2.1. Search strategy

A comprehensive literature search was conducted using electronic databases, including PubMed and the Cochrane Library, to identify relevant peer-reviewed, open-access articles published in English between 1997 and January 2024. The search included keywords and MeSH terms such as:

The reference lists of relevant studies were also screened to capture additional eligible articles.

2.2. Inclusion and exclusion criteria

2.3. Study Selection and Screening

A total of 1,587 articles were initially identified. After removing duplicates and applying access, language, and age-group filters, 523 open-access articles remained, out of which 519 were in English. Retaining middle-aged populations further reduced the pool to 240 articles.

Of these, studies directly assessing the link between dietary diversity and gastric cancer were selected. The final selection process and article flow are summarized in Figure 1.

Figure 1

Flow diagram for the extraction of data.strongly recommended post-surgery.

2.4. Quality assessment

Although a formal PRISMA framework was not strictly followed, efforts were made to incorporate structured screening and documentation. Future iterations of this review may adopt full PRISMA compliance and include quality assessments using tools such as the Newcastle-Ottawa Scale or GRADE, where appropriate.

3.1. Gastric Cancer and Nutritional Challenges

The digestive system is responsible for processing, digesting, and absorbing nutrients from food. The gastrointestinal tract and dietary composition are closely interlinked and exert reciprocal influences on a daily basis [Cencioni et al., 2022]. Dietary problems are frequently observed among individuals with gastrointestinal disorders of various kinds [Corsello et al., 2020; Axelrod and Saps, 2020]. In the case of gastric cancer, the most common symptoms include weight loss, multiple micronutrient deficiencies, and inadequate protein intake [Maconi et al., 2008]. At the time of diagnosis, approximately 31–87% of patients report weight loss, often occurring within the six months preceding diagnosis, while malnutrition is especially prevalent among those with advanced-stage disease [Grochowska et al., 2004].

The decline in nutritional status may occur both before and after surgery in patients with gastric cancer. Preoperative malnutrition is frequently driven by cancer cachexia and reduced oral intake caused by gastric outlet obstruction, whereas postoperative malnutrition is associated with anatomical changes following gastrectomy, adjuvant therapy, and poor oral tolerance [Yuen et al., 2019; Wang et al., 2022]. These changes collectively predispose patients to micronutrient deficiencies and body composition alterations, as summarized in Table 1.

Recent studies further substantiate this relationship. Yang et al. (2025) reported that nutrition-impact symptoms such as appetite loss and early satiety independently predict poorer overall survival and diminished quality of life in patients of gastric cancer, emphasizing the prognostic significance of nutritional deterioration decline. Similarly, Chen et al. (2022) demonstrated that the introduction of a hospital-based Nutrition Support Team (NST) in elderly post-gastrectomy patients resulted in improvements in BMI and reduction in postoperative infections, highlighting the importance of structured nutritional care even in the absence of immediate survival gains. Furthermore, Zhang et al. (2023) identified that elevated preoperative nutritional risk scores (NRS-2002 ≥ 3) were associated with prolonged hospitalization stays and increased complication rates, validating the importance of routine preoperative screening as a clinical priority.

Postoperatively, Park et al. (2023) reported that sarcopenia affects approximately 41 % of long-term gastric cancer survivors and is strongly associated with inadequate protein intake and overall malnutrition. Li et al. (2021) confirmed significant declines in fat-free mass and serum albumin following laparoscopic gastrectomy, underscoring the need for continuous nutritional monitoring. More recently, Liu et al. (2025) identified that greater dietary diversity supports improved gut microbiome composition and enhanced nutritional recovery in post-gastrectomy patients, suggesting that dietary variety plays a crucial role in restoring nutrient balance and promoting overall health outcomes.

Collectively, these findings indicate that malnutrition and micronutrient deficiencies remain major determinants of postoperative outcomes in gastric cancer patients. The prevalence of undernutrition and sarcopenia is particularly high among total gastrectomy patients [Xu et al., 2022]. Additional nutritional challenges commonly encountered include weight loss, dysphagia, reduced dietary intake, and elevated inflammatory markers such as C-reactive protein [Taleghani et al., 2021; Deans et al., 2009]. Nutritional inadequacy has a significant effect on prognosis and quality of life, contributing to complications such as delayed healing, fatigue, and micronutrient deficiencies [Kiani et al., 2022; Jann, 2024; Mulita et al., 2021]. Nonetheless, evidence suggests that timely symptom management and nutritional intervention can substantially improve patients’ functional status and quality of life following surgery [Gharagozlian et al., 2020].

