Nutrition is important whether you lift weights, do endurance exercise, or play a sport. You use carbohydrates to rebuild muscle glycogen stores so your muscles can produce ATP to fuel exercise. If you strength train, you need amino acids from the protein you eat to rebuild and repair your muscle tissue. Yet, a growing body of research suggests that other components in foods called nitrates have benefits that go beyond providing fuel and building blocks. These components found naturally in green, leafy vegetables may give your workout an extra boost.
There’s no doubt that vegetables are packed with vitamins, minerals, and phytonutrients. What’s also apparent is some vegetables contain substantial quantities of inorganic nitrates. The word “nitrate” may conjure up negative images of processed meat where nitrates are listed as a preservative, especially since studies link nitrates in processed meats with a greater risk of cancer. Yes, these are nitrates too but the nitrates in processed meats are ultimately converted to nitrites and then to compounds called nitrosamines in your stomach. It’s nitrosamines that are harmful to your body and capable of causing cancer, not nitrates or nitrites themselves.
Nitrates from plant sources behave differently and have positive benefits that the nitrates in meat do not. That’s because plants contain phytonutrients that block the conversion of nitrates and nitrites to nitrosamines. Instead, nitrates are broken down to nitrites and then to nitric oxide. It’s nitric oxide, based on preliminary research, that gives exercise performance a boost.
The Power of Nitric Oxide
When you eat vegetables high in nitrates, your body converts the nitrates in these foods to nitrites. In turn, some of nitrites are made into nitric oxide, a gas. This conversion happens in the inner walls of your blood vessels.
What’s so special about nitric oxide? When you’re training, especially during aerobic exercise, you need efficient delivery of oxygen to your muscles. When your muscles get plenty of oxygen, they use aerobic metabolism to make ATP, the energy currency that fuels muscle contraction. As long as your muscles get plenty of oxygen, lactic acid doesn’t build up and your muscles don’t fatigue to the point you have to stop exercising. Nitric oxide widens those blood vessels and improves oxygen delivery.
According to a study published in Cell Metabolism, nitric oxide has another fitness benefit. It improves how efficient mitochondria are. Mitochondria are the energy powerhouses inside your cells – the ones that do the job of making ATP. This study found that nitric oxide makes mitochondria more efficient producers of ATP. More efficient mitochondria make the oxygen cost of an exercise session lower. That gives you greater endurance and exercise tolerance.
As one study pointed out:
“A growing body of evidence demonstrates that acute (2–3 h) and short term (3–6 days) pharmacological (e.g., sodium/potassium nitrate) or dietary (e.g., beetroot juice) nitric oxide− supplementation reduces whole body oxygen cost during moderate-intensity exercise, and improves exercise tolerance—at least in sedentary or moderately trained subjects”
A study also showed that nitrates from beetroot juice enhance performance with short bursts of exercise, in this case sprinting. More efficient production of ATP may also boost weight training performance. That’s why bodybuilders rush out to buy arginine supplements, in hopes of lifting longer and getting a bigger “muscle pump.”
What happens when they take an arginine supplement? In theory, your body should convert the arginine to nitric oxide. The nitric oxide, in turn, would theoretically improve oxygen delivery to the muscle so it gets more oxygen at a given exercise intensity. What’s questionable is whether arginine is converted to nitric oxide at high enough amounts in your body to offer these benefits. That’s why it’s best to get nitric oxide precursors from dietary components like green, leafy vegetables and beetroot rather than taking an arginine supplement.
Other Benefits of Nitrate-Rich Vegetables
Since nitric oxide opens up arteries that carry blood, making the blood vessel less tight, they also lower your blood pressure. In one study, participants drank a glass of regular beetroot juice and another group guzzled a glass of beetroot juice where the nitrates had been removed. After researchers measured their blood pressure, they discovered those who drank the nitrate-rich beetroot juice experienced a significant drop in blood pressure – 8 mm. systolic and 4 mm. diastolic. That’s comparable to what you get with some blood pressure medications. A study published in the Journal of Nephrology even showed nitrate-rich vegetables lowers the risk of developing hypertension. As you might expect, beetroot juice and green, leafy vegetables are heart healthy as well.
Which Vegetables Are Highest in Nitrates?
Green, leafy vegetables, such as Swiss chard, spinach, arugula, beet greens, and kale, top the list of vegetables high in nitrates. In fact, Swiss chard has the highest quantity of nitrates of any green, leafy vegetable. Even butterleaf lettuce has substantial quantities of nitrates.
Beets are another source but not as high as most green, leafy vegetables. Still, separate studies looking at beetroot juice as a performance enhancer are encouraging. For example, a study carried out at the University of Exeter in 2010 showed beetroot juice improved exercise endurance by 16%. In other words, the participants were able to exercise 16% longer after drinking beetroot juice. Several other small studies also show that beetroot juice enhances exercise endurance.
Stlll, you don’t have to drink beetroot juice to get the benefits. Green, leafy vegetables offer inorganic nitrites as well. What you don’t want to do is get your nitrites from processed meat. Remember, the nitrates here are ultimately converted to nitrosamines, carcinogenic compounds and don’t necessarily end up as fitness-friendly nitric oxide.
The Bottom Line
As if you needed more reasons to eat green, leafy vegetables, now you have one more. You can also get inorganic nitrates by drinking beetroot juice but it’s high in natural sugar as well. Even better, pile your plate high with green, leafy vegetables in all varieties. You can’t go wrong doing that!