Required major (macro)minerals
need more than 100 mg/day
Calcium, phosphorus, magnesium, sodium, chloride, and potassium
Required trace minerals
need less than 100mg/day
iron, copper, iodine, selenium, chromium, manganese molybdenum, and zinc
Which of the following individuals is likely to have more osteoblast than osteoclast activity?
1-year-old Robby
The relationship between blood glucose and glucagon is analogous to the relationship between blood calcium and _____.
PTH
Biochemical tests are often required to assess status of specific nutrients.
Is blood calcium a good indicator of calcium status?
False
Factors that increase calcium absorption
- Active vitamin D hormone
- Lactose and other sugars
- Adequate protein intake
- Increase calcium needs (e.g. during pregnancy and infancy)
Factors that inhibit calcium absorption
- Lack of stomach acid
- Vitamin D deficiency
- High phosphorus intake
- Phytates: phytochemicals in the bran of whole grain
- Oxalates: in dark green leafy vegetables (spinach)
What is the bioavailability of a nutrient in food?
The amount of nutrient absorbed and ready to be used by the body.
Almost all (99%) of the calcium in the body is used to ______.
form hydroxyapatide
When blood calcium is low, _____ .
- parathyroid hormone is relased
- absorption of calcium from the intestine increases
- reabsorption of calcium from the kidney increases
- resorption of calcium from the bone increases
During rising blood calcium levels, the thyroid secretes what?
Calcitonin: Inhibits Vit D activation, prevents kidney reabsorption, and limits intestinal absorption to inhibit osteoclasts and lower blood calcium levels
Factors that decrease PBM:
- Lack of key minerals (Celiac, ED, etc)
- Smoking (↓ Ca2+absorption)
- Excessive alcohol
- Early menopause
- Abnormal absence of periods (amenorrhea)
Factors that enhance iron absorption
- Increased requirements
- Consumption of animal tissues – Meat Fish Poultry (MFP)
- Ferrous form (Fe2+) is better absorbed than ferric form (Fe3+)
- Heme iron is better absorbed
- Vitamin C increases absorption of non-heme iron by keeping iron in ferrous form
- Gastric acid reduces ferric iron to ferrous form
Factors that inhibit iron absorption
- Decreased requirements, ie. Good iron status (body doesn’t need more iron)
- Phytate in whole grains and legumes
- Oxalate in green leafy vegetables
- High fiber intake
- Polyphenols (e.g., tannins found in tea)
- Excessive intake or supplement of calcium, zinc, and manganese
Which of the following proteins carries iron through the blood to tissues?
Transferrin
When iron levels within cells are low, _____.
IRPs (Iron Regulatory Proteins) bind to the IREs (Iron Responsive Elements)
Which of the followings has a relationship to iron, similar to the relationship of insulin to glucose?
Hepcidin
Which of the following statements is correct?
- Hepaestin (ferroxidase) contains copper.
- Divalent metal transporter (DMT) transports reduced nonheme iron.
- Ferroportin facilitates cellular iron export.
Which of the followings indicates iron deficiency?
high total iron-binding capacity
Which of the following mutations could result in hemochromatosis?
Mutations leading to impaired production of hepcidin
To decrease the extent of iron deficiency in the U.S., some legislators propose a bill requiring that more foods, like fruit juices, are fortified with iron.
As an expert witness who is concerned about the prevalence of hemochromatosis, what position should you take?
Oppose the legislation because iron toxicity could occur in susceptible individuals since very little iron is lost once it has been absorbed.
Which of the following tests can serve as an early indicator of iron depletion?
Serum ferritin
The relationship between zinc and metallothionein is similar to the relationship between iron and ____.
ferritin
The relationship between iron and hepcidin is similar to the the relationship between calcium and ____.
calcitonin
