Detoxification of dangerous, bad fat takes place only after the heart has given the fat-laden fluid a powerful push to pump it through the system and the droplets of fat happen to end up in one of the blood vessels of the liver. The liver contains quite a large amount of blood, and so the probability is high that such a meeting will take place sooner rather than later, but before that happens, our heart and our blood vessels are at the mercy of everything that McDonald’s and similar fast-food outlets were able to get hold of at the lowest purchase price.
Just as bad fat can have a negative effect, good fat can work wonders. Those who are prepared to spend that little bit extra on cold-pressed (extra virgin) olive oil will be dunking their baguette in a soothing balm for their heart and blood vessels. Many studies have been carried out into the effects of olive oil, and results show that it can protect against arteriosclerosis, cellular stress, Alzheimer’s, and eye diseases such as macular degeneration. It also appears to have beneficial effects on inflammatory diseases such as rheumatoid arthritis and help in protecting against certain kinds of cancer. Of particular interest to those fighting fat is that olive oil also has the potential to help get rid of that spare tire. It blocks an enzyme in fatty tissue—known as fatty acid synthase—that likes to create fat out of spare carbohydrates. And we are not the only ones who
benefit from the properties of olive oil—the good bacteria in our gut also appreciate a little pampering.
Good-quality olive oil costs a little bit more. However, it tastes neither greasy nor rancid, but rather green and fruity, and it sometimes leaves a peppery feeling in your throat after you swallow it. This is due to the tannins it contains. If this description sounds too abstract, simply try out various oils to find the best, using the various quality seals as a guide.
But merrily drizzling your olive oil into the pan for frying is not such a good idea as heat can cause a lot of damage. Hotplates are great for frying up steaks or eggs, but they are not good for oily fatty acids, which can be chemically altered by heat. Cooking oil or solid fats such as butter or hydrogenated coconut oil should be used for frying. They may be full of the much-frowned-upon saturated fats, but they are much more stable when exposed to heat.
Fine oils are not only sensitive to heat, they also tend to capture free radicals from the air. Free radicals do a lot of damage to our bodies because they don’t actually like being free, much preferring to bond with other substances. They can latch onto almost anything—blood vessels, facial skin, or nerve cells—causing inflammation of the blood vessels (vasculitis), aging of the skin, or nerve disease. That’s why you should always close the bottle or container of olive oil carefully after use and keep it in the fridge.
The animal fats found in meat, milk, and eggs contain far more arachidonic acid than vegetable fats. Arachidonic acid is converted in our body into neurotransmitters involved in the sensation of pain. Oils such as rapeseed (canola), linseed, or hempseed oil, on the other hand, contain more of the anti-inflammatory substance alpha-linolenic acid, while olive oil contains a substance with a similar effect called oleocanthal. These fats work in a similar way to ibuprofen or aspirin, but in much smaller doses. So, although they are no help if you have an acute headache, using these oils regularly can help those who suffer from inflammatory disease, regular headaches, or menstrual pain. Sometimes, pain levels can be reduced somewhat simply by taking care to eat more vegetable fat than animal fat.
However, olive oil should not be seen as a panacea for all skin and hair conditions. Dermatological studies have shown that pure olive oil can even irritate the skin slightly, and that using olive oil as a hair treatment leaves hair so oily that the amount of washing required to remove the oil negates any possible beneficial effects.
It is easy to overdo it with fats inside our bodies, too. Large amounts—of either good or bad fat—are simply too much for the body to deal with. It’s comparable to smearing too much moisturizer on your face. Nutritional physiologists recommend we get between 25 and a maximum of 30 percent of our daily energy requirement from fat. That works out at an average of 2 to 2½ ounces (55 to 66 grams) of fat a day. Larger, more athletic types may consume a little more; smaller, more sedentary types should try to consume a little less. This means if you eat just one Big Mac, you will have conveniently covered half your daily requirement of fat—the only question is, with what kind of fat? A sweet onion chicken teriyaki sandwich from the fast-food chain Subway contains less than 1/6 of an ounce of fat (only 4.5 grams). How you consume the other 2 ounces (53 grams) is then entirely up to you.
