Are Nitrates or Nitrites Bad? Not Really

nitrate freeWhen you see a package of hot dogs saying “Nitrate Free” you probably think that you are doing something healthy for you and your family.  Somewhere you heard vague whispers of nitrates being bad for you, or preserved meats causing cancer. First, rest easy, and second, don’t buy nitrate-free processed meats.

In the 1980′s nitrates/nitrites and nitric oxide were considered a toxic environmental hazard, and any environmental hazard was thought to cause cancer. This idea has not left the popular press, and  there were recommended daily allowances in an attempts to regulate amounts of dietary nitrates/nitrites. Nitrates were found in drinking water, and in particular in farm areas where levels of nitrates/nitrites were are used for fertilizer.

While today people think about at nitrates they often think about processed meats (bacon, hot dogs, antipasta, and other delicious charcuterie). Nitrites are the anti-bacterial agent desired for their anti-bacterial effect on food. But  the highest levels of nitrates/nitrites are found in vegetables.  But what is more fascinating is that the highest levels of nitrates are in human saliva.

Your Body Uses Nitric Oxide Gas to Regulate Blood Vessels
One of the great discoveries in modern biochemistry/physiology is that our body uses nitrates. In fact, it uses nitric oxide, a gas, for regulation of blood pressure, digestion, and to prevent clotting, among other things.

The technical stuff:  Sodium Nitrate is converted to Sodium Nitrite in our digestive system. The biochemistry is that dietary nitrate (NO(3)) and nitrite (NO(2)) are sources for the production of NO(x) which is a group of chemicals the body uses, such as nitric oxide (a gas – yes your body produces gas for some great things),  and others such as nitrosothiols and nitroalkenes.

Dietary nitrates/nitrites, it turns out,  are the building blocks for the material that is beneficial to the heart and blood vessels. Even the mechanism of action of drugs for erectile function, such as Viagra, increase nitric oxide in the vessels of the penis to help develop and maintain an erection. That our body uses nitric oxide to regulate blood vessels would never have been considered before its discovery in the 1990′s.  So where, you might ask, is the controversy about nitrates?


What about Cancer and Nitrates?


There are a number of  potential “carcinogenic” agents in processed meats. Nitrates do not appear to be them, and the entire discussion about processed meats and cancer needs some context.

Of all the types of scientific studies to perform, the population studies are the most difficult to use, because recalling amounts and types of foods is never easy. As we have reported before, these studies are prone to error unless there is very high statistical evidence that a link exists. For example: smoking with lung cancer had a relative risk of 20,  but most of the population studies with humans show relative risk ratios of  1-2. The second difficulty with population studies is “processed meat” can be anything from bacon to cured sausage.  As people eat more processed meats the relative risk goes up.

Colon cancer risk increases up to 140 g of processed meat a day, then flattens out. This figure taken from reference 4.

As you can see, the relative risk is real- and statistically it is a real trend, but it is not overwhelming. Look at the chart below. See the Relative Risk numbers for lung cancer as they increase with cigarettes.  These are RR above 5, where the chart above shows RR below 1.5 at its highest. The important point is this: the factors in processed meats, if there are factors that increase cancer risk, are not anywhere near the increased risk of developing lung cancer from tobacco.  Some would argue that with a relative-risk ratio of less than 2, one cannot determine effect.

This table shows huge risks of increasing smoking to lung cancer- look at the relative risks from this, vs. processed meats and cancer. – this table from reference 12

The real question is this: is this “trend” from  nitrates/nitrites or some other factor? Is the risk of getting cancer from processed meat   outweighed by the health benefits in maintaining the NO(x) levels needed? Some would note that nitrate-containing foods such as fruits, leafy green vegetables provide enough for the body to maintain NO(x) levels without the risk of colo-rectal cancers from the vegetarian group.

Are Vegetarians More at Risk than Bacon Eaters?
Here is the fun part of population studies. With processed meats the relative risk of colorectal cancer is  mildly elevated, what about vegetarians and nitrates? Turns out they consume more nitrates than people who eat processed meats. But before we make the assumption about vegetarianism, or whole food plant diets, and cancer, we have to look at the real data.  For example, fiber is primarily from vegetable sources, and it is the breakdown of that fiber by bacteria that provide us with chemicals that reduce colo-rectal cancer, one has to wonder if the answer is for meat eaters to increase fiber.  Besides fiber, plants provide  phytochemicals and other micronutrients that are associated with decreasing cancer in the laboratory, as well as in some human studies. Supplements do not provide this support (eat the food, don’t take the supplement).

BOTTOM LINE: 

Bacon

Candied bacon- maybe not a balanced diet, but close

If you are a fan of charcuterie, as I am, know that nitrites are the best way to prevent bacteria, especially botulism. If you buy nitrate -free products, they are at a higher risk. But more important, A balanced diet contains more than just processed meats. Nitrates/nitrites are probably not the issue- if there is an issue. Eat more fruits and vegetables.

REFERENCES:
(1) Hord NG. Dietary nitrates, nitrites, and cardiovascular disease. Curr Atheroscler Rep. 2011 Dec;13(6):484-92. PMID: 21968645

(2) Milkowski A, Garg HK, Coughlin JR, Bryan NS. Nutritional epidemiology in the context of nitric oxide biology: a risk-benefit evaluation for dietary nitrite and nitrate. Nitric Oxide. 2010 Feb 15;22(2):110-9.PMID: 19748594

(3) Hord NG, Tang Y, Bryan NS. Food sources of nitrates and nitrites: the physiologic context for potential health benefits.Am J Clin Nutr. 2009 Jul;90(1):1-10.PMID: 19439460

(4) Chan DS, Lau R, Aune D, Vieira R, Greenwood DC, Kampman E, Norat T. Red and processed meat and colorectal cancer incidence: meta-analysis of prospective studies.PLoS One. 2011;6(6):e20456. PMID: 21674008

(5) Tyrovolas S, Panagiotakos DB. The role of Mediterranean type diet on the development of cancer and cardiovascular disease, in the elderly: a systematic review. J Maturitas. 2009;65(2):122–130.

(6) World Cancer Research Fund/American Institute for Cancer Research. Food, nutrition, physical activity, and the prevention of cancer: a global perspective. Washington DC: AICR; 2007. pp. 22–25.

(7) Craig WJ. Health effects of vegan diets. Am J Clin Nutr. 2009;89(Suppl):1627S–1633S

(8) Divisi D, Di Tommaso S, Salvemini S, Garramone M, Crisci R. Diet and cancer. Acta Biomed. 2006:118–123.

(9) Dewell A, Weidner G, Sumner MD, Chi CS, Ornish D. A very-low fat vegan diet increases intake of protective dietary factors and decreases intake of pathogenic dietary factors. J Am Diet Assoc. 2008;108:347–356.

(10)  Key TJ, Appleby PH, Spencer EA, et al. Cancer incidence in British vegetarians. Br J Cancer. 2009;101:192–197

(11) Fraser GE. Associations between diet and cancer, ischemic heart disease, and all-cause mortality in non-Hispanic white California Seventh-day Adventists. Am J Clin Nutr. 1999;70(Suppl):532S–538S.

(12) The graf reproduced from this source: http://www.cancerresearchuk.org/cancer-info/cancerstats/causes/lifestyle/tobacco/tobacco-and-cancer-risk

MSG: Does Chinese Restaurant Syndrome Exist?

Mono-sodium-glutamate (MSG) – the cause of “Chinese Restaurant Syndrome.”  It turns out  this syndrome is a myth.

