How come claims regarding nutritional value keep changing?

Everything in moderation and not too much faux food is the mantra I try to live by.

Problem is, as new research streams in everything is subject to change. Coffee is a good example, it has been touted as good, bad and indifferent as many other substances have.
Also, as @janbb says, moderation, one glass of red wine a day has health benefits, 5 have health consequences.
As with everything nothing is all good or all bad, short of extreme substance abuse.

I have a friend with MS that swears taking a few puffs off of a cigarette helps her pain levels. She smokes about one cigarette a month, OMG…so BAD! lol

Here ya go.

www.sciencedaily.com/releases/2011/06/110602162820.htm

Part of the problem with your proposal is the extreme unlikelihood of maintaining diets among “control” and “study” groups that would be rigorous enough to qualify as “real science” among nominally free adult humans. Our diets are so varied in the first place that this could hardly be studied in the context of a “free society”. (In fact, it would be hard even to do this in a prison population, where diets are more strictly controlled “by others”.)

Aside from the dietary issue, our lives themselves are so filled with co-factors (stress, emotional issues, allergens and other living conditions, even down to local climate issues) that I hardly see how a proper control group can even be set up – at least in any ethical way.

But you may as well ask whether the original studies, the ones that found problems with high-carbohydrate and high-fat diets, were themselves properly organized and whether proper conclusions were drawn.

This is, as a matter of fact, how science works. Small statistical changes in data from one study group to another lead to generalized conclusions – and this is when the study itself is performed flawlessly. (They are seldom flawless.) From there, in order to make “an interesting story” media types (including scientists with an interest to cultivate media attention) make the small conclusions less nuanced and more dramatic.

Science is a messy business.

What gets me is that in 60’s and 70’s we ate a ton of fat and sugar, but the vast majority of people were not over weight. Then society decided to focus on food, and people started cutting out fats and sugars and got fat.

@CWOTUS Under my proposal, people would be employed full time to monitor what they eat. The sample size would be huge – not a few undergraduates but a 1000 or 10,000 or whatever it takes to get meaningful data. They would be restricted in what they could do and would be very carefully monitored. That may seem invasive, but that is what they are getting paid for. It may not be the most glamorous work, but I can think of worse.

And no one would ever lie, right? Since no one with a full-time job ever lies about what they do at work. No one in a scientific study would ever take drugs, either, or indulge in other confounding behavior, and of course “everyone is created equal”, which explains why our bodies are so uniform…

All I’m saying is that when you take a study such as this from controlled animal studies into human populations there are so many confounding co-factors that it will be impossible to control for them all.

Might just as well ask why don’t we still believe the world is flat. Each day brings new data, new knowledge, new understanding, new everything.

I agree the information on nutrition is frustrating. A lot of nutritional ideas are promoted and catch on and are just some muscle guy writing a book and a whole bunch of people decide it sounds good.

Many studies are done that are biased. Like oatmeal lowering cholesterol. Yup, I could have told you oatmeal in lieu of eggs and bacon would lower cholesterol. Basically, any grain cholesterol free will be better that cholesterol filled foods.

A very wise penguin said moderation. I agree. Although, as I get older my mantra is more and more little to no consumption of animal for better health for me and my malfunctioning body when it comes to fats and cholesterol.

Information about nutrition keeps changing because scientists do keep researching. However, often the media broadcast fragments of that body of research and we aren’t seeing the whole picture, so the message may be skewed. Also, there isn’t going to be one simple answer. The body is a complicated machine and we still have a lot to learn. I agree with @janbb and her suggestion that it’s really all about moderation and I also avoid processed foods. I find sticking to whole, natural foods and avoiding commercially processed foods works for me.

This is a really interesting but disturbing documentary about obesity and the misinformation that’s been circulated about diet, nutrition, exercise etc. It also covers how government decisions have been influenced by corporate lobbying.

This Ted talk from Peter Attia is interesting.

Gary Taubes has some interesting ideas too.

My understanding is that they don’t keep changing – well not as much as people feel they do. There is the science (the whole peer-review process and the ability to get closer to an understanding of reality that more closely matches the truth), and then there is reporting of the science. Often, what people are frustrated about is the reporting.

The whole low-fat nightmare was not necessarily a nutrition science problem. Rather, it was a reporting problem that got carried along by a political machine. The evidence against low-fat diets has been pretty solid for a long time – yet, we already had food pyramids and whole industries (and marketing) designed to benefit from selling the low-fat diet myth.

I’m not saying that the research doesn’t yield different results. But it’s not as all over the place as people claim it is. We get better at these studies, and corrections are made. We’re also continually learning about biology, which is still pretty complex and amazing.

Often, when I hear someone complaining that “they keep changing their minds”, it’s usually a case of just not having paid attention.

Because the people behind it are never perfect, so it ends up being the best guess for the season.

Actually, a lot of people, me included, really don’t pay that much attention to nutritional value of foods in the first place. People just continue to eat and drink whatever they please. Personally, I eat anything that I want but in moderation. I am not over weight, I exercise daily and my yearly lab results are always within normal limits.

^^^^ True that.

@hominid I would argue the science for health. and especially heart health, shows a much much lower fat diet than some of the fads out there is what Americans need. True some if it has to do with reporting, I couldn’t agree more, but still low fat is better, especially in America where we eat a ton if fat and our concept of low is askew.

One example is olive oil. Now studies argue it isn’t the olive oil in Mediterranean diets that cause longer life spans and healthier hearts, but rather the Mediterranean diet has a lot of vegetables. American just started cooking their same fatty foods and consuming lots of animal still, just doing it all in olive oil and that had not yielded healthier bodies. As I write that I see it reinforces your statement about the reporting and also the interpretation.