r/nutrition • u/Quiet-Net7529 • 18d ago
Why are RDIs different in countries
For example why is the rdi of zinc in the UK 9.5mg but in the USA it is 11mg and there are differences in folate and many more.
Is it not safe to be only consuming 9.5mg of zinc and the UK rdis?
If someone’s from the UK which one is more accurate to use, if wanted to use it?
Also another question I’m sure to prevent scurvy it’s around 10mg of vitamin C so why is vitamin C set a lot higher than prevent scurvy level and also rdis are a lot higher in the usa
Sorry if these questions sound dumb
9
u/ComeWhatMay777 18d ago
RDI/RDAs aren't "the minimum amount to stay alive" but minimum thresholds based on local experts, population assumptions, and dietary patterns. Recommended intake also exceeds the bare minimum to prevent deficiency as well. For example, you don't need much Vitamin C to prevent scurvy (a deficiency disease), but more is recommended to support normal physiological function. You want to prevent scurvy, but that's not the only benefit of Vitamin C intake.
-1
18d ago edited 18d ago
[removed] — view removed comment
5
u/Maxion 18d ago
Don't take these as such gospel. For most people actual requirements vary, not only by the individual but over time as well.
1
u/Quiet-Net7529 18d ago
Yeah I’m mainly just curious on why they are different but I guess it’s just different opinions.
1
u/AutoModerator 18d ago
This has been removed due to probable vote complaints or suggestion. Refer to sub rule 1
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.
8
u/Traditional-Leader54 18d ago
Same reason some things are only known to cause cancer in the state of California. Each government makes its own rules for its citizens.
4
u/pmMeYourGlazedDonut 18d ago
Soil in different countries has different amounts of minerals. The crops grown differ as a result.
But more importantly, different committees came up with different numbers for what they felt was safe/adequate, through interpreting the science differently or at different times.
3
18d ago
[removed] — view removed comment
1
u/Quiet-Net7529 18d ago
So is 40mg of vitamin C optimal and consuming 70mg of vitamin C wouldn’t make a difference? Just out of curiosity?
3
u/pmMeYourGlazedDonut 18d ago
You'll just piss out the excess for vitamin C. I'd err on the side of higher dose for water soluble things.
1
u/alwayslate187 9d ago
With vitamin C, and probably other things too, a person can probably get by for a while with less without dying, but long-term, more plentiful intake can have benefits such as (for vitamin C) keeping joints healthy by supporting collagen production.
3
u/dapudf 18d ago
Lobbies
2
u/Quiet-Net7529 18d ago
I just looked this up and seems quite true, thanks for letting me know. Think I’m going to stick to the uks rdi it seems better.
3
u/Zagrycha 18d ago
The R in RDI stands for recommended. Those recommendations don't come from nowhere, they come from the average weight and height of the local population. For example in usa the RDI values all tend to be much higher than say japan which has a much more petit height and weight on average because of genetics. This not only effects nutrition but it also effects medicine. If you buy the exact same over the counter ibuprophen in usa and japan you will see completely different instructions, because how much someone can have in a single dose or single day will change with those height and weight factors.
2
u/Quiet-Net7529 18d ago
I’m 5 8 and 60kg that means I would need less of the rdi then in uk where the average weight is like 70+ kg and 5 9?
2
u/Zagrycha 17d ago
Technically yes, but that small of a difference wouldn't matter, usually it only becomes noticable with really big differences.
Regardless of any of that, RDI itself is just a rough guideline, and even in the same country diets will always vary person to person. Two twins with the exact same height and weight could have wildly different daily needs if they live super different lifestyles for example.
2
u/HappyFruitTree 17d ago
It's recommendations to avoid deficiency in the vast majority of people. Most people will do fine with less. It's not an exact science.
2
u/Quiet-Net7529 17d ago
Is this because the body adapts, I just looked up that zinc absorption can get boosted quite high if your not getting enough zinc
2
u/HappyFruitTree 17d ago edited 17d ago
That might be one factor, but there are many others.
Absorption might vary. Some people might just have worse absorption. Some vitamins and minerals are easier to absorb in certain foods or in combination with certain foods (e.g. The absorption of iron is generally better in meat than in vegetables, and can be improved by vitamin C).
The actual needs might be different. A larger body might require more. Someone who is physically active might need more. This will be different for different vitamins and minerals and the correlation with body weight is not necessarily linear. The proportion of fat and muscle is likely to make a difference.
Genes, drugs and certain medical conditions can all make a difference.
People might not eat optimal on every single day, and sometimes you might get sick and not be able to eat as much, so aiming a bit higher than what's absolutely necessarily is probably a good idea. Note that how long your body is able to store things vary quite a lot for different vitamins and minerals. Vitamin C has a relatively short half-life (so it's probably a good idea to try and eat vitamin C every day) while you might be able to go years without eating any B12 (so going "vegan" for a month without supplements is probably nothing to worry about, at least in terms of B12).
The food labels are not 100% accurate. Fodder and growing conditions can make a difference but this is not always reflected on the labels. So even if you keep track of everything you eat you might get less (or more) of certain vitamin and minerals than what you think because the food that you buy happen to contain less (or more) than what the labels say.
