Unfortunately, the public has been given a lot of misinformation about vitamin A.
If you look on the back of a can of tomatoes, it will say the tomatoes contain a certain amount of vitamin A. There are many books on nutrition and internet sources that tell you to get lots of vitamin A by eating carrots, sweet potatoes, dark leafy greens, cantaloupe, and bell peppers.
However, when we look up vitamin A in the biochemistry textbooks, or in the Merck Manual, we learn that there is no vitamin A in plant foods. It occurs only in animal foods. Plant foods contain the precursors to vitamin A, which are called carotenes. Sally Fallon Morell, author of Nourishing Traditions, asserts that our government allows the food industry to call the carotenes in plant foods vitamin A because otherwise it would be obvious that the food-pyramid diet contains very little vitamin A.
Carotenes are converted into the true vitamin A in the intestines of animals, including humans. The carotene with the highest conversion factor, that is, the carotene that is most easily converted, is beta-carotene. Various enzymes and vitamins are needed to split beta-carotene into molecules of true vitamin A. As the Weston A. Price Foundation explains, when we are in excellent health, it takes at least 6 molecules of carotene to produce one molecule of vitamin A. As Chris Kresser highlights in The Healthy Baby Code, that means one must eat 4 1/2 pounds of carrots to potentially get the amount of useable vitamin A as in 3 oz. of beef liver. What happens if we have digestive issues, hormone imbalances, or other health problems? The conversion is even more difficult to make.
So while it is true that humans can convert some of the carotenes in their food into vitamin A, many conditions interfere with this conversion. Sally Fallon Morell explains that children make this conversion very poorly and infants don’t make it at all. “You can give the baby carrot juice until he turns orange – and he will turn orange – but he will not make this conversion.” This is why babies and growing children right up to age 18 need more vitamin A in their diet as a function of body weight than adults do. Plant foods will not provide adequate amounts of vitamin A. The books on infant feeding back in the 1930s and 1940s recommended 2 teaspoons of cod liver oil per day for infants over 3 months old.
From the work of Dr. Weston A. Price, we can assume that the amount of vitamin A in traditional diets was about 50,000 IU per day, which could be achieved in a modern diet by consuming generous amounts of whole raw milk, cream, butter and eggs from pastured animals; beef or duck liver in the form of pâté several times per week; and 1/2 tablespoon high-vitamin cod liver oil per day. The vitamin A in butter is the easiest to absorb of any food.
A popular objection to eating liver is the belief that the liver is a storage organ for toxins in the body. While it is true that one of the liver’s role is to neutralize toxins (such as drugs, chemical agents and poisons), it does not store these toxins. Toxins the body cannot eliminate are likely to accumulate in the body’s fatty tissues and nervous system. Remember that it is essential to eat meat and organ meats from animals that have been raised on fresh pasture without hormones, antibiotics or commercial feed. Pasture-raised animal products are much higher in nutrients than animal products that come from commercial feedlots.
Update: Please note that we recommend whole food sources of vitamin A first and foremost rather than supplementation. Learn more from the Weston A. Price Foundation: