Amyotrophic Lateral Sclerosis (ALS): A Nutrition and Natural-Health Reference
Definition and Overview
Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a rare terminal neurodegenerative disease defined by the progressive loss of both upper and lower motor neurons that normally control voluntary muscle contraction. The disorder is named for its underlying pathophysiology, with "amyotrophy" referring to the atrophy of muscle fibers, which are denervated as their corresponding anterior horn cells degenerate, while "lateral sclerosis" refers to the changes seen in the lateral columns of the spinal cord as the upper motor neuron axons in these areas degenerate and are replaced by fibrous astrocytes (gliosis).
ALS was first described in 1869 by the French neurologist Jean-Martin Charcot and hence is also known as Charcot disease; however, it gained popular recognition and its best-known eponym in the United States after the baseball player Lou Gehrig announced his diagnosis. ALS is a fatal disease, with a median survival period of 3 years from onset of weakness. Although a small percentage of patients may have a longer survival time (up to 10 years), in most cases, the median survival time is from 20 to 48 months.
Clinical Presentation
ALS often presents with gradual muscle stiffness, twitches, weakness, and wasting. Motor neuron loss typically continues until the ability to eat, speak, move, and breathe without mechanical support is lost. Early symptoms are usually muscle weakness or stiffness in the arms and legs, as well as trouble with speech and swallowing, which can make everyday tasks like writing or eating more challenging. Over time, symptoms typically spread throughout the body, with the speed of progression varying from person to person; as symptoms become more severe, the individual may have trouble breathing, standing, or walking.
At least 50% of people with ALS experience significant changes in thinking and behavior, with 15% of individuals going on to develop frontotemporal dementia. ALS affects "voluntary" muscles, those controlled by conscious thought, such as the arm, leg, and trunk muscles. ALS, in and of itself, does not affect sensation, thought processes, the heart muscle, or the "smooth" muscle of the digestive system, bladder, and other internal organs.
While disease onset is typically focal involving upper or lower limbs, bulbar or respiratory regions, the ensuing progressive course affects contiguous body regions resulting in global muscle weakness, with respiratory dysfunction representing a terminal phase of the disease. Weight loss is observed in approximately 70% of ALS patients, mainly because of loss of oral intake and metabolic alterations.
Body Systems Involved
ALS is a progressive neurodegenerative disease affecting motor neurons in the spinal cord, cerebral cortex, and medulla oblongata. Key pathological findings include gross atrophy of anterior spinal nerve roots, neuronal loss and gliosis affecting the anterior horn of the spinal cord and primary motor cortex, pallor of corticospinal tracts, Bunina bodies and skein-like inclusions (TDP-43 and ubiquitin positive) in motor neurons.
Beyond the motor nervous system, ALS has been found to affect multiple other systems:
- Gastrointestinal system and gut–brain axis: Gastrointestinal dysfunction and gut microbiota dysbiosis intensify disease pathology by driving immune dysregulation, compromising the intestinal barrier, and altering gut–brain axis signaling, advancing neurodegeneration.
- Metabolic and energy systems: Metabolic alterations, including hypermetabolism, lipid imbalances, and glucose dysregulation, are pivotal contributors to the onset and progression of ALS. These changes exacerbate systemic energy deficits, heighten oxidative stress, and fuel neuroinflammation.
- Immune and neuroinflammatory systems: Neuroinflammation and neuroinflammatory cells, such as astrocytes, oligodendrocytes, microglia, and lymphocytes, and overall the cellular microenvironment, have been proposed as pivotal players in the pathogenesis of ALS.
- Respiratory system: ALS leads to profound muscular dystrophy, hyperreflexia, fasciculations, and paresis of the bulbar as well as the skeletal musculature. ALS causes increasing physical fatigue and the patients soon become bedridden and respiratory insufficient.
Pathophysiological Mechanisms
The pathogenesis of ALS involves multiple, overlapping molecular and cellular processes:
Glutamate Excitotoxicity: Reduced uptake of glutamate from the synaptic cleft, leading to glutamate excitotoxicity, is mediated by dysfunction of the astrocytic excitatory amino acid transporter 2 (EAAT2). The resulting glutamate-induced excitotoxicity induces neurodegeneration through activation of Ca2+-dependent enzymatic pathways. Glutamate excitotoxicity induces cytoplasmic calcium accumulation and increased oxidative stress.
