For many people, organs are both loved and feared. They are feared because they contain too much fat and cholesterol, and because they can be contaminated. They are loved because of their taste and texture.
Today, let's not talk about taste, let's focus on nutrition. Do organs really contain a lot of fat and cholesterol? Are they not beneficial for our health? The reality is quite different.
Can we eat animal organs? What nutrition do they provide?
Excluding the pale white parts of the stomach and intestines, most organs have a deep red color, especially the liver, kidneys, heart, and spleen.
People who understand nutrition know that eating deep red animal organs, such as liver, can help people with iron-deficiency anemia because the purple-red color of organs comes from "hemoglobin." Hemoglobin is the reason why organs, muscles, and blood appear red, and it contains iron. Organs have a darker color because they contain more hemoglobin than meat, and the iron in it has a very high absorption rate. This is also the reason behind folk sayings like "eating pig liver can replenish blood."
For example, when adding complementary foods to larger infants, just adding a spoonful of liver puree can effectively supply iron and prevent common iron-deficiency anemia in infants. In addition to pig liver, chicken liver, duck liver, goose liver, and lamb liver are also good choices. Duck gizzards, chicken hearts, pig kidneys, and other deep red organs are also good options. Any deep red organ can help with iron supplementation, but liver is easier to turn into puree.
People also know that liver can help improve eye health for some individuals because animal livers contain high amounts of vitamin A, much more than other foods such as milk, eggs, meat, and fish. Vitamin A can effectively prevent and treat night blindness, dry eye disease, and corneal softening. Ancient medical texts have mentioned that liver can "replenish blood" and "brighten the eyes" because of its high nutrient content.
In fact, the nutritional value of the liver goes beyond this. In animals, the liver is a storehouse of nutrients and contains all 13 vitamins that the human body needs, with particularly high levels of vitamin A, vitamin D, vitamin B2, and vitamin B12. Liver has more protein than lean pork, and it is rich in iron, zinc, copper, manganese, and other trace elements. It is one of the most nutrient-rich foods in nature. Wild carnivorous animals never give up this important source of nutrition and always consume the liver along with the rest of the prey.
In addition to the liver, animal kidneys also contain a lot of vitamin A and vitamin D, which are much lower in regular meats. In terms of B vitamins and trace elements, kidneys, hearts, and poultry gizzards are significantly higher than regular meats. In other words, they are "red meat" with higher nutrient content.
Some people worry that the liver contains too much vitamin A, and excessive intake of this vitamin can cause toxicity. Some people have heard that pregnant women should not eat liver because excessive intake of vitamin A can lead to fetal deformities. However, these situations only occur when consumed in excessive amounts, and do not include other organs such as the heart and kidneys.
In China, most people do not get enough vitamin A in their diet, and most people do not meet the recommended intake amount (700 micrograms per day for women, 800 micrograms per day for men). According to China's latest Dietary Reference Intake (DRIs), the "tolerable upper intake level" for vitamin A for healthy adults, including pregnant women, is 3000 micrograms per day. In other words, even if you consume less than 3000 micrograms of vitamin A every day for a long time, it will not cause any problems.
Based on current medical evidence, acute toxicity can occur in adults who take more than 100 times the recommended amount of vitamin A, and chronic toxicity can occur in those who take more than 25 times the recommended amount every day. Based on the vitamin A content in chicken liver and pig liver, eating 50 grams of liver once a week would provide approximately 5000 and 2500 micrograms of vitamin A, respectively, which is only 7 times and 3.5 times the recommended daily amount for adult women, far from the level of acute toxicity. If we average this value over 7 days, it would be only 1 time and 0.5 times the recommended amount. In other words, occasionally eating animal liver, such as once or twice a month, even in larger quantities than 50 grams, would not result in vitamin A toxicity. Unless you take excessive vitamin A capsules or drink excessive amounts of fish liver oil, the claim that eating liver occasionally can cause vitamin A toxicity is an exaggeration.
However, some people are afraid of eating organs because they believe that liver is a high-fat and high-cholesterol food. Indeed, the fat content of fatty duck liver and fatty goose liver is relatively high, usually ranging from 10% to 30%, which is comparable to foods like fatty beef. However, the fat content of normal liver is less than 5%, lower than lean pork, making it a high-protein and low-fat food. Healthy kidneys are also high-protein and low-fat foods, while the fat content of the heart is comparable to regular meats.
