1. Dietary vitamin deficiencies tend to be multiple, not single
2. Clinical evidence of vitamin defi ciencies develops gradually, and early symptoms, such as fatigue and weakness, may be vague, ill-defi ned, and nonspecific
3. The physical examination cannot be relied upon to make a diagnosis of early vitamin deficiency; classic features of vitamin deficiencies, such as the corkscrew hairs of scurvy, are only detectable after a profound deficiency state has been attained
4. The rate of development of vitamin defi ciencies is highly variable. In general, most water-soluble vitamins may be depleted within several weeks; longer periods are needed for significant depletion of fat-soluble vitamins. Several years are required for clinical manifestations of vitamin B12 deficiency unless there are complicating factors, such as ileal resection or inflammatory bowel disease involving the ileum
5. The impact of dietary deficiencies of vitamins is greatly augmented by the long-term chronic use of certain medications that may affect absorption, utilization, or excretion of vitamins. Chief among these are laxatives and diuretics. These considerations are particularly relevant to older individuals, who use the largest number of drugs and remedies, for the longest duration, and may have marginal diets to begin with
6. The concept of “risk factors” may be helpful in assessing factors, such as drugs and alcohol, that contribute to accelerating the clinical presentation of a given dietary inadequacy.
2. Clinical evidence of vitamin defi ciencies develops gradually, and early symptoms, such as fatigue and weakness, may be vague, ill-defi ned, and nonspecific
3. The physical examination cannot be relied upon to make a diagnosis of early vitamin deficiency; classic features of vitamin deficiencies, such as the corkscrew hairs of scurvy, are only detectable after a profound deficiency state has been attained
4. The rate of development of vitamin defi ciencies is highly variable. In general, most water-soluble vitamins may be depleted within several weeks; longer periods are needed for significant depletion of fat-soluble vitamins. Several years are required for clinical manifestations of vitamin B12 deficiency unless there are complicating factors, such as ileal resection or inflammatory bowel disease involving the ileum
5. The impact of dietary deficiencies of vitamins is greatly augmented by the long-term chronic use of certain medications that may affect absorption, utilization, or excretion of vitamins. Chief among these are laxatives and diuretics. These considerations are particularly relevant to older individuals, who use the largest number of drugs and remedies, for the longest duration, and may have marginal diets to begin with
6. The concept of “risk factors” may be helpful in assessing factors, such as drugs and alcohol, that contribute to accelerating the clinical presentation of a given dietary inadequacy.
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