RDA, NRV, and UL: Understanding the jargon related to nutrition guidelines.

What is RDA?

Do you know the difference between RDA and NRV? Perhaps you know what one means but not the other. If you’re interested in reading this, you're probably one of those people that like to read the nutritional labels on the back of the food packets. And you are right to do so, as the nutritional information is important to help us make the right choices when it comes to healthy eating.

Even though the information is for our benefit to help us make an informed decision, many of us find it too technical and are not sure what it all means. For instance, what do the terms RDA or NRV mean to you?

In this article we will try to summarise and explain what these terms, which you are likely to come across, mean in the world of supplements and nutrition.

What does RDA stand for?
RDA stands for Recommended Daily Allowance. It was introduced by the US Food and Nutrition Board in the 1940s with the aim of “Providing standards to serve as a goal for good nutrition”1. This approach of setting nutritional levels was then subsequently adopted by the WHO (World Health Organization) and most countries around the world.

RDAs are defined as the levels of intake of essential nutrients that, on the basis of scientific knowledge, are judged to be adequate to meet the known nutrient needs of all healthy people2. Or in other words, the amount of an essential nutrient that a healthy person needs in order to continue being healthy.

RDAs are estimates that are calculated for general or specific subgroups of the population (such as infants or pregnant women) rather than individual requirements.

So, although RDA is a term that is familiar to many people, you are not likely to find it on many packs. What you will see instead is RI which stands for Reference Intake. This is pretty much the same as RDA, and it’s used for macronutrients such as carbohydrates, proteins and fats. It is also used to refer to the amount of energy (in form of Kcalories or KJoules) that a food can provide, in relationship to the estimates needed.

What is NRV and why is it so important?
NRV stands for Nutrient Reference Value and is a term that you will mainly find on the labels of pre-packed foods and food supplements.

The term NRV was initially proposed by a 1988 joint FAO/WHO expert consultation in response to the European Commission’s request to recommend reference nutrient amounts for food labelling purposes3. The European Regulation (EU) No 1169/20114, that came into effect in 2014, changed the way in which nutritional information for vitamins and minerals was displayed on the packaging of food products, from RDA to NRV. NRV allows consumers to compare the nutrient content of different products, as well as giving them information about the contribution of the vitamins and minerals present in the product in relationship to the recommended daily amounts.

So, although NRVs are based on the amount of vitamins and minerals needed to be consumed on a regular basis to maintain good health in the average person, they actually refer to the nutritional content of the food product, as displayed in the food packaging.

NRVs help us to choose the right food product, by being able to assess and compare how much vitamins and minerals can provide.

At the moment, NRVs are standardised at European level. Since the UK has now left the EU, we don’t know yet whether NRVs will be maintained as they are or changed in the future.

What does UL mean?
With some nutrients, it can be sometimes a case of too much of a good thing. So understanding the upper intake level or UL is important. While having too little is usually bad for you, you can also have too much. This is particularly relevant when you are taking food supplements, as they can provide a larger amount of vitamin or mineral that you would normally get from diet.

Therefore, some vitamins and minerals have defined upper intake levels, or upper levels. ULs are defined as the maximum level of total chronic daily intake of a nutrient, from all sources, judged unlikely to pose a risk of adverse health effects to humans [ref: EFSA Tolerable Upper Intake levels for vitamins and minerals]. In other words, if you take more than that amount of nutrient for a long time, it could have some negative effects on your health.
UL apply to the general healthy population and people with underlying conditions might have a lower UL.

It is very unlikely that you have to worry about UL unless you take multiple supplements with extremely high doses of vitamins and minerals.

In the UK, we have label advisory statements for nutrients that help you be aware of the potential issues of taking high doses of nutrients during long periods of time. For example, although the defined UL for vitamin A for adults is 3000µg (micrograms), products containing more than 800µg of retinol (a type of vitamin A), are required to have a warning telling pregnant women not to take this product unless being told by the doctor. This is because high doses of vitamin A during pregnancy could cause developmental problems in the fetus. But, for men or non-pregnant women, the product would be perfectly fine.

Why are NRVs sometimes different from DRVs?
Dietary Reference Values or DRV is the name of the nutritional requirements systems used by the UK Department of Health and the European Food Safety Authority (EFSA). These are numbers that policy makers use to establish dietary guidelines. DRVs are generally set at country level, as the requirements vary depending on the geography and diet. DRVs also vary between the different groups of the population; for example, the requirements for the elderly, which generally absorb nutrients less well, will be quite different from the requirements for children, who are growing and tend to use lots of energy.As we mentioned earlier, NRVs are displayed in food packaging to help us make the right choices. But we can sometimes get a bit too hung up on them and forget the context of their value.

For example, the current NRV for vitamin D is 5µg (micrograms). So, a food or food supplement that contains or provides 5µg of vitamin D will say it provides 100% of the NRV. But, if you look at the recommended levels for the UK, the current DRV is 10µg, so 200% of the NRV. Isn’t that confusing?

In this case, 5µg (the NRV) is the minimum amount of vitamin D that the general population, as defined by the EU authorities, requires in order to not develop rickets, which is a disease that happens when you don’t have enough vitamin D. Does that mean that you should only get 5µg of vitamin D? Well, probably not. You might not develop rickets, but probably you won’t feel great.
In the UK, the guidelines recommend getting 10µg of vitamin D from the diet. Some people might need less, some people might need more. But if you aim to get around that value, you are closer to ensure you won’t be deficient.

How does all of this help me to stay healthy?
Being aware of the nutritional content of your food is important, because it helps you understand whether you might be missing some nutrients, or having too much of others. But each individuals’ requirement is different, and depends on many factors such as gender, genetics or lifestyle.

Moreover, it’s virtually impossible for most of us to follow those guidelines all the time. Afterall, fresh fruit and vegetables don’t have NRVs on their labels, but we all know they are good for us. So following a healthy and varied diet containing plenty of fruit and vegetables, lean protein, and some dairy products should provide us with the nutrients we need to keep us in good shape. But if you think your diet alone will not provide you with the appropriate level of nutrients to stay healthy (for example, if you follow a vegan diet, you are very likely to not have enough iron or vitamin B12), then looking for food products that provide you with sufficient levels, like food supplements, can be helpful. Nevertheless, if you think your levels of any vitamin or mineral are low, you should talk to your doctor, as he will be in a better position to know if you need supplements.

1. NRC (National Research Council). 1943. Recommended Dietary Allowances. Report of the Food and Nutrition Board, Reprint and Circular Series No. 115. National Research Council, Washington, D.C. 6 pp

2. National Research Council (US) Subcommittee on the Tenth Edition of the Recommended Dietary Allowances. Recommended Dietary Allowances: 10th Edition. Washington (DC): National Academies Press (US); 1989. 2, Definition and Applications. Available from: https://www.ncbi.nlm.nih.gov/books/NBK234926/

3. Lewis J. 2019. Codex nutrient reference values. Rome. FAO and WHO.

4. Regulation (EU) No 1169/2011 of the European Parliament and of the Council of 25 October 2011 on the provision of food information to consumers, amending Regulations (EC) No 1924/2006 and (EC) No 1925/2006 of the European Parliament and of the Council, and repealing Commission Directive 87/250/EEC, Council Directive 90/496/EEC, Commission Directive 1999/10/EC, Directive 2000/13/EC of the European Parliament and of the Council, Commission Directives 2002/67/EC and 2008/5/EC and Commission Regulation (EC) No 608/2004
5. Dietary reference values. https://www.efsa.europa.eu/en/topics/topic/dietary-reference-values
6. Public Health England. Government Dietary Recommendations for energy and nutrients for males and females aged 1-18 years and 19+ years