Vitamin C breakdown – Sensible and essential supplementation

As winter approaches, we all dread falling victim to the attack of the cold and flu viruses that are doing their rounds, especially with the change of season. Taking vitamin C may be at the top of your ‘to do list’ to banish those winter sniffles, but will it really help?

The questions asked by the many health conscious about vitamin C supplementation seem never ending:

  • Can vitamin C help fight colds and flu? If so, how does it work?
  • How much vitamin C do we really need?
  • Can we get enough through our diets?
  • How much vitamin C is too much?
  • Do high vitamin C intakes lead to ‘expensive urine’, with most of the valuable vitamin C going down the drain?
  • Are there any side effects of taking too much vitamin C?

CAN VIT C HELP FIGHT COLDS AND FLU?

The mechanisms of vitamin C’s protective effects are very interesting. Since our immune cells are responsible for protecting our bodies against invading viruses and bacteria, it comes as no surprise that vitamin C’s actions are directly focused on these immune cells. According to test results¹ there’s up to 100 times more vitamin C in our white blood cells than in the plasma (fluid component) of our blood.

Vitamin C has also been shown to increase the production and activity of our immune cells, as well as prolong the survival of these cells that fight against invading viruses.

Did you know?

The Hungarian scientist Albert Szent-Györgyi, was awarded the Noble Prize in 1937 for discovering vitamin C. He and his colleagues were the first to extract vitamin C from a food, notably the paprika plant, also known as Capsicum annuum, or red pepper. In fact, raw, sweet red peppers contain more than three times the amount of vitamin C than that found in oranges of the same mass.

HOW DOES IT WORK?

Preliminary research² suggests that vitamin C levels in white blood cells decrease at the onset of a cold. This reflects the increased usage of vitamin C by our immune cells whilst fighting an infection. There’s also preliminary evidence that vitamin C is retained better by the body during a cold, due to decreased excretion as there is an increase in utilisation. It may therefore be suggested that boosting vitamin C intake at the onset of a cold may be beneficial.

MANAGING COLDS AND FLU

Vitamin C is well-known for its role in assisting with the nutritional management of the common cold. A review published in the Cochrane Central Register of Controlled Trials in 2000 revealed that vitamin C reduces the severity and duration of cold symptoms.³ This research also demonstrated that vitamin C intake of up to 1g per day for several winter months showed a modest, but consistent, beneficial therapeutic effect on the duration of cold symptoms. The intake of vitamin C after the onset of cold symptoms showed greater benefits with larger doses than with lower doses.

HOW MUCH VIT C DO WE REALLY NEED?

Daily intake of vitamin C is essential, since this water soluble vitamin cannot be stored in sufficient levels in the body. Nutrient Reference Values (NRVs) show that we need a minimum of 100 mg per day. However, when our immune systems are fighting an infection, our bodies benefit from higher intakes. Research has pinned the optimal intake during colds and flu at 1 000 mg per day for adults and 1 500 mg per day for athletes, as high intensity exercise increases our need for vitamin C.

CAN WE GET ENOUGH THROUGH DIET?

It is no challenge to ingest 100 mg of vitamin C – that is easily provided by two small oranges, half of a small guava or 50 g of raw red pepper. However, to get to the therapeutic dose of 1 000 mg, 16 small oranges, five guavas or 500g of raw red peppers are not realistic to ingest on a daily basis.

VITAMIN C CONTENT OF WELL-KNOWN FOODS

Food Source: Vitamin C/100g

  • Guavas……………………………..347 mg
  • Red peppers, raw……………….190 mg
  • Chillies, raw……………………… 132 mg
  • Lemons………………………………77 mg
  • Cauliflower, raw………………….70 mg
  • Cauliflower, boiled………………38 mg
  • Strawberries……………………….58 mg
  • Oranges……………………………..53 mg
  • Grapefruit…………………………. 34 mg
  • Youngberries………………………21 mg
  • Blueberries…………………………..13 mg
  • Gooseberries………………………..11 mg
  • Cherries…………………………………9 mg

Source: MRC Food composition tables

HOW MUCH VITAMIN C IS TOO MUCH?