HISTORY OF THE MYTH:
The syndrome was first reported in a letter to The New England Journal of Medicine in April of 1968. A physician wrote that he developed a syndrome which he thought might be associated with salt or MSG, and asked the medical community to respond to this syndrome. He described the symptoms as “ numbness at the back of the neck, gradually radiating to both arms and the back, general weakness and palpitation.” He said several of his friends had it also. He speculated that it might be the cooking wine, or the soy sauce- although the restaurant he went to used the same brand of soy sauce he used. He also noted his friends suggested it might be the seasoning of MSG used by the restaurant. (1)  The next month ten letters responded – one didn’t think it was MSG, one noted it didn’t happen in all Chinese restaurants – and might be placebo, and another reported a patient developing a stroke after eating the food. The media picked up the new disease “Chinese Restaurant Syndrome” and it became a food-type allergy. Ten months later the journal Science reported that Monosodium L-glutamate “is the cause of the Chinese restaurant syndrome and can precipitate headaches.” (2)  The report in Science, was written by one of the people who wrote the letter back to NEJM that May, Dr. Schaumburg. In fact, a later one of his letters was initially done in great humor, “ With the enthusiastic co-operation of the Shanghai Cafe one of us ate Chinese food for breakfast, lunch and dinner until the search had been narrowed to either hot and sour soup or wonton soup, both of which produced the reaction. A rough filtrate of wonton soup also produced the reaction. Upon sampling of the individual ingredients, the dagger of suspicion pointed at monosodium glutamate. Further experiments confirmed this suspicion. The experiments were performed with the use of approved blind and double-blind technics on three volunteers. If the suspicion that irresponsible human experimentation was done has crossed your mind, be at ease. The days of Walter Reed are not past.” (3)

MSG

My mother had this in her kitchen. Pure MSG – it made food taste a lot better

The MSG Follow Up Research
Forty years after that original letter, and in spite of years of trials, and clinical trials, it was finally put to rest that “so-called ‘Chinese restaurant syndrome’ and in eliciting asthmatic bronchospasm, urticaria, angio-oedema, and rhinitis. Despite concerns raised by early reports, decades of research have failed to demonstrate a clear and consistent relationship between MSG ingestion and the development of these conditions.” (4)

In spite of good clinical data putting this myth to rest, there will be plenty of people whose confirmation bias tells them they cannot eat in Chinese Restaurants, and will blame MSG, all the while not realizing that without MSG their bodies would cease to function, and that there is more MSG in the Italian food they prefer, than the Chinese food they shun. In test after test, MSG was not any worse than the placebo given in random studies.

In 2011 the Food and Drug Administration’s committee on GRAS (Generally Recognized as Safe) substances stated this: “  There is no evidence in the available information on L-glutamic acid, L-glutamic acid hydrochloride, monosodium L-glutamate, monoammonium L-glutamate, and monopotassium L-glutamate that demonstrates, or suggests reasonable grounds to suspects, a hazard to the public when they are used at levels that are now current and in the manner now practices. However, it is not possible to determine, without additional data, whether a significant increase in consumption would constitute a dietary hazard.”  Much like salt, too much isn’t a good thing. (5)

Why MSG is so Important to you
Proteins are made up of molecules of amino acids – some of those amino acids our body can manufacture (they are called non-essential because we do not need to get them from our diet) and some amino acids we must obtain from our diet (called essential amino acids). Glutamic acid, and its form MSG, is a non-essential amino acid – meaning, our body produces glutamate and uses it to build the proteins we need. Without MSG you would be unable to build proteins, run the metabolism your body needs– without this amino acid you would not exist.While glutamic acid  is present in every food that contains protein, umami can only be tasted when it is separated from the protein – and functions as an individual amino acid.

MSG – It is one of the tastes you perceive
Before MSG was known for “Chinese Restaurant syndrome” it was used for the flavor it produced, to enhance food.  MSG  produces a  distinct savory flavor that is called Umami. MSG is a common additive in China- while visiting you would see it used almost as we would use salt here. In the United States MSG was sold under the name “Accent.”

China Lamb

In every market in China, such as here in Xi’an, one of the common flavors added to foods is MSG

We have discovered that humans have taste buds for  Glutamic acid  (MSG).  That flavor, umami, or savory (meat-like)  stimulates specific receptors located in taste buds, and is now recognized as one of the five basic tastes in addition to sweet, salty, sour, and bitter.  MSG is found in many foods, especially in parmesan cheese, tomatoes, soy sauce.  One would think if MSG was a real problem there would be an “Italian Restaurant Syndrome.”

There is no one region of the tongue that tastes sour, salt, bitter, sweet, or umami.  You may have seen “tongue” maps that show this, it turns out that the taste buds are distributed throughout the tongue. The entire tongue, has taste buds throughout – as well as the intestine (but that is for another blog).

