Whole Grains Vs Refined Grains

The discovery that refining the grains would make them last longer in storage than whole grains, help farmers to maximised their crops and minimised their loses. Since the late 1800s with the invention of the new milling technology, most grains have been refined.

Refining the grain involves removing the bran and the germ, where most of the nutrients like fibre, phytonutrients, vitamins and minerals are, leaving just the endosperm, which is mostly carbohydrates. The disastrous side effects in human health of refining the grains were soon reveal in the general population with high incidences of beri-beri (Thiamine or Vit B1 deficiency) and pelagra (Niacin or Vit B3 deficiency). That’s why refined grains today are fortified with these two vitamins (see chart below). However, many other nutrients, and most importantly the fibre, are lost in the refining process, and this also has a detrimental effect in health (1).

Whole grains vs refined grains

Fibre in whole grains slows down the release and absorption of carbohydrate content in the gut, which allows a more steady insulin level in the bloodstream, without spikes. It also improves food transit through the gut, increases stool bulk, and feeds our gut bacteria. This is probably why whole grains have been associated with lower heart disease, protection against cancer, diabetes and weight gain (2). The Framingham Heart Study also found that three or more daily servings of whole grains were associated with a slimmer waist.

The lack of fibre in refined grains on the other hand, makes them easily digested and quickly absorbed in the gut, raising excessively the blood sugar and thus generating insulin spikes. If we add some animal based foods like chicken to the meal, the insulin spike gets even greater than with the refine grains alone, which makes things even worse (3). The same happens if we add chicken breast to mash potatoes, a higher insulin spike with added animal products, and if we add some butter, the spike gets dramatically higher. It can sometimes even double the insulin response (4,5). Whereas if we add avocado or nuts to the refined grains, instead of worsening, the insulin response improves (6). It may be that the naturally occurring fibre and phytonutrients in whole plant foods are able to slow down a bit the absorption of the easily digested carbohydrates in refined grains.

The combination of refined carbohydrates and fat has an extremely powerful effect on promoting fat accumulation in the body, as insulin also promotes the storage of fat in the body and encourages the fat cells to swell. As more fat is stored in the body, it interferes with insulin uptake into our muscle tissues. Our pancreas then senses that the glucose level in the bloodstream is still too high and pumps out even more insulin. A little extra fat around our mid-section results in so much interference with insulin’s effectiveness, that two to five times as much insulin may be secreted in an overweight person than in a thin person. The higher level of insulin, in turn, promotes more efficient conversion of our caloric intake into body fat, and the vicious cycle continues. People get heavier and heavier as time goes by. Eating refined carbohydrates, as opposed to whole grain carbohydrates causes the body’s “set point” for body weight to increase. The body converts food fat into body fat quickly and easily. 100 calories of ingested fat can be converted to 97 calories of body fat by burning merely 3 calories. Fat is appetite stimulant, the more you eat, the more you want. If a food could be scientifically engineered to create an obese society, it would have fat, such as butter, mixed with sugar and white flour (7).                  

1 – https://wholegrainscouncil.org/whole-grains-101/whats-whole-grain-refined-grain
2 – Mellen, Walsh, et al. 2008; Slavin 2003; Ye, Chacko, et al. 2012. (“Proteinaholic”, Garth Davis, M.D.)
3 – Sun L, Ranawana DV, Leow MK, Henry CJ. Effect of chicken, fat and vegetable on glycaemia and insulinaemia to a white rice-based meal in healthy adults. Eur J Nutr. 2014 Dec;53(8):1719-26.
4 – Hätönen KA, Virtamo J, Eriksson JG, Sinkko HK, Sundvall JE, Valsta LM. Protein and fat modify the glycaemic and insulinaemic responses to a mashed potato-based meal. Br J Nutr. 2011 Jul;106(2):248-53.
5 – Bornet FR, Costagliola D, Rizkalla SW, Blayo A, Fontvieille AM, Haardt MJ, Letanoux M, Tchobroutsky G, Slama G. Insulinemic and glycemic indexes of six starch-rich foods taken alone and in a mixed meal by type 2 diabetics. Am J Clin Nutr. 1987 Mar;45(3):588-95.
6 – Wien M, Haddad E, Oda K, Sabaté J. A randomized 3×3 crossover study to evaluate the effect of Hass avocado intake on post-ingestive satiety, glucose and insulin levels, and subsequent energy intake in overweight adults. Nutr J. 2013 Nov 27;12:155.
7 – Fat and Refined Carbohydrates: Married to Your Waist, “Eat To Live”, Joel Fuhrman M.D.

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