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Minggu, 23 Agustus 2015
Hypervitaminosis A and sweet potatoes
Can consumption of sweet potatoes cause hypervitaminosis A? The answer is “no”, even if you eat ten or more sweet potatoes per day. Sweet potatoes do have high vitamin A content, more than almost any other food. However, most of it is in the form of β-carotene, which is used by the body to produce the active form of vitamin A, retinal (yes, with an “a”), only if the body’s vitamin A status is low.
The graph below shows the vitamin A content of different foods, together with the recommended daily allowance. It was prepared with information from Nutritiondata.com (), with the horizontal axis in international units (). The graph also takes into consideration some key research findings related to the bioavailability of vitamin A. For example, the sweet potato is assumed to be taken with some fat to facilitate the absorption of vitamin A.
Primarily, vitamin A is available either as retinol, from animal foods; or β-carotene, from plant foods. There are other carotenes available from plant foods, but their vitamin A contribution is relatively small compared with β-carotene. High β-carotene content is “advertised” by plant foods to animals via a characteristic orange color. The main sources of β-carotene throughout human evolution have probably been fruits, which plants “want” animals to eat so that the plants’ seeds are dispersed.
Retinol also needs to be converted by the body to retinal, and when consumed in excess it tends to be stored in body fat reserves – hence lean individuals tend to store less retinol than fat ones. It seems that intake of retinol from sources like beef liver is naturally controlled via satiety. In the case of plant sources, like sweet potatoes, a key control mechanism is limited internal production of retinal. My impression is that most people, if given the chance, would prefer to eat a lot of sweet potato than a lot of beef liver.
Like all of the fat-soluble vitamins, the bioavailability of vitamin A from foods is dependent on whether they are consumed together with fat. For example, a lot more vitamin A will be absorbed from a sweet potato if it is eaten with butter than if it is eaten by itself (again, if the body’s vitamin A status is low). I should note that butter is itself a good source of vitamin A, in addition to providing the fat needed for absorption. Beef liver is low in fat, which means that the vitamin A content in the graph above may be an overestimation.
Hypervitaminosis is a fat-soluble vitamin phenomenon, and it is usually associated with consumption of supplements (e.g., cod liver oil). Generally speaking, one does not develop noticeable hypervitaminosis symptoms from consumption of natural food sources. This is probably due to a combination of satiety and internal regulation of the production of the active forms of the vitamins.
Senin, 03 Februari 2014
Beef heart
I have posted here before about the nutrition value of beef liver, nature’s “super-multivitamin”. I have even speculated that grain-fed beef liver could be particularly nutritious (). What I should have done also was to post about beef liver’s equal in terms of nutrition value – beef heart. In this post I am correcting the omission.
Contrary to popular belief, not all organ meats are inherently fatty. The fat that is attached to an animal’s heart after slaughter, even if from grain-fed cattle, can be easily removed. The resulting cut will have a very low fat-to-protein ratio; often significantly less than fat-trimmed non-organ muscle cuts.
I don't say this because I consider fat to be unhealthy. In fact, dietary fat is necessary for the absorption of fat-soluble vitamins, and can thus be uniquely healthy. However, fat also is the most calorie-dense macronutrient. Even though the caloric values of macronutrients vary based on a number of factors, excess calories tend to be stored as excess body fat.
A 100 g portion of cooked beef heart, as in the photos below, will have 28 g of protein and only 5 g of fat (see this link, you may have to reset the serving size field: ). The photos below show two different beef heart dishes I have prepared. In the first the beef heart was barbecued. In the second it was simmered in a pan with vegetables for about 8 h.
Below is a simple recipe for the barbecued beef heart, which I recommend cutting into steaks. For the simmered beef heart I suggest cutting it into chunks that resemble cubes; then you can just add the dry seasoning powder mentioned below to the water, some vegetables, enough water to last about 8 h, and leave it simmering.
