Recommended Daily Intake of Supplements

How complicated can it be?

The dosage of vitamins is not an exact science.  It is important to state from the start that you should read the manufacturer’s guidelines on the side of your vitamins and follow the advice given.  You have got to love a good disclaimer.

If you look at the labels on supplements you may notice a whole alphabet of letters linked to dosage.  This does not help lead to simple daily routines.  So, here’s what the letters mean:

RDA – recommended daily allowance.

AI – adequate intake.

DV – daily value, sometimes but not always the same amount as RDA.  This is the recommended amount for someone on an average 2000 calorie a day diet.

UL – is the upper limit, which is the highest safe amount you can take before you run the risk of damage to your health.

You may be curious about the idea of potential damage to health, maybe you have never thought about vitamins in this way before.  You can be forgiven, as we sometimes forget that these supplements are actually a chemical concoction similar to drugs. We are meticulous about following dosage guidelines for drugs, even aspirin, and understand the dangers of overdose.  Yet, we do not consider vitamins in the same way, mostly because we store them in the same category as food in our heads.

There is no need to promote fear.  The upper limits of most vitamins are massive.  However, taking too much of the fat-soluble vitamins could lead to health issues such as: gastric problems, hair loss, restlessness and agitation.  Some doctors warn that too much Vitamin D could cause heart problems and too much folic acid could lead to a B12 deficiency and nerve problems.  Vitamin K helps blood to coagulate, so too much can counter the effects of drugs such as Wharfrin. Doctors also warn that iron and selenium might cause medical issues. But the important words of claim and could show how little certainty there is about the overuse of vitamins.  If in doubt seek advice from your medical professional.  If you have existing health issues, check with your doctor.

The Food and Drug administration does not give recommended allowances for most vitamins.  This is mostly because there is no agreement about the ideal or maximum dose of a lot of supplements.  Also, people can take in vitamins from sources other than the supplement, so setting a dosage to follow is difficult with such vagaries involved. The vitamin manufacturers are only required to carry the RDA and not the upper limit.  This is because of the lack of space on labels and the need for a standard measurement that the consumer can understand. 

So, how complicated can dosage be? The answer is: very.  Let’s see if some simple guidelines will simplify the picture a little.

Upper Limits (UL)

Recommended Daily Intake

Awareness of upper limits will promote safety. So, here are the upper limits of some of the more common vitamins, so you have a chance to keep an eye of what you are taking in:


2500mg a day


3600mg a day

Vitamin B Complex

3500mg a day


1000 mcg a day


10 mg a day


1100 mcg a day


45mg a day


350mg a day


11mg a day


2000 mcg a day


400 mcg a day


2300 mg a day


1.8 mg a day

Vitamin A

10000 IU a day

Vitamin B3

35 mg a day

Vitamin B6

100 mg a day

Vitamin C

2000 mg a day

Vitamin D

100 mg a day

Vitamin E

1500IU a day


40 mg a day


It is important to know these upper limits to avoid putting your health at risk but remember, the recommended daily dosage is likely to be much lower.  Also, keep in mind that you may be getting some of these nutrients from your diet, so from more than one source.  Therefore, using the dosage stated on the labels as a guideline is important.

Daily Values (DV)

The most useful guide to dosage is the DV or RDA of your daily supplements.  However, many of the recommended dosages suggested include a margin of error, as manufacturers assume you will gain some of your nutritional needs through your diet.  In reality, the state of nutrition in the large proportion of our diets is such that we are hardly receiving any nutrient intake from our food and drink.  Therefore, we must adapt our dosages with that in mind.

With this is mind, the daily values suggested for some of the most commonly used supplements include:

Vitamin A

15000 – 20000 IU a day

Vitamin C

1000 mg a day

Vitamin D

50 ng/ML within the bloodstream

Vitamin E

300 – 400 IU a day


50 mg a day

Vitamin B2

50 mg a day

Vitamin B3

100mg a day

Vitamin B6

75 mg a day

Folic Acid

800 mcg a day

Vitamin B12

150 mcg a day


300 mcg a day

Pantothenic Acid

50 mg a day


200 mg a day


1000 – 1500 mg a day


150 mcg a day


500 mg a day


30 mg a day


200 mcg a day


2 mg a day


10mg a day


200 mcg a day


130 mcg a day

But, remember, the easiest way to be certain is to follow the guidelines the manufacturer prints on the side of their products.

The athletes among us…

Recommended Daily Intake

If you are an athlete or you work out to gain muscle definition, there are some supplements that will help with your performance.  These products have specific results, depending on what you are hoping to achieve through your training.  Some general advice for use includes:

Caffeine 150 – 400 mg a day to help with mental alertness, agility and cognitive performance.  Be aware that too much caffeine can lead to agitation and restlessness.

Arginine: 1 – 3 grams per serving with up to 10 grams a day.  This is used for stimulating the release of nitric oxide, which will help with higher blood flow and better transportation of nutrients and oxygen.

