Retinol-Binding Serum Yes Retinol levels are highly correlated to May be measure of physiologically available protein RBP(p192). form. Not if certain disease processes (p 192). Beta-carotene Plasma Yes Yes (p 194) although blood levels much more Yes (p 197) responsive to supplemental beta-carotene than beta-carotene from food sources (p 193) Plasma Yes Yes (p 194) There is some evidence for interaction between Beta-cryptoxanthin carotenoids during intestinal absorption, which Lutein+zeaxanthin may complicate relationship between intake and Lycopene blood levels (p 198) Vit E Plasma Yes Yes (p 196) Plasma, red and blood cells. Yes, if used NB. Strong confounding with serum cholesterol for vit E supplements. Yes, although if used for and total lipid concentrations (p 196). diet, associations are only moderate (p199) Exposure Measured Valid? Reason (Willett) Reason (Margetts / Nelson) in Vit D: D25 (OH)D Plasma Yes Yes (P 198/199) NB. Seasonal variation exists, Both can be used to measure vit D status, but Serum especially in elderly populations, decreasing in the higher plasma concentration and lesser winter and rising during summer (p 198) metabolic control of d25 makes this, by far, the Sunshine exposure is most important better option (p 198). determinant; level is better marker of dietary intake in subjects with low sun exposure Vit D: 1.25 (OH)2D No No. Influenced by calcium and phosphate levels and parathyroid hormone (p 199). Vit D: Alkaline Serum No No. Is indirect measure of vit D status and is No info phosphatase activity susceptible to other disease processes (p 199) Vit C Plasma Yes Yes (p 200). Leukocyte may be preferred for Yes (p 209), vit C exhibits the strongest and long-term intake and plasma and reflects most significant correlation between intake and more recent intake (p 201)
Retinol-Binding protein Serum Yes Retinol levels are highly correlated to RBP(p192). May be measure of physiologically available form. Not if certain disease processes (p 192). Beta-carotene Plasma Yes Yes (p 194) although blood levels much more responsive to supplemental beta-carotene than beta-carotene from food sources (p 193) Yes (p 197) Beta-cryptoxanthin Lutein+zeaxanthin Lycopene Plasma Yes Yes (p 194) There is some evidence for interaction between carotenoids during intestinal absorption, which may complicate relationship between intake and blood levels (p 198) Vit E Plasma Yes Yes (p 196) NB. Strong confounding with serum cholesterol and total lipid concentrations (p 196). Plasma, red and blood cells. Yes, if used for vit E supplements. Yes, although if used for diet, associations are only moderate (p199) Exposure Measured in Valid? Reason (Willett) Reason (Margetts / Nelson) Vit D: D25 (OH)D Plasma Serum Yes Yes (P 198/199) NB. Seasonal variation exists, especially in elderly populations, decreasing in winter and rising during summer (p 198) Sunshine exposure is most important determinant; level is better marker of dietary intake in subjects with low sun exposure Both can be used to measure vit D status, but the higher plasma concentration and lesser metabolic control of d25 makes this, by far, the better option (p 198). Vit D: 1.25 (OH)2D No No. Influenced by calcium and phosphate levels and parathyroid hormone (p 199). Vit D: Alkaline phosphatase activity Serum No No. Is indirect measure of vit D status and is susceptible to other disease processes (p 199) No info Vit C Plasma Yes Yes (p 200). Leukocyte may be preferred for long-term intake and plasma and reflects more recent intake (p 201) Yes (p 209), vit C exhibits the strongest and most significant correlation between intake and