Note: After reading this article, please also read the Vitamin A, Vitamin D and Cod Liver Oil: Some Clarifications section in our Cod Liver Oil Basics and Recommendations article.
Note: This article has been expanded and updated as Vitamin A Saga. It remains online because other articles reference it and to provide the original English version for comparison with a translation that was provided for it.
Vitamin A is in the news again, this time in the form of front page reports on a recent article that appeared in the November 23rd issue of the New England Journal of Medicine. “Teratogenicity of High Vitamin A Intake” by Kenneth J. Rothman of the Boston University School of Medicine and his colleagues, correlates vitamin A consumption among more than 22,000 pregnant women with birth defects occurring in subsequent offspring. “Study Links Excess Vitamin A and Birth Defects” by Jane Brody appeared on the front page of the New York Times on October 7, 1995; on November 24, 1995, the Washington Times reported: “High doses of vitamin A linked to babies’ brain defects.”
When a single study receives such extensive media coverage, its time to take a closer look, especially as those familiar with the work of Weston Price are well aware of the importance of vitamin A in preventing birth defects. In fact, the defects listed as increasing with increased vitamin A dosage—cleft lip, cleft palate, hydrocephalus and major heart malformations—are also defects of vitamin A deficiency.
In the study, researchers asked over 22,000 women to respond to questionnaires about their eating habits and supplement intake before and during pregnancy. Their responses were used to determine vitamin A status. As reported in the newspapers, researchers found that cranial-neural-crest defects increased with increased dosages of vitamin A; what the papers did not report was the fact that neural tube defects decreased with increased vitamin A consumption, and that no trend was apparent with musculoskeletal, urogenital or other defects. The trend was much less pronounced, and less statistically significant, when cranial-neural-crest defects were correlated with vitamin A consumption from food alone.
The study is compromised by a number of flaws. Vitamin A status was assessed by the inaccurate method of recall and questionnaires; no blood tests were taken to determine the actual usable vitamin A status of the mothers. Researchers did not weight birth defects according to severity; thus we do not know whether the defects of babies born to mothers taking high doses of vitamin A were serious or minor compared to those of mothers taking lower amounts. Researchers also failed to distinguish manufactured vitamin A in the form of retinol, found in supplements and added to fabricated foods, from natural vitamin A complex, present with numerous co-factors, from vitamin-A-containing foods like liver, butter, cream, eggs and cod liver oil. It is well known that synthetic vitamins are less biologically active, hence less effective, than naturally occurring vitamins. This is especially true of the fat soluble vitamins like vitamin A, because these tend to be more complex molecules, with numerous double bonds and a multiplicity of forms. Natural vitamin A occurs as a mixture of various isomers, aldehydes, esters, acids and alcohols. Pure retinoic acid, a metabolite of vitamin A used to treat adult acne, is well known to cause birth defects. Apparently pure retinol has teratogenic properties in high amounts as well. Researchers found that cranial-neural-crest defects increased in proportion to the amount of retinol from supplements consumed during the first trimester of pregnancy (although the total number of defects remained stable up to 15,000 IU daily).
Research into vitamin A has indicated that many factors interfere with its absorption and utilization. Inadequate fat in the diet, poor production of bile salts, low enzyme status, and compromised liver function can all interfere with the uptake and usage of vitamin A, especially when given as a supplement in the form of retinol, rather than as a component of whole foods. It may be that the teratogenic effects of commercial vitamin A preparations are exacerbated in women whose dietary practices and general health status are poor. Some researchers believe that synthetic vitamin A interferes with the proper utilization of natural vitamin A from foods.
Pure retinol is added to many fabricated foods like margarine, breakfast cereals and pizza. The study made no distinction between those women whose vitamin A was supplied by whole foods such as butter, eggs, cheese, liver and cod liver oil, and those who ingested retinol added to margarine, white flour and extruded breakfast cereals—foods which contain many other factors that can cause birth defects. Synthetic retinol seems to be teratogenic in amounts exceeding 10,000 IU daily, yet one 3 1/2 ounce serving of beef liver contains over 50,000 IU. Before the anti-fat and cholesterol hysteria hit America, pregnant women were encouraged to eat liver weekly, in order to ensure adequate nutrients for the developing child. Doctors of a generation or two ago understood that a diet rich in vitamin A from liver, eggs, butter, cream and cod liver oil was the best possible protection against birth defects.
Distinctions between synthetic and natural vitamin A have been absent in the extensive media coverage of this study—on the contrary, the newspaper reports contain implied warnings against pregnant women eating liver, dairy products, meat and eggs, but none against eating fabricated foods like margarine and breakfast cereals to which synthetic vitamin A is added—and one is moved to ask if there might be a hidden agenda in bringing these results before the public. There is, in fact, tremendous debate among the public health community about whether vitamin A supplements should be given to pregnant women and children in third world countries. Research indicates that vitamin A, even in supplement form, is highly effective in preventing birth defects, childhood illness, blindness, protein deficiency disease and infant death in regions where poverty is endemic and vitamin-A-containing animal foods are scarce. A number of critics have suggested that our public health programs would be more effective if vitamin A supplements were routinely given to the needy in third world countries. (They might even—horror of horrors—replace the immunizations and antibiotics that currently form the backbone of government-sponsored public health programs.) The high profile reports on the dangers of vitamin A supplements will have the effect of nipping these positive suggestions in the bud. This kind of vitamin A knavery has been around for a long time in the form of frequent warnings about the toxicity of this vital fat-soluble nutrient—when in fact vitamin A has never caused a single death but has the potential for saving millions of lives.
The value of the Boston University study may be as a warning against relying on synthetic vitamin A supplements to prevent birth defects, rather than naturally occurring vitamin A from whole foods. The pioneering research of Weston Price established that vitamin-A-rich foods are absolutely necessary for optimum health, not only for pregnant women and growing children, but for us all.
Copyright: ©1999 Sally Fallon. All Rights Reserved.