Having examined carbohydrates and fats, there is just one more nutritional building block to consider. It is probably the least familiar: amino acids. It seems strange to imagine, but both tofu, with its neutral-to-nutty taste, and salty, savory meat are made up of lots of tiny acids. As with carbohydrates, these tiny building blocks are linked in chains. This is what gives them their different taste and a different name—proteins. Digestive enzymes break down these chains in the small intestine and then the gut wall nabs the valuable components. There are twenty of these amino acids and an infinite variety of ways they can be linked to form proteins. We humans use them to build many substances, not least of which is our DNA, the genetic material contained in every new cell we produce every day. The same is true of other living things, both plants and animals. That explains why everything nature produces that we can eat contains protein.
However, maintaining a healthy meat-free diet that does not lead to nutritional deficiencies is more difficult than most people think. Plants construct different proteins than animals, and they often use so little of a given amino acid that the proteins they produce are known as incomplete. When our body tries to use these to make the amino acids it needs, it can continue to build the chain only until one of the amino acids runs out. Half-finished proteins are then simply broken down again, and we excrete the tiny acids in our urine or recycle them in our body. Beans lack the amino acid methionine; rice and wheat (and its derivative meat substitute, seitan) lack lysine; and sweetcorn is, in fact, deficient in two amino acids: lysine and tryptophan. But this does not spell the final triumph of the meat eaters over the meat-avoiders. Vegetarians and vegans simply have to be cleverer in combining their foods.
Beans may be lacking in methionine, but they are packed with lysine. A wheat tortilla with refried beans and a yummy filling will provide all the amino acids the body needs for healthy protein production. Vegetarians who eat cheese and eggs can compensate for incomplete proteins that way. For centuries in many countries around the world, people have intuitively eaten meals made up of foodstuffs that complement each other: rice and beans, pasta with cheese, pita bread and hummus, or peanut butter on toast. In theory, combining does not even have to take place within one meal. It is enough to take in the right combination over the course of a day. (Thinking about these combinations can often inspire even the most uninventive of cooks when they are trying to decide what to make for dinner.) There are plants that do contain all the necessary amino acids in the necessary quantities. Two of these are soy and quinoa, but others include amaranth, spirulina, buckwheat, and chia seeds. Tofu has a well-deserved reputation as an alternative to meat—with the caveat that increasing numbers of people are developing allergic reactions to it.
Allergies and Intolerances
ONE THEORY ABOUT the origin of allergies begins with the digestive processes in the small intestine. If we fail to break down a protein into its constituent amino acids, tiny bits of it will remain. Under normal circumstances, those tiny particles simply don’t make it into our bloodstream and there is no problem. However, hidden power often lies in the most inconspicuous places—in this case, in the lymphatic system. Those tiny particles can enter the lymphatic system, embedded in fat droplets, and once there, they attract the attention of ever-vigilant immune cells. When the immune cells discover a tiny particle of peanut in the lymphatic fluid, for example, they naturally attack it as a foreign body.
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The next time the immune cells encounter a peanut particle, they are better prepared to deal with it and can attack it more aggressively. And so it goes on, until we reach the stage where just putting a peanut in our mouth causes our immune cells to whip out the big guns straightaway. The result is increasingly severe allergic reactions, such as extreme swelling of the face and tongue. This explanation applies to allergies caused by foods that are both fatty and rich in protein, such as milk, eggs, and, most commonly, peanuts. There is a simple reason almost no one is allergic to greasy bacon. We are made of meat ourselves, and so we generally have few problems digesting it.
Celiac Disease and Gluten Sensitivity
ALLERGIES THAT DEVELOP in the small intestine are not limited to fats. Allergens such as prawns, pollen, or gluten, for example, are not, in themselves, fat-bombs, and people who eat a fatty diet do not necessarily suffer from more allergies than others. Another theory about how allergies develop is this: the wall of our gut can become temporarily more porous, allowing food remnants to enter the tissue of the gut and the bloodstream. This is the theory under most scrutiny from researchers who are interested in gluten—a protein found in wheat and related grains.