Oxidative Stress: The impaired mitochondrial electron transport chain function in ALS affects oxygen consumption and membrane potential, causing an increase in reactive oxygen species (ROS) and a decrease in ATP production. The excessive ROS induce oxidative stress in cells and accelerate neuronal degeneration and death. These findings strongly suggest that dysfunction of mitochondria is critical in the development of ALS.
Protein Aggregation and RNA Dysregulation: Mutations in the C9ORF72, FUS, TDP-43, and SOD1 genes lead to RNA dysregulation, which results in accumulation of intraneuronal aggregates and defective axonal transport. Additionally, microglia activation and neuroinflammation result in the secretion of proinflammatory cytokines and neurotoxicity, which also determine the neurodegeneration.
A key shift in the understanding of ALS pathogenesis occurred with the discovery that the main component of the ubiquitinated protein aggregates found in sporadic ALS patients was TAR DNA-binding protein 43 (TDP-43). Further histological studies confirmed that TDP-43 is present in the cytoplasmic aggregates of the majority of ALS patients including sporadic cases without pathogenic variants in the TARDBP gene.
Cortical Hyperexcitability: Transcranial magnetic stimulation techniques have established cortical hyperexcitability as an important pathogenic mechanism in ALS, correlating with neurodegeneration and disease spread.
Genetic Factors
Most ALS cases are sporadic; patients do not have a family history of ALS and the cause of their disease is unknown. However, about 5%–10% of ALS cases have a family history of the disorder, typically with dominant inheritance.
Expanded G4C2 hexanucleotide repeat in the intronic region of C9orf72 and mutations in the genes encoding cytosolic superoxide dismutase 1 (SOD1), TAR DNA-binding protein 43 (TDP-43), and fused in sarcoma (FUS) account for around 60% of familial ALS cases. So far, more than 50 genes have been found to be associated with ALS. Among them, C9orf72, SOD1, TDP-43, and FUS genes were most closely related to the pathogenesis of ALS.
Mutation of the SOD1 gene interrupts cellular detoxification and results in free radical toxicity and cell death. Mutations in SOD1 have been reported in approximately 20% of familial ALS and in approximately 1–4% of sporadic ALS cases. In all ALS patients, the mutation frequencies of common ALS-related genes were ranked from highest to lowest as SOD1 (2.2%), C9orf72 (2.1%), ATXN2 (1.7%), FUS (1.7%), TARDBP (0.8%), VCP (0.6%), UBQLN2 (0.6%), and SQSTM1 (0.6%).
Contributing and Associated Risk Factors
The etiology of amyotrophic lateral sclerosis (ALS) remains largely unknown. A 2023 global meta-summary published in PMC, drawing on 230 eligible studies, systematically evaluated non-genetic and genetic risk factors for ALS. Exposure to heavy metals (OR = 1.79), pesticides (OR = 1.46), solvents (OR = 1.37), previous head trauma (OR = 1.37), military service (OR = 1.29), stroke (OR = 1.26), magnetic field (OR = 1.22) and hypertension (OR = 1.04) are significant risk factors, but use of antidiabetics (OR = 0.52), high BMI (OR = 0.60 for obese and overweight vs. normal and underweight), living in urban areas (OR = 0.70), diabetes mellitus (OR = 0.83), and kidney disease (OR = 0.84) decrease the risk for ALS.
A separate 2023 systematic review and meta-analysis published in Frontiers in Neuroscience, including 36 observational studies, found that six factors exacerbated disease progression: head trauma (OR = 1.26), physical activity (OR = 1.06), electric shock (OR = 2.72), and military service (OR = 1.34).
A comprehensive 2015 review of non-genetic risk factors in ALS (PMC4334292) noted that lifestyle factors reviewed include smoking, intake of antioxidants, physical fitness, body mass index, and physical exercise, as well as occupational and environmental exposures including electromagnetic fields, metals, and pesticides. ALS is typically fatal within 2–5 years of symptom onset.
Environmental and Occupational Exposures
- Heavy metals: Lead, mercury, and other heavy metals have been associated with increased ALS risk (OR = 1.79 in meta-analysis above).
