New research supports difficulty of setting upper limits for harmful nutrients

09-May-2011 - Last updated on 14-Mar-2017 at 22:44 GMT

Related tags Nutrition

New research suggests that even though there is enough evidence to suggest a causal link between intake of saturated fat, trans fat and cholesterol and heart disease risk, it is not feasible to define tolerable upper intake levels.

The study’s authors, from the Food and Drug Administration’s Office of Nutrition, Labeling and Dietary Supplements, said that tolerable upper intake levels for nutrients are important, partly because they can be used to estimate how many people are at risk of adverse effects from excessive nutrient intake. However, the Institute of Medicine (IOM) has not set tolerable upper intake levels for trans fat, saturated fat and cholesterol because any consumption of these nutrients at all has been associated with an increase in LDL cholesterol (low-density lipoprotein, or so-called ‘bad’ cholesterol).

In addition, the IOM considers that it is not possible to completely avoid trans fat, saturated fat and cholesterol within the framework of a normal diet.

Current guidelines

Nevertheless, the 2010 Dietary Guidelines Advisory Committee concluded that there is strong evidence that saturated fat intake is associated with increased risk of coronary heart disease and recommended that people should get less than ten percent of their energy from saturated fat. They added that further benefits could be achieved by limiting saturated fat consumption to seven percent of energy intake, and replacing saturated fat with mono- and polyunsaturated fats, basing this conclusion on prospective cohort studies.

The Committee also said there are benefits to limiting artificial trans fat as much as possible and upheld the prevailing recommendation that cholesterol intake should be limited to less than 300mg a day.

Through their revision of available data, the authors of this latest paper found that may be possible to establish a lowest-observed-adverse-effect-level for trans fat and saturated fat by identifying the lowest percentile of intake at which increased risk was found. However, they could not identify such a threshold for cholesterol through their analysis of observational studies, although they claim that there is sufficient evidence to link cholesterol intake with markers of heart disease risk.

“The results of this analysis confirm the limitations of the risk assessment model for setting [upper limits],” they wrote.

Source: Nutrition Reviews

Vol. 69, issue 5, pp 270–278

“Tolerable upper intake levels for trans fat, saturated fat, and cholesterol”

Authors: Paula R Trumbo and Tomoko Shimakawa

3 comments

The Key Word is Suggest

Posted by John, 11 May 2011 - 16:32 GMT

Even though studies suggest a causal link, after 34 years of ant-cholesterol and fat thinking, research, and policy we have absolutely no proof there is such a relationship. None! Can we please give our heads a shake here? We've evolved eating animals. The earliest cave etchings are of men with spears, not hoes. It is naive to think this very recent form of heart disease we suffer is due to foods we've always eaten. But of course laying blame on modern grains and veggie oils is herecy, at least in terms of corporate profits. All hail Cargill and Monsanto and Pfizer!

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Enough evidence

Posted by Aaron, 11 May 2011 - 01:18 GMT

How can you possibly state "enough evidence to assign causal link"

if there is a causal link, you already know the dose response relationship between a nutritent and health. The major issue with the evidence around saturated fat/dietary cholesterol nad even trans fat, is it relies upon epidemiology, from which no causality can be displayed.

In the case of SAFA and Cholesterol, the evidence for an association with CVD is poor, and recent meta-analysis on the subject highlights this majorly.

Highlighting the guidelines is also a worthless endevour, as htey are the general representation of the desired AMDR for the population. We dont have enough evidence for any UL development, but we do have some vague assosciations that we like, so will stick with them.

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Over interpretation of Tolerable Upper Intake Levels

Posted by John Hathcock, 10 May 2011 - 16:43 GMT

The UL is a useful concept but it cannot be used to estimate how many people are at risk of adverse effects from excessive intakes. Intakes exceeding the UL suggest that some people might be at risk, but do not provide quantitative information about how many. The UL is a threshold concept, not a probability function. The UL is not the threshold for adverse effects, but is a statement that the threshold for adverse effects is higher than this. There is no numerical relationship between exceeding the UL and the probability of adverse effects, except that the probability is higher when intakes eceed the UL than when they do not.

Let's be careful about interpretations of the UL.

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