WHOLE GRAINS, REFINED
• Oat: steel- cut and whole rolled are comparable in nutrition, though “quick- cooking” often has some fiber removed (to hasten preparation); associated with lower LDL; gluten- free.
• Quinoa: botanically a seed that comes in red, white, and black;
almost twice the protein of other grains and includes all of the essential amino acids and many micronutrients; gluten- free.
• Rice: black brown, and red are common colors; high in manga-nese; gluten- free.
• Rye: robust flavor with similar nutrition to barley and wheat;
mainly used in the US to make whiskey.
• Sorghum: aka, guinea corn, dura, milo; rich in anthocyanins;
gluten- free.
• Wheat: aka, bulgur, spelt, emmer, einkorn, durum, farro, cracked wheat, and wheat berries; white winter wheat and summer red wheat are common varieties: the former is softer and milder and used in “white whole wheat flour,” whereas the latter gives (regular) whole wheat flour its red– brown hue.
• Wild rice: botanically a grass; gluten- free.
Rice, wheat, and maize comprise 60% of the world’s energy intake in today’s diets, whether consumed intact or through flours used in a vast array of foods the world over, bread to pasta, tortillas to tamales, cookies to crackers.
What’s the difference between “whole” and “refined” grains?
All grains have a hull (hard outer shell), which is inedible and al-ways removed before consumption. Whether a grain is “whole”
or “refined” refers to how it’s further processed before getting to eaters. A “whole grain” includes three major parts of the plant: bran (outer fibrous layer), germ (reproductive organ, rich in polyunsatu-rated fats, vitamins, and minerals), and endosperm (starchy interior that provides energy). For millennia, whole grains were consumed in porridges, breads, and other dietary staples. All of this changed during the Industrial Revolution, which brought mechanization to feed a growing population. An automated milling process removed
the bran and germ, leaving only the sweeter, whiter endosperm, now referred to as a “refined” grain.
Refined grains are easier and quicker to cook and more shelf- stable as the oil- containing germ, which can become rancid, has been removed. Americans and western Europeans began to prefer the milder flavor of foods made with refined grains, like white bread, compared to their heartier counterparts with their darker colors and toothsome textures. There are sociological reasons, too, rooted in race, class, culture, and xenophobia: the color difference came to reflect a “refined” palate associated with higher wealth and incomes— and those individuals usually had white skin.
Refining grains also reduces many valuable nutrients. For ex-ample, vitamins B1, B2, B3, B6, E, K, and folate; minerals magnesium, potassium, iron, calcium, and selenium; and fiber and protein are all lower in white flour compared to whole wheat flour. To address this issue, some nutrients are added back to the refined grain mix-ture through “enrichment,” namely thiamin, riboflavin, niacin, folate, and iron. Fiber is not added back, however, which is a sig-nificant loss in diet quality as most people don’t consume enough for good health. Thus, while calories are similar— micronutrients and fiber have negligible energy content— whole grains are more nutrient- dense.
What is gluten, and are gluten- free diets important for health?
Gluten is an insoluble protein found in several cereal grasses, notably wheat, barley, and rye. Its physiochemical properties provide desir-able baking qualities, like elasticity, structure, and volume, which is why gluten- containing flours are favored for breads and pastries.
Like other proteins, an allergic response to gluten can arise in some people. Celiac disease occurs when an immune reaction in the small intestine leads to atrophy and malabsorption. (Wheat allergy is a sep-arate disease with its own mechanism.) While screening and diag-nosis of celiac disease have improved and underdiagdiag-nosis is still an issue, the prevalence has increased from 0.03% in the 1970s to about 1% (0.5– 1.26%) in 2017 in both Europe and the US. Algerians have the highest prevalence (5.6%) and Japanese and Chinese the lowest.
Gluten- related disorders have also increased, including non- celiac
gluten sensitivity (NCGS) and gluten intolerances, estimated at about 6% in the US; NCGS presents with numerous gastrointestinal symptoms but is not an autoimmune disease.
Dietary, environmental, and genetic differences contribute to gluten disorders (such as in the varying frequency of HLA- DG2 and other genetic variants), though the precise reasons for the rapid increase in celiac and other gluten disorders remain unclear.
Consumption of wheat and vital gluten (which is separated from the starch component of wheat to impart desirable food processing properties) has increased globally, and some studies suggest that the timing of introduction of gluten and wheat into the diet during in-fancy and breastfeeding may play a role. Others have questioned whether changes in wheat production enhancing gluten content might be a factor, although agricultural data from the past cen-tury do not support this hypothesis. More recently, fermentable oligo- , di- , and monosaccharides and polyols (commonly known as
“FODMAPS”), a group of sugars found in grains as well as some vegetables and fruits, have been associated with gastrointestinal distress. Research is currently investigating their potential roles in gluten- related disorder as the two are highly correlated.