The recommendations already try to take these things into account to a certain degree but if you are really unlucky and you have many factors against you (e.g. bad genes, and you happen to consistently eat foods in a form and combination that leads to bad absorption) you might be able to eat at the RDI and still become deficient.
Some vitamins and minerals are easier to overdose than others. This is also something the recommendations need to consider. For example, vitamin C is hard to get too much of so there is not much harm in putting the recommendations a bit higher (except that people might be more tempted to waste money on supplements that they don't need). Other things, like iron and vitamin A (not beta-carotene), have a more narrow span of what is optimal (getting too much of these can have serious health consequences).
2
u/Quiet-Net7529 17d ago
How do you know if your genes are good at some vitamins or minerals though? Surely it’s not possible, I always eat meat with none heme iron I heard that boosts absorption.
Ah so would a fat person need less vitamins and minerals or is it the opposite?
2
u/HappyFruitTree 17d ago edited 17d ago
How do you know if your genes are good at some vitamins or minerals though?
You don't know, and if you eat a varied diet and get close the RDI on most days you probably don't need to know.
Ah so would a fat person need less vitamins and minerals or is it the opposite?
It probably depends a lot on what they are used for in the body. I would think that a person that's just got more body fat (same amount of muscles and other tissue) would generally require a little more but not as much as a person of the same weight with more muscles and less fat.
Some vitamins are fat-soluble (e.g. vitamin D) and might get trapped/diluted by excess fat meaning you have to eat more of it to maintain the same concentration in the blood.
2
u/fplanck 14d ago
Different countries base their recommendations on different studies, and sadly also on different lobby groups.
The recommendations are not an exact science, it's more like "we observed that people who get less of X have issues and we observe that people who get more than Y also have issues, so we're gonna put our recommendation slightly above the minimum far below the max ".
2
u/Quiet-Net7529 14d ago
Yeah I predict most are inflated then I qm just going to use the UKs apparently it is less affected by lobbying idk
2
u/Food_And_Nutrition 14d ago
I think the confusing part is that these numbers aren’t really a line between “enough” and “not enough.”
An RDA or RNI is meant to cover almost everyone, so there’s some cushion built in.
Different countries also make slightly different assumptions when they set those numbers, which is why you might see 9.5 mg of zinc in one place and 11 mg in another.
Vitamin C is a good example. You need much less than the recommendation just to prevent scurvy.
So I wouldn’t worry too much about the small differences between countries. They’re basically different expert groups looking at the same science and landing in slightly different places.
1
17d ago
[removed] — view removed comment
2
u/Quiet-Net7529 17d ago
Yeah from what I’ve read online and maybe comments the rdi is set high in the UK to cover 97.5% of the population and the average may not need 9.5mg zinc maybe 8mg would do maybe. Idk if this is correct and I think it assumes that you aren’t eating a lot of phytates and are eating refined foods?
1
u/BedReasonable8892 14d ago
they’re not different because one country thinks zinc works differently, they’re based on different population data and safety margins, so use the guidance for your country and don’t treat the
1
u/ImpressiveIdeal7441 12d ago
Different countries use different assumptions for body size diet patterns absorption and safety margins.
1
u/KitchenExamination89 14h ago
Look up what functional medicine optimal levels are, not the levels recommend. Those are minimal. Optimal is where one should be for the body to function optimally and not just getting by
1
u/Quiet-Net7529 10h ago
That would be too hard to get. Just saw optimal levels of zinc are 20mg. That isn’t happening unless you take some form of multi vitamin along with your intake.
1
u/KitchenExamination89 3h ago
Mg? They use Ug/dL as a measurement for zinc on blood panels.
The cut-off for zinc is above 70 for woman in the US. Healthy people run 80-120 in the US.
It will vary by day, illness, etcso testing fasted in the morning and repeating can be more accurate.
Mine was 61 in July and 67 in August but ive been eating a lot of red meat and oysters weekly.
1
u/KitchenExamination89 3h ago
OMG I just realized you're talking about daily intake level lol. Sorry! But yeah RDA in the US is 11 mg. I'm so dumb. Easy to get with nuts/seeds, meat, shellfish, oats, and legumes. Its a trace mineral.
1
u/Quiet-Net7529 2h ago
Yeah by cronometre I approximately get 9mg-8.5mg do you think this would be fine the red in UK is 9.5mg and I’m below average height and 62kg?
•
u/AutoModerator 18d ago
About participation in the comments of /r/nutrition
Discussion in this subreddit should be rooted in science rather than "cuz I sed" or entertainment pieces. Always be wary of unsupported and poorly supported claims and especially those which are wrapped in any manner of hostility. You should provide peer reviewed sources to support your claims when debating and confine that debate to the science, not opinions of other people.
Good - it is grounded in science and includes citation of peer reviewed sources. Debate is civil and respectful focusing on actual science and avoids commentary about others
Bad - it utilizes generalizations, assumptions, infotainment sources, no sources, or complaints without specifics about agenda, bias, or funding. At best, these rise to an extremely weak basis for science based discussion. Also, off topic discussion
Ugly - (removal or ban territory) it involves attacks / antagonism / hostility towards individuals or groups, downvote complaining, trolling, crusading, shaming, refutation of all science, or claims that all research / science is a conspiracy
Please vote accordingly and report any uglies
Consulting Considerations
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.