The luxus vitamins--A and B12

Area of Science:

• Nutrition Science
• Biochemistry
• Human Physiology

Background:

• Micronutrient intake and body storage patterns are crucial for understanding nutritional status.
• Vitamin A and vitamin B12 are essential micronutrients with unique metabolic pathways.
• The concept of 'luxus' intake, or excessive consumption, is relevant for specific vitamins.

Purpose of the Study:

• To investigate the hypothesis that vitamin A and vitamin B12 are micronutrients with habitually excessive intake.
• To compare habitual intake and total body content with established requirements and Recommended Dietary Allowances.
• To explore the physiological mechanisms underlying the accumulation and loss of these vitamins.

Main Methods:

• Comparative analysis of habitual dietary intake versus Recommended Dietary Allowances.
• Assessment of total body content and liver concentrations in relation to physiological requirements.
• Examination of plasma value ranges and exponential body loss patterns.
• Discussion of vitamin A and B12 localization and chemical forms within liver cells.

Main Results:

• Evidence suggests a 'luxus' state for vitamin A and vitamin B12 intake among known micronutrients.
• Both vitamins accumulate in the liver with age, with concentrations correlating to dietary intake.
• Wide ranges in 'normal' plasma values and exponential body loss related to body stores were observed.
• The stellate cell in the liver appears to be a key storage site for vitamin A.

Conclusions:

• Habitually excessive intake ('luxus' state) is proposed for vitamin A and vitamin B12.
• Liver accumulation, age-related concentration changes, and wide plasma ranges support this hypothesis.
• A 'last come, first served' mechanism influences vitamin A and B12 storage, consistent with a luxus intake state.