It is back to school time and for me that means the dreaded return of all those germs. I love my child, but let’s be real, kids are basically petri dishes. Petri dishes that are all too excited about sharing with the family. In this blog post I am looking into the science behind nutrition and immune support. Specifically, examining whether or not grape juice can prevent the tummy bug and how much Vitamin C you really need.
True or False: Drinking grape juice can prevent the tummy bug
How it is supposed to work
It is true that grape juice is rich in Vitamin C, but according to the internet grape juice prevents the tummy bug by changing the pH of the stomach. Supposedly, the grape juice makes the stomach more acidic, preventing the virus from attaching. Unfortunately, I learned that norovirus (the virus commonly responsible for the tummy bug) attaches in the intestines and not the stomach.
Why the stomach is part of the immune system
The stomach is naturally very acidic. At any given time, it is usually at a pH of between 1-2. To put this into perspective, coffee is about a 5 and vinegar is about 3. Only battery acid is lower at less than 1. Stomach acid’s main job is to kill bacteria and viruses that have the potential to make us sick. Yes, it is true that it does also serve some function in digestion, but its main function should be considered part of the immune system.
All day long viruses and bacteria make their way into our stomach. They are on the food we eat. Underneath the finger nails that so many people chew. On the straw you share with your kid. The stomach acid kills many of these and keeps us healthy. Therefore, the stomach acid serves are part of the immune system.
This very low pH can slightly altered by the food we eat, but in a temporary manner. Anytime you add food or drink to the stomach it can dilute the stomach acid. But the mixing the churning of the stomach quickly spreads the acid out, the stomach cells make more, and pH stays low.
While it is true that many dangerous organisms die in the stomach, some have the ability to survive the stomach’s harsh environment and do make us ill. Organisms such as H.pylori which causes ulcers; E. Coli 0157.H7 which can cause a potentially fatal illness; and the norovirus. These organisms not only survive the stomach acid, they move into the intestines where they attach themselves and cause people to become sick.
The so what
Because norovirus does not attach in the stomach and because it can survive the acidic environment is why drinking grape juice will not prevent a person from becoming ill. So how do you prevent norovirus? Aggressive disinfection and hand hygiene. This article contains some great tips. Bleach, hydrogen peroxide, and healthcare grade cleaners are really the only defense against this nasty bug.
For the record, I keep these in my house, along with bleach and hydrogen peroxide at all times.
If someone does becomes ill, remember to provide consistent, small amount of liquids, avoid spicy foods, and maintain a lactose-free diet for 3-5 days.
True or False: Vitamin C will help prevent the common cold
GENERAL POPULATION : FALSE
CERTAIN POPULATIONS : TRUE (read on)
In the 1970s Linus Pauling, a Nobel Prize winning scientist, first touted the benefits of high dose Vitamin C to prevent and treat the common cold. His claim was not without scientific basis, but his study was small and not representative of the entire population. Research in the years since, have consistently failed to reproduce his work, but has made some other interesting discoveries.
How Vitamin C does support the immune system
Randomized, controlled trials with Vitamin C have shown that, while it does not decrease the rate of infection, in the GENERAL POPULATION, it may do so in those who are under physical STRESS (ex: marathon runners). Vitamin C is a potent antioxidant. Humans produce free radicals (“oxidants” if you will) simply by breathing. Exercise increases the rate of production. The muscle soreness so many of us associate with working out is partly caused by the oxidative stress of exercise. While I have not seen research to support this hypothesis, I have a strong suspicion that those who participate in more intense exercise programs are quickly using up Vitamin C. This in turn increases their need for the vitamin. Those with increased needs of certain nutrients are more likely to suffer from minor deficiencies and therefore more likely to benefit from supplementation. This could explain why Vitamin C supplements decrease infection risk in those to exercise strenuously, but not for most of the population.
Vitamin C is used by the cells of the immune system. When a person becomes ill, the immune cells kick into action. This will cause the body to use more Vitamin C for immune purposes than normal. There is research showing that Vitamin C does help in treating a type of very severe illness called sepsis (sepsis treatment occurs in a hospital). High doses of Vitamin C appear to improve sepsis outcomes by improving immune cell function and working as an antioxidant.
It has also been shown that Vitamin C MAY reduce the LENGTH and SEVERITY of colds. Because immune cells do hold onto Vitamin C, their increased action during illness is supported by having a little extra of the vitamin on board.
The so what
For the majority of the population, who eat a varied diet and engage in no more than moderate exercise, a Vitamin C supplement is unnecessary. However, for those who pursue intense exercise or maybe don’t enjoy fruits and vegetables very much (*ahem* your picky eater child), I think it is reasonable to include a little supplemental Vitamin C. These supplements should NOT be viewed as immune boosters, but rather support for the immune system that is already in place.
So how much do you really need?
The current Recommended Dietary Allowance (RDA) is below.
These values are set to meet the needs in 97-98% of the population. They are great numbers to aim for on a daily basis. To put it into food terms: 1/2 cup of green pepper provides 60mg, 1 medium orange provides 70mg, and 1/2 of grapefruit provides 39mg.
According to research, during illness, children need 1-2 grams (1000-2000mg) and adults 6-8 grams (6000-8000mg) of supplemental Vitamin C to see a decrease in severity and duration of the common cold. This is a significant dose of Vitamin C and I would not continue with the supplementation longer than the illness.
How much Vitamin C is required by those who participate in intense exercise? Well, that number is a little more difficult to be certain of. The research pool isn’t deep and some of it is in rats, but I think it if likely fair to say 1000mg per day as a supplement.
Don’t get carried away
A big word of caution with Vitamin C supplements – it can cause major GI distress! Remember learning about osmosis in high school biology? Water follows a concentration gradient? Ascorbic acid (which is just another name for Vitamin C) creates a big concentration gradient. High doses of Vitamin C supplements will pull significant amounts of water into the intestines. The result – lots of bloating followed by major diarrhea.
The Tolerable Upper Intake Limit (UL) of Vitamin C is 2000mg for adults. I would not consistently exceed this amount. I have used supplements at amounts higher than a UL to treat deficiency and it is fine for short term use as a part of therapeutic plan, but should not be routine.