Most vitamins have tolerable upper intake levels (UL), which indicate the maximum level of daily long-term intake, at which no side effects have been detected. The UL for vitamin C is 2 000 mg per day, so this guideline tells us not to take more than 2 000 mg per day, for long durations of time.

EXPENSIVE URINE

Vitamin C is water soluble, which explains why excess intakes are excreted through one’s urine. It is believed that under normal healthy conditions, the human body comfortably absorbs up to 300 mg of vitamin C. Taking a dose of 1 000 mg may therefore exceed the body’s ability to absorb and retain vitamin C. However, during an infection, our bodies are able to absorb more vitamin C and research has shown 1 000 mg to be the optimal dose in supporting the immune system, this demonstrates that our bodies can indeed tolerate and utilise higher doses. If, however, one supplements over the levels your body can absorb and use, there will be an increase in excretion of the vitamin C not absorbed or utilised.

The regular intake of caffeine can increase vitamin C losses due to the diuretic effect of caffeine. Caffeine is found in coffee, tea, cola drinks and other energy tonics that contain caffeine, as well as certain pain killers and cold medicines.

TIPS!

  • During cold and flu season, take 1 000 mg of vitamin C per day, or 1 500 mg if you are an athlete, or if you lead a very active lifestyle.
  • Select a vitamin C supplement enriched with ingredients such as hesperidin, rutin, glutathione and alpha lipoic acid as these nutrients help optimise the absorption and utilisation of vitamin C.
  • Take your vitamin C tablets after breakfast, as the presence of food slows down the digestion and allows more time to optimally absorb the vitamin C from your supplement. This also reduces the risk of digestive system irritation.
  • Take your vitamin C supplement with cold or room temperature water. The heat from hot beverages will destroy some of the valuable vitamin C, and the tannins and caffeine found in coffee and tea can bind some nutrients, making them less available for absorption.

SIDE EFFECTS OF TOO MUCH VITAMIN C?

High doses of vitamin C are tolerated better by some individuals than others. Side effects of intakes higher than 2 000 mg include digestive system discomfort and possible diarrhoea. Excessive intake of vitamin C is not recommended in individuals who suffer with, or who are at risk of oxalate kidney stones. The fact is that vitamin C cannot cause kidney stones, but with supplementation of doses of more than 2 000 mg per day, excess vitamin C that cannot be utilised by the body is filtered out by the kidneys – the acidic nature of vitamin C may then contribute to the risk of oxalate kidney stones, a specific kind of kidney stone that forms as a result of the accumulation of oxalates, a component found in various foodstuffs including certain vegetables.

Editor’s note: Camu Camu (2g per vit C/100g) is the most potent source of vitamin C known to man!

TIPS!

  • During cold and flu season, take 1 000 mg of vitamin C per day, or 1 500 mg if you are an athlete, or if you lead a very active lifestyle.
  • Select a vitamin C supplement enriched with ingredients such as hesperidin, rutin, glutathione and alpha lipoic acid as these nutrients help optimise the absorption and utilisation of vitamin C.
  • Take your vitamin C tablets after break- fast, as the presence of food slows down the digestion and allows more time to optimally absorb the vitamin C from your supplement. This also reduces the risk of digestive system irritation.
  • Take your vitamin C supplement with cold or room temperature water. The heat from hot beverages will destroy some of the valuable vitamin C, and the tannins and caffeine found in coffee and tea can bind some nutrients, making them less available for absorption.

References

  1. Leibovitz B. and Siegel B.V. Ascorbic Acid and the immune response. Adv Exp Med Biol 1981; (135): 1-25.
  2. Hemila H. and Herman Z.S. Vitamin C and the common cold: a retrospective analysis of Chalmer’s review. J Am Coll Nutr 1995; (14): 116-23.
  3. Douglas R.M. et al. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 2000; 2:CD000980.

 

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Vitamin C breakdown – Sensible and essential supplementation

Andrea du Plessis
About The Author
- Andrea is a registered dietician. Following her initial career as a consulting dietitian, she furthered her studies in the field of sports nutrition with a Master’s degree in Sports Science. As nutrition expert, she has a passion for healthcare through nutrition, natural remedies and an active lifestyle.