It is a generally understood fact that several nutrients are removed from grains as they are refined into flours. I did a nutritional study from information compiled by the USDA and downloaded from fatfree.com to see if this was so and found the following:
Refined Flour Made from Wheat
Refined Meals Made from Corn
Triticale and Buckwheat Flour
The Nutritional Charts
References
Refined Flour Made from Wheat
The calorie content of refined white flour actually increases about 10% because of everything else that has been taken out.
An average of 66% of the B vitamins have been removed.
An average of 70% of all minerals have been removed.
79% of the fiber has been removed.
An average of 19% of the protein has been removed.
Most refined flours made from wheat are fortified. Let's take a look at the nutritional content of fortified flours
The B vitamins thiamin, riboflavin and niacin have been added to enriched flours giving an average of 230% of these vitamins over hard red wheat.
Most of the vitamins B6 and folacin has been removed in refined flour. These two nutrients are already fairly low in wheat and aren't generally fortified in enriched flour.
Of 9 minerals, Calcium, phosphorus, and iron are the only minerals that are fortified in refined flour. And of them, it is not a sure thing that even each of these minerals will be fortified. Check the label before you buy.
Mention should be made about chelation. The minerals that have been taken out are chelated, or wrapped in protein. In their chelated form, these minerals are easily absorbed by our bodies. As chelated minerals are expensive, I would expect the minerals that have been added back in are not chelated, and therefore have a very low ratio of absorbtion by our digestive systems.
Summary:In the flour refinement process, except for the carbohydrates, most of the nutrients are removed. To give us confidence in their products, it is sold as fortified flour. Yet the refined flour we buy, except for the few nutrients they choose to fortify, has far fewer nutrients than the wheat it was born from. When we eat white flour, we are eating a nutrient poor food that happens to be fortified in some areas. It is questionable that the nutrients they do fortify are as natural or health promoting as the nutrients they took out of the wheat during the refinement process.
Refined Meals Made from Corn
Cornmeal fares much better during the refinement process than flour made from wheat. As it is less refined than wheat flour, most of the nutrients have been left in:
20% of the protein has been removed.
19% of the W3 and W6 essential fatty acids have been removed. Getting the essential fatty acids is one of the big reasons for eating corn.
70-100% of the fiber has been removed.
31% of the B vitamins have been removed. Depending on the cornmeal you buy, B vitamins may have also been fortified by an average of 180%.
The same is generally true for the minerals. On average 20% of the minerals that have been taken out, but a greater quantity of minerals have been added.
Summary:Cornmeal isn't harmed significantly by the refinement process and is still a healthy food. Probably the biggest drawback to cornmeal, however, isn't what has been taken out, but rather what has been left in: the oleic acid (18:1) and linoleic acid (18:2/n6). These are fats, of which linoleic acid is especially good for us and is one of the two essential fatty acids we must get from our diets. Cornmeal contains by weight 2 and1/2% of these two fats. So how can eating an oil that is so good for us be bad? Nothing if the corn has been freshly ground. However, these fatty acids oxidize and go rancid rather quickly and are less than nutritious when eaten rancid. The rancidity also destroys the flavor of the meal. Grind your corn fresh and you will be surprised at how delicious it is compared to the cornmeal pulled from the grocery shelves.
Triticale and Buckwheat Flour
Both of these flours have not been significantly harmed by the refinement process and retain 85-100% of the nutrients found in the seed they were made from.
Rye flour didn't manage so well.