- Pesticides: Pesticide exposure has been consistently associated with elevated ALS risk (OR = 1.46).
- BMAA (β-methylamino-L-alanine): BMAA, a cyanobacterial neurotoxin, is among the environmental factors reviewed in association with ALS risk.
- Military service: Multiple meta-analyses identify military service as a significant risk factor, potentially reflecting combined exposures to physical trauma, toxins, and other hazards.
Lifestyle Factors as Risk Contributors
Smoking: Smoking has been studied as a potential ALS risk factor. Although recent genetic studies have substantially improved understanding of the causes of ALS, especially familial ALS, an important role of non-genetic factors in ALS is recognized and needs further study. Smoking's association with ALS is discussed in risk-factor reviews; the direction of association remains debated in the literature, with some analyses reporting modest positive associations.
Body weight and BMI: A low body mass index at diagnosis is an indicator of poor prognosis, and post-diagnosis weight gain is reported to be associated with longer survival. Interestingly, higher pre-morbid BMI has been inversely associated with ALS risk in meta-analyses, suggesting that higher adiposity may confer some protective effect against disease onset, even while undernutrition worsens outcomes after diagnosis.
Physical activity: High levels of intensive physical activity have been associated with a small but statistically significant increase in ALS risk in meta-analyses. However, the mechanism and magnitude of this association remain under investigation.
Metabolic Abnormalities in ALS
Metabolic alterations, including hypermetabolism, lipid imbalances, and glucose dysregulation, are pivotal contributors to the onset and progression of ALS. These changes exacerbate systemic energy deficits, heighten oxidative stress, and fuel neuroinflammation.
The pathogenesis and risk factors for ALS are still unclear: among the various aspects taken into consideration, metabolic abnormalities and nutritional factors have been the focus of recent interests. Although there are no consistent findings regarding prior type-2 diabetes, hypercholesterolemia and ALS incidence, abnormalities in lipid and glucose metabolism may be linked to disease progression, leading to a relatively longer survival, probably as a result of counteracting malnutrition and cachexia in the advanced stages of the disease.
Poor nutritional status and weight loss in ALS resulting from poor oral intake, progressive muscle atrophy, and the potential hypermetabolic state have been associated with rapid disease progression. Larger energy intake to maintain energy balance is crucial, particularly in the light of the observed hypermetabolism and increased physical activity–energy expenditure in ALS patients compared to controls.
Dietary Factors: Evidence from Authoritative Sources
Dietary Risk: Glutamate Intake
Among potential dietary risk factors, a higher risk of ALS has been associated with an increased intake of glutamate, while the consumption of antioxidant and anti-inflammatory compounds, such as vitamin E, n-3 polyunsaturated fatty acids, and carotenoids, has been related to lower incidence. The anti-glutamate drug riluzole, approved for ALS since 1995, mechanistically supports the role of glutamate excitotoxicity in disease progression.
Caloric Intake and Body Weight Management
Early initiation of gastrostomy contributes to weight maintenance, and high-calorie therapy may delay disease progression, particularly in those with rapid progression. A retrospective analysis of 104 ALS patients examined optimal caloric intake: survival data showed that patients consuming less than 25 kcal/kgIBW had a median survival of 24 months, increasing to 38 months for those consuming between 25–30 kcal/kgIBW and 63 months for those consuming 30 kcal/kgIBW or more. This is a retrospective study with significant limitations, but it underscores the relationship between caloric adequacy and outcomes. Consumption of less than 25 kcal/kgBW emerged as a significant negative predictor of patient outcome, independent of factors such as age, gender, or disease progression.
Regarding body fat specifically, higher average monthly change in body fat percentage and availability of oral food intake are prognostic factors in ALS survival.
Mediterranean Diet and Anti-Inflammatory Patterns
Diets enriched with antioxidants, omega-3 fatty acids, and anti-inflammatory compounds—such as the Mediterranean diet—have shown potential in reducing oxidative stress and systemic inflammation in the context of ALS-related metabolic perturbations. However, direct large-scale clinical trials of the Mediterranean diet specifically in ALS populations are lacking, and this evidence is largely inferential from mechanistic and observational data.
