109: Are Nitrates and Nitrites Dangerous? Here’s the Real Science

Bikman spends considerable time dismantling the fear that nitrates are inherently harmful. He points to the fact that vegetables deliver the vast majority of dietary nitrate, yet are associated with health benefits rather than harm. On the benefits side, he describes multiple human and animal studies: nitrate improves vasodilation and blood pressure; in a human exercise study, nitrate-rich beetroot juice reduced oxygen cost and increased ATP per oxygen; in animal models, nitrite improved glucose tolerance and insulin signaling through the cyclic GMP–PKG pathway; and nitrate may even encourage beige-ing of white fat, increasing energy expenditure. The overarching message is that the food matrix matters and that whole-vegetable sources of nitrate should be embraced, not feared. This protocol is implicitly recommended throughout the lecture rather than stated as a discrete prescription, but the logic strongly supports intentional inclusion of high-nitrate vegetables.

Bikman cites a human study where healthy volunteers drank nitrate-rich beetroot juice and subsequently demonstrated a reduction in oxygen cost during exercise and increased ATP yield per oxygen consumed. He clarifies that this same nitrate chemistry is present in processed meats, but the benefit observed came from a vegetable source, underscoring that the molecule itself can be beneficial. He connects this to his own research focus on mitochondrial bioenergetics, explaining that mitochondrial coupling—the efficiency of converting fuel into ATP rather than wasting energy as heat—is improved by nitrate-derived nitric oxide. While he does not prescribe a personal regimen, the protocol is implied by the evidence he presents.

Bikman stresses that the fear of nitrates is largely misdirected. He points out that leafy greens—foods encouraged by health authorities—invariably contain high nitrate levels. While processed meats have been targeted as the problem, the quantitative data shows vegetable intake dominates exposure. This irony is crucial: if nitrates were inherently toxic, we would expect epidemiological signals from vegetable consumption, yet those studies show benefits, not harm. He uses this to argue that the context (food matrix, co-factors like heme iron, antioxidant content) likely determines whether nitrates pose risk or yield benefit, rather than the molecule itself being dangerous.

Bikman acknowledges the biochemical mechanism as plausible but insists that human causation has not been demonstrated. He cites the NutriNet-Santé cohort’s association between food-additive nitrites and prostate cancer risk, yet underscores its observational nature. A 2011 meta-analysis found only a modest association between processed meat and colorectal cancer, heavily confounded by diet and lifestyle. For heme iron specifically, EPIC cohort data and Mendelian randomization studies revealed no consistent causal relationship with breast, prostate, or kidney cancers. He emphasizes that confounding variables like overall diet quality, smoking, exercise, and socioeconomic status make isolating nitrate effects nearly impossible. His position is that fear has outpaced evidence, and the public has accepted a narrative built on correlation rather than rigorous human experimental data.

Bikman highlights a human trial where healthy volunteers ingested nitrate-rich beetroot juice and subsequently exhibited lower oxygen consumption at a given exercise workload and higher ATP yield per oxygen molecule. This implies that nitrate sharpens oxidative phosphorylation, making mitochondria more ‘coupled’—i.e., less energy is wasted as heat. He connects this to his own research on mitochondrial bioenergetics, noting that improved mitochondrial efficiency during exercise could mean better fuel utilization (glucose and fats). This finding shifts nitrate from a mere preservative or passive dietary component to an active metabolic signaling molecule that can influence energy production, particularly under hypoxic or high-demand conditions like exercising muscle.

Bikman explains that nitric oxide from dietary nitrate activates the enzyme guanylyl cyclase, increasing cyclic GMP. Cyclic GMP then activates protein kinase G (PKG). PKG appears to enhance the insulin receptor’s downstream signaling, which includes translocation of GLUT4 glucose transporters to the cell membrane, facilitating glucose uptake. Additionally, cyclic GMP exerts anti-inflammatory effects, and since inflammation is a cardinal driver of insulin resistance, this provides a complementary route to improved insulin sensitivity. He notes that rodent studies where cyclic GMP-dependent signaling is disrupted show impaired blood flow, elevated glucose, insulin resistance, and inflammation, underscoring the pathway’s physiological importance. While acknowledging that much of this evidence originates from animal models, he points out that the same level of evidence (animal models) is used to vilify nitrates, so applying it symmetrically is fair.

Bikman argues that individuals who avoid processed meat are also more likely to exercise regularly, avoid smoking and excess alcohol, sleep better, and have more positive social interactions—all factors that independently reduce cancer risk. These behaviors are difficult to measure accurately in surveys, leading to residual confounding even after statistical adjustments. He contends that the observed associations are so heavily confounded that they cannot be interpreted as evidence of direct harm from nitrates. This critique extends beyond nitrates to many nutritional epidemiology findings, reinforcing his preference for causal evidence from controlled experiments.