36% of the protein has been removed
40% of the B vitamins have been removed
The Minerals: Rye flour did better here, only losing an average of 11%
The Nutritional Charts
Below you will find abbreviated nutritional data for white flour, cornmeal, triticale, buckwheat and rye flour. In each table the nutritional content of the flour or meal has been compared to the whole grains they came from and are displayed as a percentage of the nutritional content of the whole grain. For example, the first row and column in the white flour table shows white unenriched flour contains 111.3 percent of the calories found in wheat. Be aware, the flour has been fortified with a nutrient any time you find a number well over 100 percent. If you find these tables interesting, all the numbers used to calculate this data can be downloaded in spreadsheet text and comma format. You should be able to import this csv file into any spreadsheet. (8K zip file)
Nutritional Percentage of Different Refined Wheat Flours Compared to Hard Red Winter Wheat| Nutrient | Flour White All-Pur Un-Enriched | Flour White All-Pur SelfRis Enriched | Flour White Bread Enriched | Flour White All-Pur Enriched Bleached |
| Food energy | 111.3% | 108.3% | 110.4% | 111.3% |
| Protein | 81.9% | 78.4% | 95.0% | 81.9% |
| Protein | 81.9% | 78.4% | 95.0% | 81.9% |
| Total lipid (fat) | 63.6% | 63.0% | 107.8% | 63.6% |
| Carbohydrate, by diff. | 107.2% | 104.3% | 101.9% | 107.2% |
| Total saturated fat | 57.6% | 57.2% | 90.7% | 57.6% |
| Ttl monounsaturated fat | 43.5% | 43.0% | 70.0% | 43.5% |
| Ttl polyunsaturated fat | 65.9% | 65.4% | 115.9% | 65.9% |
| Cholesterol | Not applicable2 |
| Sodium | 100.0% | 63500.0% | 100.0% | 100.0% |
| Total dietary fiber | 21.4% | 26.2% | 19.0% | 21.4% |
| Vitamin A | Not applicable2 |
| Ascorbic acid | Not applicable2 |
| Thiamin | 31.3% | 176.0% | 212.0% | 205% |
| Riboflavin | 34.8% | 360.0% | 445.2% | 429.6% |
| Niacin | 22.9% | 106.7% | 138.3% | 108.1% |
| Vitamin B6 | 14.7% | 16.7% | 12.3% | 14.7% |
| Folacin | 68.4% | 110.5% | 76.3% | 68.4% |
| Vitamin B12 | Not applicable2 |
| Potassium | 29.5% | 34.2% | 27.5% | 29.5% |
| Calcium | 51.7% | 1165.5% | 51.7% | 51.7% |
| Phosphorus | 37.5% | 206.6% | 33.7% | 37.5% |
| Magnesium | 17.5% | 15.1% | 19.8% | 17.5% |
| Iron | 36.7% | 146.4% | 138.2% | 145.5% |
| Zinc | 26.4% | 23.4% | 32.1% | 26.4% |
| Pantothenic acid | 45.9% | 45.9% | 45.9% | 45.9% |
| Copper | 33.2% | 25.8% | 41.9% | 33.2% |
| Manganese | 17.1% | 0.0% | 19.9% | 17.1% |
| Ash | 29.9% | 275.8% | 29.9% | 29.9% |
| Water | 91.0% | 80.8% | 102.0% | 91.0% |
| Food energy | 111.3% | 108.2% | 110.4% | 111.3% |
| Myristic acid (14:0) | 0.0% | 0.0% | 100.0% | 0.0% |
| Palmitic acid (16:0) | 63.2% | 94.0% | 93.2% | 63.2% |
| Stearic acid(18:0) | 53.8% | 53.8% | 76.9% | 53.8% |
| Palmitoleic acid(16:1) | 0.0% | 1075.0% | 62.5% | 0.0% |
