The Bioavailability of Iron PDF

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Lab report for CHEM 1315 ...

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University of Oklahoma

General Chemistry 1315-021 Kacia Harris The Bioavailability of Iron

Introduction: Iron has the greatest abundance of any trace element in the human body. Iron is very important in the human body because it is used in so many different areas. It is found circulating in our blood, muscle tissue, the spleen, bone marrow, and liver (Pereira, Bruggaber, et. al). Iron can be found in many different food sources, but less than 15% of the iron in our diets and different food can be used by our bodies. It is estimated that 25% of the iron intake in the United States is made from various forms of fortification iron (Hurrell). Fortification is the process of adding more of a trace element to a certain food than what it previously had. Fortificated iron only results in low bioavailability, and is only 15% as well used as food with native iron, which is why iron still needs to use other substances to make it more bioavailable to the human body (Uauy, Hertrampf, Reddy). My hypothesis is that substances that have a high pH make iron less bioavailable. In this experiment, we tested what substances may affect the bioavailability of Iron, and either make it more or less usable by the human body. Methods: For the first part of the experiment, we first obtained 20 mL of 5% sodium hydroxide in a labeled 50 mL beaker. The NaOH solution was clear in color. We then obtained 30 mL of pH 2 dissolved iron solution in a different 50 mL beaker. The pH 2 dissolved iron was a liquid that was dark yellow in color. Then to test the behavior of dissolved iron with sodium hydroxide, we placed 5 mL of pH 2 dissolved iron in a large test tube. We slowly added 5% solution of sodium hydroxide into the same beaker that contained the pH 2 dissolved iron. We added 5 drops of NaOH to the iron solution, obtained a small sample on the end of a glass stirring rod, and transferred a drop of the solution to pH paper to test the pH. After the first 5 drops of NaOH, the solution had only reached a pH of 2. We then began to test the pH of the solution after every 5 drops were added until the solution reached a pH of 8. To reach a pH of 8, it took 20 drops of NaOH. The solution became a clear liquid on top with a dark red precipitate on bottom. In the second half of the experiment, we tested the effects of different additive substances from Table 1.0 on dissolved iron. Table 1.0- Different substances that may have an effect on bioavailability Substance

Dietary Sources

Ascorbic Acid

Fruits, vegetables, potatoes

Oxalic Acid

Vegetables

Caffeine

Soft drinks, coffee, tea

Lysine Hydrochloride

Milk, meat, eggs

Sodium Carbonate

Calcium, antacids

Citric Acid

Fruits, soft drinks

University of Oklahoma

General Chemistry 1315-021 Kacia Harris

Sodium Phosphate

Soft drinks

Fructose

Fruits (ripened), honey

Tannic Acid

Tea

Histidine

Milk, eggs, meat

Methionine

Milk, eggs, meat

To test the effect of different additive substances on dissolved iron, we began by placing 5 mL of pH 2 dissolved iron in a large test tube. We then added 0.2 grams of one of the substances from Table 1.0, and stirred until it dissolved. We then took the initial pH of the solution of dissolved iron and a substance from Table 1.0. After this, we slowly added 5% solution of sodium hydroxide into the solution. We added this by 5 drops at a time until the pH of the substance reached 8. We then repeated these exact steps 2 more times with 2 other substances. In total, my group tested the effect of Methionine, citric acid, and fructose on the bioavailability of Iron. We obtained the observation data for the 8 remaining substances from other groups participating in the experiment. Results: After performing the experiment, it was clear to see which substances made iron more bioavailable. Table 1.2 shows the results of adding different substances to dissolved pH 2 iron, and how these substances affected pH and appearance of the iron. Table 1.2: The data gathered from this experiment Substance

Initial pH

Amount of Substance (g)

Initial Appearance

Drops of NaOH or Sulfuric Acid

Fina l pH

Final Appearance

Ascorbic Acid

2

.204g

Clear liquid

30 Drops NaOH

8

Liquid turned black

Oxalic Acid

1

.204

Bright Yellow Liquid

50 Drops NaOH

8

Liquid turned to an orange rust color

Caffeine

1

.202

Yellow, cloudy precipitate

18 Drops NaOH

8

Orange/red cloudy precipitate

Lysine

N/A

N/A

N/A

N/A

N/A

N/A

University of Oklahoma

General Chemistry 1315-021 Kacia Harris

Hydrochlorid e Sodium Carbonate

8

.201g

Orange/brown liquid

0 Drops NaOH

8

Orange/brown liquid

Citric Acid

1

.202g

Dark yellow liquid

60 drops NaOH

8

Very dark orange/red aqueous solution

Sodium Phosphate

7

.205g

Pale yellow liquid

10 8 drops of NaOH

Dark, milky orange with precipitate

Fructose

1

.202g

Dark yellow liquid

8 15 drops of NaOH

Dark, red liquid

Tannic Acid

10

.202g

Dark black/blue liquid

20 Drops of Sulfuri c Acid

8

Green/brown liquid

Histidine

5

.205g

Dark red liquid

9 Drops of NaOH

8

Burnt orange cloudy liquid

Methionine

2

.203g

Dark red liquid

15 8 drops of NaOH

Light, orange liquid

Table 1.2 shows the substances that were tested, the initial and final pH of iron with each substance and the appearance of each substance once it was mixed with the iron solution. No data was recorded for Lysine Hydrochloride, so it is not applicable. Discussion: The bioavailability of iron can be changed by adding different substances to change the pH of the iron. The bioavailability of iron increases when the pH is closer to a neutral base, or a pH of 8. For this experiment, we added different substances to iron to change the pH, thus, making the iron more bioavailable. The substance that makes iron the least bioavailable is tannic acid. This makes sense because the pH of tannic acid is so high. Since this substance had such a high pH, we had to add sulfuric acid to bring the pH back down. Tannic acid can be found in different types of teas. Another substance that lessens the bioavailability of iron is caffeine. Like tannic acid, caffeine can be found in tea, and soda. This brings me to the conclusion that these types of drinks should be considered in moderation since they provide almost no iron at all. Conclusion: In conclusion, my research shows that a substance with a higher pH level will lower the bioavailable level of iron. With these findings, my hypothesis was supported. I came to this

University of Oklahoma

General Chemistry 1315-021 Kacia Harris

conclusion because looking at the results, tannic acid made iron the least bioavailable. The pH of tannic acid is the highest of all the substances, and it took adding sulfuric acid to get it to an absorbable pH.

University of Oklahoma

General Chemistry 1315-021 Kacia Harris

Works Cited Hurrell; Richard; Egli; Ines. Iron bioavailability and dietary reference values. https://academic.oup.com/ajcn/article/91/5/1461S/4597424 (accessed Feb 17, 2019). Pereira, D.I.A., Bruggraber, S.F.A., et al. Nanoparticulate iron(III) oxo-hydroxide delivers safe iron that is well absorbed and utilised in humans. Nanomedicine: Nanotechnology, Biology, and Medicine 10 2014, 1877–1886 Uauy; Ricardo; Hertrampf; Eva; Reddy; Manju. Iron Fortification of Foods: Overcoming Technical and Practical Barriers. https://academic.oup.com/jn/article/132/4/849S/4687272 (accessed Feb 17, 2019)....