Potential Dietary Drivers of Colorectal Cancer Among Alaska Native People: Traditional Food Preservation, Processed Meat, and Evidence Gaps

Abstract

Alaska Native people experience disproportionately high colorectal cancer incidence and mortality, with substantial variation across tribal health regions. This review examines colorectal cancer variation across Alaska and its potential dietary drivers including food-preservation practices and the increased consumption of commercially processed meats that may contribute to these rates. Alaska CRC rates vary significantly across regions from as low 41 cases Aleutians and Pribilofs to as high as 112 cases Norton Sound region per 100,000 Alaska Native people. The consumption of smoked fish and game may contribute to this variation by the digestion of polycyclic aromatic hydrocarbons including benzo[a]pyrene, a compound known to form DNA adducts and potentially disrupt pathways involved in colorectal carcinogenesis. The consumption of processed meats introduces additional exposure to nitrates, nitrites, heme iron, and endogenously formed N-nitroso compounds. These exposures are further intensified by chronic high-fat, low-fiber dietary patterns in the Alaska Native regions which can increase inflammation, alter bile-acid metabolism, and changes in the gut microbiome. Current evidence does not establish these exposures as primary causes of regional colorectal cancer disparities due to limited data. However, regional differences in colorectal cancer rates across Alaska exist, suggesting that further research should examine the possible dietary drivers: food availability, preservation methods, and the transition towards processed food. Further research should include community-based exposure research, evaluation of safer smoking practices, reduced consumption of commercially processed meat, improved access to fiber-rich foods, and continued screening. Efforts should include cultural respect and strategies that support subsistence food systems, and tribally governed research is needed to quantify regional exposures and develop culturally appropriate colorectal cancer prevention strategies.

Introduction

Colorectal Cancer (CRC) is a significant public health issue for Alaska Native people with a 2.5 increased incidence rate when compared to other racial groups in the US. The 2018 age-adjusted incidence rate among American Indian and Alaska Native people had the highest incident rate of 86 cases per 100,000 people compared to others (Haverkamp et al., 2023; Alaska Native Tribal Health Consortium [ANTHC], 2026). The issue is also present at younger ages among Alaska Native people. CRC incidence increased among Alaska Native people younger than 50 years during 1990 to 2017, even as older age groups experienced a decline (Nash et al., 2021). The Alaska Registry analysis has estimated that an average annual increase of 5.2% is present among Alaska Native adults aged 20-49 years during 1996-2019 (Haverkamp et al., 2023). Screening remains essential, the Alaska Native Medical Center guidelines recommend beginning screening at age 40 for an Alaska Native adult at average-risk (Alaska Native Medical Center, 2021).

This analysis examines the potential roles of polycyclic aromatic hydrocarbons (PAH)-rich smoked subsistence foods and nitrate-laden commercial meats as plausible carcinogenic pathways. While current data warrant rigorous investigation of these specific dietary exposures, their status as the primary drivers of CRC disparities remains unconfirmed. Traditional food systems are important, providing essential omega-3 fatty acids and supporting cultural continuity and food sovereignty (Redwood et al., 2019; Sanders et al., 2022). This discussion emphasizes the distinction between risks introduced by specific processing conditions and the holistic nutritional value of wild-harvested foods.

Scope and Approach

The scope of this analysis is to serve as a review of existing literature rather than an exhaustive systematic meta-analysis, and prioritizes contemporary peer-reviewed research alongside authoritative Tribal and governmental documents published between 2017 and August 2026. Sources were selected specifically to focus on five critical domains: regional CRC epidemiology, indigenous nutritional practices, the presence of PAHs within smoked subsistence resources, the proliferation of ultra-processed and commercially preserved meats, and the biological interplay of fiber, the microbiome, and bile-acid metabolism.

A methodological approach was applied based on the underlying study design. Population-level trends were derived from registry and longitudinal cohort data, while food chemistry and molecular investigations provided a framework for establishing biological plausibility. Community-led reports were used to determine culturally appropriate public health interventions. Notably, experimental molecular or animal models are presented as supporting evidence for carcinogenic pathways rather than definitive proof of population causation.

CRC Burden and Regional Variation

The state of Alaska is divided into 12 Tribal health regions (Figure 1) that serve specific cultural groups, including Yup’ik, Cup’ik, Inupiaq, Unangax̂, Athabascan, Tlingit, Haida, and Tsimshian peoples (Alaska Native Tumor Registry, 2026).

