There was an interesting programme on BBC2 recently. Part of the Horizon series. It was called Clean Eating – The Dirty Truth. You should watch it. Dr. Giles Yeo, a Cambridge research scientist, was dispatched to condemn the health claims made by various ‘clean eating’ advocates. No evidence, he said. No proof. There is a lot of this around at the moment. A backlash against health living. Of course we should sense check any new lifestyle advice before diving in. But how much evidence do we need?

When it comes to what we should be eating, some evidence can be helpful. Especially if the advice goes against the conventional wisdom. But Dr. Giles seemingly won’t accept anything less than cast-iron. I agree we shouldn’t blindly follow any old food cult just because it’s popular. But to hold cookbooks to the same burden of proof as chemotherapy is bonkers. Now, the case of ‘Dr.’ Robert Young is very different. He lured desperate cancer patients to his ranch promising a cure with the ‘pH Miracle’ diet. People died. Young is going to prison for practising medicine without a licence. And rightly so. But he’s a distraction from the main issue. The question of whether there is evidence to support the claims in ‘clean eating’ cookbooks.

I’m going to focus on the claim that grains should not be part of our diet. No evidence, Giles said. I beg to differ. There is good evidence. From established principles in evolutionary biology, food biochemistry and physiology. And from observational and experimental research. Which is worrying. Grains and grain-based products are the cornerstone of the UK diet. And the government tells us to eat more of them. Let’s put this one to bed.

Grains are the seeds of grasses. And include wheat, rye, barley, oats, rice, millet, and corn. These grasses were first cultivated during the agricultural revolution. The period in history when our hunter-gatherer ancestors got tired of their nomadic lifestyle and settled into communities. Which turned into villages, towns, cities, and empires. This all started around 10,000 to 12,000 years ago in the Middle East. Before the agricultural revolution, grains were not part of the human diet. Ever. They grew in small amounts in few places. And they required complex processing to make them edible. Conclusion: Our species has not evolved to eat grains. We don’t have the machinery to digest then properly. The proteins cannot be broken down by our digestive enzymes. And to make matters worse, grains contain compounds that inhibit those enzymes. Most of the minerals and some of the vitamins are bound to phytic acid, and so cannot be absorbed in our gut. Surely, if we were meant to eat grains we would have the ability to make use of the nutrients.

There’s more. Eating whole grains may actually be harmful. The culprits are prolamins and agglutinins. Two proteins found in high concentrations in grains and legumes. These molecules are not broken down during digestion (as discussed earlier), and reach the gut intact. They are able, through various mechanisms, to cross the gut barrier into the tissue. This stimulates an immune response. Which in turn damages the cells of the gut. Creating holes through which the contents of the gut – other types of food, bacteria and toxins – can pass. Which further intensifies the immune response. And so continues the cycle. The effects on health are profound. Celiac disease and other autoimmune conditions in susceptible individuals. More subtle, slowly developing problems in many others. Chronic inflammation is implicated in a lot of diseases.

The most famous and most studied prolamin is gliadin (one of the two major proteins in gluten). It’s well established that gliadin exposure is the main cause of celiac disease in susceptible individuals. But there is evidence of gut damage and immune stimulation in non-celiacs. Ricin is the celebrity of the agglutinin world. Due to its starring role in the assassination of Georgi Markov on Waterloo Bridge in 1978. Found in castor beans, ricin makes for a very effective poison (especially if injected with the tip of an umbrella!). But it’s wheat germ agglutinin (WGA) that has been the focus of research in a food and health context.

The effects of both gliadin and WGA on intestinal permeability and the immune system have been demonstrated in more than a few studies. This paper from 2013 does a good job of reviewing the available literature. A recent study from last year also suggests that wheat causes a leaky gut and an immune response in non-celiac subjects (likely through the action of both gliadin and WGA). Prolamins (referred to as ‘glutenoids’) and agglutinins in other grains have not been studied to the same extent. But it is believed that their effects are similar to gliadin and WGA. Indeed, several human studies have shown the positive impact on various health markers of excluding grains from the diet. Although, admittedly, there are other variables.

This looks like a decent body of research to me. And let’s be absolutely clear: This is significantly more evidence than we have for the government-sponsored advice of increased (whole) grain consumption. A supposedly ‘evidence-based’ policy which relies on inconclusive population studies and experiments comparing whole grains to – wait for it – refined grains (not exactly a good benchmark!). So, I’m sorry Giles, there is good evidence to support a grain-free diet. And very little to support the official NHS stance.

Of course, this evidence only demonstrates that grains are probably not a great idea for most people. To know if they’re a problem for you, you’ll have to do a little self-experimentation. Eliminate grains for a while and see how you feel. There’s no downside. No nasty side-effects. I don’t know of anyone having suffered from a grain deficiency. Many people have done it, and seen great results. Including me.

When it comes to dietary and lifestyle advice, it’s relatively straightforward to parse the sensible from the dubious and the ludicrous. Logic and common sense will get you most of the way there. Look at the available evidence. If it makes sense, give it a try and observe what happens. Generate some results. That’s the scientific method in practice. That’s owning your health. There’s no downside. And the potential upside is enormous. The alternative is to listen to the orthodoxy-supporting ‘experts’. To wait until the evidence is officially accepted. That took 50 years in the case of smoking and lung cancer. Have you got that long?

Own your health.