Perspectives and progress on upper levels of intake in the United States

Emerging Concepts in Nutrient Needs

Dietary reference intakes (DRIs) are quantitative, nutrient intake-based standards used for assessing the diets and specific nutrient intakes of healthy individuals and populations and for informing national nutrition policy and nutrition programs. Because nutrition needs vary by age, sex, and physiological state, DRIs are often specified for healthy subgroups within a population. Diet is known to be the leading modifiable risk factor for chronic disease, and the prevalence of chronic disease is growing in all populations globally and across all subgroups, but especially in older adults. It is known that nutrient needs can change in some chronic disease and other clinical states. Disease states and/or disease treatment can cause whole-body or tissue-specific nutrient depletion or excess, resulting in the need for altered nutrient intakes. In other cases, disease-related biochemical dysfunction can result in a requirement for a nonessential nutrient, rendering it as conditionally essential, or result in toxicity for a food component at levels usually tolerated by healthy people, as seen in inborn errors of metabolism. Here we summarize examples from a growing body of literature of disease-altering nutrient requirements, supporting the need to give more consideration to special nutrient requirements in disease states.

An examination of the nutrient content and on-package marketing of novel beverages

Changing regulatory approaches to fortification in Canada have enabled the expansion of the novel beverage market, but the nutritional implications of these new products are poorly understood. This study assessed the micronutrient composition of energy drinks, vitamin waters, and novel juices sold in Canadian supermarkets, and critically examined their on-package marketing at 2 time points: 2010-2011, when they were regulated as Natural Health Products, and 2014, when they fell under food regulations. We examined changes in micronutrient composition and on-package marketing among a sample of novel beverages (n = 46) over time, compared micronutrient content with Dietary Reference Intakes and the results of the 2004 Canadian Community Health Survey to assess potential benefits, and conducted a content analysis of product labels. The median number of nutrients per product was 4.5, with vitamins B6, B12, C, and niacin most commonly added. Almost every beverage provided at least 1 nutrient in excess of requirements, and most contained 3 or more nutrients at such levels. With the exception of vitamin C, there was no discernible prevalence of inadequacy among young Canadian adults for the nutrients. Product labels promoted performance and emotional benefits related to nutrient formulations that go beyond conventional nutritional science. Label graphics continued to communicate these attributes even after reformatting to comply with food regulations. In contrast with the on-package marketing of novel beverages, there is little evidence that consumers stand to benefit from the micronutrients most commonly found in these products.

Discretionary fortification--a public health perspective

'Discretionary fortification' refers to the addition of vitamins and minerals to foods at the discretion of manufacturers for marketing purposes, but not as part of a planned public health intervention. While the nutrients added may correspond to needs in the population, an examination of novel beverages sold in Toronto supermarkets revealed added nutrients for which there is little or no evidence of inadequacy in the population. This is consistent with the variable effects of manufacturer-driven fortification on nutrient adequacy observed in the US. Nutrient intakes in excess of Tolerable Upper Intake Levels are now observed in the context of supplement use and high levels of consumption of fortified foods. Expanding discretionary fortification can only increase nutrient exposures, but any health risks associated with chronically high nutrient loads from fortification and supplementation remain to be discovered. Regulatory bodies are focused on the establishment of safe levels of nutrient addition, but their estimation procedures are fraught with untested assumptions and data limitations. The task of determining the benefits of discretionary fortification is being left to consumers, but the nutrition information available to them is insufficient to allow for differentiation of potentially beneficial fortification from gratuitous nutrient additions.

Voluntary food fortification in the United States: potential for excessive intakes

BACKGROUND

Historically, the voluntary addition of micronutrients to foods in the United States has been regarded as an important means to lessen problems of nutrient inadequacy. With expanding voluntary food fortification and widespread supplement use, it is important to understand how voluntary food fortification has an impact on the likelihood of excessive usual intakes. Our objective was to investigate whether individuals in the United States with greater frequency of exposure to micronutrients from voluntarily fortified foods (vFF) are more likely to have usual intakes approaching or exceeding the respective tolerable upper intake levels (UL).

SUBJECTS/METHODS

The National Cancer Institute method was applied to data from the 2007-2008 National Health and Nutrition Examination Survey (NHANES) to estimate the joint distribution of usual intake from both vFF and non-vFF sources for 12 nutrients and determine the probability of consuming these nutrients from vFF on a given day. For each nutrient, we estimated the distribution of usual intake from all food sources by quintile of probability of consuming vFF and compared the distributions with ULs.

RESULTS

An increased probability of consuming zinc, retinol, folic acid, selenium and copper from vFF was associated with a greater risk of intakes above the UL among children. Among adults, increased probability of consuming calcium and iron from vFF was associated with a greater risk of intakes above the UL among some age/sex groups.

CONCLUSION

The high nutrient exposures associated with vFF consumption in some population subgroups suggest a need for more careful weighing of the risks and benefits of uncontrolled food fortification.

Summary of workshop discussions on establishing upper limits for amino acids with specific attention to available data for the essential amino acids leucine and tryptophan

The morning of the first day of the 8th Amino Acid Assessment Workshop was organized and co-sponsored by the International Council on Amino Acid Science (ICAAS) and the International Life Sciences Institute Research Foundation and was focused on the International Life Sciences Institute Research Foundation's approach to establishing upper limits of nutrients. The remainder of d 1 and all of d 2 were focused on the safety of leucine and tryptophan, with special emphasis on determining the upper level of the safe range of intake. It was recognized that some toxicological frameworks, mainly the key-events dose response framework, might be applicable to amino acids and provide appropriate assistance to regulators in establishing upper limits for amino acids as a group of nutrients used in dietary supplements. ICAAS-funded projects for determining the upper intake limits for the essential amino acid leucine provided the main pool of leucine data discussed at the workshop. The acute clinical study suggests 500 mg/(kg · d) as a possible upper limit for leucine in healthy humans, but the safety margin needed to widen this limit to the general population has not been determined. For tryptophan, the workshop participants found less ground for consensus. Older efficacy studies suggested that tryptophan at 8-15 g/d was well tolerated, but human research was abruptly terminated in the late 1980s and no new data are available. Animal results obtained in pigs and rodents were discussed and 2 possible strategies for applying those outcomes to humans were described.