Figure 1. Alaska Tribal Health Regions. Administrative and geographic Tribal health regions used for health surveillance. Regions should not be treated as one-to-one proxies for cultural identity or individual dietary practice. Reproduced from the submitted manuscript; original source: Cancer in Alaska Native People, 1969-2023: The 55-Year Report (ANTHC, 2026).

CRC Incidents rates vary drastically among cultural groups in these regions, ranging from 41 cases (Aleutians and Pribilofs) to 112 cases (Norton Sound region) per 100,000 Alaska Native people (Alaska Native Tumor Registry, 2026). The 55-year report by the Alaska Native Tumor Registry, provides a statewide age-adjusted CRC incidence of 86 cases per 100,000 Alaska Native people, compared with 32 cases per 100,000 U.S. White people. Regional statistical estimates suggest that the magnitude of this variation reflects many important variables including: age structure after standardization, small data counts and statistical uncertainty, screening and diagnostic patterns, migration, access to services, commercial food availability, and multiple environmental and behavioral exposures. Understanding this is important for research planning, however it does not prove that regional food preservation practices alone caused the differences (ANTHC, 2026).

Figure 2. Colorectal cancer incidence by Alaska Tribal health region, 2009-2023. Choropleth map displaying the age adjusted CRC incidents rates per 100,000 Alaska Native people across 12 tribal health regions. Data was obtained from the Alaska Native Tumor Registry (2026).

Recent dietary studies also caution against treating traditional smoked food intake as a single exposure. In remote Yup’ik communities, greater intake of fish, tundra greens, and berries was associated with better overall diet quality (Hill et al., 2023). In Norton Sound, traditional eating was associated with cultural and community factors and included nutrient-rich marine foods (Sanders et al., 2022). A longitudinal Alaska Native and American Indian cohort found continued participation in harvesting but a decline in the variety of traditional foods consumed (Redwood et al., 2019). These findings support a strengths-based distinction between traditional foods and specific smoking conditions that may create carcinogenic properties.

Traditional Smoked Foods and Mechanism of Carcinogenesis

A large part of the traditional Alaska Native diet relies on subsistence, wild-harvested food, some of which go through a process of smoking and drying for preservation. While these foods are vital culturally and provide important nutrients like omega-3 fatty acids, the process of smoking potentially introduces significant carcinogenic risks (Boardman et al., 2007; Cheng et al., 2021).

Polycyclic Aromatic Hydrocarbons (PAHs) form in the surface of the fish during smoking due to incomplete combustion of organic matter such as wood (Cheng et al., 2021; Sugimura et al., 2004). PAHs are inactive, however once digested they bioactivate and convert into PAH-diol epoxides which forms covalent bonds to DNA (Cheng et al., 2021; American Cancer Society, 2024). This interaction results in the increased expression of KRAS protein expression which results in uncontrollable growth, and a decrease in TP53 mRNA which leads to cell cycle dysregulation and carcinogenesis as a result (Cheng et al., 2021; American Cancer Society, 2024). Research done by Cheng et al., (2021) has shown that triple-smoked meats contain significantly higher concentrations of PAHs like phenanthrene, anthracene, and fluorene when compared to meats that were smoked only once. Benzo[a]pyrene (B[a]P), is a well studied PAH and is a known group 1 carcinogen that can form DNA adducts in the colon (Cheng et al., 2021; American Cancer Society, 2024). Studies of smoked fish outside Alaska have measured wide variation in PAH profiles and show that processing conditions affect contamination of PAHs (Aksun Tumerkan, 2022; Savin et al., 2024). These results establish a measurement priority, however they should not be used as direct exposure estimates for Alaska Native communities.

Research done in vitro by Cheng et al., (2021) has shown molecular disruption due to exposure to PAHs which are commonly found in smoked foods modify gene expression related to CRC (Figure 3). Specifically, B[a]P has been shown to decrease mRNA expression of the TP53 gene, which is a known gene that is critical for tumor suppression which increases expression of the KRAS oncogene (Cheng et al., 2021). The action of both decreasing TP53 and increasing KRAS expression leads to uncontrolled growth which provides a biological basis on how smoke preservation methods may initiate, and contribute to cancer development (Cheng et al., 2021).