| Oleic acid(18:1) | 45.3% | 202.1% | 70.3% | 45.3% |
| Linoleic acid (18:2/n6) | 65.2% | 3.7% | 114.2% | 65.2% |
| Linolenic acid(18:3/n3) | 81.5% | 81.5% | 159.3% | 81.5% |
| Histidine | 80.7% | 77.2% | 89.1% | 80.7% |
| Isoleucine | 77.9% | 74.7% | 96.9% | 77.9% |
| Leucine | 83.1% | 79.6% | 97.0% | 83.1% |
| Lysine | 68.1% | 65.4% | 69.0% | 68.1% |
| Methionine | 91.0% | 87.1% | 104.5% | 91.0% |
| Cystine | 68.0% | 65.2% | 83.5% | 68.0% |
| Methionine+Cystine | 76.9% | 73.6% | 91.6% | 76.9% |
| Phenylalanine | 87.8% | 84.1% | 99.8% | 87.8% |
| Tyrosine | 80.6% | 77.0% | 84.8% | 80.6% |
| Phenylalanine+Tyrosine | 85.0% | 81.3% | 93.9% | 85.0% |
| Threonine | 77.0% | 73.7% | 87.7% | 77.0% |
| Tryptophan | 79.4% | 75.6% | 86.9% | 79.4% |
| Valine | 74.6% | 71.4% | 90.3% | 74.6% |
| Arginine | 70.1% | 67.1% | 69.9% | 70.1% |
| Alanine | 73.8% | 70.4% | 81.3% | 73.8% |
| Aspartic acid | 68.0% | 65.0% | 75.6% | 68.0% |
| Glutamic acid | 87.0% | 83.3% | 105.0% | 87.0% |
| Glycine | 70.3% | 67.4% | 77.7% | 70.3% |
| Serine | 88.1% | 84.3% | 99.0% | 88.1% |
Nutritional Percentage of Cornmeals Compared to Yellow Dent Corn| Nutrient | Corn Flour Whole Grain Yellow | Cornmeal Self Risng Bolted Plain Enriched Yellow |
| Food energy | 98.9% | 91.5% |
| Protein | 73.6% | 87.9% |
| Total lipid (fat) | 81.4% | 71.5% |
| Carbohydrate, by diff | 103.5% | 94.6% |
| Total saturated fat | 81.4% | 71.7% |
| Ttl monounsaturated fat | 81.4% | 71.7% |
| Ttl polyunsaturated fat | 81.3% | 71.7% |
| Cholesterol | Not applicable2 |
| Sodium | 14.3% | 3562.9% |
| Total dietary fiber | 28.5% | 0.0% |
| Vitamin A | 100.0% | 100.0% |
| Ascorbic acid | 100.0% | 100.0% |
| Thiamin | 63.9% | 171.7% |
| Riboflavin | 39.8% | 199.0% |
| Niacin | 52.4% | 145.9% |
| Vitamin B6 | 59.5% | 86.8% |
| Folacin | 131.6% | 300.0% |
| Vitamin B12 | Not applicable2 |
| Potassium | 109.8% | 88.9% |
| Calcium | 100.0% | 5157.1% |
| Phosphorus | 129.5% | 382.9% |
| Magnesium | 73.2% | 67.7% |
| Iron | 87.8% | 212.5% |
| Zinc | 78.3% | 90.5% |
| Pantothenic acid | 155.2% | 100.2% |
| Copper | 73.2% | 47.8% |
| Manganese | 94.8% | 102.7% |
| Ash | 120.8% | 454.2% |
| Water | 105.2% | 454.2% |
| Food energy | 99.0% | 91.6% |
| Palmitic acid (16:0) | 81.4% | 71.7% |
| Stearic acid(18:0) | 81.3% | 72.0% |
| Palmitoleic acid(16:1) | 75.0% | 75.0% |
| Oleic acid(18:1) | 81.4% | 71.7% |
| Linoleic acid (18:2/n6) | 81.4% | 71.7% |
| Linolenic acid(18:3/n3) | 81.4% | 71.7% |
| Histidine | 73.5% | 88.2% |
| Isoleucine | 73.6% | 87.8% |
| Leucine | 73.6% | 87.9% |
| Lysine | 73.6% | 87.9% |
| Methionine | 73.6% | 88.3% |
| Cystine | 73.5% | 87.6% |
| Methionine+Cystine | 73.6% | 88.0% |
| Phenylalanine | 73.4% | 87.9% |
| Tyrosine | 73.6% | 88.0% |
| Phenylalanine+Tyrosine | 73.5% | 87.9% |
| Threonine | 73.7% | 87.9% |
| Tryptophan | 73.1% | 86.6% |
| Valine | 73.6% | 87.8% |
| Arginine | 73.4% | 87.9% |
