- The problem with gluten-free grains
- Dependence on grains drives processed food consumption
- Glycaemic index of grains
- Grains as a primary source of refined carbohydrates
- What about the benefits of ‘Heart-Healthy Whole-grains’ ?
- What is the evidence for oats?
Read time: 13 minutes (2700 words)
1. The problem with gluten-free grains
With the rise in popularity of gluten-free diets manufacturers have been quick to fill the free-from food aisle with gluten-free breads, cakes, crackers, biscuits, breakfast cereals and snacks. However, studies around the world have revealed that many of these replacement foods are high in sugar as well as having lower nutrient levels than the products they replace.
In my clinical experience many of these gluten-free foods and grains prevent a large sub-set of patients from fully resolving their symptoms, and this is unsurprising when the full range of detrimental effects of grains is considered
As we have so often emphasised in these posts a real gluten-free diet should be fully grain-free. This is not only because many of the alternative grains contain associated immune activating proteins (see table above), but also because most grains are highly processed, high in carbohydrates with a high glycemic index (GI), and are low in key nutrients. A further concern is that due to contamination grains are the major source of dietary heavy metal and fungal toxins exposure – something I will cover in part 5.
2. Dependence on grains drives processed food consumption
More than 50% of the worlds calories come from grains (Awika, 2011) leading commentators to point out that “cereal grains literally stand between mankind and starvation” (Mangelsdorf, 1966), and that “We have become canaries” (Harlan JR, 1992). I created the graphic below for one of my talks, based on data from Loren Cordains 1999 paper ‘Grains: a double edged sword’ to illustrate just how dependent we are.
Even in a developed country such as Britain, nearly one quarter of calories are derived from grains – and almost all of that from refined wheat [Explore the interactive National Geographic ‘What the World Eats’]
Refined grains drive processed food consumption
A majority of grains are milled into flours and in most cases the bran and germ (wheat germ) are discarded. Consequently most countries mandate fortification to try to fix the nutritional damage done by refining. This typically involves adding calcium carbonate (chalk), iron, thiamine (vitamin B1) and nicotinic acid or nicotinamide (B3). In many countries artificial folic acid is added to replace the missing folate. However, these additives are not nature-identical versions of the nutrients they are attempting to replace leading to a range of issues. For example, most countries use forms of iron that have low-bioavailability (Hurrell, 2010).
- See our post on folic acid fortification here.
Breads are also considered good vehicles for delivering nutrients to the public as part of government health programmes, to tackle deficiencies. Supplementation has included vitamin A, vitamin D, vitamin B12 and zinc. Due to its ubiquity, bread is a perfect vehicle for delivering these much-needed nutrients to many people at once, but, ironically it is the over-reliance on grains which drives down dietary diversity and leads to population level deficiencies in the first place.
Fortification means that most flours are themselves processed foods containing artificial additives. Foods made with these flours such as pasties, breakfast cereals and cakes contribute to the highly processed diets that appear to be a major driver of obesity (Poti, 2017). This is partly behind the push for people to eat the less processed whole-grain foods, as these contain the natural forms of calcium, iron and folate.
But as we shall see this processing is only part of the problem with grains and being awarded the coveted ‘whole-grain guarantee’ label does not magically turn industrial food products into health foods, despite what the marketing hype would have us believe.
3.Glycaemic Index of Grains
Like all grains, wheat is mainly starch. White flour is typically 68% carbohydrates, but even whole wheat flour which retains the bran and germ is still 60% starch. Swapping to whole grains, therefore, will not affect the macronutrient profile very much.
Many people are unaware that the starch in grains breaks down during digestion almost entirely into sugar (glucose), meaning that a typical 44g slice of bread will be rapidly converted into 3 teaspoons (15g) of glucose/sugar.
It is not surprising then that one of the main problems with grains is that they cause a large spike in blood sugar when consumed. This is because their starch is readily available to digestive enzymes so turns into glucose faster than the same weight of table sugar. Glycemic index (GI) is a measure of how much the carbohydrate in different foods raise blood sugar. As the graph below shows, grains as a group have a very high GI, leading to large blood sugar spikes.
Notice that the GI of bread is higher than that of table sugar. Also, note that the difference between white and whole grain bread is negligible, so in terms of blood sugar control eating whole grains is no better than eating table sugar.
