Been meaning to post these for a while. The first article is on dietary nitrates, the second on the pH and muscle mass. These articles appeared back-to-back in Muscular Development's December 2009 issue (pages 138-141). These articles really helped me understand two things I found out after becoming vegan: I have more energy and my muscles don't waste as much. Because I'm typing out the entire articles, there may be a few typos as I hammer through them quickly. Please forgive me.
DIETARY NITRATES: A New Way of Increasing Nitric Oxide Production
-by Robbie Durand, M.A., Senior Editor
Nothing beats getting a good pump in the gym. Traditionally, bodybuilders have resorted to using nitric oxide (NO) products to enhance NO production. Many bodybuilders know that nitric oxide can be increased via the synthesis of nitric oxide synthase, through the amino acid arginine. What many bodybuilders may not know is that NO can be produced via an alternative pathway without NO synthase.
Diet is a major provider of nitrates in the body. Nitrates can enhance the production of nitric oxide, independent of the arginine-dependent NO synthase pathway. In 2004, it was demonstrated that inorganic nitrate from dietary sources could be a major source of circulating nitrite -- which enhances nitric oxide production independent of the arginine-NOS pathway.
In one experiment, healthy subjects who ingested a dietary nitrate experienced a four-to-fivefold increase in plasma nitrite, It turns out that much of the dietary nitrite from food entering the stomach from saliva survives intact and reaches the systemic circulation. This suggests that inorganic nitrate from food can be a substrate for NO formation in the body. Nevertheless, based on numerous studies, it seems clear that dietary nitrates are indeed bioactive in the body.
Sources of Dietary Nitrates
Incorporating some fruits and vegetables into the diet in place of high protein can help facilitate greater production of nitric oxide production. A diet rich in fruits and vegetables is associated with a lower blood pressure and reduced risk of cardiovascular events. Despite extensive research, the active ingredient(s) responsible fo this effect has not been pinpointed, and trials with single nutrients have been largely unsuccessful. (StrawberryRiddick's Note: to me, this just promotes the importance of whole foods)
Remarkably, in a recent study of healthy volunteers, the blood pressure-lowering effect of dietary nitrate supplementation was similar to what was seen in the healthy control group in the DASH project, a classic vegetable/fruit diet trial -- indicating that nitrate could be an important and active ingredient of this diet. This means taking a nitrate supplement could be just as effective as eating fruits and vegetables for increasing NO production.
It should be noted that the dosage of nitrate used in the study (0.1 mmol/kg/day) is readily achievable through a diet rich in vegetables. So for those guys who are not eating fruits and vegetables, you may be missing out on getting better pumps in the gym.
Beetroot Juice - A High Source of Nitrates
In a recent study, Webb and colleagues found that blood pressure decreases if healthy volunteers ingest a natural nitrate source (beetroot juice). Researchers demonstrated that it was the nitrate in the juice that had the effect, and it occurred via the nitrate's chemical reduction to nitrite. In the study, 0.5 L of fresh beetroot juice decreased systolic blood pressure as much as 10 mmHg, and blood pressure was still significantly reduced 24 hours later. The researchers found that blood pressure was reduced within just one hour of ingesting beetroot juice, with a peak drop occurring three to four hours after ingestion. Some degree of reduction continued to be observed up to 24 hours after ingestion.
Researchers demonstrated that the decrease in blood pressure was due to the chemical formation of nitrite from the dietary nitrate in the juice. The nitrate in the juice is converted in saliva, by bacteria on the tongue, into nitrite. This nitrite-containing saliva is swallowed, and in the acidic environment of the stomach is either converted into nitric oxide or re-enters the circulation as nitrite. The peak time of reduction in blood pressure correlated with the appearance and peak levels of nitrite in the circulation -- an effect that was absent in a second group of volunteers who refrained from swallowing their saliva during, and for three hours following, beetroot ingestion.
A reduction in blood pressure was also demonstrated in 2006, in healthy volunteers, after three days of dietary supplementation with inorganic nitrate. In 2007, it was shown that dietary nitrate decreases whole-body oxygen consumption in humans during submaximal exercise. This could be due to the vasodilation of the blood vessel walls, causing less need for oxygen consumption by muscle. The nitrate-nitrite-NO pathway may be viewed as complementary to the classical arginine-NOS pathway. These pathways work partly parallel to each other, but when oxygen availability is reduced and NOS activity is decreased, nitrite reduction to NO becomes more pronounced.
In sum, consuming natural foods high in nitrates may enahnce muscle pumps in the gym. Or you could try beetroot juice, which is naturally high in nitrates.
1. Lundberg JO, Weitzberg E, Cole JA and Benjamin N. Nitrate, bacteria, and human health. Nat Rev Microbiol, 2004 jul;2(7):593-602
2. Lundberg JO and Govoni M. Inorganic nitrate is a possible source for systemic generation of nitric oxide. Free Radic Biol Med, 37, 395-400 (2004)
3. Larsen FJ, Ekblom B, Sahlin K, Lundberg JO and Weitzberg E. Effects of dietary nitrate on blood pressure in healthy volunteers. N Engl J Med, 355, 2792-2793 (2006).
