If Paleo were a comic book movie, liver would be the superhero. It’s the closest we can get to an all-natural, completely unprocessed multivitamin pill, wrapped in a delicious (really!) and inexpensive package. Although it does pose some health risks if you eat it to excess, a moderate amount of liver can add powerful nutritional boost to your diet.
Health Benefits of Liver
Ask most people where they get their vitamins, and their first response will be “fresh fruits and vegetables!” (complete with a guilty explanation of why they just can’t find the time/money/appetite to eat enough). Fruits and vegetables are certainly important, but liver is even more nutrient-dense. Just one ounce of liver contains a massive dose of Vitamin A and a series of B vitamins that rival a multivitamin pill: B2 (also called riboflavin), B3 (niacin), Vitamin B5 (pantothenic acid), B6, B12, and folate. Liver is also one of the most important dietary sources of copper, as well as providing significant amounts of selenium, phosphorous, and iron. And although live doesn’t contain Vitamin D itself, liver consumption may have a beneficial effect on Vitamin D levels: one study found that fish liver helped reduce the risk of Vitamin D deficiency during the long, dark Scandinavian winter, despite the study subjects’ limited sun exposure.
The nutrients in liver play a variety of important roles in the body. Vitamin A is vitally important for vision, reproduction, and healthy cell development. The B vitamins (B2, B3, B5, B6, B12, choline, and folate) support some of your most important cognitive and neurological processes. They also keep your immune system up to scratch, help your body digest food and convert it to energy, and support the production of red blood cells and the synthesis of DNA. Choline in particular helps protect against fatty liver disease. Copper and iron also maintain a healthy level of red blood cells, as well as normal thyroid function. The iron in liver is especially useful because it’s a form called heme iron (found only in animal sources), which your body digests and uses much more efficiently than non-heme iron (found in plant sources like spinach and pumpkin seeds).
As if its vitamin content weren’t enough, liver also contains an enzyme called CoQ10, an antioxidant that helps your body produce energy and may help in the treatment of a variety of diseases. Liver also seems to have mysterious anti-fatigue properties that scientists can’t pin down to any particular vitamin it contains.
This laundry list of nutrients covers several common deficiencies. Vitamin A deficiency is rare in developed countries (although prevalent in the developing world), but B vitamin deficiencies are common and often go unnoticed. And according to the CDC, iron is the most commonly deficient mineral in America, especially among children and pregnant women. B vitamin and iron deficiencies can exacerbate each other, since both vitamins play such an important role in blood health. Chronic iron and B12 deficiency can both cause anemia; since B vitamins are so important for brain health, deficiencies can also bring on immune problems, consistent fatigue, weakness, depression, and other neurological symptoms.
Liver and Vitamin A
Liver provides a convenient antidote to two of the most common nutrient deficiencies that still plague the developed world. But vitamin intake can be a double-edged sword: deficiency is dangerous, but hypervitaminosis (consuming excessive amounts of a vitamin) can also cause serious problems. This leads many people to be concerned about liver consumption because they fear that the incredibly high levels of vitamin A might actually be harmful. Pregnant women in particular tend to shy away from liver consumption, since hypervitaminosis A has been shown to cause various birth defects.
Hypervitaminosis is a valid health concern – and hypervitaminosis A has serious consequences. Vitamin A toxicity comes in two forms: acute (caused by a one-time megadose) and chronic (caused by months of less extreme overconsumption). Symptoms of acute toxicity include headache, nausea, vomiting, vertigo, and vision problems; symptoms of chronic toxicity include anorexia, hair loss, dry skin, brain pressure, menstrual irregularities, and fatigue. Children suffering from hypervitaminosis A also have abnormal bone development. Excessive levels of Vitamin A are definitely a problem to avoid, but a moderate amount of liver consumption is unlikely to cause any problems.
For healthy adults, acute toxicity requires a one-time dose of 500,000 IU or more; chronic toxicity occurs at an intake of 25,000 IU/day for several months. Scientists specifically addressing pregnant women’s intake of Vitamin A found vanishingly low risk of birth defects under 25,000 IU/day. They also stressed that avoiding foods rich in Vitamin A could cause a pregnant woman to become Vitamin A deficient, a much more common problem that can also cause birth defects. Additionally, some research has shown that hypervitaminosis A is only harmful at this level in people who are also deficient in other fat-soluble vitamins, especially Vitamin D. With an adequate Vitamin D intake, the threshold for toxicity could be much higher. This makes the risk of hypervitaminosis A much less worrying for anyone eating a Paleo diet rich in all the micronutrients necessary for health.
Judging the nutritional content of liver against these numbers reveals that most people have no reason to worry. A 4-oz serving of liver contains 18,928 IU of Vitamin A. This is almost 400% of your RDA, but still not enough to cause serious problems. A larger portion of liver might reach the 25,000 IU threshold, but for chronic toxicity to occur you’d have to eat that much liver every day for several months. Eating a moderate amount of liver one or two days a week will not create the consistent, daily excess needed for chronic Vitamin A toxicity. In fact, sporadic Vitamin A consumption (a slight overdose on some days balanced out by a slight underdose on other days) seems to be the normal human dietary pattern, and does not appear to cause any problems. Since Vitamin A is fat-soluble, the human body has a high ability to stockpile it for later use: rather than worrying about your daily intake, a more useful approach might be to multiply your RDA by 7 and make sure you don’t go over that every week.
An extreme example of this is the approach to treating Vitamin A deficient children in the developing world. Public health officials cannot reach these children consistently, so they administer megadoses of the vitamin 2-4 times per year. The children treated this way show temporary symptoms of hypervitaminosis A, but suffer no long-term harm and do not develop the problems associated with Vitamin A deficiency. This is unnecessary for anyone with consistent access to adequate food, but it demonstrates the human body’s ability to adapt to very sporadic Vitamin A intake.