Grains do not like us to eat them. What plants really want is to reproduce—and then along we come and eat their children. Instead of creating an emotional scene, plants respond by making their seeds slightly poisonous. That sounds much more drastic than it is—neither side is going to lose much sleep over a few guzzled wheat grains. The arrangement means humans and plants both survive well enough. But, the more danger a plant senses, the more poisonous it will make its seeds. Wheat, in particular, is such a worrier because it has only a very short window of opportunity for its seeds to grow and carry on the family line. With such a tight schedule, nothing must be allowed to go wrong. In insects, gluten has the effect of inhibiting an important digestive enzyme. A greedy grasshopper might be put off by a little stomachache after eating too much wheat, and that is to the benefit of both plant and animal.
In humans, gluten can pass into the cells of the gut in a partially undigested state. There, it can slacken the connections between individual cells. This allows wheat proteins to enter areas they have no business being in. That, in turn, raises the alarm in our immune system. One person in a hundred has a genetic intolerance to gluten (celiac disease), but a considerably higher proportion suffer from gluten sensitivity.
In patients with celiac disease, eating wheat can cause serious infections or damage to the villi of the gut wall; it can also damage the nervous system. Celiac disease can cause diarrhea and failure to thrive in children, who may show reduced growth or winter pallor. The tricky thing about celiac disease is that it can appear in more or less pronounced forms. Those with more subtle forms may live with the symptoms for years without realizing it. They may have the occasional stomachache, or their doctor might discover signs of anemia during routine blood tests. Currently, the most effective treatment is a lifelong gluten-free diet.
Gluten sensitivity, by contrast, is not a sentence to a life of gluten avoidance. Those with this condition can eat wheat without risking serious damage to their small intestine, but they should enjoy wheat products in moderation—a little bit like our friend the greedy grasshopper. Many people notice their sensitivity when they swear off gluten for a week or two and see an improvement in their general well-being. Suddenly, their digestive problems or flatulence clear up, or they have fewer headaches or less painful joints. Some people find that their powers of concentration improve, or that they are less plagued by tiredness or fatigue. Researchers began exploring gluten sensitivity in detail only recently. Currently, the diagnostic picture can be summarized as follows. Symptoms improve when a gluten-free diet is introduced, although tests for celiac disease show negative. The villi are not inflamed or damaged, but eating too much bread still appears to have an unpleasant effect on the immune system.
The gut can also become porous for a short time after a course of antibiotics, after a heavy bout of drinking alcohol, or as a result of stress. Sensitivity to gluten resulting from these temporary causes can sometimes look the same as the symptoms of true gluten intolerance. In such cases, it can be helpful to avoid gluten for a time. A thorough medical examination and the detection of certain molecules on the surface of the blood corpuscles are important for a definitive diagnosis. Alongside the familiar blood groups A, B, AB, and O, there are many other indicators for categorizing human blood, including what doctors call DQ markers. Those who do not belong to group DQ2 or DQ8 are extremely unlikely to have celiac disease.
Lactose Intolerance and
Fructose Intolerance
LACTOSE INTOLERANCE is not an allergy or a real intolerance at all, but a deficiency. But it, too, results from a failure to break down certain nutrients completely into their component parts. Lactose is found in milk. It is derived from two sugar molecules that are linked together by chemical bonds. The body requires a digestive enzyme to break that bond, but, unlike other enzymes, this one does not come from the papilla. The cells of the small intestine secrete it themselves on the tips of their tiny little villi. Lactose breaks down when it comes into contact with the enzyme on the gut wall, and the resulting single sugars can then be absorbed. If the enzyme is missing, similar problems arise to those caused by gluten intolerance or gluten sensitivity, including bellyache, diarrhea, and flatulence. Unlike in celiac disease, however, no undigested lactose particles pass through the gut wall. They simply move on down the line, into the large intestine, where they become food for the gas-producing bacteria there. Consider the resulting flatulence and other unpleasant symptoms as votes of thanks from extremely satisfied, overfed microbes. Although the results can be unpleasant, lactose intolerance is far less harmful to health than undiagnosed celiac disease.
