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Nutrition

Paleo-mythic diet and why you should be consuming whole grains

The Paleo diet is today’s hottest dietary trend. It’s all about eating primal to mirror our cavemen ancestors as a way to optimal health. Grains are one food that are eschewed on the Paleo diet; most would say needlessly. Master of Human Nutrition student, Carolyn English delves further into the health benefits that grains can play in the diet.

The year of 2014 was all about the Paleo Diet here in Australia and I have met countless people who have eschewed grains in search of better health. It is time to put to rest the myth that grains are bad for our health. In order to promote better health I pronounce 2015 to be the year of Whole Grains!

Why whole grains? Most people know grains are a source of energy, fibre and B-group vitamins.  And many people believe they can get all the fibre and B-group vitamins they need from vegetables so eliminate grains entirely.  However, whole grains have a whole lot more going for them than just fibre and B-group vitamins.  They are nutritional powerhouses and have been associated with lower risks of type 2 diabetes, cardiovascular disease, cancer, inflammation and even weight gain.

So what are whole grains?  Examples include wheat, oats, barley, brown rice, maize (corn), rye, millet, sorghum, teff, triticale, amaranth, buckwheat, farro, freekah, bulgar, emmet, spelt, Kamut and quinoa. Whole grains, according to the American Association of Cereal Chemists International and the FDA in the US, consist of “the intact, ground, cracked or flaked fruit of the grain whose principal components, the starchy endosperm, germ and bran, are present in the same relative proportions as they exist in the intact grain.” Here is an illustration detailing the different components of a whole grain:

 Fibers of the Wheat Kernel

Source: Bernstein et al. Nutrients 2013;5:1471-1487

 

During the processing of whole grains into refined flour the outer bran and inner germ layers are removed and only the remaining endosperm is processed into flour. So compared with refined grains, whole grains are much richer in dietary fibre, minerals, vitamins and phytochemicals.  Whole grains are also rich sources of lignans, beta-glucans, inulin, phytosterols, phytin, and sphingolipids.

Phytochemicals

Whole grains are a rich source of phytochemicals. Phytochemicals are bioactive, non-nutrient plant compounds that contribute to good health by protecting against chronic diseases like cancer and cardiovascular disease.  Whole grains have different phytochemical profiles from fruits and vegetables. But when eaten together, the whole grain phytochemicals complement the phytochemicals in the fruits and vegetables creating an additive and synergistic effect.  Thus it is important to include whole grains in the diet along with plenty of fruits and vegetables in order to consume a diverse number of phytochemicals in the diet.

One type of phytochemical, called phenolic compounds, are abundant in whole grains. Phenolic compounds act as antioxidants in the body by donating hydrogen atoms to neutralise free radicals. Trolox equivalent antioxidant capacity (TE) is a measure of the antioxidant capacity of a given nutrient. One study found the antioxidant capacity of whole grain breakfast cereals ranged from 2200 to 3500 TE while fruits averaged in the range of 600 to 1700 TE. Red plums and berries had the highest TE of fruits containing 2200 and 3600 TE respectively. Vegetables averaged 450 TE with a high of 1400 TE for red cabbage. The antioxidant capacity of 41 grams of ready-to-eat whole grain breakfast cereal was found to contain 1120 TE compared to an 85 gram serving of vegetable which contained 380 TE. So you can see it is important to include whole grains in order to maximise the antioxidant content of your diet.

Other Nutrients

Whole grains are loaded with carotenoids like lutein, zeaxanthin, beta-cryptoxanthin, beta-carotene and alpha-carotene.  Carotenoids protect against the risk of diseases such as cancer and eye disease like macular degeneration. Some carotenoids (like beta-cryptoxanthin, beta-carotene, and alpha-carotene) act as antioxidants and have provitamin A activity.

Whole grains contain Vitamin E which acts as an antioxidant and maintains the integrity of cell membranes. Whole grains also contain the monounsaturated fatty acids oleic acid (also found in olive oil) which has been shown to lower cholesterol levels. Whole grains contain fibre and resistant starch which lowers cholesterol, blood glucose and insulin concentrations and improves digestive health and lowers the risk of gastrointestinal cancer.  The fibre and resistant starch in whole grains also gets converted into short chain fatty acids by the gut microbiota. These short chain fatty acids bind to immune cells, reducing allergies and inflammation.

Whole Grain Studies

There is strong evidence of the protective benefit of whole grains against cardiovascular disease with one study showing a 28% reduction in risk of coronary artery disease with the consumption of 3 servings of whole grains a day. Researchers in the Women’s Health Study found women who consumed 4 servings of whole grains a day had a 23% reduced risk of developing hypertension.  In addition, a review of 45 prospective studies and 32 randomized controlled trials found that individuals who consumed 3 to 5 servings of whole grains per day had a 26% lower risk of developing Type 2 Diabetes.

Antinutrients

So there are lots of good reasons to consume whole grains. But what about the antinutrients found in whole grains like phytic acid and lignans? The Paleo diet tells us we should exclude grains as these antinutrients bind to vitamins and minerals preventing our bodies from absorbing them.  Our gut microbes in the large intestine actually produce an enzyme called bacterial phytase that degrades phytic acid in grains releasing the bound minerals like calcium, magnesium and phosphate allowing the body to absorb them.

In addition, phytic acid suppresses the oxidant damage associated with free radicals produced by the colonic bacteria thereby protecting our intestinal cells from damage. Our gut microbiota also converts lignans into enterolactone and enterodiol which have strong antioxidant and phytoestrogenic effects and provide protection against hormone related cancers, diabetes and heart disease.  Even more health benefits of whole grains!

Want to know more about whole grains or need some recipe ideas? Check out the Whole Grain Council in the US http://www.wholegrainscouncil.org or the Grains and Legumes Nutrition Council in Australia at http://www.glnc.org.au.

References

J Nutr. 2012 Jul;142(7):1304-1313

J Nutr. 2011 May;141(5):1011S-22S

Nutr. 2004 Dec vol. 134 no. 12 3479S-3485S

J AM Coll Nutr. 2000;19:S312-9

Nutr. 2015, 7(1), 17-44

AM J Clin Nutr. 2003;78(3):383-390

Am J Clin Nutr.2007:86(2):472-479

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About Deakin Nutrition

Nutrition and dietetics has a long history at Deakin with a world-leading research profile, and degree programs in high demand taught by engaged teaching staff

Discussion

One thought on “Paleo-mythic diet and why you should be consuming whole grains

  1. Nice summary Carolyn! Go the WHOLEGRAIN! 🙂

    Posted by Sarah | January 31, 2015, 4:26 PM

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