Nutrients, Herbs, and Natural Ingredients Studied in Relation to ALS
The following section separates traditional use from scientific evidence for each substance discussed in the peer-reviewed literature.
Vitamin E (Alpha-Tocopherol)
Traditional Use: Vitamin E has been used historically as a general antioxidant supplement across many cultures, primarily to support cardiovascular and skin health. Its application to neurological conditions is a more modern development based on understanding of its free-radical scavenging properties.
Scientific Evidence: Vitamin E is a group of lipid-soluble antioxidants commonly found in plant products. A potential reduction in risk for ALS is suggested in those with higher vitamin E levels, or those with low baseline vitamin E levels who are receiving vitamin E supplementation. Despite these positive associations, oral administration of vitamin E does not impact ALS survival or quality of life. The evidence strength for vitamin E in ALS is weak to preliminary: observational data suggest a modest association between higher vitamin E status and reduced ALS risk, but randomized clinical trial data do not show a benefit on survival or functional decline. The effect of vitamin E supplementation on cognitive functions and neurological diseases is controversial.
Vitamin B12 (Methylcobalamin)
Traditional Use: Vitamin B12 has been traditionally used for support of the nervous system, energy metabolism, and treatment of deficiency states across conventional medicine. It has no historically specific traditional use for motor neuron disease.
Scientific Evidence: Vitamin B12 is a water-soluble vitamin that plays an essential role supporting the health of the nervous system. Humans are unable to synthesize vitamin B12, and hence must obtain it through dietary sources. Methylcobalamin, an active form of vitamin B12, has been trialed at high doses in ALS. A pivotal phase 3 randomized controlled study, known as the JETALS trial (NCT03548311), investigated ultra-high dose methylcobalamin in Japanese ALS patients and was completed in 2025. Studies used very high, injected doses, which appear to be available only by prescription. Lower over-the-counter doses administered orally have not been studied. Evidence for methylcobalamin in ALS is preliminary; phase 3 results were awaited at the time of this writing, and oral over-the-counter doses remain unstudied.
Coenzyme Q10 (Ubiquinone)
Traditional Use: Coenzyme Q10 has no specific traditional ethnobotanical history; it emerged as a nutritional supplement primarily in the late 20th century, largely in Japan, where it was first used for cardiovascular conditions.
Scientific Evidence: Oxidative stress is considered to be one of the primary pathogenic mechanisms in ALS, and it is not surprising that dietary supplements with antioxidant effects are commonly used. Common antioxidants include vitamins, carnitine, and coenzyme Q10 (CoQ10). A double-blind, randomized, placebo-controlled Phase II clinical trial of high-dose CoQ10 in ALS was conducted (NCT00243932). The Phase II trial of CoQ10 for ALS found insufficient evidence to justify a Phase III trial. Despite the lack of bona fide clinical trial data to demonstrate positive effects in ALS for the majority of antioxidants, high tolerance and safety combined with ease of availability do not discourage their use by patients. The overall evidence for CoQ10 specifically in ALS is negative or insufficient based on the completed Phase II trial.
Creatine
Traditional Use: Creatine has no traditional herbal or ethnobotanical history. It has been used as a sports nutrition supplement since the early 1990s, primarily for muscle performance enhancement.
Scientific Evidence: The rationale for studying creatine in ALS lies in its role in cellular energy metabolism and potential protection against mitochondrial dysfunction. A double-blind, randomized, placebo-controlled trial of the safety and efficacy of creatine in patients with ALS was conducted at multiple US sites. The study aimed to provide preliminary data on the safety and efficacy of creatine in ALS. However, despite the lack of bona fide clinical trial data to demonstrate positive effects in ALS for the majority of antioxidants, creatine has similarly not demonstrated meaningful clinical benefit in ALS in completed trials. Evidence is negative to inconclusive; controlled trials did not support benefit sufficient to advance to large-scale Phase III studies.
Omega-3 Polyunsaturated Fatty Acids
Traditional Use: Fish oil and omega-3-rich foods have been used in Nordic, Japanese, and coastal Mediterranean traditions for general health, particularly cardiovascular and inflammatory conditions. No specific traditional application to motor neuron disease exists.
