organic / science

The Effects of Refining Wheat into Flour

A recent Facebook post stated we lose 95% of nutrients through the refining of wheat into enriched white flour. So I decided to do some fact checking to see if this was true.

I spent some time gathering data on the nutritional value of wheat as well as the effects of flour refining and enrichment on wheat to learn about what is lost (more sources at the bottom). After avoiding the “organic” sites, blogs and other nutty sites, I think I have a good enough understanding to post some data.

What is lost through refining?

Diagram of a Wheat SeedThe process of refinement removes both the bran & the germ of the wheat seed. In layman’s terms it’s the shell and the plant embryo that are removed. So, through the process of refining flour we lose nutrients which include:

  1. Vitamin E: 95%
  2. Pyridoxine (B6): 87%
  3. Magnesium: 84%
  4. Manganese: 82%
  5. Riboflavin (B2): 81%
  6. Niacin (B3): 80%
  7. Fiber: 78%
  8. Zinc: 76%
  9. Potassium: 74%
  10. Thiamin (B1): 73%
  11. Iron: 70%
  12. Phosphorus: 69%
  13. Copper: 62%
  14. Sodium: 60%
  15. Pantothenic Acid (B5): 57%
  16. Calcium: 56%
  17. Selenium: 52%
  18. Folate (B9): 41%
  19. Protein: 25%

We’ve lost all the things!

It seems like a lot of vitamins and minerals are removed until you realize that wheat is not a significant source of the following nutrients (<10% DV):

  1. Copper: 0.05%
  2. Sodium: 0.08%
  3. Calcium: 2.23%
  4. Vitamin E: 3.06%
  5. Potassium: 7.72%
  6. Riboflavin (B2): 9.23%
  7. Folate (B9): 9.50%

Ok, but what about the rest?

So, if I take into account the original % daily value of each nutrient (>10%) and how much of those daily values we lose through the processing of flour, I find that we lose a significant portion for the following nutrients (>20% DV):

  1. Manganese: -142.25%
  2. Selenium: -66.84%
  3. Fiber: -38.06%

But, what about enrichment?

Evil Flour MillEven though we lose the above nutrients we also gain nutrients through the enrichment process (total DV added):

  1. Thiamin (B1): +37.25%
  2. Folate (B9): +27.65%
  3. Niacin (B3): +24.91%
  4. Riboflavin (B2): +19.48%
  5. Iron: +15.95%

The above nutrients are hard to come by in poverty stricken areas and will prevent death from malnutrition.

Quantitative Verdict

If we were to take the daily values of the 20 nutrients I tracked (excluding Managese and Selenium)* and weight them as a percent of the total daily values (100%), the result is a 11% loss. That is, 100% of the nutrients provided by wheat, minus those lost through refining, plus those added through enrichment, returns a net loss of 11%.

Subjective Verdict

The loss of the few nutrients stated above creates a low cost way to produce food that is somewhat nonperishable,** portable and versatile. This product can be sent to areas of poverty at a relatively low cost to keep humans alive.

And in America?

Enriched White FlourWe have a larger variety of food available to us than in nearly every other country. We can easily make up for the 11% loss in nutrients with other foods. There is nothing wrong with buying whatever kind of wheat based item you want, but the loss of nutrients is not significant enough to get up in arms about it.

Conclusion

Enriched wheat flour does not lose 95% of vitamins during the refining and enriching process. Further the actual loss of nutrients does not include any that are difficult to find in other foods. There is a reason enriched flour has become a staple among the world’s population, it provides the nutrition necessary to sustain life at a cost that does not require affluence.

 

 

Sources

Effects of Flour Refining: USDA
Nutritional Value of Wheat: USDA
Calculations: Done by me (XLS)

* I excluded Manganese and Selenium because Enriched White Flour is still a major source of these (31% and 61% respectively). Wheat originally provides 173.48% DV of Manganese and 128.55% DV of Selenium. The loss from these two made them outliers adding 50% to the aggregate score of 11% loss.

** Removing the bran and germ gives flour a longer shelf life. Enriched flour can be stored approximately 50% longer than 100% whole wheat flour.

Leave a Reply