Balance of flavor
If you ever eat something that is too salty, you want to balance it with sweetness – why we love dessert. But umami, that savory taste is why we love the balance in Italian cooking. We add Romano cheese to noodles to enhance the “flavor” – romano is filled with umami. America is in love with ketchup, and tomatoes provide that unique umami flavor. In Japan, instead of adding Romano or Parmesan to their noodles, they are judged by dashi – a broth that is made with seaweed (kombu) that has lots of MSG (and where some of the original MSG was derived from).

While in China, our favorite places to eat were on the streets – and beside almost every wok was a bowl of MSG – used to liberally season the foods, much like we use salt here. Street food in China is among the best food you can get. Some have even suggested that the balance of flavor that umami provides is one reason the Chinese are not subject to obesity (more about that later).

In Australia and the United Kingdom Vegemite and Marmite are all MSG or glutamate based – and all an essential part of that culture.

We are born to appreciate that flavor- human breast milk has almost 3o times higher glutamate than cow’s milk.

In my home state of Alaska, we prefer oysters, clams, and crabs when harvested in February through March – and it turns out they have their highest level of glutamates then. One would think that the Bering Sea would be better to harvest in the tranquil months of summer, but in August the lowest levels of glutamate are then, and Natives will tell you there just isn’t the flavor of the crab that you would like.

Whale Tale

August is great in Alaska to see whales, but not great for getting oysters, clams, or crab – the MSG levels are too low and they have less flavor

If you have an imbalance in flavor, then you compensate. Umami, it has been suggested, would provide a better balance if used more in foods. In other words, the emphasis on fat, sweet, and salty has led to some of the obesity, had there been more emphasis on umami, less food would be consumed, because there would be more of a balance. (6)

MSG and Obesity:

Apparently this “non essential” amino acid is now being blamed for obesity and short stature.  As you can see by reference (6) MSG can be used to help regulate appetite. Then came a paper in 2011 (7) claiming to show a correlation between MSG and obesity.  Sadly- this was one of the most poorly written papers, and was taken apart for multiple flaws in (7). To quote them: ”

Finally, even though observational studies often provide useful information for hypothesis formulation, given the significant questions and concerns raised in this study, it is premature to even generate a plausible hypothesis on MSG intake and obesity.

The current epidemic of obesity is worldwide, including in Asia. Because MSG has been extensively used as a flavoring agent in Asia, it could also potentially play an important role of enhancing palatability and acceptability of calorie-reduced diets. Until further confirmatory information becomes available, extreme caution needs to be exercised not to raise undue public safety concerns regarding MSG consumption.”

:

(1) Chinese-Restaurant Syndrome. Kwok, RHM. N Engl J Med 1968; 278:796April 4, 1968 (Letter to the editor)

(2) Monosodium L-glutamate: its pharmacology and role in the Chinese restaurant syndrome. Schaumburg HH, Byck R, Gerstl R, Mashman JH. Science. 1969 Feb 21;163(3869):826-8.PMID: 5764480

(3) Sin Cib Syn: Accent on Glutamate. Schaumburg HH, Byck R, N Engl J Med 1968; 279:105-106July 11, 1968 (Letter to the editor)

(4) Monosodium glutamate ‘allergy’: menace or myth?Williams AN, Woessner KM.Clin Exp Allergy. 2009 May;39(5):640-6. PMID: 19389112

(5) From the US Food and Drug Administration GRAS database.

(6) Umami flavour as a means of regulating food intake and improving nutrition and health. Mouritsen OG.  Health. 2012 Jan;21(1):56-75. PMID: 22544776

(7)↵ He K, Du S, Xun P, Sharma S, Wang H, Zhai F, Popkin B. Consumption of monosodium glutamate in relation to incidence of overweight in Chinese adults: China Health and Nutrition Survey (CHNS). Am J Clin Nutr 2011;93:1328–36.

(8)A lack of epidemiologic evidence to link consumption of monosodium L-glutamate and obesity in China.vBursey RG, Watson L, Smriga M.Am J Clin Nutr. 2011 Sep;94(3):958-60; author reply 960-1. doi: 10.3945/ajcn.111.020727.