- Prepare some dry seasoning powder by mixing salt, garlic power, chili powder, and a small amount of cayenne pepper.
- Season the beef heart steaks at least 2 hours prior to placing them on the grill.
- Grill with the lid on, checking the meat every 10 minutes or so. (I use charcoal, one layer only to avoid burning the surface of the meat.) Turn it frequently, always putting the lid back on.
- If you like it rare, 20 minutes (or a bit less) may be enough.
Beef heart is a very good source of vitamins and minerals, and is one of the least expensive cuts of meat (in meat sections of grocery stores, not in paleo restaurants). Many people prefer beef heart over beef liver because of beef heart’s texture.
While I have restricted my comments in this post to “beef” heart, the hearts of most animals that are eaten by humans (e.g., chicken, duck, deer, turkey) are fairly nutritious, and they seem to have that uniformly meaty texture that many people like.
Here is an interesting factoid. The largest known carnivorous marsupial of modern times was the now extinct Tasmanian tiger. It was an elusive and solitary animal, and the subject of the beautiful film "The Hunter (2001)" (). The Tasmanian tiger was known to frequently eat only the hearts of prey. I hope this is not why it became extinct!
Senin, 30 September 2013
How to handle a dog attack
For most people, dog attacks are not very common. But they happen occasionally, and the experience can be traumatic. Incidentally, they are also a good reason why I am not a big fan of barefoot walking or running. Broken glass pieces and nails can be a problem if you are barefoot; so can dog attacks.
The photo below, from Dreamstime.com, shows a charging dog. It reminds me of an incident many years ago where a dog attacked my two oldest sons, who were very young at the time. They were unsuspectingly playing at a park in Southern New Jersey, when I saw a dog running in their direction across the park. Part of what I will say in this post is based on experiences like that.
I should also say that I grew up around dogs. My grandfather had a farm that was managed by my uncle, and dogs were critically important in managing the farm. One problem we had was that domesticated pigs would often become feral, or would mate with wild boars, in some cases leading to a particularly vicious breed of large feral pigs. I was once attacked by one of these feral pigs while hunting. One of the farm dogs came to my rescue and probably saved my life.
If you are like most people, when you go walking outdoors, you do not carry a walking stick or a cane. Maybe you should. But if you don’t, thick-soled sneakers can be used in a reasonably effective defense in a dog attack situation.
Dogs attacks’ main targets: The faces of children
Dogs tend to be loyal friends, but they must be monitored for signs of aggression, and can be particularly dangerous to children. A significant proportion of dog attack victims are children 5 years of age or younger, who more often than not sustain injuries to the face, with secondary target areas being the hands and feet ().
At the time of this writing the web sites Documentingreality.com and Arbtalk.co.uk had some grisly photos of dog attack victims (, ). They show evidence that the face is often targeted, and some possible consequences of real dog attacks.
Artificial selection: Dogs and Moby-Dick
Modern dogs are descendants of wolves who came into contact with humans about 12,000 year ago. (This general date is often cited, but is the subject of intense debate, with DNA studies suggesting much earlier contact.) Wolves are apex predators; this was true also for wolves that lived around the time they first came into contact with humans. They hunt and live in packs, and rely on fairly complex body language, a variety of sounds, and a keen sense of smell to communicate.
Even being apex predators, wolves were no match for humans. Therefore, as humans and groups of wolves co-evolved, dogs emerged. Dogs evolved instincts that made them sociable toward and submissive to humans, particularly those humans who fed them and also asserted authority over them – those become their “owners”.
Humans, in turn, came to rely heavily on dogs for protection and hunting, and probably evolved instincts that are still largely unexplored today. For example, there is strong evidence suggesting that having pet animals, many of which are dogs, is generally health-promoting (, ).
The evolution of sociability and submissiveness traits is an example of what is often referred to as “artificial selection”, where animals and plants evolve traits almost exclusively in response to the selection pressure applied by humans. In the case of dogs, this was later taken to new heights through selective breeding; leading to the emergence of a variety of dog breeds, some for utilitarian purposes and others for pure vanity, each with very distinctive characteristics.