| Alanine | 73.5% | 87.9% |
| Aspartic acid | 73.6% | 87.9% |
| Glutamic acid | 73.5% | 87.9% |
| Glycine | 73.6% | 87.8% |
| Serine | 73.6% | 87.9% |
Nutritional Percentage of Triticale, Buckwheat & Rye Flour Compared to the Whole Grains They Came From| Nutrient | Triticale Flour | Buckwheat Flour | Rye Flour |
| Food energy | 100.6% | 97.7% | 105.7% |
| Protein | 101.0% | 95.2% | 63.6% |
| Total lipid (fat) | 86.6% | 91.2% | 70.8% |
| Carbohydrate, by diff. | 101.4% | 98.7% | 111.1% |
| Total saturated fat | 86.9% | 91.4% | 96.0% |
| Ttl monounsaturated fat | 86.7% | 91.3% | 68.6% |
| Ttl polyunsaturated fat | 87.0% | 91.3% | 68.8% |
| Cholesterol | Not applicable2 |
| Sodium | 40.0% | 1100.0% | 50.0% |
| Total dietary fiber | 100.0% | 100.0% | 100.0% |
| Vitamin A | Not applicable2 |
| Alpha tocopherol | 22.2% | ?% | 61.7% |
| Ascorbic acid | Not applicable2 |
| Thiamin | 90.9% | 412.9% | 90.8% |
| Riboflavin | 98.5% | 44.7% | 45.4% |
| Niacin | 200.0% | 87.6% | 40.4% |
| Vitamin B6 | 292.0% | 277.1% | 91.2% |
| Folacin | 101.4% | 180.0% | 31.7% |
| Vitamin B12 | Not applicable2 |
| Potassium | 140.4% | 125.4% | 128.8% |
| Calcium | 94.6% | 227.8% | 72.7% |
| Phosphorus | 89.7% | 97.1% | 55.3% |
| Magnesium | 117.7% | 108.7% | 62.0% |
| Iron | 100.8% | 184.5% | 79.4% |
| Zinc | 77.1% | 130.0% | 53.4% |
| Pantothenic acid | 163.8% | 35.7% | 33.8% |
| Copper | 122.3% | 46.8% | 63.8% |
| Manganese | 130.4% | 156.2% | 203.7% |
| Ash | 83.0% | 121.0% | 74.3% |
| Water | 95.2% | 114.4% | 90.0% |
| Food energy | 100.6% | 97.7% | 105.7% |
| Myristic acid (14:0) | 88.9% | 92.0% | 66.7% |
| Palmitic acid (16:0) | 86.9% | 91.3% | 69.0% |
| Stearic acid(18:0) | 87.1% | 91.5% | 66.7% |
| Palmitoleic acid(16:1) | 88.9% | 91.3% | 70.0% |
| Oleic acid(18:1) | 86.5% | 91.3% | 68.6% |
| Gadoleic acid (20:1) | 86.7% | 91.7% | 69.2% |
| Linoleic acid (18:2/n6) | 86.9% | 91.3% | 68.8% |
| Linolenic acid(18:3/n3) | 86.9% | 91.0% | 68.8% |
| Histidine | 101.0% | 95.1% | 56.9% |
| Isoleucine | 101.0% | 95.2% | 65.9% |
| Leucine | 101.0% | 95.2% | 66.2% |
| Lysine | 101.1% | 95.2% | 53.7% |
| Methionine | 101.0% | 95.3% | 56.5% |
| Cystine | 101.1% | 95.2% | 56.2% |
| Methionine+Cystine | 101.0% | 95.3% | 56.3% |
| Phenylalanine | 100.0% | 95.2% | 70.5% |
| Tyrosine | 101.0% | 95.4% | 54.6% |
| Phenylalanine+Tyrosine | 101.0% | 95.3% | 65.2% |
| Threonine | 101.0% | 95.3% | 61.1% |
| Tryptophan | 100.6% | 95.3% | 68.8% |
| Valine | 101.0% | 95.3% | 62.9% |
| Arginine | 101.0% | 95.2% | 52.3% |
| Alanine | 101.0% | 95.2% | 54.6% |
| Aspartic acid | 101.1% | 95.1% | 54.9% |
| Glutamic acid | 101.0% | 95.2% | 71.6% |
| Glycine | 101.1% | 95.2% | 51.1% |
| Serine | 101.0% | 95.2% | 75.0% |
References:1: All data was computed from USDA data downloaded from fatfree.com
2: Data not applicatable because the whole grains the flour came from contains none of this nutrient