Figure 3. Flow Chart Diagram of PAH Formation to Carcinogenesis. Smoked fish are actuated metabolically into DNA reactive compounds that cause DNA adducts and alter KRAS and TP53 expression that promote carcinogenesis

Processed Meat and Ultra-Processed Foods

While distinct in their nutritional classifications, ultra-processed products and commercially processed meats represent overlapping dietary impacts. The latter specifically comprises meat products altered via curing, fermentation, or chemical smoking to enhance preservation. In contrast, ultra-processed foods encompass a more expansive category of industrial formulations, extending beyond meat-based items to include various shelf-stable commodities.

Through the process of globalization, traditional food systems have changed, and store bought processed meats and ultra-processed foods have become more prevalent in rural Alaska (Monetathchi et al., 2025; O’Brien et al., 2017). Ultra processed foods contribute to approximately 25%-60% of the daily energy intake in many populations, and research has shown that their consumption is directly linked to an increased risk of CRC precursors, which includes conventional adenomas and serrated lesions (Fu et al., 2024; Wang et al., 2022). Commercially available processed meats such as sausages, ham, salami, and canned meats are often treated with preservatives such as nitrates and nitrites (Fu et al., 2024; Santarelli et al., 2010). Nitrates and nitrites are compounds that can be converted into N-nitroso compounds in the gut, a potent DNA damaging agent (Fu et al., 2024; Santarelli et al., 2010). Research by Santarelli et al (2010) on animal models have shown that nitrite treated cured meats promotes mucin depleted foci, an early biomarker of colon carcinogenesis.

Global health guidelines confirm that consumption of processed meat is a cause of CRC and advise limiting or avoiding its consumption (World Cancer Research Fund/American Institute for Cancer Research [WCRF/AICR], 2018). Key biological pathways driving this risk include heme-induced oxidative stress, the endogenous production of N-nitroso compounds, and exposure to chemical contaminants generated during processing. In Alaska Native populations, the dietary transition toward commercially processed meats, alongside the consumption of traditionally smoked foods creates a health concern (Monetathchi et al., 2025). Concurrent exposure to PAHs from traditional smoking practices and nitrates from store-bought items act synergistically within the colon to elevate CRC risk, compounding the ongoing CRC epidemic among Alaska Native people.

Inflammation, Genetics, and Epigenetics

The high incident rate of CRC in the Alaska Native population is likely driven by the combination of a diet-induced biological pathway and a specific genetic vulnerability (Boardman et al. 2007; Monetathchi et al. 2025; and Nash et al. 2021).

The traditional Alaska Native diet is high in fats from marine mammals and fish (Boardman et al., 2007). However, with the addition of the modern high fat processed food, significantly increases the production of secondary bile acids (Ocvirk et al., 2020). High levels of secondary bile acids are known to be indicative of a high fat diet, and are known to promote inflammation and carcinogenic effects to the colonic epithelium (Monetathchi et al., 2025; Ocvirk et al., 2020).

While Alaska Native CRC patients have a similar frequency of defective DNA mismatch repair to those of other groups, differences exist in the inactivation of key genes like hMLH1, which provides instructions for making a protein that repairs copying mistakes made when DNA divides (Boardman et al., 2007). The tumors of Alaska Native CRC patients were found to more likely be caused by a methylation of the hMLH1 gene rather than germline mutations (Boardman et al., 2007). These differences in mechanisms are vital, because a germline mutation is an inherited susceptibility to CRC whereas a promoter being hypermethylated is an epigenetic silencing of the genes that occurs in somatic cells (Boardman et al., 2007). These pathways can be differentiated by testing mutations such as BRAF V600E which can be found normally in sporadic tumors with hMLH hypermethylation whereas in germline mutations they are typically absent (Boardman et al., 2007). This information suggests that dietary exposure contributes to the active shutdown of critical repair genes during a lifetime (Boardman et al., 2007).

Chronic inflammation and the microbiome also play a key role in CRC, and the shift from a fiber rich diet on traditional plants like wild berries and greens in the summer towards a low fiber diet of processed foods throughout the winter can significantly alter the gut microbiota (Monetathchi et al., 2025; Ocvirk et al., 2020). A comparative study done by Ocvirk et al (2020), found that Alaska Native individuals have lower production of protective short chain fatty acids compared to a low risk population, which likely contributes to chronic inflammation in the colon. This is directly related to transition of a modern diet containing low fiber and commercially processed foods (Monetathchi et al., 2025; Ocvirk et al., 2020). Dietary fiber is essential as it plays a large role in the gut microbiome. The bacterial populations in the gut are in charge of fermentation and the production of short chain fatty acids, which regulate chronic inflammation and play a protective role and antineoplastic effects (Monetathchi et al., 2025). Low fiber consumption, lower production of short chain fatty acids, chronic inflammation, and consumption of ultra-processed foods suggests a combined role in the increase in CRC rates among Alaska Native people.

