Monday, 16 November 2015

Fat Problems: Oils, Nuts, Seeds and Other Omegas

When I announced my intention to spend November eating a lot of beans and lentils, I was told I would probably wind up eating 'a lot of fat' for 'flavour.' Personally, I have nothing against fat. The low-fat mantras of the 1990s and early 2000s have given way in recent years - in extremis to the Atkins diet, but more generally to the idea that it's sugar that's ruining our waistlines, rather than fat. We need fats for our immune systems to work properly, and women need enough body fat to menstruate. But there's no doubt that there is too much fat circulating in the Western diet, and that much of this - far from being animal-sourced - comes in the form of plant oils. A couple of weeks ago, the BBC's Dr Michael Mosley presented evidence that instead of cooking with groundnut and sunflower oil, we should be using lard and dripping. Fat is back: but what kind? And what should vegans be eating?

Before starting my vegan adventure I had two main questions about fats. First, which oils have the highest smoke points for cooking? Smoking oils are carcinogenic, which is why re-using oil is a massive no-no (especially the kind with little black bits floating around in it, probably found in every kebab van or panini hole-in-the-wall you've ever patronised). Ideally we're meant to use high-smoke-point oils for high-temperature cooking. Recently coconut oil has risen in the ranks for its high smoke point, making it the oil of choice for roast sweet potatoes or Thai stir-fries. Although it contains a lot of saturated fat, this is apparently 'healthy' saturated fat. Coconut oil comes at a price, and you're probably more likely to use something like sunflower, soybean, or peanut oil, all of which smoke at pleasingly high temperatures and are full of polyunsaturates. Excellent, you think - especially if you're vegan.

However, Michael Mosley had to go and throw a spanner in the works with a study that compared the toxic compounds (aldehydes) produced by various oils when fried. The results were sobering. All those polyunsaturated oils that we've been thinking of as healthy are producing more toxic sludge at high temperatures than we realised. Olive oil, vilified for years because of its lower smoke point, actually produces many fewer aldehydes - and butter and lard are the real winners. Their high levels of monounsaturated and saturated fats are much more stable at high temperatures, and the few nasty compounds that they do produce are easier for our bodies to cope with. So vegans should be throwing away the sunflower oil, and stocking up on olive.

It gets even more complicated when I introduce my second question: which oils have the best balance of omega 3 and 6? The guidance varies about what ratio we need to meet in our consumption of these essential fatty acids. Some say the ideal is 1:1, others 4:1 or 3:1. It's suggested that modern-day Westerners eat a ratio of somewhere between 1:12 and 1:25. Basically, we are eating far too much omega 6 and not enough omega 3, largely thanks to processed foods containing large amounts of cheap omega-6-rich oils. Even the less-aldehyde-producing olive oil has an omega 3:6 ratio of 1:13. We might as well go back to butter, with a slightly more respectable 1:9, and we should certainly be avoiding processed foods.

Omega 3 is the reason we're told to eat two portions of oily fish per week. It has anti-inflammatory effects and protects our heart health; it's also supposed to support our brain functioning. Although a study involving dietary supplements recently called this into question, we know that pills do not stand up against a diet that consists of actual food. Vegans and vegetarians sing the praises of omega-3-rich flax and hemp seed, so I duly laid in both earlier this month: the hemp milk (delicious) boasted that a glassful provided 50% of my recommended daily intake of omega 3, and I bought a gigantic packet of flaxseeds from the trendy health food store in East Oxford, and stored them in a nice glass jar that looked like something straight out of a Naturally Sassy cookbook. I figured I was set for heart and brain health this November - but I was wrong.

The bad news for plant-eaters is that not all sources of omega 3 are created equal. We humans metabolise the essential bits of omega 3 far better from oily fish than from even the flaxiest of flax seeds. Salmon fat contains no omega 6, and the kind of helpful omega 3 (DHA) that gets to work right away without having to be converted in our bodies, slowly and wastefully, from the other less helpful kind (ALA) found in plant seeds. Apparently the conversion of ALA to DHA in our bodies is even more difficult for vegans and vegetarians, because we are more likely to be iron-deficient. Women of child-bearing age already have to contend with the fact that iron is much more bioavailable from meat than from plants - I've been drinking orange juice (Vitamin C) with my spinach all month to make this process more efficient. As I wrote last week, the network effect of cutting out substantial food groups increases our tendency to one or another nutritional deficiency. One deficiency ropes in another, and they wind up having a party. Slowly. In your arteries.

The imbalance of omegas is looking worse for vegans than for vegetarians because many butter substitutes are based on soybean or sunflower oil. A tasty enough sunflower spread is sitting in my fridge right now, and apparently it has an omega 3 to 6 ratio of 1:40. I don't necessarily want to switch to the soybean version, because I'm already drinking soya milk and eating tofu, and I don't want to eat too much soy - so it's back to the olive oil spread...assuming they've ditched the trans-fats. My brand of vegan diet just received another nudge away from the processed 'substitute' wagon. And don't get me started on the amount of 'xanthan gum' I must be consuming in my soya milk. I never signed up for 'xanthan gum'.

To cap it all, I was eating my omega-3-rich flaxseeds with oats for breakfast last weekend when I made the fatal mistake of Googling them. A few websites in, I discovered that when raw they contain a toxin similar to cyanide, and that for this reason one is not supposed to eat more than two spoonfuls a day. I spent the next half hour fishing out the damn flaxseeds. Then I read another website that said that the level of cyanide-esque toxins in flaxseeds are fine. You can't win. Also, avoid the internet at breakfast.

The take-home message for vegans on fats and oils? Avoid processed foods, cook your own, and cook it at lower temperatures. Use olive oil, and consider an algae-derived omega 3 supplement. Meanwhile, meat-eaters everywhere are descending on the lard and badgering their butchers for dripping: Waitrose, you have been warned.

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