Interestingly, artificial selection applied by humans does not always produce more sociable and submissive animals. The opposite happened around the mid 1800s due to excessive hunting of sperm whales. The least aggressive were easier to kill, so they were overhunted. Over generations, this placed selection pressure in favor of the evolution of aggressiveness toward humans. The attack on the Essex by a large bull sperm whale, which served as inspiration for Herman Melville's novel Moby-Dick, was one of the first incidents that resulted from this selection pressure (). Whaling increased, and, predictably, attacks started becoming more and more frequent.
When a dog attacks, stand your ground in a non-threatening way
Dogs, like wolves, are territorial animals. Many dog attacks are likely motivated by humans invading what a dog perceives as its territory at a given point in time. I mentioned earlier in this post that a dog once attacked two of my children. They were playing at a park during the winter. Nobody else was there. I saw this large black dog running from a distance in their direction, and I immediately knew that it was trouble. The dog probably saw us as invading its territory.
Having grown up surrounded by dogs, I pretty much knew what to do. I walked toward my children and placed myself between them and the charging dog. I told the children not to move at all, just freeze. The dog came running until it realized that we were not running. It was a “fake charge”, like most are. It stopped close to me, and barked very aggressively, coming closer. I was wearing boots. I raised one of my boots toward the dog’s snout, and when it bit it, I pushed the boot against its snout.
Here is where I think most people would tend to make a key mistake. They would probably try to hurt the dog to scare it off, by, say, kicking the dog as they would kick a soccer ball. The problem is that, because the dog is a lot faster than they are, if they do that they may end up missing the dog entirely and worse - they may end up losing their balance and falling to the ground. This is when dogs can do the most damage, since they would go for the face of the fallen person.
As a side note, often you hear that dogs attack the throat of their human victims, but that is not what the statistics show. Most victims of dog attacks display injuries on the face and extremities. The "myth" that dogs target the throat is probably based on the notion that dogs attack humans because they see them as prey. However, with exception of feral dogs such as Australian dingos, evidence of dogs preying on humans is very rare. I've reviewed many dog attack photos for this post, and could not find one with evidence that the throat was targeted.
So I pushed my boot against the dog’s snout a few times, firmly but not with the goal of hurting the dog, and did not do anything threatening toward the dog otherwise. This calmed the dog down a bit, but it was still acting aggressively and would not go away. Sometimes firm commands to "seat", "stop", "go away" make the dog react submissively. I tried them but they didn't work; instead they probably made the dog more excited. Then I did what probably is the one thing that most land animals instinctively fear from humans …
Sapiens the thrower
I picked up a few pieces of ice from the ground and threw at the dog. One piece of ice hit the dog on the side of its body; a couple of others were glancing blows. As a result the dog became visibly confused and submissive (telltale sign: tail between the legs), and ran away. Here is where another big mistake may happen. People may try to hurt the dog and become too excited when throwing objects at it. In doing so, they may end up not only missing the dog with the flying objects that they are throwing, but they may also excite the dog, and face another attack.
The best approach here is to focus on having whatever you are throwing at the dog land on top of or as close to the dog as possible; explicitly without trying to hurt it, in part because this improves your aim. Having flying objects coming from you toward the dog is enough to trigger the dog’s instinct to get out of the way of “Sapiens the thrower”. Moreover, if you don’t try to hurt you’ll be relatively calm, displaying the type body language that will trigger submissiveness.
I’ve long suspected that throwing has been a key component of Sapiens’ climb to the top of the food chain, to the point that all land animals have an instinctive fear of humans – even large predators, and much bigger animals such as elephants (as long as they are not “in musth”). One short video has been circulating on YouTube for years; it has various hunting scenes where primitive spears are used (). Many find this video cruel. It clearly shows the enormous evolutionary advantage of humans being able to throw pointy things at other animals. If humans happened to live when Tyrannosaurus rex was around, there is no doubt in my mind that the latter would be the prey.
