NFS302 Week 11: Vitamins and Minerals Part 2 & Disordered Eating

Main functions of iron

1. Transporting ooxygen in the blood and muscles

   1. Hemoglobin and myoglobin

   2. Iron binds O2 in hemoglobin molecule

2. Energy metabolism → citric acid cycle and ETC

3. Immune system

4. DNA synthesis

Iron Requirements by Biological Sex

• Men:

  • 14-18: 11mg/day

  • Adults: 8mg/day

• Women:

  • 14-18: 15mg/day

  • Adults: 18mg/day (over 2x men)

Canadians above iron intake EAR

• 96-98% of men are getting enough iron

• Only 80% of women are getting enough iron

Highest Iron Content Foods

• Moose blood = 55.8mg iron per 90g serving

• Blood pudding is 2nd

• Wild animals (game), organ meats are highest sources of iron

Most Conventional Animal Sources of Iron

• Beef liver → 9.6mg

• Striploin steak → 4.41mg

• Ground beef → 3.9mg

• Dark meat chicken → 2.04mg

Highest non-animal iron sources

• Natto - fermented soybean product → 11.13mg iron/175mL

• Specific cereals → 5.08-7.48mg

• Beans → 3.9-7.87mg

• Seaweed → 9.96mg

2 types of iron absorbed differently

1. Heme iron = absorbed well

   1. Animal flesh

2. Non-heme forms = not absorbed well

   1. Fruits/veg - oxalates

   2. Whole grains - phytates

Like calcium absorption differs

Enhancing non-heme iron absorption

1. Consume vitamin D with the non-heme iron sources

   1. Vitamin C helps free up iron for absorption

2. Consume small amounts of heme iron (animal) with non-heme iron

   1. Helps absorption

3. Use iron cookware

   1. Cast-iron pan or iron fish → iron leeches into food

Factors contributing to iron deficiency

• Poor diet

• Genetics

• Menstrual blood loss

• Exercise-induced hemolysis and hematuria

• Gastrointestinal losses

• Inflammation

• Small amount lost in sweat

Anemia

• Prevalent in ~24.8% of people (WHO)

• End stage of iron deficiency

• Detrimental to health and performance, occurs when Hb drops below specific levels (differ for men vs. women)

• If severe, treated with blood transfusion

Reference ranges for hemoglobin

• Female: 115-155 g/L

• Male: 135-170 g/L

Why iron differences for male vs. female?

• Differences in hemoglobin levels don’t manifest until after puberty

• Similar differences can be seen in other mammals, birds and reptiles

• Males have proportionally more muscle mass → more oxygen needed

Who should supplement with iron?

• Someone with anemia as diagnosed by a doctor using bloodwork

  • 60-120mg iron supplementation for 2-3 months (non-heme iron so absorption is low, therefore large dose)

  • Take on an empty stomach

  • Typically ferrous salts i.e. gluconate, sulfate, fumarate

Whose iron levels should we monitor closely?

• Elite athletes

  • IOC statement (2009) recommends routine hemological screening for anemia and decreased iron stores

  • Particularly female endurance athletes

• Vegetarians

• People with a documented history of anemia/low serum ferritin

Problems with inappropriate supplementing

• No improvement in sports performance

• GI problems i.e. constipation

• Interferes with absorption of other minerals i.e. calcium, zinc (which is why you have on an empty stomach)

• Iron overload can lead to serious health condition hemochromatosis (genetic condition in 0.2-0.5% of North Americans)

  • Improper iron metabolism

• Never a good idea to rely on supps over proper diet

Natural antioxidant system

• Very complex; many individual components have been studied including:

  • Tocopherols (vitamin E)

  • Vitamin C

  • Super oxide dismutase

  • Catalase

  • Glutathionine peroxidase

  • Glutathionine reductase

  • Carotenoids

  • A-lipoic acid

  • N-acetylcysteine

  • Polyphenols

Vit. E and C are the most relevant to the diet and this lecture

Free Radicals

• Antioxidants negate effects of free radicals (destabilized e^-)

• Free radicals target electrons from our bodily structures (protein, lipids and DNA) → destabilize them

What causes free radicals?

• Exercise, i.e. muscle contraction

• Also exposure to: oxygen, radiation, drugs, air pollutants, alcohol, heavy metals, bacteria, viruses, sunlight

• Creation of free radicals is a normal feature of our metabolism

• Antioxidants negate the consequences of free radicals

Vitamin C Quick Facts

• Also called L-ascorbic acid

• Water soluble vitamin

• Many mammals can synthesize their own vitamin C (not humans)

• Many biological functions including:

  • Biosynthesis of collagen (connective tissue, wound healing)

  • Immune fxn

  • Absorption of iron

  • Antioxidant

Vitamin E Quick facts

• Name given to several chemically distinct members of the tocopherol family

• Fat soluble vitamin

• Many biological fxns including:

  • Blood vessel fxn

  • Immune fxn

  • Antioxidant

Vitamin C RDAs

• Males (>19y/o)

  • 90mg/day

• Females (>19y/o)

  • 75mg/day

• Upper limit

  • 2000mg/day

Vitamin E RDAs

• Males (>19y/o)

  • 22.4 IUs

• Females (>19y/o)

  • 22.4 IUs

• Upper limit

  • 1493 IUs

Does physical exercise modify antioxidant requirements?

• Review says no

• Not a sports-specific nutrient either

History of antioxidant vitamins

• 2x Nobel Prize winner Linus Pauling

• Claimed that mega-doses on vitamin C could prevent the common cold and treat cancer - misinformation

Scurvy

• Extremely low vitamin C levels

  • Alleviated easily with vitamin C intake

No effect of vitamin C in exercise

• 1500mg/day of vitamin C in test vs. placebo group

• No measure of oxidative damage or immune function found to be different post-race

No Effect of Vitamin E on exercise

• 1200 IUs/day of vitamin E

• Non-resistance trained men were assigned to supplement group (n = 9) or placebo group (n = 9) for three weeks

• No differences between the groups in muscle soreness, performance measures, markers or membrane damage, oxidative stress