Animal products, fats and oils, on the other hand, have an effective GI of zero because they do not contain carbohydrates. Such foods have very little effect at all on blood sugar. It is no surprise, then, that very low carb diets have been found to provide “exceptional glycemic control” in type 1 diabetes (Lennerz, 2018). Likewise, a systemic review of low GI diets in type 2 diabetes concluded that they are more effective than higher GI diets in controlling HbA1c (Ojo, 2018), and in these studies they didn’t even use diets with particularly low GIs . Finally, low Gi diets have been found to be as effective at treating metabolic syndrome as metformin — the classic blood sugar lowering drug used in type 2 diabetes (Rajabi, 2015).
Finally, you may have heard that some wheat products — such as pasta — are digested more slowly. In such cases the resistant starch does indeed reduce the glycemic index of the food by about half, but this still places it above nuts, seeds and legumes which are truly low GI carbohydrates.
4. Grains are a primary source of refined carbohydrates
In the scientific literature the consumption of refined carbohydrates in the form of sugars and refined grain flours, are widely recognised to be detrimental. For example:
Exposure to refined carbohydrates has been found to be associated with disorders such as increased blood pressure, retinopathy, adipose tissue inflammation, glucose intolerance, type 2 diabetes mellitus, poor metabolic profile, esophageal adenocarcinoma, and small intestine, prostate, pleural, and pancreatic cancers. Additionally, recent studies have demonstrated that ingestion of refined carbohydrates is related to secretion of cytokines and chemokines. (Delibasi & Cakir, 2014)
Carbs, cholesterol and cardiovascular disease
When it comes to heart disease many people mistakenly believe that saturated fats are the problem, not appreciating that carbohydrates raise LDL (bad) cholesterol levels just as much. In fact refined carbohydrates specifically increase the amount of small, dense LDL, which is more strongly associated with an ‘adverse cardiovascular risk profile’ than the large buoyant LDL particles that are found after saturated fat consumption.
Studies conducted during the past few years have quite unanimously shown that the quantity of carbohydrates ingested is associated with a decrease of LDL particle size and an increase in its density. Conversely, diets that aim at a reduction of carbohydrate intake are able to improve LDL quality. Furthermore, a reduction of the glycaemic index without changing the amount of carbohydrates ingested has similar effects. Diseases with altered carbohydrate metabolism, for example, type 2 diabetes, are associated with small, dense LDL particles. – Gerber PA & Berneis K, 2012
As well as reducing LDL particle quality carbohydrates also raise triglycerides more than saturated fats – again creating a worse cardiovascular profile.
And it should be remembered that in all of the above examples carbs and saturated fat are being compared on the basis of substituting equal calories of carbs for saturated fat. In real life, however, people do not swap pure carbs for pure saturated fat. They swap high carb foods for high sat-fat foods. This is not the same thing. If for example an individual swaps 500kCal of bread, cakes, biscuits and pasta each day for 500kCal of eggs, sausages, bacon, and cheese, only some of the carb calories are being swapped for saturated fat, most are being swapped for calories from protein and other unsaturated fats. Although we think of these low-carb foods as being high in saturated fats, they actually contain large amounts of mono- and poly-unsaturated fats too. Hence in practice the cardiovascular profile on a low-carb or grain-free diet tends to improve far more, even, than the above studies might suggest.
This is born out powerfully in the epidemiological data across Europe where the countries that consume most fat and animal products have the lowest cardiovascular mortality:
And those that eat the most carbs have the highest mortality:
5. What about the benefits of ‘Heart Healthy Wholegrains’ ?
Studies within populations that compare those who eat most whole grains (whole grain bread, oats, quinoa etc) have a reduced risk of cardiovascular events than those who eat fewer. Calculations from these studies have led to recommendations that people should eat three portions of whole grains per day to achieve meaningful population level reductions in cardiovascular incidence.
Unfortunately, the same population studies also show a correlation between whole grain consumption and a generally healthy lifestyle. This confounder is not unexpected. Ask yourself, who chooses brown rice over white, or wholemeal over white bread? In most cases whole grain products do not taste better than their refined counter parts, so people who choose them are predominately doing so because they believe them to be healthier. Such people tend to follow a generally ‘healthy lifestyle’ all round by smoking less, exercising more and eating more fruit and vegetables. This creates a healthy lifestyle bias in such studies.
The only way to properly test the ‘heart healthy whole grain’ hypothesis and identify whether there is an actual causal link is through controlled trials. Yet despite dozens of such studies results have been… well… disappointing is the polite way to put it. The claimed benefits of whole grains for heart health just have not materialised.