Interest in gluten- free (GF) diets has climbed substantially in the past decade, due in part to increased prevalence, media attention, and the common occurrence of gastrointestinal issues. But gluten misinformation, demonization, and celebrity nutrition (GF is the most popular Hollywood diet) also play a role. Indeed, recent polls indicate around 25% (!) of American adults are going gluten- free, particularly women aged 20– 39. The market for GF foods is booming, estimated at an annual growth rate of 10.4%. Yet there is no reason those without diagnosed gluten- related conditions should cut gluten- containing foods from their diet. There is no evidence to show that GF diets are helpful for weight loss— beyond any inde-pendent effect due to calorie deficit— or that gluten is beneficial for heart disease prevention. While GF foodstuffs have improved con-siderably in taste and texture, many remain higher in sugar, sodium, and saturated fat and lower in fiber, B- complex vitamins, minerals, and phytonutrients compared to their whole grain counterparts.
Thus, a number of studies have even found that those consuming GF diets have a poorer overall diet because vital nutrients can be
compromised without careful dietary planning, as can happen whenever entire food groups are removed from the diet.
Do whole and refined grains differently impact the body?
While many strive to cut gluten, hence grains, from their diets under the pretense of better health, scientific research continues to accu-mulate showing that diets rich in whole grains are beneficial for gastrointestinal health and beyond. Studies including randomized controlled trials (RCTs) have shown that consuming whole grains leads to a significant reduction in LDL and that oats are particularly effective. A 2017 study including 21 meta- analyses observed 18% and 11% reductions in cardiovascular disease (CVD) cancer mortality, respectively, among those consuming approximately 2– 3 servings (45 g) of whole grains daily; protective effects for type 2 diabetes, cardiovascular disease (CVD), and colorectal, pancreatic, and gastric cancers were also observed. Stronger effects were obtained for a 90-g intake, with risk reductions occurring through 7– 7½ servings daily for many health outcomes; whole grain bread, whole grain breakfast cereals, and added bran, as well as total bread and total breakfast cereals, were independently associated with reduced risks of CVD and all- cause mortality. An additional meta- analysis of 20 studies showed 25% and 6% lower risks of mortality from CVD and cancer, respectively, for each additional 3 servings (90 g) of whole grains.
Whole grain benefits are likely due not to any single component or biological mechanism but, rather, to their additive and synergistic effects in the body. Newer studies are showing beneficial results of whole grains on the microbiome, a function of their prebiotic fibers and resistant starches that feed “good” bacteria (Chapter 4). And a greater variety of whole grains led to both a higher amount and a greater diversity of gut microbes. There may also be undiscovered phytochemicals that contribute.
Many observational studies also show that whole grains have small but favorable effects on body weight, a function of their met-abolic effects on appetite, satiety, nutrient availability, and energy utilization. Evidence from RCTs isolating a specific effect of whole grains on weight loss has been inconsistent, however.1 Type and
amount of grains consumed may play a role, as well as the nature of consumption (e.g., hot or cold, which impacts glycemic index).
One might expect refined grains to have a deleterious effect on health, given their higher glycemic index and lower nutrient content compared to whole grains. Interestingly, the extant lit-erature is equivocal, though swapping whole grains for refined grains appears beneficial among diabetics. Isolating the effects of singular elements, even a food group, is challenging due to correlations with other dietary and behavioral elements. There are likely genetic and other biological factors involved, too, that impact metabolic processes. Several intriguing studies recently showed that white sourdough bread, which contains live bac-teria and yeast, did not lead to expected changes in glucose and insulin in some people— and neither did non- sourdough white bread. The authors hypothesized differential effects on the microbiome (Chapter 4) and other factors may have impacted glycemic response. The studies were small and findings need to be reproduced, but underscore the phenomenon that the same foods can have different effects on different people, another har-binger of personalized nutrition (Chapter 18).
Insulin sensitivity is also directly related to body mass index (BMI). Thus, those with a healthy body weight are better able to manage the sugar boost from refined grains. And impact on blood sugar is related to what else is consumed in the meal alongside re-fined grains. Even though rere-fined grains on their own don’t always show a negative impact on health, studies of total dietary patterns that consider all intakes in concert show that consumers with higher intakes of refined grain foods— like cookies, crackers, pizza, white bread, pasta, and rice— do have a higher BMI, more T2DM, and greater risk of CVD. Here, and elsewhere, the total composition of the diet is more important than any individual food or food group.
How do you ensure grains are “whole”?
It takes a bit of effort to figure out which grains are “whole,” due to crowded food packaging with misleading labels. To ensure the healthier option:
• Look for the word “whole” on the ingredient list (e.g., whole oats, whole wheat, whole corn); “enriched” does not mean whole, nor does “fortified.”
• Ignore the food color, which is often adjusted to a browner hue to appear healthier.
• Understand that “multigrain” simply means that more than one grain is included: a multigrain bread may have wheat, corn, and oats, for example, but unless it’s made with whole wheat, whole corn, and whole oats, it’s not whole grain— even if has added bran, fiber, or seeds.
• Check the supermarket bulk bins for whole grains, where they are less expensive and have less packaging.
• Remember basic nutrition principles: processed foods such as granola bars may be “100% whole grain” since they’re made with whole oats— but are often loaded in added sugar, so-dium, and calories.