Ethical and Public Health Implications

Addressing the profound CRC difference observed between distinct Alaska Native populations requires a shift beyond conventional clinical screening protocols. The Alaska Tribal Health System should lead these initiatives, ensuring that community-led engagement and Tribal sovereignty remain the cornerstone of all strategic development. Public health interventions should prioritize a tripartite approach: enhancing screening accessibility, advocating for traditional dietary patterns while mitigating high-risk preservation techniques through culturally respectful methods, and fortifying the integrity of subsistence food systems.

A prevention focused framework must create an increase in screening, treatment access, and support for subsistence systems with targeted investigations into modifiable risk factors. Due to the rising incidence of early-onset CRC, the recommendation by the Alaska Tribal Health System’s to initiate screening at age 40 should remain a critical component of clinical guidance.

Subsistence food systems represent an important cultural asset that must be protected. Public policy and intervention strategies should avoid approaches that might influence hunting, fishing, or gathering rights, and seeing as restrictions could result in the an increase of in food insecurity and drive an increased dependence on expensive, ultra-processed commercial commodities. As emphasized by community stakeholders and experts, CRC research and prevention must be co-designed with Alaska Native people, and community in mind. This includes establishing Tribal governance over data and research objectives, collaborating with local advisors, and ensuring that any modifications to traditional methods are developed through community partnership.

Communication strategies should meticulously avoid characterizing traditional foods as intrinsically carcinogenic. Rather, messaging should clarify that specific combustion conditions may increase carcinogenic contaminant concentrations, while acknowledging that precise exposure levels in regional practices require further quantification. Ultimately, local communities must lead the decision-making process regarding risk mitigation. Simultaneously, limiting the consumption of commercially processed meats and improving access to fiber-rich traditional and whole foods remains a cornerstone of evidence-based CRC prevention.

Research gaps

There are gaps in our understanding of CRC disparities among Alaska Native populations. There is no current program which focuses on surveillance of the modern Alaska Native diet that examines how specific regional differences in the method of food preparation and consumption correlate to tumor subtypes (Boardman et al., 2007). Further gaps also include how environmental contaminants such as heavy metals and persistent organic pollution in subsistence food and their methods of molecular interaction with dietary carcinogens (Haverkamp et al., 2023; Redwood et al., 2025). There is no current research that has quantified the amount of PAHs in salmon after smoking, and the amount of PAHs produced when using traditional methods of smoking salmon (Aksun Tümerkan, 2022).

Future direction

Current amounts of PAHs present in traditionally smoked fish are unknown, and research should focus on examining the amount and type of PAHs introduced when using traditional preservation methods (Aksun Tümerkan, 2022). Koller et al. (2021) is currently conducting the Alaska FIRST trial which is investigating if the increase of dietary fiber can reduce the CRC risk by altering the microbiome in the gut (Monetathchi et al., 2025). Further research should examine the contribution of toxins to CRC risk such as PAHs, nitrates and nitrites. This could take the form of creating a program focused on surveillance of food consumed and prevention methods taken during the surveillance to ensure correct statistical analysis. Once these have been conducted, research initiatives should examine if a reduction in CRC and early onset CRC risk is present, and whether the introduction of evidence, education, and intervention with cultural sensitivity showed significant results.

Conclusion

Alaska Native people face a disproportionally large CRC incident rate. The reliance on ultra-processed foods and traditionally smoked foods may introduce PAH mediated genetic silencing through methylation that is further worsening with the modern shift and introduction of nitrate heavy processed meats that increase the rate of chemical induced carcinogenesis and metabolic disruptions. Recent evidence supports processed meat as a modifiable CRC risk factor in the general population and supports plausible roles for PAHs, fiber, microbial metabolites, and bile acids. The large variation on the incident rate between different tribal health regions such as the CRC risk differences found in Northern Sound and the Aleutians, provides us with an example for the need in further research. Reducing the CRC burden on Alaska Native people should include a multisectoral approach, support for subsistence food systems, address the biological impacts of diet on CRC, and cultural consideration of intervention strategies that preserves scientific accuracy while aligning prevention with cultural respect.