In other words:
“To call the liver a simple filter is incorrect. If we want to maintain the metaphor, it’s more like a chemical processing plant. The liver receives shipments, determines what they contain, and reacts accordingly. It converts protein to glucose, converts glucose to glycogen, manufactures
triglycerides, among many other tasks, but its best-known responsibility is to render toxins inert and shuttle them out to be expelled – usually in the urine via the kidney. It doesn’t just hang on to toxins, as if the liver is somehow separate from the body and immune to contamination. The liver is part of the body! If your liver contains large amounts of toxins, so do you!”
What About Vitamin A?
“As for concerns about vitamin A, these stem from studies in which moderate doses of synthetic vitamin A were found to cause problems and even contribute to birth defects. But natural vitamin A found in liver is an extremely important nutrient for human health and does not cause problems except in extremely large amounts.
According to the authoritative Merck Manual, acute vitamin A poisoning can occur in children after taking a single dose of synthetic vitamin A in the range of 300,000 IU or a daily dosage of 60,000 IU for a few weeks. The Manual cites two fatalities from acute vitamin A poisoning in children, which manifests as increased intracranial pressure and vomiting.
For the vast majority, however, recovery after discontinuation is “spontaneous, with no residual damage.”
In adults, according to the Merck Manual, vitamin A toxicity has been reported in Arctic explorers who developed drowsiness, irritability, headaches and vomiting, with subsequent peeling of the skin, within a few hours of ingesting several million units of vitamin A
from polar bear or seal liver. Again, these symptoms clear up with discontinuation of the vitamin A-rich food. Other than this unusual example, however, only vitamin A from megavitamin tablets containing vitamin A when taken for a long time has induced acute toxicity, that is, 100,000 IU synthetic vitamin A per day taken for many months.
Thus, unless you are an Arctic explorer, it is very difficult to develop vitamin A toxicity from liver. The putative toxic dose of 100,000 IU per day is contained in two-and-one-half 100-gram servings of duck liver or about three 100-gram servings of beef liver. From the work of Weston Price, we can assume that the amount in primitive diets was about 50,000 IU per day.
As for liver for pregnant women, a study carried out in Rome, Italy, found no congenital malformations among 120 infants exposed to more than 50,000 IU of vitamin A per day (Teratology, Jan 1999 59(1):1-2). A study from Switzerland looked at blood levels of vitamin A in pregnant women and found that a dose of 30,000 IU per day resulted in blood levels that had no association with birth defects (International Journal of Vitamin and Nutrition Research 1998 68(6):411-6). Textbooks on nutrition written before the Second World War recommended that pregnant women eat liver frequently, yet today pregnant women are told to avoid this extremely nutritious food. Don’t eat beef liver, cautions Organic Style magazine in a February 2005 article on diets for pregnant women, “. . . it has high levels of retinol, a vitamin-A derivative that can cause birth defects.””
Choosing a Healthy Source
One fact that is well established is that the health of an animal largely affects the health of its organs. For this reason, just as with any meat, it is very important to choose healthy sources.
Often, I can find quality meats and organ meats from local farmers and just make sure that the animal was grassfed, raised on pasture and (if possible) not given grains or antibiotics.