4. Appel LJ, Moore TJ, Obarzanek, E, Vollmer WM, Svetkey LP, Sacks FM, Bray GA, Vogt TM, Cutler JA, Windhauser MM, Lin PH and Karanja N, A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med, 336, 1117-1124 (1997)
5. Webb AJ, Patel N, Loukogerogakis S, Okorie M, Aboud Z, Misra S, Rashid R, Miall P, Deanfield J, Benjamin N, Macallister R, Hobbs AJ and Ahluwalia A. Acute blood pressure lowering, vasoprotective, and antiplatelet properties of dietary nitrate via bioconversion to nitrite. Hypertension, 51, 784-90 (2008)
6. Larsen FJ, Ekblom B, Sahlin K, Lundberg JO and Weitzberg E. Effects of dietary nitrate on blood pressure in healthy volunteers. N Engl J Med, 355, 2792-2793 (2006).
7. Larsen FJ, Weitzberg E, Lundberg JO and Ekblom B. Effects of dietary nitrate on oxygen cost during exercise. Acta Physiol (Oxf), 191, 59-66 (2007).
The Role of pH and Muscle Mass
-by Robbie Durand, M.A., Senior Web Editor
This month I spent some time with MD's Evan Centopani, filming his training session in his off-season. Besides noticing that Evan is looking like a beast, I walked into Evan's house and noticed this small apparatus next to the sink that had some blinking lights on the side and was filled with water.
I said, "Evan, what the hell is that?"
Evan explained it was a water ionizer, which adjusted the pH of the water. By using a water ionizer, it helped to create a more basic pH in the body, and reduce blood acidity. Evan explained that he had been doing a lot of reading on the role of pH and health. He is correct that pH has a profound effect on health, but also on muscle mass.
Having na acidic pH not only causes lower muscle mass, but can also lower plasma levels of IGF-1. Having an acidic pH is not conducive to building muscle. In fact, researchers make the blood more basic to counteract losses in muscle mass.
Interestingly, a mild but progressive metabolic acidosis occurs in elderly individuals who are exposed to a continuous challenge from acid-producing diets (e.g., diets relatively rich in meat and cereal grains compared to the fruit and vegetable content). Oral administration of bicarbonate increases blood pH (makes the blood more basic) in a dose-related manner in healthy adults, both at rest and during exercise. Metabolic acidosis has long been known to promote protein breakdown and nitrogen excretion.
In several studies, daily administration of bicarbonate -- which acts as a blood buffer and reduces acidity -- improved muscle power during intense exercise in healthy subjects. However, the role of pH and muscle mass has never been clearly defined, so researchers set out to examine if blood pH has any effect on muscle mass.
Researchers from Tufts University examined 162 older adults and had them consume either a treatment with potsasium bicarbonate, sodicum bicarbonate, potassium chloride, or a placebo. Remember that bicarbonates reduce blood acidity and promonte a more alkaline environment. Interestingly, after three months of supplementation, only the bicarbonate altered the amount of acid production. The reduction in acid production resulted in less nitrogen excretion (greatr protein retention) iin men.
In the men, the change in net acid excretion (the amount of acid being excreted from the body) was positively correlated with how much nitrogen was being lost. Although nitrogen excretion is not a specific indicator of muscle breakdown, in the setting of stable protein intake, exercise level, and bodyweight, a decrease in nitrogen excretion is consistent with decreased net muscle catabolism.
Treatement with bicarbonate significantly lowered nitrogen excretion. Therefore, using a blood buffer such as potassium bicarbonate may be a way of reducing muscle tissue breakdown.
Loss of muscle is associated with aging, but this occurs in conjunction with increased blood acidity. A possibility is that muscle wasting is influenced by the mild metabolic acidosis that occurs with aging. With muscle breakdown, amino acids released into the bloodstream provide substrate for the hepatic synthesis of glutamine. Glutamine is used by the kidneys to synthesize ammonia. Glutamine acts as a blood buffer when pH is acidic by being removed from muscle.
So Evan may be on to something good. It seems that drinking alkaline water or eating fruits and vegetables or using a bicarbonate supplement may prevent muscle tissue breakdown.
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6. Cersosimo E, Williams PE, Radosevich PM, Hoxworth BT, Lacy WW, Abumrad NN (1986) Role of glutamine in adaptations in nitrogen metabolism during fasting. Am J Physiol, 250:E622-E628.
7. Dawson-Hughes B, Castaneda-Sceppa C, Harris SS, Palermo NJ, Cloutier G, Ceglia L, Dallal GE. Impact of supplementation with bicarbonate on lower-extremity muscle performance in older men and women. Osteoporos Int, 2009 Sep 1.
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