Adequate Intake biotin

Biotin is widespread in foods, although its availability is affected somewhat by the presence of binding proteins. Biotin is required in only small amounts. Although US RDA values have not been established, the estimated safe and adequate intake of biotin is 30-100 g day -1 for adults. The Department of Health (1991) suggested that biotin intakes between 10 and 200 iig day-1 are safe and adequate. Biotin is reported to be non-toxic in amounts up to at least 10 mg day-1. 

Adequate Intake For some vitamins, notably biotin (Section 11.5) and pantothenic acid (Section 12.6), dietary deficiency is more-or-less unknown, and there are no data from which to estimate average requirements or derive reference intakes. In such cases, the observed range of intakes is obviously more than adequate to meet requirements, and the average intake is used to calculate an adequate intake figure. 

It is apparent from the discussion in Section 11.3 that there is Utde information concerning human biotin requirements and no evidence on which to base recommendations. Average intakes of biotin range between 15 to 70 /rg per day. Such intakes are obviously adequate to prevent deficiency, and the safe and adequate range of biotin intakes is set at 10 to 200 /xg per day (Department of Health, 1991 Scientific Committee for Food, 1993). The U.S./Canadian adequate intake for adults is 30 /xgper day (Institute of Medicine, 1998). 

The Food and Nutrition Board of the US National Research Council has released adequate intakes for infants, adults and pregnant women (Mock 2004 National Research Council 1989 Yates et al. 1998). These recommendations (Table 43.1) refer to studies assuming that, with a daily dose of 60 pg of biotin, adults on parenteral nutrition declared they were symptom-free for six months and with diets supplying 28 2pg/day, no inadequate biotin status was observed. The dietary biotin intake in Western populations has been estimated to be 35-70 pg per day (143-287 nmoles per day). 

Mammals cannot synthesize biotin and depend on a regular dietary supply of this water-soluble vitamin (Zempleni et al., 2009). The Adequate Intake for biotin in adults is 30 pg/d (National Research Council, 1998). The classical role of biotin in mammalian intermediary metabolism is to serve as a covalently bound coenzyme in five carboxylases (Zanpleni et al., 2D09). Both the cytoplasmic acetyl-CoA carboxylase 1 (ACCl) and the mitochondrial acetyl-CoA carboxylase 2 (ACC2) catalyze the binding of bicarbonate to acetyl-CoA to generate malonyl-CoA, but the two isoforms have distinct functions in intermediary metabolism (Kim et al., 1997). ACCl produces malonyl-CoA for the synthesis of fatty acid synthesis in the cytoplasm ACC2... 

RECOMMENDED DAILY ALLOWANCE OF BIOTIN. It is difficult to obtain a quantitative requirement for biotin, for the reason that intestinal microflora make a significant contribution to the body pool of available biotin often humans excrete via the feces and urine considerably more biotin than they have ingested. However, the estimated safe and adequate intakes of biotin are given in the section on VITAMIN(S), Table V-5, Vitamin Table. 

Table 1. 1989 Estimated Safe and Adequate Daily Dietary Intake for Biotin...

RDA have been established for many essential nutrients however, present knowledge of human nutritional needs of pantothenic acid and biotin is incomplete. Therefore, to ensure adequate nutrient intake, obtain the recommended allowances from as varied a selection of foods as possible. Nutritionists suggest that dietary planning include regular intake of each of the four basic food groups ... 

The problem is a functional deficiency of biotin, due both to inability to release free biotin from dietary biocytin and also to failure of the normal recovery of free biotin by biotinidase action on the biocytin released by proteolysis of biotin-containing enzymes. Normal intakes of biotin are inadequate to meet the requirements of these patients the provision of pharmacological doses of free biotin provides an adequate amount to meet requirements without the need for reutUization. The delayed development of clinical and biocheimcal abnormalities is a result of the accumulation of biotin by the fetus, so that at birth the infant has adequate stores of the vitamin. 

Dietary Reference intakes. These have been difficult to determine. There has been some speculation that humans might obtain part of their biotin requirements from the intestinal flora in the colon. The question that has not been adequately answered is whether there is significant absorption of bacteria-pro-duced biotin from the colon. 

The estimated safe and adequate daily dietary intake (ESADDI) for biotin is 0.30 mg, and in a normal diet, biotin deficiency is almost imknown. However, when it does occur, the symptoms include dermatitis (scaling and hardening of the skin), loss of appetite and nausea, muscle pain, and elevated levels of blood cholesterol. 

The estimated safe and adequate daily dietary intake (ESADDI) for biotin is... 

There is no recommended dietary allowance for biotin, although it suggested that a safe and adequate oral intake is 85 pg for four- to six-year-olds and 100-200 pg for adults (Recommended Dietary Allowance, 1980). A recent review contains a recommendation of 30 pg/kg/d for infants and 5 pg/kg/d for adults fed intravenously (Shenkin and Wret-lind, 1978). 

Concerning parenteral nutrition, the problem is the same but the existing formulas contain amino acids with adequate vitamin and mineral supplementation. Continuous consumption of raw eggs containing the protein avidin is well-known for causing biotin deficiency as the solid combination avidin/biotin is not absorbed. Nevertheless, such dietary intake is rather rare. Biotin deficiency can be considered as a public health problem in developing countries where severely malnourished children lack of multivitamins (Zempleni et al. 2008). 

For some nutrients, such as the vitamins biotin (section 11.12) and pantothenic acid (section 11.13), and a number of trace minerals, deficiency is unknown except under experimental conditions. For these nutrients there are no estimates of average requirements, and therefore no reference intakes. As deficiency does not occur, it is obvious that average levels of intake are more than adequate to meet requirements. For these nutrients there is a range of intakes that is defined as safe and adequate, based on the observed range of intakes. 

There is no evidence on which to estimate requirements for biotin. Average intakes are between 10 and 200 Jg/day. As dietary deficiency does not occur, such intakes are obviously more than adequate to meet requirements. 

An intake of 50 mcg/1,000 kcal should provide adequate biotin intake for infants and older children. 

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