The science is not settled and in some cases has been reversed

The science is not settled.

On salt:

Throughout its report, the Guidelines recommend cutting sodium without reservations. But research has determined there is a daily minimum salt intake below which there is no additional health benefit, and that salt consumption below that level can harm the health of those with chronic diseases.

“We were told the science was settled. Yet new research suggests that salt is not nearly as dangerous as the government medical establishment has been proclaiming for many decades—and a low-salt diet may itself be risky.”
The Salt Libel, Wall Street Journal (2014)

On saturated fats:

Numerous recent review papers (see resources page for more information) have concluded that saturated fats are not as harmful as carbohydrates — yet the Guidelines still recommend a diet that is low in saturated fats and high in carbohydrates.

“However, recent meta-analyses of prospective observational studies did not find a significant association between higher saturated fat intake and risk of CVD in large populations.” — 2015 DGA expert report

“The Questionable Link Between Saturated Fat and Heart Disease: Are butter, cheese and steak really bad for you? The dubious science behind the anti-fat crusade” —Wall Street Journal (2014)

The scientific report guiding the US dietary guidelines: is it scientific?

“…Several prominent papers … failed to confirm an association between saturated fats and heart disease.” British Medical Journal (2015)

On caffeine:

Will 2015 Dietary Guidelines For Americans Further The Demonization Of Caffeine?

“Ideally, the Dietary Guidelines should make no reference to caffeine whatsoever. But if they do, the document should not incorporate the DGAC’s unsupported assertion that some sources of caffeine are worse than others. Such statements in the federal government’s most recognized official pronouncement on nutrition will unjustifiably fuel the demonization of caffeine and products that contain it.” Glenn Lammi, Forbes (2015)

On low-fat vs. whole-fat milk:

For decades, the government steered millions away from whole milk. Was that wrong?

“Scientists who tallied diet and health records for several thousand patients over ten years found, for example, that contrary to the government advice, people who consumed more milk fat had lower incidence of heart disease.”
Peter Whoriskey, The Washington Post (2015)

Some key tenets of the Guidlines have been reversed.

The low-fat diet:

“I think we all agree… that low-fat diets are probably not a good idea and they induce dyslipidemia.” — Alice Lichtenstein, DGAC Vice Chair, at a public meeting of the DGAC in September 2014

**Dyslipidemia refers to adverse blood lipids, such as low HDL-cholesterol, increased triglycerides, etc

“…dietary advice should put the emphasis on optimizing types of dietary fat and not reducing total fat.” 2015 DGA expert report

Caps on cholesterol:

“Previously, the Dietary Guidelines for Americans recommended that cholesterol intake be limited to no more than 300 mg/day. The 2015 DGAC will not bring forward this recommendation because available evidence shows no appreciable relationship between consumption of dietary cholesterol and serum cholesterol… Cholesterol is not a nutrient of concern for overconsumption.”

2015 DGA expert report