3.2. Nutritional deficiencies and their effect on overall health outcomes

Chronic nausea, heartburn, sarcopenia, early satiety, belching, lack of appetite, dysphagia, diarrhea, and abdominal pain are common complications of gastric surgery [Gharagozlian et al., 2020; Xu et al., 2022]. More than half of the patients experience malnutrition or are at risk following a gastrectomy. Consequently, targeted nutritional and therapeutic interventions should be incorporated into malnutrition prevention and management and to improve quality of life [Gharagozlian et al., 2020; Heneghan et al., 2015]. Patients undergoing oncological esophagectomy or gastrectomy are also at high risk of vitamin and micronutrient deficiencies before, during, and after surgery [Finze et al., 2024].

Among these factors, deficiencies in protein and albumin are some of the earliest markers of malnutrition in gastric cancer patients, occurring in approximately 45–70% of cases [Wang et al., 2022; Hua et al., 2024]. These deficiencies indicate inadequate dietary intake, impaired absorption, and chronic inflammation, which contribute to to sarcopenia, delayed wound healing, and decreased survival rates.

Calcium deficiency is also frequent, often secondary to vitamin D malabsorption and fat intolerance. It contributes to osteopenia and neuromuscular irritability and is further aggravated by duodenal bypass after surgery [Sharma et al., 2024; Clinical Nutrition ESPEN Review, 2024]. The development of osteomalacia and osteoporosis is influenced by this calcium deficiency, as ingested food bypasses the duodenum, pH in the upper gastrointestinal tract changes, and lactose intolerance limits milk intake [Veeralakshmanan et al., 2020]. The incidence of osteoporosis following gastrectomy affects nearly 40 % of patients, especially among elderly women and those with diabetes [Seo et al., 2018].

Copper deficiency may occur when gastric acid production is reduced and the proximal small intestine is bypassed. This leads to impaired copper absorption, resulting in anemia unresponsive to iron and peripheral neuropathy [Sasaki et al., 2021; Clinical Nutrition ESPEN Review, 2024].

Fat-soluble vitamin deficiencies are equally concerning. Deficiency of vitamin A is common after gastric resection because of reduced lipid digestion, which leads to impaired vision, epithelial atrophy, and poor mucosal repair [Li et al., 2021; Clinical Nutrition ESPEN Review, 2024]. Similarly, deficits in other fat-soluble vitamins (D, E, K) are also more likely following gastrectomy [Teixeira et al., 2023].

Thiamine (vitamin B₁) deficiency can develop rapidly within weeks of surgery—especially in vomiting-prone or undernourished gastric cancer patients. It manifests as neuropathy or even Wernicke’s encephalopathy if left untreated [Ryu et al., 2023].

Selenium deficiency is increasingly recognized as another concern among gastric cancer survivors. Low selenium levels are associated with higher oxidative stress and decreased immune competence, while supplementation has been shown to improve antioxidant capacity and recovery [Liu et al., 2025].

Between 10 % and 75 % of patients who have undergone gastrectomy also experience zinc deficiency, contributing to poor wound healing, dysgeusia, and immune dysfunction [Teixeira et al., 2023]. Vitamin D deficiency often coexists, with postoperative serum levels dropping by as much as 36 % [Rawla and Barsouk, 2019], further aggravating calcium loss and bone demineralization.

The combined burden of these deficiencies iron, vitamin B₁₂, folate, calcium, zinc, copper, selenium, and fat-soluble vitamins leads to systemic malnutrition and worsened prognosis. Iron deficiency anemia, affecting 40–70 % of gastrectomy patients [Veeralakshmanan et al., 2020; Seo et al., 2018], arises from altered pH and bypass of the duodenum and jejunum, the main absorption sites [Jun et al., 2016]. Vitamin B₁₂ deficiency, due to intrinsic factor loss and mucosal changes, commonly causes megaloblastic anemia [Misra, 2018; Akad et al., 2024], and is further influenced by the altered gut microbiome after gastric surgery [Guetterman et al., 2022; Affairs and Policy, 2011]. Other deficiencies particularly folate [Finze et al., 2024; Dello et al., 2023], vitamin D [Veeralakshmanan et al., 2020; Fox et al., 2020; Rino et al., 2007], and zinc [Namikawa et al., 2021; Salle et al., 2010] are also widespread in this population.

