However, this meta-analysis included two large studies of smokers, so it is not clear that the results apply to the general population. The review only studied the influence of synthetic antioxidants and the results should not be translated to potential effects of fruits and vegetables. β-Carotene and photosensitivity
Oral β-carotene is prescribed to people suffering from erythropoietic protoporphyria. It provides them some relief from photosensitivity. Carotenemia
Carotenemia or hypercarotenemia is excess carotene, but unlike excess vitamin A, carotene is non-toxic. Although hypercarotenemia is not particularly dangerous, it can lead to an oranging of the skin (carotenodermia), but not the conjunctiva of eyes (thus easily distinguishing it visually from jaundice). It is most commonly associated with consumption of an abundance of carrots, but it also can be a medical sign of more dangerous conditions. Production
Carotenes are produced in a general manner for other terpenoids and terpenes, i.e. by coupling, cyclization, and oxygenation reactions of isoprene derivatives. Lycopene is the key precursor to carotenoids. It is formed by coupling of geranylgeranyl pyrophosphate and[geranyllinalyl pyrophosphate.Most of the worlds synthetic supply of carotene comes from a manufacturing complex located in Freeport, Texas and owned by DSM. The other major supplier BASF also uses a chemical process to produce β-carotene. Together these suppliers account for about 85% of the β-carotene on the market. In Spain Vitatene produces natural β-carotene from fungus Blakeslea trispora, as does DSM but at much lower amount when compared to its synthetic β-carotene operation.
For example, one association is with mutations in the XBP1 gene, which is involved in the unfolded protein response pathway of the endoplasmic reticulum. The gene variants of NOD2/CARD15 seem to be related with small-bowel involvement. Other well documented genes which increase the risk of developing Crohns disease are ATG16L1, IL23R, IRGM, and SLC11A1. There is considerable overlap between susceptibility loci for IBD and mycobacterial infections. Genome-wide association studies have shown that Crohns disease is genetically linked to coeliac disease.Crohns has been linked to the gene LRRK2 with one variant potentially increasing the risk of developing the disease by 70%, while another lowers it by 25%. The gene is responsible for making a protein, which collects and eliminates waste product in cells, and is also associated with Parkinsons disease. Immune system
There was a prevailing view that Crohns disease is a primary T cell autoimmune disorder; however, a newer theory hypothesizes that Crohns results from an impaired innate immunity. The later hypothesis describes impaired cytokine secretion by macrophages, which contributes to impaired innate immunity and leads to a sustained microbial-induced inflammatory response in the colon, where the bacterial load is high. Another theory is that the inflammation of Crohns was caused by an overactive Th1 and Th17 cytokine response.In 2007, the ATG16L1 gene was implicated in Crohns disease, which may induce autophagy and hinder the bodys ability to attack invasive bacteria.