Super Interesting Article on Nutrition Myths
Super interesting article just came out in the New York Times where they asked 10 nutrition scientists about their pet peeves, the common nutrition myth they wish would die. I already went through, I agree with some, I have questions about others, so let's take a look.
Myth #1: Fresh Fruits and Vegetables Are Always Healthier Than Canned, Frozen, or Dried
Myth number one, fresh fruits and vegetables are always healthier than canned, frozen, or dried. Yeah, I agree this is a myth, there are specific studies looking at this and measuring, and in general, freezing is pretty good at keeping nutrient content. Sometimes it's even better than buying fresh because in reality, we don't eat everything the day we buy it; it sits in the fridge for a couple of days, and by the time we eat it, the frozen product may actually have more nutrition preserved because it degrades slower. So, studies have actually measured and shown that. Now, leafy greens may be a bit of an outlier—freezing things like spinach can cause some nutrients, like some vitamins, for example, their level can come down by 25% or so. But depending on how long your vegetables sit in the fridge if you buy them fresh, the difference between refrigerated and frozen isn't that big. The other factor, of course, is waste. Sometimes vegetables sit in the fridge too long, they go bad, and we have to toss them, so buying frozen can actually result in saving some kaching and of course less environmental impact because that's less food that gets produced only to be thrown away. Now, one caveat of preserved food are the additives, canned beans for example can come with a lot of sodium added, and canned fruit sometimes comes in this sugary, syrupy water, so those are some things to look out for. But in general, frozen fruits and vegetables are pretty good options.
Myth #2: All Fat Is Bad
Myth number two, all fat is bad. Yeah, this is a relic from the 20th century, from last century, and I still see this here and there on social media. I think what happens is sometimes people lose weight on a low-fat diet, and then they get told, "See, it was the fat you took out that's unhealthy." It's not. We can lose weight on all kinds of diets, it doesn't necessarily mean that the thing we left out is automatically unhealthy; you just cut out a source of calories. Eating too many calories is bad for us, whether it's from fat or not. One problem with the fat phobia is people can be drawn to buy and consume ultra-processed foods labeled low-fat or no fat added and end up eating a lot of refined carbohydrates. I know most viewers of this channel wouldn't fall for that, but that's a pretty common problem. Now, some people like to eat low-fat diets mostly from whole foods, and that's completely fine as a personal preference, but we don't have to fear fat. The question is not so much the amount of fat, it's the type of fat. As the professor of medicine from UCLA who contributed this section writes, saturated and trans fats can increase your risk of heart disease or stroke, while healthy fats like mono and polyunsaturated fats help reduce risk. So, vegetable oils, avocados, nuts, seeds, fatty fish, etc. We've actually covered this topic in a lot of previous content; we went over all the evidence, all the cohort studies, all the trials, so we're not going to spend too much time on this, we're going to move on to myth number three.
Myth #3: Calories In, Calories Out Is the Most Important Factor for Long-Term Weight Gain
Myth number three, calories in, calories out is the most important factor for long-term weight gain. Okay, so this one I found strange. I read it several times, and it's still not clear to me exactly what he means. This one was contributed by Dariush Mozaffarian, who's a professor of nutrition at Tufts, and he says the critical thing for weight loss is avoiding ultra-processed foods. I agree with that in general, and he recommends a shift from counting calories to prioritizing healthy eating overall—quality over quantity. Agree 100%. Focusing on healthy foods tends to take care of the calorie problem. I just think the title is weird, how he worded it, the myth he chose, right? Calories in, calories out being the most important factor for weight gain—that's the top myth for him. It's true that conscious focus on calories doesn't seem helpful for most people, but that doesn't mean calories in, calories out isn't a key factor. In fact, we know that eating ultra-processed foods leads to overconsumption of calories, so they're not mutually exclusive. I think his wording conflates best approaches with what the underlying physiological factors might be. But let me know in the comments if you disagree and if you interpret his words differently. I agree with his bottom line though: minimizing ultra-processed foods in general and focusing on quality foods. It's just I would have worded the myth as something like, "Focusing on calories is the best approach for weight loss" or "Trying to eat less is the best approach for weight loss," something like that, and then explain that it's better to focus on eating better instead of eating less.