As the liver is the place where cholesterol is synthesized in the body, its cholesterol content is usually 3 to 4 times that of lean meat. Compared to 100 grams of raw pork liver, it contains slightly more cholesterol than a chicken egg. In comparison, the cholesterol content of kidneys is slightly lower, while the cholesterol content of the heart is almost the same as regular meats, so there is no need to worry about it.
Recently, the American Society for Nutrition has just removed the dietary limit on cholesterol. China's latest Dietary Reference Intake also does not restrict cholesterol intake. This is because researchers have repeatedly reviewed studies on the relationship between cholesterol and heart disease and have not found reliable evidence to prove that consuming more cholesterol necessarily leads to increased blood cholesterol levels and cardiovascular disease. Although nutritionists do not advocate frequent consumption of cholesterol-rich liver, if the total amount of meat consumed daily is not excessive and one consumes liver once or twice a month, with each serving being one or two ounces, there is no need to worry too much.
However, there are still claims in society that "eating liver can be toxic" and "organs are highly contaminated," which makes many people hesitate to consume them. Indeed, the liver is like a huge "chemical factory." It is the most important organ for nutrient synthesis in the animal body, as well as a detoxifying organ. All kinds of toxins are sent to the liver to be processed, and the kidneys are involved in detoxification as well. It is difficult to avoid contact with toxins.
Nutrients in food are digested and absorbed into the blood as small molecules, and then transported to the liver for further synthesis of various substances needed by the body. Various toxins also enter the liver for detoxification, and through various detoxification pathways, they are ultimately converted into harmless substances or small molecules that are soluble and excreted from the body. If an animal is diseased, or if excessive amounts of medication are used, or if there is an excessive amount of heavy metals and other difficult-to-decompose environmental pollutants in the feed, these substances may accumulate in the liver for a long time. Therefore, the claim that "eating liver can be toxic" is not entirely unfounded.
However, these harmful effects of the liver are based on the premise that the animal itself is sick, or that excessive amounts of veterinary drugs are used, or that the feed and water sources are contaminated. The same goes for kidneys. If you consume products that have undergone animal quarantine and inspection, and control the intake amount and cooking methods, generally speaking, poisoning is unlikely to occur.
Should we eat organs or not?
Having said that, the way to coexist peacefully with organs is clear.
1. If you are not anemic or deficient in zinc or vitamin A, there is no need to regularly eat liver and kidneys. People who do not eat these organs can ensure their vitamin A intake by eating spinach, carrots, eggs, whole milk, and fatty fish. They can also obtain easily absorbed heme iron from consuming red lean meat.
2. If a doctor recommends eating animal liver as an adjunct treatment for anemia, night blindness, dry eye disease, or other conditions, or when feeding complementary foods to infants, it is best to consume no more than 20 grams (a full tablespoon of liver puree) at a time. This way, excess vitamin A intake can be avoided, and the total amount of pollutants will not be excessive.
3. If healthy individuals enjoy eating liver and kidneys, it is fine to consume them once or twice a month, replacing other meats. Each time, the amount should not exceed 100 grams. It is recommended to purchase reliable products with quarantine and inspection labels from reputable supermarkets. Choosing organic, green, or pollution-free foods is relatively safer in terms of environmental pollution accumulation. Do not eat organs that are diseased or not fresh, and make sure to cook them thoroughly. Do not eat undercooked organs just for the sake of a tender and smooth texture.
4. Under the same breeding environment, large animals such as cattle and sheep have a longer growth period, resulting in a relatively higher accumulation of environmental pollutants in their livers. On the other hand, chickens and ducks have a shorter growth period, so the accumulation of pollutants in chicken liver and duck liver is even less than that of pig liver. They also have a finer and smoother texture, making them more suitable for making liver puree for infants.
5. Compared to liver and kidneys, animal hearts and poultry gizzards are safer options. They have excellent protein quality, are rich in various trace elements, and have higher B vitamin content. Overall, they are superior to regular lean meats. At the same time, the fat and cholesterol content of hearts and gizzards is not excessively high, and they have a great taste and texture. They are suitable for consumption by all healthy individuals and are good foods for preventing iron-deficiency anemia.