Scientific Evidence: Observational evidence suggests that dietary omega-3 intake may be associated with a modestly lower ALS incidence. However, supplementation data in animal models raise important cautions: testing the hypothesis that a high level of dietary EPA could exert beneficial effects in ALS, researchers exposed ALS model mice (G93A SOD1 mutation) to EPA at a pre-symptomatic or symptomatic stage. Daily dietary EPA exposure initiated at the disease onset did not significantly alter disease presentation and progression. In contrast, EPA treatment initiated at the pre-symptomatic stage induced a significantly shorter lifespan. The microglia in the spinal cord of G93A-SOD1 mice treated with EPA showed a significant increase in 4-hydroxy-2-hexenal, a highly toxic aldehydic oxidation product of omega-3 fatty acids. These data show that dietary EPA supplementation in ALS has the potential to worsen the condition and accelerate disease progression, suggesting that great caution should be exerted when considering dietary omega-3 fatty acid supplements in ALS patients.
These findings are from animal models (SOD1 transgenic mice) and should not be directly generalized to humans; nonetheless, they underscore the complexity and potential for unexpected effects in this disease context. Evidence in humans remains observational and inconclusive.
Curcumin (from Curcuma longa)
Traditional Use: Curcumin is the principal bioactive polyphenol of turmeric (Curcuma longa L.), a rhizome used for centuries in South and Southeast Asian traditional medicine (Ayurveda, Traditional Chinese Medicine) and as a culinary spice. Traditional applications included use as an anti-inflammatory and digestive agent, and in wound healing. No historical specific use for motor neuron disease is documented.
Scientific Evidence: A diet based on antioxidant and anti-inflammatory compounds, such as curcumin, creatine, coenzyme Q10, vitamin E, vitamin A, vitamin C, and phytochemicals could reduce the risk of ALS, according to a 2021 dietary review published in Foods (MDPI). However, this statement is based on preclinical and mechanistic reasoning rather than clinical trial evidence in ALS patients specifically. Curcumin has demonstrated the ability in human participants to modulate multiple cell signaling molecules such as pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), apoptotic proteins, NF-κB, COX-2, STAT3, and antioxidants in clinical research across various conditions, but direct ALS human clinical trials for curcumin are absent from the published literature. Bioavailability is a significant limiting factor for curcumin at physiologically relevant doses. Evidence specifically in ALS is preliminary and theoretical — mechanistically plausible but lacking human trial data in ALS populations.
Carotenoids (including Beta-Carotene, Lycopene, Lutein)
Traditional Use: Carotenoid-rich foods (e.g., carrots, tomatoes, leafy greens) have been used across diverse traditional dietary systems, with associations to eye and immune health, but no specific traditional use in motor neuron disease.
Scientific Evidence: Carotenoid intake has been associated with reduced ALS incidence in epidemiological analyses. The consumption of antioxidant and anti-inflammatory compounds, such as vitamin E, n-3 polyunsaturated fatty acids, and carotenoids, has been related to lower ALS incidence. This association is derived primarily from prospective observational and dietary data. No randomized controlled trial evidence of carotenoid supplementation in ALS is available in the indexed literature. Evidence is observational and preliminary.
Vitamin D
Traditional Use: Vitamin D is not a herb or traditional botanical remedy; its role as a nutrient has been recognized through nutritional science. Traditional use across cultures includes sun exposure practices to prevent rickets. Specific application to motor neuron disease is a modern scientific inquiry.
Scientific Evidence: Vitamins are involved in the development of the nervous system and could serve as prognostic factors. They may also be used in the treatment of ALS for their cellular antioxidant properties. A Mendelian randomization study (PMC8912818) evaluated the causal associations between circulating essential nutrient levels, including 25-hydroxyvitamin D, and ALS risk using large-scale GWAS data. The study obtained large-scale European-based ALS GWAS summary data from a recently published study, which included 27,205 ALS patients and 110,881 controls. Mendelian randomization approaches help address confounding but cannot replicate clinical intervention. Evidence for vitamin D specifically in ALS is mixed and preliminary.