Every human being has the genes needed to digest lactose. In extremely rare cases, problems with lactose digestion can occur from birth. Such newborns are unable to digest their mother’s milk, and drinking it causes severe diarrhea. In 75 percent of the world’s population, the gene for digesting lactose slowly begins to switch off as they get older. This is not surprising, as by then we are no longer reliant on our mothers’ milk, or formula milk, to nourish us. Outside of Western Europe, Australia, and the United States, adults who are tolerant to dairy products are a rarity. Even in our parts of the world, supermarket shelves are increasingly full of lactose-free products. Recent estimates say about 25 percent of people in the United States lose their ability to break down lactose after weaning. The older a person, the greater the probability that she will be unable to break down lactose—although very few sixty-year-olds would dream of blaming their daily glass of milk or that delicious dollop of cream for a bloated stomach or a little bit of diarrhea.
However, lactose intolerance does not mean you must cut out milk products altogether. Most people have enough lactose-splitting enzymes in their gut. It is just that their activity is somewhat reduced—down to about 10 to 15 percent of their initial level, let’s say. So if you notice your stomach feels better when you don’t drink that glass of milk, you can simply use trial and error to find out just how much your body can deal with, and how much dairy produce it takes to make the problems come back. A nibble of cheese or a splash of milk in your tea or coffee will usually be fine, as will the occasional milk pudding or cream filling in your cake.
A common children’s counting rhyme in Germany, comparable to the “eeny, meeny, miny, moe” of the English-speaking world, translates as “Ate cherries, drank water, got tummy ache, went to hospital!” The most common food intolerance in the Western hemisphere is trouble digesting the fruit sugar fructose, with about 40 percent of the population affected. Fructose intolerance can be the result of a severe hereditary inability to metabolize fruit sugar, which causes patients’ digestive systems to react to even the tiniest amounts of the substance. But most people affected by fructose intolerance actually have a condition more accu
rately described as fructose malabsorption, and they experience problems only when they are exposed to large amounts of the sugar. When fructose is described on food packages as “fruit sugar,” consumers often assume it is a healthier, more natural option. This explains why food manufacturers choose to sweeten their products with pure fructose, and consequently why our digestive system is exposed to more of this type of sugar than ever before.
An apple a day would not present a problem to most people who are fructose intolerant if it weren’t for the fact that the ketchup on their fries, the sweetening agent in their breakfast yogurt, and the can of soup they heated up for lunch, all contain added fructose. Some types of tomato are specially bred to contain large amounts of this sugar. Furthermore, globalization and air transport mean that we are now exposed to a previously unheard-of overabundance of fruit. Pineapples from the tropics nestle on our supermarket shelves in the middle of winter, next to fresh strawberries from Mexico, and some dried figs from Morocco. So, what we label a food intolerance may in fact be nothing more than the reaction of a healthy body as it tries to adapt within a single generation to a food situation that was completely unknown during the millions of years of our evolution.
The mechanism behind fructose intolerance is different once again from that involved in the digestion of gluten or lactose. The cells of people with hereditary fructose intolerance contain fewer fructose-processing enzymes. That means fructose may gather in their cells, where it can interfere with other processes. Fructose intolerance that appears later in life is thought to be caused by a reduced ability of the gut to absorb fruit sugars. Such patients often have fewer transporters (called GLUT5 transporters) in their gut wall. When they ingest even a small amount of fruit sugar—for example, by eating a pear—their limited transporters are overwhelmed and, as with lactose intolerance, the sugar from the pear ends up feeding the flora of the large intestine. However, some researchers question whether a lack of sufficient transporters really is the cause of this problem, since even those without the condition pass some of the fructose they eat into the large intestine undigested (especially after eating very large amounts of it). The problems experienced by such people may be due to an imbalance in their gut flora. When they eat a pear, the extra sugar is gobbled up by the gut bacteria squad, which then produces rather unpleasant symptoms. Of course, the more ketchup, canned soup, or sweetened yogurt they have eaten, the worse their troubles will be.
Gut: The Inside Story of Our Body's Most Underrated Organ (Revised Edition) Page 5
