Public health messages: everything in moderation, make small long term lifestyle changes toward a varied diet and active lifestyle. If you drink more than X, or weight more than Y you'll probably damaging your health.
Media messages: doing X leads to short term weight loss, you can be fat and fit, a pill or super food extract is the key to health, eating healthily is hard and expensive. Red wine is good for health one week and bad the next...
Make it illegal for anyone other than doctors to give health advice...
Seriously, I don't know. It does seem that so much time and effort is 'wasted' by Sense About Science, NHS Choices and many, many others simply debunking and correcting what so-called health journalists pontificate on. And of course, this is all done after the damage has been done and the misinformation spread over front pages.
That's not to say there aren't many great health journalists. There are, of course, it's just that all their column-inches, quietly explaining the latest research and what it really means is drowned out by some others who have louder voices - as indicated by the colour of the masthead. (Having said that, even the DM can sometimes write good health stories.)
Then there are the quacks, whose businesses depend on misinformation and misunderstanding by the general public. I don't doubt that many of them are genuine in their ignorance and misunderstanding.
Of course, death/toxins/detox/vaccine scare stories/personal anecdotes of lives 'saved' by homeopathy are all powerfully written to appeal to human emotion. And that is why they sell papers.
The answer? I have no idea - except try to educate health journalists? Is there a qualification they could be persuaded to reach for? One that, if obtained, would help them write accurate, helpful health advice that people wanted to read as much as the "Latest vaccine kills millions" type story? Something that educated readers rather than misinformed?
I think it's the doctors and public health authorities that are letting us down!! They are in the pay of big Pharma, pushing statins and diabetes meds, etc when the answers to so many health problems seen today lie in eating the right foods. Also government, which is in the pay of the multinationals and massive corporates, pushing sugar and grains down our throats at every turn. Thank god for the media, and the internet. They may not get it right every time, but at least they question the conventional "wisdom" and dogma!!
We would both be referred to as members of the "tinfoil hat" brigade - I so agree with you. Having seen so much evidence of scare-mongering, lazy journalism and, yes, downright corruption in the highest places, I now question everything - and my watchword is "follow the money". The Wisdom of Crowds is a wonderful youtube video that makes clear that things are not always done in the best interests of citizens, in fact rarely.
Unfortunately I am coming round to the idea that good science needs to be backed up by anecdote. You can bang on all you want about risk factors for breast cancer, but it's Angelina that made the difference. "Just the facts" tends not to hit the button. Personally that makes me uncomfortable, so I guess that it is a case of linking case stories with strong, substantiated facts.
Yes, the public has a voracious appetite for new-and-exciting short-cut ways to good health (or more usually, great looks: shiny hair/ slim hips/ clear skin etc), and advising exercise and balanced diet has limited appeal as a media message: it is not 'news'. There is no one answer, as observing historic examples of health information communication shows many similar challenges to the ones today. I suppose best suggestion is teach media about science, and teach scientists about communication skills. And remind everyone involved about ethics and transparency, to support validity of public health messages
It is small improvements over time that will continue to make the difference. In my youth Thalidomide was sold without being first put through any recognised clinical trials at all! Believe me that we are the lucky beneficiaries of double-blind placebo-controlled randomised trials that have resulted in marvels of medicine during my lifetime. Sense About Science, Good Thinking and Science-Based Medicine organisations are small steps in the right direction regarding good solid researched information and the campaign to make trials data open to all is another. All human acivity is prone to error (as "Concerned" has mentioned) and the scientific method is probably the best way we have to reduce the risk. Minimum qualifications for science/health journalists? It would be good. Can't see the editors/owners going for it though. You always get more sensational press from an unqualified credulous Nutritionist than a qualified Dietician.
And to be fair, not everyone is convinced by some of the new research either. A very important reason why things take a while to change is that new evidence is often not very secure and needs more evidence over a period of time to shaw it up. Often, of course, the new evidence ends up failing the tests too. This makes people understandably cautious.
It is often down to book sales. For instance, on another thread here, the Sun published an article that is full of pseudo science.
Digging a bit deeper, the article is not written by one of the in house journalists, but by some person just trying to flog her new book of nonsense. News papers quite often run these sorts of articles, but it is not clear what is more or less advertorial, and what is genuine reporting.
You cannot and shouldn't get rid of the confusion however - the public has the right to make up its own mind. But it would be nice if the messages from people who actually know what they are talking about were substantially louder and more easily available and that the public were encouraged to question more.
Mind you, I think expecting the public to forensically examine evidence (as is often suggested by promoters of good science) is a bit much. Who on earth has time? And lets face it, with the exception of a handful of celeb scientists and doctors, the scientific community can seem very dry and scarily out of touch with what it takes to be popular!
Maybe more need to be encouraged to be part of a pop band before they take up their scientific career....
Not completely, no. You are assuming that the new evidence is completely good - and therein lies the problem relating to the OP.
How does the average non-scientific person decide whether it is the accepted knowledge that is right, or the new contradictory evidence that is right? Or is it somewhere between the two? Or are neither right and actually the answer lies in a completely different direction altogether?
Most scientists that I know (and I have the odd one including a notable profs kicking around the family table), never think in absolutes. They break down the knowledge and the questions and look at things piecemeal. It is rare (if ever) than anything is completely right or wrong, and everything is open for re-examination at all stages; it is just they way they think.
It tends to be journalists, politicians, conspiracy theorists and PR people that look at everything as either Good or Bad - and that is where it all gets messed up.
What can be done? Simple. Don't rely on the media for any sources of advice on diet.
Go to the governments health website (NHS Direct in UK) and follow their scientific-evidence-based advice on healthy diet and you can't go far wrong.
Ignore all these media reports of 'new' scientific discoveries with often confusing or conflicting advice, or the new fad diet reports often endorsed by celebrities.
Stick to a sound scientific-based source of information. If you want to look into the subject further and assess your own individual needs (always a good approach) the government has advice on how to do this, and there's plenty of books written by qualified and respected nutritionalists. Just avoid the fad and follow the facts.
How to read health news
Metabolism
If sugar is bad for you, Is there any evidence to suggest low fat milk is healthier than full fat?
To GE or Not to GE, that is the Question 
What evidence supports this proposal?