oils.

wendy is not the only member of our family with oil issues. When Keisha was pregnant with her first child, she had morning sickness like I've never seen, followed by horrific pain in her lower right abdomen. We rushed her to the hospital, wondering if it was premature labor or perhaps appendicitis. Turns out it was neither; she had an inflamed gallbladder, brought on by a life time of poor diet, and pushed over the edge by pregnancy. (I have since learned that this is not uncommon.) They couldn't remove the gallbladder with the baby in the way, and it was much too early to deliver. The raging infection made the situation critical. "If we can't get a handle on this," warned her doctor, "she's going to get a helicopter ride to U of M Medical Center in An Arbor." antibiotics suppressed the infection, and we took her home in a couple days, but she had to eat no oil, as in zip zero nada, for the next two months. The gallbladder must not be disturbed. She ate a lot of plain pasta and watermelon, as I recall. The baby was delivered full term and healthy in September, and Keisha's gallbladder was removed in October. Soon thereafter we went to Olive Garden to celebrate, and Keisha had chicken alfredo, swimming in cheese. she was a happy girl!

Our next patient is my sister in-law, who had gastric bypass in 2004. She was in distress for several weeks after the operation. "I can't eat anything - I just can keep anything down except for these damn nutra-shakes, and I'm really getting sick of those." I read the ingredients in one of her shakes - it was a high protein drink with not a gram of fat. I told her to stay on a low fat diet, very low, and that was a turning point for her. Today, ten years later, she can have some fat in moderation, but a junk food meal will definitely make her ill for 24 hours.

That's the human world, how about other animals? Dogs and wolves eat plenty of meat, but squirrels and rabbits are pretty scrawny, and there aren't any french fries in the wild, so we shouldn't be surprised if their ability to digest fats is limited. I've had several dogs in my lifetime, and every one of them got sick if I gave them too much fat. Even rib bones were too rich for Remmy, though I could tell she loved the taste. I could give her one with dinner, and that was it. Once again, the type of oil matters. Our little dog Oreo shouldn't eat half a bag of french fries, but she does pretty well with cheese. In fact she craves it, even jumps up on the counter if cheese is left unattended. dogs, like people, are individual in their response to food.

Oils really pack it in when it comes to energy storage, but they aren't easy to digest. When people tell me they have an undiagnosed digestive disorder, the first thing I tell them to do is to go see a doctor. After that, I suggest cutting back on fats. We're not built to eat all the oils that are commonplace in a western diet.

Further Reading

Organic oils and their component fatty acids
Butter and butyric acid
Eating for IBS
Pregnancy and the gall bladder