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Ask ten people what “eating healthy” means and you’ll get ten confident answers, several of which contradict each other. Eggs are a superfood one year and a cholesterol bomb the next. Carbs are fine, then they’re not, then they’re fine again. Most of these ideas stick around because they’re simple, memorable, and repeated by someone with a large following. The problem is that simple advice rarely survives contact with actual research.
Here are the common nutrition myths and facts worth untangling, with the numbers behind each one.
Eggs and Cholesterol: A Myth With Nine Lives
One large egg contains about 186 mg of cholesterol, which is why the old advice capped people at two or three per week. That guidance has largely fallen apart. For most people, dietary cholesterol has a modest effect on blood cholesterol; saturated and trans fats matter far more. The committee behind the 2015 US Dietary Guidelines dropped its 300 mg daily cholesterol limit entirely, noting there wasn’t enough evidence to set one.
Meanwhile, the yolk is where nearly all the good stuff lives: choline, lutein, zeaxanthin, vitamin D, and vitamin A. Ordering egg-white omelettes to protect your heart and then dumping the yolk in the bin is a strange trade. If you have familial hypercholesterolaemia or diabetes, talk to your doctor about your own numbers. For everyone else, eggs are a cheap, high-quality protein source that fits comfortably into a normal week.
Fat Doesn’t Make You Fat, But the Type Matters
Fat carries nine calories per gram against four for carbohydrate and protein, which is where the fear came from. The 1980s low-fat boom then gave us fat-free yoghurts, biscuits, and salad dressings loaded with sugar to replace the flavour. Obesity rates climbed through that entire period.
The evidence now points clearly at fat quality rather than quantity. Unsaturated fats from olive oil, nuts, seeds, avocado, and oily fish are associated with lower cardiovascular risk. Trans fats are the ones to avoid outright, and most countries have been phasing them out of processed food for years.
A quick word on cooking oils
Smoke point matters more than most people think, especially if you cook at high heat. Rice bran oil holds up past 230°C, carries a decent balance of monounsaturated and polyunsaturated fats, and contains a compound called gamma-oryzanol that has drawn interest for cholesterol research. If you’re curious about how it performs in everyday cooking, there’s a useful breakdown on cooking with rice bran oil and its health benefits.
Carbs Aren’t the Enemy; Refined Carbs Are
Cutting bread and rice out of your diet reliably produces fast weight loss in the first two weeks. Most of that is water bound to glycogen, not fat. Once you eat carbohydrate again, the glycogen refills and the scale bounces back.
The more useful distinction is between refined and whole carbohydrates. Rolled oats, barley, lentils, and wholegrain bread come packaged with fibre, which slows digestion and feeds gut bacteria. A plain bagel and a bowl of oats have similar carbohydrate counts and completely different effects on how full you feel two hours later. Most adults eat around 15 g of fibre a day when the target sits nearer 30 g, and that gap is a bigger deal than the total grams of carbohydrate on any label.
Fresh Produce Isn’t Always Better Than Frozen
Fresh sounds superior, but fresh food travels. By the time green beans reach a supermarket shelf, they may have spent a week in a truck, and vitamin C degrades steadily during that stretch. Frozen vegetables are usually blanched and frozen within hours of picking, locking in nutrients at their peak.
- Frozen spinach keeps more of its vitamin C and folate than a bag of fresh leaves that’s been sitting in your fridge for six days.
- Frozen peas and corn are almost nutritionally identical to fresh, and often sweeter because they were picked ripe.
- Canned beans and tomatoes are fine, but check for added salt and sugar on the label.
- Fresh is still excellent when it’s local and in season, so buy both and stop treating them as opponents.
The Protein Myth: More Isn’t Automatically Better
The recommended daily allowance for protein is 0.8 g per kilogram of body weight, which works out to roughly 56 g for a 70 kg adult. Most people in high-income countries clear that comfortably without trying. Active people and adults over 60 do benefit from more, somewhere in the 1.2 to 1.6 g/kg range, because muscle protein synthesis becomes less efficient with age.
What doesn’t follow is that doubling everything on top of that produces double the muscle. Excess protein beyond what your body needs is either burned or stored, and it isn’t cheap to buy. Powders are convenient, particularly if you’re training around a full-time job, but they’re a delivery format rather than a magic ingredient. There’s a good rundown of the common myths about protein powder if you’ve been wondering whether whey is secretly necessary.
Detoxes and Cleanses Fix a Problem You Don’t Have
Your liver processes toxins in two phases and your kidneys filter waste continuously. Neither of them needs a £40 bottle of lemon juice and cayenne to function. There’s no regulatory definition of the word “detox” in food marketing, which means it can mean whatever sells.
People do often feel better after a three-day juice cleanse. They’ve also just cut several hundred calories, slept differently, and skipped alcohol. That’s a calorie deficit and a behaviour change, not evidence of toxins leaving the body. The weight returns within a fortnight, and the money doesn’t come back.
The Longevity and Supplement Pitch
Anti-ageing supplements have become an enormous industry, and the honest position is that we’re years away from knowing whether most of them do anything in humans. Resveratrol looked extraordinary in mice and then disappointed in trials. NAD precursors like NMN have promising early data and almost no long-term human evidence. Anyone selling you a certainty is selling you something else. The realistic picture of what extreme longevity and health optimisation actually demand is far duller: sleep, resistance training, blood pressure control, and not smoking.
That logic extends to pets. Owners buy canine multivitamins using the same instinct that sells human supplements, assuming more nutrients must mean a healthier animal. It’s a reasonable instinct and often a misplaced one, as this piece on common myths about dog vitamins explains. A dog on complete kibble is usually already getting what it needs.
How to Judge the Next Claim You See
New nutrition headlines arrive weekly, and you don’t need a degree to filter them. A few habits will do most of the work.
- Check the dose against the study. A trial might use 500 mg of a compound while the product on the shelf contains 50 mg. The headline rarely mentions this.
- Ask who paid for it. Industry-funded research isn’t automatically wrong, but it’s worth knowing before you change your shopping list.
- Distrust single studies. Nutrition science is messy because people are messy. One trial of 40 participants is a hint, not an answer.
- Treat “natural” as a marketing word. Arsenic is natural. So is hemlock. Safety comes from the substance and the dose, not the origin story.
- Watch for the swap. Many demonised foods get replaced with something more processed and less useful, which is exactly how the low-fat era went wrong.
The most reliable pattern in nutrition research hasn’t changed in decades: vegetables, fruit, legumes, whole grains, nuts, fish, and enough protein to protect your muscle, eaten consistently over years. That’s not a viral claim, and it doesn’t come with a subscription. It does, however, keep showing up in the data, which is more than most of the myths above can say.
