Vitamin A & The BCO1 Gene

Vitamin A & The BCO1 Gene

Vitamin A is not found in plants.

The USDA food labels that you see on bags of carrots or bottles of juice claiming “Vitamin A: 80%” is erroneous.

Beta carotene is found in plants, and human metabolism can convert some of the carotenoids into Vitamin A.

However, there are well studied genetic variants that significantly reduce the ability to convert ß-carotene into Vitamin A. The gene is known as BCO1 (beta carotene monooxygenase 1).

Homozygous carriers of the G risk allele for rs11645428 have shown a 51% decrease in the conversion efficiency of ß-carotene into Vitamin A . Homozygous carriers of the A risk allele for rs6420424 have shown a 59% decrease in the conversion efficiency of ß-carotene into Vitamin A. Homozygous carriers of rs6564851 also show reduced metabolism of ß-carotene into Vitamin A (R).

Combined homozygotes for rs12934922 and rs7501331 have shown a reduced ß-carotene to Vitamin A conversion by 57%. Heterozygotes for the SNP’s also have shown reduced conversion into Vitamin A (R).

Another gene, CYP26B1 is a cytochrome enzyme involved in the catabolism of one of the primary Vitamin A metabolites, retinoic acid. The A risk allele for rs2241057 is associated with an increased breakdown of retinoic acid, and is also associated with Crohn’s disease (R).

Why Is Vitamin A Important?

  • Vitamin A is a fat soluble nutrient
  • The Vitamin A receptor (RXR) when activated by Vitamin A forms a heterodimer with the Vitamin D receptor (VDR), and this heterodimer is critical for gene expression and immune activation (R).
  • Vitamin A regulates the steroid hormone enzyme 17ßHSD in the endometrium, effectively converting the sex hormone estradiol into estrone (R)
  • Studies have yet to be performed on Vitamin A influencing Testosterone through 17ßHSD (which is an enzyme that converts androstenedione into testosterone), yet there appears to be a relationship given the study on 102 boys below
  • In a study of 102 boys with short stature & delayed puberty, Vitamin A supplementation induced growth acceleration similar to the testosterone-supplemented group (R)
  • In rats, greater concentrations of retinoic acid (Vitamin A) in testes show higher testosterone concentrations (R)
  • Vitamin A deficiency impairs the function of immune cells such as macrophages, neutrophils, and natural killer cells (R)
  • Vitamin A is necessary for the development of T and B-cell lymphocytes (R)
  • Studies in mice have found that Vitamin A deficiency impairs the ability to form immune antibodies via TH2 immune cytokines (R)
  • Zinc deficiency may cause Vitamin A deficiency (R, R)

Why Vegan or Vegetarian Diets May be A Bad Idea for Carriers of the BCO1 Gene

If you have a reduced ability to synthesize Vitamin A from plant-derived beta carotene, you run the risk of becoming deficient in Vitamin A if you are obtaining little dietary Vitamin A from animal fats.

Carriers of the BCO1 gene variants can prevent Vitamin A deficiency by including high quality animal foods such as:

  • Liver
  • Egg yolk
  • Grass fed Butter & whole fat dairy products

Blood Tests For Vitamin A

  • Serum Retinol testing can assess Vitamin A sufficiency
  • The Lab Corp reference range for Vitamin A is 33-100 ug/dl
  • During acute phase responses (aka acute inflammation) Vitamin A testing is less accurate. (R, R). Therefore, if you have elevations in acute phase proteins such as CRP, Complement factors, or Ceruloplasmin don’t test your Retinol levels if acute inflammation is present.
Michael
Michael McEvoy
michael@metabolichealing.com

Michael McEvoy is the founder of Metabolic Healing and cofounder of TrueReport. Michael is recognized as a thought leader, systems creator, educator and integrator of diverse clinical modalities. Michael has created the Metabolic Healing Institute out of the need for deeper clinical applications, and clarity of vision in the field of functional medicine and integrative healthcare.

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