- “High-fiber cereal foods did not improve conventional markers of glycemic control or risk factors for CHD in type 2 diabetes over 3 months.” – Jenkins DJ (2002)
- “Intake of whole-grain and fiber-rich rye bread versus refined wheat bread does not differentiate intestinal microbiota composition in Finnish adults with metabolic syndrome.” – Lappi J (2013)
- “Replacing refined grains with whole grains within a weight-loss diet does not beneficially affect abdominal fat” Harris Jackson K (2014)
- Substituting whole grains for refined grains in their daily diets… “No significant change in plasma metabolic disease markers over the study period was observed.. No effect of dietary interventions on anthropometric measurements and body composition was found.” Vitaglione P (2015)
- “Subjects substantially increased their whole grain intake (to >80g/day), but there was little effect on blood biochemical markers, body composition, blood pressure, fecal measurements, or gut microbiology.” Ampatzoglou A (2015)
A 2016 Cochrane review summarised the entire 80 years of studies thus:
There is insufficient evidence from RCTs of an effect of whole grain diets on cardiovascular outcomes or on major CVD risk factors such as blood lipids and blood pressure. Trials were at unclear or high risk of bias with small sample sizes and relatively short-term interventions, and the overall quality of the evidence was low.
6. So are oats any better?
Turning to oats which have benefitted from particularly good marketing spin — even getting the moniker ‘superfood’ to stick — one can indeed find studies demonstrating cholesterol-reducing benefits which are often used to support the whole-grain mantra.
Putting aside the question of whether cholesterol reduction actually matters, it appears that these studies should be taken with a pinch of salt. A 2007 review by the highly respected Cochrane collaboration concluded:
…these positive findings should be interpreted cautiously. Many of the trials identified were short term, of poor quality and had insufficient power. Most of the trials were funded by companies with commercial interests in wholegrains. There is a need for well-designed, adequately powered, longer term randomised controlled studies in this area. In particular there is a need for randomised controlled trials on wholegrain foods and diets other than oats. – Kelly SAM, Cochrane Reviews (2007) [my emphasis]
In one randomized study (McGoech, 2013) diabetic patients given an oat rich diet for 8 weeks showed no improvement in glycaemic control, oxidative stress or inflammation – the fundamental factors you want to change in such metabolic conditions.
Another study (Xue Li, 2016) claimed that 30 days on a “healthy, low fat” diet with 100g whole oats per day showed significant improvements in glycaemic control. But the actual figures reveal only a small improvement in HbA1c (a key measure of medium term diabetes control) from 8.3 to 7.7 (mmol/L) after a one month intervention.
This is marginal compared to the results I see in my clinic using a grain-free low-carb diet where we regularly get HbA1c back to 5.5 (i.e. effectively no longer diabetic) in the same time. Plus such a diet tastes better and is sustainable long term. Who wouldn’t prefer to eat a plate of eggs and bacon for breakfast (which won’t spike blood sugar at all) rather than having to wade through a double sized bowl of stodgy porridge as these poor participants had to do!
But don’t oats keep you fuller for longer?
Many people swear that eating oats for breakfast helps them stay feeling full for longer. However, a recent study (Missimer, 2017) that compared eating oatmeal verses two eggs for breakfast, found that eggs increased satiety more than oatmeal, both in terms of the hunger hormone ghrelin and participants’ sense of fullness. An additional effect of eggs for breakfast was that participants ate more protein and fats (thus fewer carbs) at subsequent meals indicating that the eggs caused a shift in food preference.
The bottom line? Oats are not especially good for the heart, nor for regulating blood sugar, nor do they keep you fuller for longer. Oh, and they don’t provide ‘central heating for kids’ either. Some super-food, eh?
If you are coeliac or suffer from NCGS (non-coeliac gluten sensitivity), the temptation to fill your cupboard with gluten-free products should be resisted. You are likely to recover more fully and have an improved diet quality if you avoid grains altogether and instead focus on other food groups.
For all of us, the idea that our health will be improved by replacing refined grains with whole-grains and oats is unlikely to live up to the hype. As we have seen, the benefits will be marginal at best. The wiser and more effective option is to build your diet around real whole foods such as meat, poultry, fish, animal fats, eggs, vegetables, nuts, seeds and dairy products, especially cheese: i.e. foods that are naturally gluten-free and low GI.
Such a diet, based on minimally processed foods, will be naturally nutrient dense and satiating.
- Make a start today: learn to cook grain-free meals. or
- Contact me if you want to arrange a one-to-one kitchen demo or group workshop. They are such fun!
In the next post we will look at the heavy metal and fungal toxin contaminants in grains: yet another reason no one should eat them.