Despite the reassuring conclusions of modern studies, a report of chronic hypervitaminosis A in a homo erectus skeleton might raise particular concern in the Paleo world, especially since the scientists analyzing the issue attributed the vitamin A intake to liver consumption. A crucial difference, however, is the type of liver consumed. This homo erectus specimen ate livers of carnivorous animals, which contain an even more concentrated dose of Vitamin A because the animals themselves ate liver. Livers of herbivores do not contain such high levels, and are safe to eat in moderation.
Another reason not to be overly concerned about Vitamin A intake from liver is that many recorded cases of hypervitaminosis A were induced by using supplements, not food. Water-miscible preparations (the kind found in vitamin pills) have the potential to be much more toxic because the body absorbs this form of Vitamin A about ten times more efficiently. In other words, you don’t need to eat nearly as much Vitamin A in supplement form to get a potentially toxic amount. The Vitamin A in supplements is not otherwise any different or more harmful, but it is easier to overconsume – this study on children’s gummy vitamins shows the danger of wrapping up such a potent dose in a candy package. Since liver is harder to mindlessly consume than gummy candy, the risk of hypervitaminosis A is much lower.
In short, the warnings about Vitamin A toxicity don’t provide any reason to avoid liver altogether, but they do support a moderate, sporadic intake. Eating liver once or twice a week won’t cause any problems, but it should never be a staple source of calories – like exercise, some is good, but more isn’t necessarily better.
Other Health Concerns
Two other health concerns lead many people to shy away from liver. First, the high levels of copper in liver, like the levels of Vitamin A, raise fears of potential overdose. Copper is one of the nutrients that makes liver such a superfood, but an excessive intake of copper without adequate zinc to balance it out can cause several different health problems. Liver doesn’t contain as much zinc as it does copper, so consuming mass quantities of liver without other zinc-rich foods could create a mineral imbalance. This, however, is not a serious risk for people consuming moderate amounts of liver a few times a week, as part of a balanced and varied diet.
Aside from the risk of hypervitaminosis, one other concern that many people have about liver is the idea that, since it filters toxins from the body, it must store them as well. While this sounds like a logical conclusion, it simply isn't true. The liver does neutralize toxins, but it doesn’t store them – its function is to channel those toxins out of your body through your excretory system. Toxins do accumulate in an animal’s fat and nervous system (this is why you should never eat the fat from animals that weren’t grass fed and organically raised), but not in the liver.
Liver for every Palate
Liver might deliver a powerful dose of vitamins, but that doesn’t necessarily make it a food you actually want to eat. Some people love its distinctive taste and texture; others can’t stand it. Fortunately, there are ways to cook and serve liver for every palate, from reveling in it to disguising it so thoroughly you’d never know it’s there.
Before you can cook liver, you have to find it: fortunately, liver is one of the easiest organ meats to get ahold of. A local organic farm is the best source of liver, but not all of us have access to one – if you’re stuck with a grocery store, try to go for grass-fed liver whenever possible, and if you have to buy conventional meat, choose calves' liver over liver from adult cows to minimize your exposure to antibiotics and hormones. Even if your grocery store doesn’t display liver with the other cuts of meat, it’s always worth asking at the counter. If you have a choice of animal, this chart shows the nutritional content of several different kinds of liver: experiment with different types and recipes to find your favorite.
Once you’ve found your liver, you can choose from a wide variety of ways to cook it. For liver lovers, there’s no need to hide the taste – enjoy the classic liver with onions, this more adventurous version with onions and lemon, or more exotic preparations like liver jalapeño poppers, spicy, crispy chicken livers, this lemon liver recipe, or liver with blueberries. And, for road trips or extended visits to relatives who think whole wheat bread is the pinnacle of healthy eating, liver jerky is a perfect Paleo-on-the-go solution.
If you’re a little more ambivalent about the taste, try chicken livers instead of beef: the flavor isn’t quite as strong. Marinating the liver overnight in milk can also help. Pâté tones down the taste (and the texture) with a healthy dose of butter; enjoy it as a veggie dip or straight off the spoon. Pâté also makes for a great midafternoon snack: it’s light to carry around, it’s easy to work into a busy workday, and it has enough fat, protein, and vitamins to tide you over until dinnertime.
If your distaste for liver goes beyond “ambivalent” into reflexive gagging at the sight of the word, even pâté might be too strong. Fortunately, you’re not alone: plenty of ingenious cooks have discovered various ways to disguise liver in various other foods. You can hide it in meatballs, burgers, meatloaf, or any other ground beef recipe. Wrapping it in bacon is another popular disguise; you could also mask the taste with a hefty dose of Indian spices.
An alternative to all of these methods is to simply eat your liver raw. Don’t try this if you’re not sure where the liver came from, but if you’re confident that the animal was organically raised and slaughtered in a clean environment, raw liver might be a tasty (or at least an exciting) experiment. The Weston A. Price Foundation recommends freezing your liver for 14 days to kill any potential bacteria. Freeze it in serving-sized chunks, then defrost and enjoy if you like the flavor; otherwise, you can freeze it in pill-sized balls and swallow it still frozen: no tasting required. Raw meat skeptics could also use the “pill method” with cooked liver: just remember to cut the liver to size before you pop it in the freezer, or you’ll be stuck hacking away at a huge block of frozen meat, trying to cut off a pill-sized piece.
While it’s important not to go overboard, liver in moderate amounts can make a tasty and nutritious addition to your diet. Luckily, even grass-fed liver is relatively cheap, so you can experiment without breaking the bank. It’s not a Paleo requirement – if you really can’t stomach it, you can get all of your nutrients from other sources – but it’s worth a try or three to find a way of cooking it that works for you.