Vitamin A Toxicity – What You Need to Know

Naomy writes…

I’m still confused and concerned about the Vitamin A during pregnancy and causing birth defects since I’m only 5 weeks pregnant… I’ve read various and conflicting information.

I want to start taking a blend of fermented cod liver oil/butter oil and not sure if I should take that AND continue taking my prenatal vitamins. Will that be too much Vitamin A?

I understand or think that it’s different Vitamin A (prenatal Vitamin A is synthetic, and cod liver Vitamin A is natural). So would I be taking too much Vitamin A if I take BOTH prenatal vitamins and cod liver oil?

Great question.

Why is Vitamin A So Important Anyway?

Vitamin A (the kind found in animal sources) is one of several fat-soluble activators that is necessary for the assimilation of minerals in the diet.  According to Sally Fallon, Vitamin A is the “concert master for a developing fetus.”  Vitamin A is also essential for eye health.

 The Difference between Vitamin A and Carotene

There are two forms of vitamin A: preformed vitamin A (also known as retinol or retinoids) and carotene.

Basically, animals sources such as cod liver oil, liver, eggs, whole milk, cream and butter contains actual, preformed vitamin A.  Whereas carotene is a precursor found in deep green and yellow or orange vegetables which, under ideal circumstances, your body can convert into vitamin A in the upper intestinal tract.

Why Not Just Eat a Bunch of Carrots and Call it a Day?

The issues with carotene are:

1) You need to eat a large quantity of carotene-rich fruits and vegetables to meet your daily requirement and

2) The carotene is not well converted in infants and children, individuals who eat a low-fat diet, or those suffering from diabetes, hypothyroidism, pancreatic disease, or digestive issues including diarrhea, or celiac disease.

Other things that can prevent conversion of carotene into vitamin A include, “Strenuous physical exercise, excessive consumption of alcohol, excessive consumption of iron (especially from “fortified” white flour and breakfast cereal), use of a number of popular drugs, excessive consumption of polyunsaturated fatty acids, zinc deficiency and even cold weather” (Fallon, Vitamin A Saga).

So the best way to get vitamin A is through food sources of the straight stuff: Cod liver oil, liver, eggs, whole milk, cream and butter.

Let’s Clear Up the Confusion about Vitamin A and Toxicity

There is some major conflicting information regarding the toxicity of Vitamin A, and as a result, the recommended dosages conflict as well.

In 1995 a study from the New England Journal of Medicine, Teratogenicity of High Vitamin A Intake, concluded that preformed vitamin A taken in excess of 10,000IU per day by pregnant women was linked to birth defects.  This single study received a great deal of attention, and consequently The FDA currently recommends that pregnant women get their vitamin A from foods containing beta carotene and no more than 5,000 IU of preformed vitamin A (if any) per day.

However, according to a recent edition of the Merck Manual (a well respected medical text book):

Acute toxicity [of vitamin A] in children may result from taking large doses (300,000IU); it manifest as increased intracranial pressure and vomiting, which may lead to death unless ingestion is discontinued.  After discontinuation, recovery is spontaneous, with no residual damage. Only two fatalities have been reported.  Within a few hours of ingesting several million units of vitamin A in polar bear or seal liver, arctic explorers developed drowsiness, irritability, headache, and vomiting, with subsequent peeling of the skin. Mega-vitamin tablets containing vitamin A have occasionally induced acute toxicity when taken for a long time.

Chronic toxicity in older children and adults usually develops after doses of >100,000IU/day have been taken for months. In infants who are given 20,000-60,000IU/day of water-miscible vitamin A, evidence of toxicity may develop within a few weeks. Birth defects have been reported in the children of women receiving 13-cis-retinoic acid [commonly known as Accutane] for skin conditions during pregnancy.

From the Vitamin A Saga, Sallon Fallon reports, “The US Recommended Daily Allowance of vitamin A is currently 5,000 IU per day (and may possibly be lowered to 2500 IU per day). From the work of Weston Price, we can assume that the amount in primitive diets was about 50,000 IU per day, which could be achieved in a modern diet by consuming generous amounts of whole milk, cream, butter and eggs from pastured animals; beef or duck liver several times per week; and 1 tablespoon regular cod liver oil or 1/2 tablespoon high-vitamin cod liver oil per day.”

So what we have here are several conflicting reports which are clearly not individually illuminating all of the facts, otherwise they would be on the same track. Which brings us to…

The Importance of Vitamin A/Vitamin D Ratios

Vitamins A and D work synergistically in their various important functions in the body.

The problem with most commercially available cod liver oil brands is they are processed and treated so most of the naturally occurring vitamins are removed. The Vitamin A and D are then added back in with too little vitamin D in ratio to the added vitamin A.

Because of this common practice, many health expert warn against cod liver oil, but in fact, they should be warning against processed cod liver oil. In it’s natural form, cod liver oil is a perfect natural supplement of Vitamins A and D.  The ideal ratio is approximately 1:5, D to A.

Is there a Difference between Naturally Occurring and Synthetic Vitamin A?

Many scientists would argue that a chemical compound is a chemical compound.  I see their point. However, vitamins that occur in nature are seldom isolated and instead are accompanied by other vitamins and potential co-factors.

Case in point: Vitamin A needs vitamin D. The study done in the New England Journal of Medicine found birth defects mostly in mothers taking supplemental preformed vitamin A, not food-sourced preformed vitamin A.

The point is, that while a synthetic vitamin and natural vitamin may look the identical when isolated under a microscope, whether or not they bring friends to the party makes a big difference in how each functions in the body.

Best Sources of Vitamin A

So.  Having covered all of that, the best sources of preformed vitamin A are:

• Fermented Cod Liver Oil or (second choice) Unprocessed Cod Liver Oil – dosage below.
• Liver from pasture-raised, healthy animals – 1-2 times per week.
• Raw, unpasteurized milk or cream – 1 quart of milk/day for pregnant or nursing moms
• Eggs from hens raised on sunny pasture – 2 or more per day

Remember, while carotene can provide Vitamin A through conversion, it is not a reliable source.  There is no need to worry if you eat some squash or carrots with your eggs and liver since carotene is not known to cause toxicity in large quantities or in combination with preformed vitamin A.

The Weston Price Foundation recommends the following dosages for fermented cod liver oil***:

Confusion cleared?  If not, ask below!

This post is part of the following blog carnivals: Kelly the Kitchen Kop’s Real Food Wednesday, I Believe in Butter’s Sunday School, and Real Food Forager’s Fat Tuesday.

photo credit: bradley j, flickr creative commons.

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