Keep your face away and your hands closed
Typically you’ll avoid a full-blown dog attack by only standing your ground for a while and not acting aggressively toward the dog. After a short standoff period, you’ll just walk away unharmed. Unfortunately this may not happen if you are facing a dog that has been trained to attack. In this case, having a stick or something like it will help a lot. (In circus acts lions are “pushed around” by trainers holding objects like sticks and wooden chairs; sometimes that doesn't end well - .) If you don’t have one it would be useful to be wearing shoes that can withstand several bites. If not, you can use a piece of clothing, such as a bundled jacket, as a shield.
If you have a stick, or something like a stick, you should not try to hit the dog with it. You should place it near the snout, and push the stick against it each time the dog bites. If you do this calmly and firmly, without trying to hurt the dog (remember, the dog is a lot faster than you are), you will probably discourage biting after a while, turning the attack into a standoff.
What if you don’t have anything with which to defend yourself at first, and a dog attacks you? Keep your hands closed into fists, to avoid having fingers bitten off, and do your best to keep the dog away from your face. As desperate as these situations may be, try to be calm and look for objects that you can use to push the dog away, that you can throw at the dog, or that can be used to wrap around your arms. Frequently there will be objects around that can be of use – e.g., sharp stones, glass bottles, pieces of canvas, loose pieces of a fence, a hose, a tree’s branch. If you fall, try to stand up right away. Very likely you'll sustain injuries to your arms, and possibly legs.
Military and law enforcement personnel are often trained on fighting techniques to handle dog attacks barehanded, such as neck cranks, sharp blows to the throat of the animal, and blinding techniques. I am not sure whether these would be really useful to the average person. In any case, this post is not aimed at military and law enforcement personnel who deal with dog attacks on a regular basis.
Eat beef liver
Beef liver is nature’s super-multivitamin. (Beef heart is just as nutritious.) Dogs, like wolves, have an exquisite sense of smell. If you have seen one of the documentaries about the groundbreaking research by Shaun Ellis (a.k.a., “The Wolfman”), you probably know that wild wolves tend to strongly associate consumption of organ meats with very high status in a pack, to the point that they will instinctively act submissively toward humans that consume organ meats. It is quite possible that dogs do that too. So if you eat beef liver, maybe a dog will “think twice” before attacking you.
Offer the dog a cigarette and a beer
Most dogs can become aggressive from time to time, but not dogs that know how to chill. Therefore, you may consider carrying special dog cigarettes and beer around - only some brands work! Okay, a clarification: the "eat beef liver" advice is not a joke, nor are the others above it.
Notes and acknowledgements
The “charging dog” photo is from Dreamstime.com. The “drunken dog” montage was created with photos from the blog Agrestemundica.
Cesar Millan's site has a number of good suggestions on how to handle dog attacks (). However, I personally think that the way he handles dogs (e.g., often with open hands) is dangerous if copied by an inexperienced person. There is a great deal of "hidden" information that is conveyed to dogs by nuances of Cesar's body language. Those nuances are difficult to copy by an inexperienced person.
An interesting source of information on how to handle dog attacks is the web site Fightingarts.com (, ).
Senin, 29 Juli 2013
Could grain-fed beef liver be particularly nutritious?
There is a pervasive belief today that grain-fed beef is unhealthy, a belief that I addressed before in this blog () and that I think is exaggerated. This general belief seems to also apply to a related meat, one that is widely acknowledged as a major micronutrient “powerhouse”, namely grain-fed beef liver.
Regarding grain-fed beef liver, the idea is that cattle that are grain-fed tend to develop a mild form of fatty liver disease. This I am inclined to agree with.
However, I am not convinced that this is such a bad thing for those who eat grain-fed beef liver.
In most animals, including Homo sapiens, fatty liver disease seems to be associated with extra load being put on the liver. Possible reasons for this are accelerated growth, abnormally high levels of body fat, and ingestion of toxins beyond a certain hormetic threshold (e.g., alcohol).
In these cases, what would one expect to see as a body response? The extra load is associated with high oxidative stress and rate of metabolic work. In response, the body should shuttle more antioxidants and metabolism catalysts to the organ being overloaded. Fat-soluble vitamins can act as antioxidants and catalysts in various metabolic processes, among other important functions. They require fat to be stored, and can then be released over time, which is a major advantage over water-soluble vitamins; fat-soluble vitamins are longer-acting.
So you would expect an overloaded liver to have more fat in it, and also a greater concentration of fat-soluble vitamins. This would include vitamin A, which would give the liver an unnatural color, toward the orange-yellow range of the spectrum.
Grain-fed beef liver, like the muscle meat of grain-fed cattle, tends to have more fat than that of grass-fed animals. One function of this extra fat could be to store fat-soluble vitamins. This extra fat appears to have a higher omega-6 fat content as well. Still, beef liver is a fairly lean meat; with about 5 g of fat per 100 g of weight, and only 20 mg or so of omega-6 fat. Clearly consumption of beef liver in moderation is unlikely to lead to a significant increase in omega-6 fat content in one’s diet (). By consumption in moderation I mean approximately once a week.
The photo below, from Wikipedia, is of a dish prepared with foie gras. That is essentially the liver of a duck or goose that has been fattened through force-feeding, until the animal develops fatty liver disease. This “diseased” liver is particularly rich in fat-soluble vitamins; e.g., it is the best known source of the all-important vitamin K2.
Could the same happen, although to a lesser extent, with grain-fed beef liver? I don’t think it is unreasonable to speculate that it could.
Senin, 04 Juli 2011
Liver and meatballs separated by a wall of sweet potatoes
A commenter wrote here some time ago that she liked to eat rice because rice can be easily used to separate food items on a plate. One can just as easily use sweet potatoes to do that; preparing the sweet potatoes in much less time than the rice. This post explains how, with a simple recipe.
- Cut up half of a sweet potato as shown on the first photo below, adding coconut oil or butter to prevent the pieces from sticking to a microwave-safe saucepan.
- Microwave the sweet potato pieces in high heat for about 5 minutes.
- Use the sweet potatoes to separate food items as in the second photo below, showing beef liver and meatballs with their respective sauces.
- Cover the dish with a wet paper towel to prevent spilling, and microwave it for as long as needed to heat up the meats. In this case, 2 minutes in high heat was enough. That will further cook the sweet potato, but not to the point of burning it.
The above assumes that the beef liver and meatballs are leftovers that had been cooked before. In this example, we have about ½ lb of meat and ½ of a sweet potato. As far as plant foods are concerned, sweet potatoes are at the very high end of the nutrition density scale. This is a very nutritious and satiating meal (for me) with over 55 g of protein, as well as a great mix of macro- and micro-nutrients.
- Cut up half of a sweet potato as shown on the first photo below, adding coconut oil or butter to prevent the pieces from sticking to a microwave-safe saucepan.
- Microwave the sweet potato pieces in high heat for about 5 minutes.
- Use the sweet potatoes to separate food items as in the second photo below, showing beef liver and meatballs with their respective sauces.
- Cover the dish with a wet paper towel to prevent spilling, and microwave it for as long as needed to heat up the meats. In this case, 2 minutes in high heat was enough. That will further cook the sweet potato, but not to the point of burning it.
The above assumes that the beef liver and meatballs are leftovers that had been cooked before. In this example, we have about ½ lb of meat and ½ of a sweet potato. As far as plant foods are concerned, sweet potatoes are at the very high end of the nutrition density scale. This is a very nutritious and satiating meal (for me) with over 55 g of protein, as well as a great mix of macro- and micro-nutrients.
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