These micronutrient deficits are often compounded by low-quality, monotonous diets. Compared with patients who maintain balanced and diverse diets, those with poor dietary diversity show a 65 % higher likelihood of reduced quality of life [Grima and Nana, 2023]. Conversely, epidemiologic evidence demonstrates that dietary diversity exerts a protective role against gastric cancer. In a case–control study of 746 gastric cancer cases and 2,053 controls in northern Italy, La Vecchia et al. (1997) observed that a richer and more varied diet significantly reduced gastric cancer incidence, supporting the concept that food diversity and micronutrient adequacy together enhance resilience against both disease onset and treatment-related malnutrition.

3.3. Mechanisms, clinical implications, and management of nutrient deficiencies

As summarized in Table 3, multiple nutrient deficiencies coexist in gastric cancer patients due to a combination of altered gastrointestinal anatomy, malabsorption, and reduced dietary intake following surgery. Protein and albumin deficiencies emerge as some of the earliest signs of malnutrition, primarily driven by early satiety, inflammation, and reduced oral intake. These deficiencies accelerate muscle wasting, delay wound healing, and increase susceptibility to infection (Hua et al., 2024; Wang et al., 2022). Iron deficiency is one of the most frequent complications after gastrectomy, resulting from reduced gastric acid secretion and duodenal bypass, which impair iron absorption and conversion to the bioavailable ferrous form. Chronic blood loss and low intake of heme rich foods further worsen microcytic anemia and fatigue (Menon et al., 2025; Sato et al., 2023).

Vitamin B12 and folate deficiencies often occur concurrently, reflecting the loss of intrinsic factor, rapid intestinal transit, and bacterial overgrowth. These deficiencies manifest as macrocytosis, neuropathy, and glossitis, underscoring the need for lifelong vitamin B12 supplementation and regular folate intake from dietary and pharmacologic sources (Sato et al., 2023; Nguyen et al., 2024). Vitamin D and calcium deficiencies are particularly concerning, as they lead to osteopenia, osteoporosis, and muscular weakness. The dual mechanism of impaired fat absorption and bypassed duodenal calcium absorption necessitates combined supplementation with vitamin D (800 to 2000 IU per day) and calcium (1000 to 1200 mg per day) for optimal bone health (Sharma et al., 2024; Clinical Nutrition ESPEN Review, 2024).

Micronutrients such as zinc, copper, and selenium also show significant post surgical depletion. Zinc deficiency, resulting from malabsorption and low protein intake, contributes to dysgeusia, poor wound healing, and immune dysfunction (Nguyen et al., 2024; Menon et al., 2025). Copper deficiency, often secondary to reduced gastric acid secretion and excessive zinc intake, manifests as anemia and neuropathy (Sasaki et al., 2021). Selenium depletion has been associated with oxidative stress, immune dysregulation, and fatigue; supplementation and diet diversification can improve antioxidant defense and recovery (Liu et al., 2025).

Deficiencies in fat soluble vitamins (A, D, E, and K) and thiamine (vitamin B1) are also frequent. Vitamin A deficiency leads to visual impairment and poor epithelial regeneration (Li et al., 2021), while thiamine deficiency can rapidly progress to Wernicke’s encephalopathy in vomiting prone or rapidly weight losing patients (Ryu et al., 2023). Vitamin C and magnesium deficiencies, often overlooked, impair wound healing, cause muscle weakness, and interfere with calcium and vitamin D metabolism (Kim et al., 2019; Li et al., 2021).

Collectively, these deficiencies not only compromise recovery but also reduce treatment tolerance, immune defense, and quality of life. Addressing these deficiencies requires an integrated management approach that includes early nutritional screening, regular biochemical monitoring, individualized oral or parenteral supplementation, and emphasis on dietary diversity. Incorporating protein and micronutrient rich foods along with tailored counseling and physical rehabilitation can effectively mitigate post gastrectomy complications and support long term survivorship in gastric cancer patients. Promoting dietary diversity is especially important, as it provides a sustainable, food based strategy to restore nutrient adequacy, enhance recovery, and improve overall quality of life after gastric cancer treatment.