Gut Microbiota and the Gut–Brain Axis in ALS
Gastrointestinal dysfunction and gut microbiota dysbiosis intensify disease pathology in ALS by driving immune dysregulation, compromising the intestinal barrier, and altering gut–brain axis signaling, advancing neurodegeneration. This is an emerging area of research; while mechanistic evidence points to a gut–brain axis contribution to ALS pathology, clinical interventions targeting the gut microbiome in ALS patients have not yet been established as effective in large-scale trials.
Dietary Patterns and Lifestyle Factors: Discussion in the Literature
Overall Dietary Pattern
Therapeutic and preventive strategies focused on nutrition offer promising opportunities to address the interconnected pathophysiological mechanisms of ALS. Diets enriched with antioxidants, omega-3 fatty acids, and anti-inflammatory compounds—such as the Mediterranean diet—have shown potential in reducing oxidative stress and systemic inflammation. These observations are based on the mechanistic parallels between ALS pathology (oxidative stress, neuroinflammation) and the documented biological effects of Mediterranean-style eating patterns, rather than on ALS-specific clinical trial outcomes.
Nutritional Management and Body Weight
Previous studies have suggested that complete general care with adequate nutritional support could delay muscle mass loss, and increasing body weight or body mass index (BMI) may improve the prognosis for ALS patients. A low body mass index at diagnosis is an indicator of poor prognosis, and post-diagnosis weight gain is reported to be associated with longer survival.
Evidence on caloric thresholds: survival data showed that patients consuming less than 25 kcal/kgIBW had a median survival of 24 months, increasing to 38 months for those consuming between 25–30 kcal/kgIBW and 63 months for those consuming 30 kcal/kgIBW or more. Deviations from total energy expenditure did not significantly affect survival. Among patients consuming less than their total energy expenditure, those consuming less than 25 kcal/kgIBW had a shorter median survival (24 months) compared to their counterparts (46 months). This is a retrospective single-center study; larger prospective trials are needed.
Physical Activity
Physical activity presents a dual picture in ALS. At population level, very high levels of physical activity have been associated with modestly elevated risk of developing ALS in meta-analyses (OR = 1.06). In patients already diagnosed, larger energy intake to maintain energy balance is crucial, particularly in the light of the observed hypermetabolism and increased physical activity–energy expenditure in ALS patients compared to controls.
Antioxidant Supplementation: General Evidence Landscape
To date there is no effective cure, but the use of antioxidant compounds could be a potential therapeutic strategy as they could help regulate the crucial biological processes involved in ALS. Compounds with antioxidant potential are present in our diet such as vitamins, curcumin, and coenzyme Q10 and could be used as therapeutic strategies. However, the overall evidence remains limited, and no antioxidant dietary supplement has demonstrated sufficient efficacy in randomized controlled trials in ALS to be adopted into standard clinical practice. Despite the lack of bona fide clinical trial data to demonstrate positive effects in ALS for the majority of antioxidants, high tolerance and safety combined with ease of availability do not discourage their use by patients.
Summary of Evidence Strength
- Nutritional support / caloric adequacy: Moderate evidence from observational and retrospective studies supporting maintenance of adequate caloric intake and body weight for improved prognosis.
- Vitamin E (dietary associations): Weak observational evidence suggesting possible risk reduction; no benefit shown in clinical trials on survival.
- Methylcobalamin (high-dose): Preliminary; phase 3 trial data (JETALS) completed but not yet fully reported in the reviewed literature; low-dose oral forms unstudied in ALS.
- CoQ10: Negative; Phase II RCT found insufficient evidence to justify Phase III.
- Creatine: Inconclusive to negative; controlled trials did not demonstrate meaningful benefit.
- Omega-3 fatty acids (dietary): Mixed; observational data suggest possible risk reduction, but animal model data raise concerns about EPA supplementation potentially accelerating progression.
- Curcumin: Preliminary and theoretical; mechanistically plausible but no ALS-specific human clinical trial data.
- Carotenoids and antioxidant dietary compounds: Observational and preliminary; no RCT evidence in ALS.
- Mediterranean dietary pattern: Plausible based on anti-inflammatory and antioxidant mechanisms; no ALS-specific RCT data.
- Environmental toxin reduction (heavy metals, pesticides): Consistent meta-analytic associations; public health relevance for risk reduction.
References
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