BCAA, (branched chain amino acids): 10 – 15 grams a day.

Beta Alanine: 2 – 5 grams a day neutralises acids in the muscle and helps reduce fatigue

Carnitine: 2 – 3 grams total per day combined with a carb rich meal.  This is an amino acid that stimulate oxidation of stored fat and improves muscle definition.

Citiulline: 3 – 6 grams per day is an amino acid which is useful for increased endurance in both aerobic and anaerobic exercise.

CLA: 3.2 – 6.4 grams per day is a mixture of fatty acids that help reduce fat deposits and improve muscle definition.

Creatine: 2.5 grams per day taken with a carb rich meal, stops the body from resorting to muscle glycogen, which supports muscle maintenance, recovery and growth.

Glutamine: 5 – 15 grams per day assists in muscle recovery.

Green Tea Extract: 0.5 – 1 gram a day is an antioxidant.

Omega: 3 2 – 4 grams, is a fatty acid used as an anti-inflammatory and it works to strengthen the immune system.

Remember though, the gap between the UL and the DV is an area of safe nutrient intake.  Many of us have diets that do not include many of the essential vitamins for a healthy lifestyle, therefore it may be necessary to go beyond the DV and even the RDA.  You need to monitor how you feel and what makes you feel better.

The sticky topic of protein

Recommended Daily Intake

So far protein has not been mentioned directly.  Protein is a major food group and according to the healthy plate guidelines should always form about an eighth of our food intake.  Some who exercise regularly see protein as the miracle nutrient, as it works to mend muscle.  It is actually the workhorse in all our cells and we do lose protein from our body with hair loss, the shedding of skin and through excretion. However, you really can get too much of a good thing and how much supplement you take in relies on how much protein you are getting from other sources in your daily diet.

The nutrition specialists calculate that on average we lose 0.36 grams of protein per kilo of bodyweight each day.  They boost this to 0.75 grams to add in a safety margin.  From this they speculate that you should be taking in 0.8 grams of protein per kilo of body weight.  If you have children or teenagers, they double this to account for the demands of growing.

Obviously, the rules are slightly different if you are training.  If you are an endurance athlete the recommendation is 1.2 – 1.4 grams per kilo of body weight.  A strength based athlete is suggested to have a little more, with 1.2 – 1.7 kilos. However, the International Society of Sports Nutrition suggests 2 grams per kilo.  This is based on the idea that you will be engaged in an intense training program, so you should also be taking in a lot of calories to support this.  This means that you are also going to be taking in more protein through your diet.

Whey protein is the most common supplement.  You could have 20 – 30 grams per serving and you should take this in before and after a workout.  If you work out more than once a day, this is likely to make up a large proportion of your protein intake.

Casein Protein forms about 80% of milk.  It has a slower absorption rate than whey protein and allows for gradual release of amino acids into the blood stream.  Casein Protein helps prevent muscle breakdown.  The DV is 20 – 30 grams depending on your daily protein intake.

You can also take in amino acids directly through such supplements as BCAA.  It is worth considering this too when you are calculating your intake of protein.

There has been a lot of reports in the media that high levels of protein intake can cause a stress on the kidneys.  Some others report claim that too much protein can lead to a higher excretion of calcium, therefore putting a stress on bone health.  There is little scientific support for these claims and a lot is speculation.  Let’s reach for our common sense and say that if you are training you will need more protein, if you are sedentary you don’t.  Keep the intake within reason and know that taking in too much of anything will likely not be optimal for performance.

In short…

It is always, always better to be informed than not.  So, even though information on dosage varies between experts, to know there is a DV or RDA or UL is to make sure we are doing the best thing for our bodies.

When considering what dosage to take of any vitamin you need to look at your diet, your lifestyle and your health.  Factors such as how healthy your diet is, how much stress you cope with in a day, how much pollution or sunlight you endure, how much exercise you take part in and if you have pre-existing conditions all impact on how much supplement you should take.

So, here is some simple advice:

A good multi-vitamin might well be enough for you and your lifestyle.  Following the dosage advice on the label will give you the optimal amount needed for the average lifestyle.

If you have a pre-existing health condition, then you should always talk to your doctor before taking in any supplements.  Medical professionals are also likely to be able to tell you what to take and how much if you lead a particularly stressful lifestyle.

If you are training, then you need to understand your body and the demands of your routine.  Following guidelines on labels and not shooting for a higher performance with more fuel is the best advice.  If you are uncertain, speaking to a good sports nutritionist will be your best course of action.  As an athlete you are aiming to create a fine tuning of chemical balance and it would take a while to understand what works for you best through trial and error but is worth your while when you eventually reap the rewards.

Adding vitamins to our modern diet is necessary for us to cope with our complex lives.  Take some time to understand what will help you to feel better.


If you enjoyed reading this article, we are sure you will enjoy the rest of the Ultimate Guide to Supplements Series:

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