3.4. Importance of dietary diversity

Dietary diversity is critically important for gastric cancer patients, especially during treatment and recovery. A varied diet ensures the intake of essential nutrients, supports healing, boosts immunity, and helps manage potential side effects of treatment or surgery. Diet quality is a key element for dietary diversity. Food diversity is based on the principle that every food has its own set of nutrients that are necessary to maintain optimal health. The consumption of diversified food was recommended by the US dietary guidelines in 1980. It has been phrased that one should “select foods each day from each of several major groups, in recommended amounts”. However, patients suffering from cancer consume a non-diversified diet due to a lack of nutrition knowledge. Cancer patients who eat poorly have a high morbidity and mortality rate [Grima and Nana, 2023]. Dietary diversification must be sustainably enhanced by addressing information and lowering adherence barriers in order to improve it [Affairs and Policy, 2015].

Various studies have been incorporated and summarised in Table 4 to see the need for a diversified diet in the field of cancer.

A diversified diet is crucial in cancer for several reasons. As depicted in Table 4, a diversified diet reduced the risk of bladder cancer [Isa et al., 2013], colorectal cancer [Fernandez et al., 1996], gastric cancer [La Vecchia et al., 1997], [Maddineni et al., 2022], and other site-specific cancers [Torheim et al., 2004].

The diversified diet adds antioxidants and a variety of nutrients to the diet [de Oliveira et al., 2018]. A diverse diet supports a robust immune system, which is vital for identifying and destroying cancerous cells before they grow and spread [Munteanu and Schwartz, 2022]. It is observed that gastric cancer patients with good nutrition knowledge had more diverse diets [Muthike et al., 2015]. Hence, the knowledge plays a major role in the management of diet and nutrition amongst gastric cancer patients.

Another study conducted in China amongst gastric cancer patients to test a certain intervention program on nutritional counselling (CANCER-AIMS) was considered efficient and enhanced the nutritional intake amongst the gastric cancer patients [80]. Review studies also suggest that a diet that is high in whole grains, fruits, vegetables, nuts, and is low in salt may reduce the risk of gastric cancer [Maddineni et al., 2022], [Gaesser et al., 2020].

Gastric cancer and its treatments (like chemotherapy and radiation) can lead to malnutrition [Jacobs and Miles, 1969]. A diverse diet ensures a broader intake of nutrients, helping to mitigate deficiencies [Guetterman et al., 2022].

As summarized in Table 5, consuming a well-balanced and diversified diet plays a crucial role in improving nutritional status and reducing micronutrient deficiencies among cancer patients [Kim and Lee, 2024; Chaudhary et al., 2022; Brazier et al., 2020; Mirmiran et al., 2006]. Food-based strategies such as dietary diversification are increasingly recognized as the most sustainable and primary approach to meeting micronutrient needs. The Dietary Diversity Score (DDS) has been widely validated as a simple yet effective indicator of diet quality. While overall dietary quality is influenced by multiple factors, the DDS provides a reliable estimate of micronutrient adequacy by counting the number of food groups consumed rather than the total number of food items [Mirmiran et al., 2006; Torheim et al., 2004].

Higher dietary diversity scores have been shown to correlate positively with improved mean micronutrient intake and greater adequacy in essential nutrients such as iron, zinc, and vitamins A and D. This relationship is particularly relevant for gastric and upper gastrointestinal (GI) cancer patients, who often face multiple nutrient deficiencies due to altered anatomy and reduced intake following surgery. Nguyen et al. (2024) demonstrated through a clinical case and literature review that severe deficiencies in albumin, iron, zinc, vitamin D, and calcium were prevalent after upper GI cancer surgeries such as gastrectomy and pancreaticoduodenectomy, highlighting the cumulative impact of surgical malabsorption and poor diet diversity. Similarly, Menon et al. (2025) found that gastric cancer survivors with low dietary diversity scores (< 4 food groups) exhibited higher rates of iron, vitamin D, and zinc deficiencies, whereas those consuming a more varied diet achieved significantly better micronutrient adequacy. Furthermore, de Heer et al. (2022) observed that among 187 patients who underwent esophagectomy or gastrectomy for cancer, the prevalence of iron (42%), vitamin D (37%), and vitamin B₁₂ (27%) deficiencies remained high even years after surgery, emphasizing the need for long-term nutritional monitoring and dietary diversification as part of survivorship care.

Collectively, these findings support the concept that dietary diversity directly influences micronutrient status and recovery outcomes in cancer patients. A varied diet not only improves biochemical nutrient markers but also enhances immune resilience, muscle strength, and overall quality of life. Thus, incorporating food-based dietary diversity interventions—emphasizing multiple food groups, especially those rich in protein, iron, zinc, and vitamins—should be a cornerstone of nutritional management in gastric and gastrointestinal cancer survivors.