Myth #4: People With Type 2 Diabetes Shouldn't Eat Fruit
Myth number four, people with type 2 diabetes shouldn't eat fruit. Yeah, this is a pretty common one to hear. I think it comes from fruit containing sugars, even though they're natural sugars in the food matrix with fiber. But there's this notion that sugars of any source are bad for diabetes. I don't have a 100% black-and-white position on this. The balance of evidence doesn't seem to support that whole fruit is a problem for diabetics. We know people who eat more fruit tend to have a lower risk of developing type 2 diabetes, and type 2 diabetics who eat more fruit tend to have a lower risk of complications and even mortality. Now, we can always argue, well, maybe it's some other healthy habit that they have; it's not the fruit itself. So we also want to see, ideally, when available, some randomized trials. I've seen a few trials specifically looking at whole fruit separate from vegetables in a population with type 2 diabetes. This one, for example, told half the participants to eat a bit more fruit and the other half to eat a little bit less, and after three months they didn't see a significant difference in body weight or hemoglobin A1c, which is an average of the glucose levels over the long run. Several caveats of this study that lower my confidence a little, for example, the difference in fruit intake was subtle. Before the trial, they ate about 190 grams of fruit a day on average, which is the equivalent of a medium apple, and during the trial, one group went up to 320 grams a day, and the other came down to 135, so it's like comparing an apple and a half to two-thirds of an apple. So the trial is saying that in the background of a whole dietary pattern, eating a little more than an apple a day versus a little less than an apple in type 2 diabetics doesn't seem to make a big difference for glucose levels, and I have no trouble believing that. I'm not knocking the trial, this is a common hurdle—getting people to achieve significantly different levels of intake, what we call contrast of exposure. In an ideal world, we'd like to see one group eat no fruit or close to it, and the other group eat five or six pieces a day, and if we still see no difference, then that's pretty compelling that fruit by itself doesn't seem to play a huge role. Another source of uncertainty is they don't specify what people ate instead of the fruit. Fruit normally replaces other desserts or snacks, so people cutting back on fruit might eat something worse instead. Another factor to bear in mind is heterogeneity. Just saying "fruit" is a very large category, I think it's entirely possible that different fruits may have different effects, particularly for people with defective metabolism like diabetics. For example, in this study, blueberries, bananas, apples, and pears, and grapefruit were associated with lower type 2 diabetes risk. Peaches and oranges with no significant difference, and cantaloupe was associated with a higher risk of type 2. Usual caveats apply—I'm not saying this demonstrates cause and effect and cantaloupes make us diabetic, but I think this raises the possibility of heterogeneity between fruit types. So what about trials looking at specific fruits? I've seen some with berries, for example, and they generally seem to improve metabolic parameters like glucose, insulin, and inflammatory markers, both in diabetics and in healthy people. I've also seen some trials with grapes meta-analyzed, and they don't find a significant effect on glucose or insulin of whole grapes, although the trials that looked at whole grapes were not in diabetics, they were in healthy people. Also seen a couple trials with dates, generally finding lower glycemia and no significant change in hemoglobin A1c. So the data I've seen doesn't point to a clear issue with fruit in type 2 diabetics, with the usual uncertainty around types of fruit and amount and replacement, etc. As we discussed recently with Dr. Nicola Guess, the main factor for type 2 diabetes remission is weight loss, and people have different strategies for that. Some people put type 2 diabetes in remission with high fruit diets, others with low carb diets where they have some low-carb fruits like berries and they generally avoid more sugary fruits like mangoes and bananas. Both approaches can work, at least for weight loss and type 2 diabetes remission. So overall, I agree the statement "diabetics shouldn't eat fruit" is a myth.
