Is Sugar Feeding Cancer?

By Ayda Page
October 26th 2025 6 minutes read
Is Sugar Feeding Cancer?

What the science says — and what you can do


When most of us think “sugar” we think calories, mainly empty calories. But new research suggests certain sugars, especially added fructose from sweetened drinks, may influence cancer biology in a more specific way.


Think of your liver as an expert “processor.” Fructose is the sweet molecule in table sugar and high-fructose corn syrup. When a large surge of fructose arrives, the liver quickly breaks it down and turns some of it into small lipid parts. Certain tumor cells can grab those parts and turn them into full phospholipids — the material that cell membranes are made of. More building parts can mean faster cell growth. Importantly, this effect has been seen even without weight gain, which tells us it's not just about calories, it's also about how the sugar is handled. 


Does that mean fruit is dangerous? No. Whole fruit is packaged with water, fiber, vitamins, and polyphenols. Fiber slows absorption, so your small intestine pre-processes much of the fructose and less reaches the liver at once. By contrast, large boluses from sodas, juices, energy drinks, and sweet teas hit fast and hard. That's why practical, cancer-smart advice focuses on added sugars and sugary beverages, not fruit. 


Human evidence is still developing, but the safest practical takeaway is simple — cut back on added sugars and sugary beverages, keep fruit (not juice) in a balanced diet, and focus on meals rich in lean protein, vegetables, whole grains, and healthy fats. Drink mostly water or unsweetened beverages.


What the latest studies show


  • 2019 (Science): In mice predisposed to intestinal tumors, daily high-fructose corn syrup made tumors grow larger and more advanced — even without obesity or metabolic syndrome. Inside the tumors, fructose revved up pathways that build new fats tumors need for growth. 
  • 2024 (Nature) & 2025 (NCI summary): Several cancers (skin, breast, cervical, in animal models) sped up growth when animals consumed fructose. However, many tumor cells can't use fructose directly. Instead, the liver converts fructose into lipids, especially lysophosphatidylcholines (LPCs), that tumors import to build new membranes. Blocking the key liver enzyme (KHK) slowed this fructose-fueled growth in mice. 
  • Human relevance: Evidence still points to sugary drinks → weight gain → higher cancer risk, across many cancer types. There's also emerging epidemiology linking sugary beverages with early-onset colorectal cancer risk in women, especially with higher intake during adolescence and young adulthood. 


Although human research is still evolving, and not every cancer behaves the same way, there's already plenty we can do. First, keep soda, sweet tea, energy drinks, and juice as the exception. If you're thirsty go for water, sparkling water with lime, or unsweetened tea. Your liver and future self will thank you.


Eat your fruit 


We can also eat our fruit, rather than drinking it. Mountain apple, papaya, pineapple, banana and mango are all delicious when eaten whole. Smoothies can be fine if they include protein (for example greek-style dairy-free yogurt or protein powder) as well as fiber (such as chia/flax), and aren't oversized. 


Build a balanced plate


Half non-starchy veggies (greens, cucumber, cabbage), a palm-size lean protein (fish, chicken, tofu), a fist of whole carbs (brown rice, ‘uala/sweet potato), and a thumb of healthy fat (avocado, nuts). This steadies energy and reduces big sugar swings.


Pair sweets with meals


If you do have dessert, have it after a protein-rich meal to blunt the sugar surge. On packaged foods be sure to check the labels for hidden sugars, and watch for ingredients like high-fructose corn syrup, corn syrup, fructose, evaporated cane juice.


Try a 5-day “Sweet Reset.”

  • Day 1–2: Replace sugary drinks with water or unsweet tea.
  • Day 3: Make fruit your only sweet (2 servings).
  • Day 4: Add 25–30 g fiber/day (veggies, beans, chia).
  • Day 5: Add a protein source to each meal/snack.
  • Most people report better energy and fewer cravings by the end.


Mind your morning


Breakfast sets the tone. Aim for protein and fiber — such as a veggie omelet with avocado; chia pudding with berries; or Greek-style dairy-free yogurt, nuts, and sliced banana.


Move a little after your meals. A 10–15 minute walk helps muscles soak up sugar so your liver has less to handle.


A healthy, Hawaiian sample day


Breakfast: Scramble with eggs (or tofu), spinach, tomatoes; side of papaya with lime; unsweetened tea.

Lunch: Poke bowl with extra greens, brown rice, avocado; water or sparkling water.


Snack: Apple and a handful of mac nuts.


Dinner: Grilled fish or chicken, cabbage-carrot slaw, roasted ‘uala (sweet potato); herb tea.


Dessert (optional): 1 square dark chocolate or fresh pineapple after dinner.


Summary


Your biggest win will come from cutting back on sugar-sweetened beverages. Whole fruit is okay and often beneficial. 

Balance your protein, veggies, whole carbs and healthy fats.

Move a little, even a short walk after meals helps.


These might look like small steps, but daily choices add up. On Kauaʻi, we're lucky to have fresh produce and an outdoor lifestyle year-round. Enjoy that, and hydrate well, savor whole foods, move your body, and let sugar be a sometimes treat, not a daily habit.



----



References:


  • High-fructose corn syrup can accelerate tumor growth in mice—even without weight gain. (Gonçalves et al., Science, 2019; PubMed abstract.) 
  • New mechanism: The liver converts fructose into lipids (incl. LPCs) that tumors use to build membranes;blocking the liver enzyme KHK slowed growth in mice. (NCI summary of a Dec 4, 2024 Nature study.) 
  • Your small intestine “pre-processes” modest fructose loads—helping protect the liver; big liquid doses overwhelm that system. (Jang et al., Cell Metabolism, 2018; plus follow-up work.) 
  • Sugary drinks & cancer risk: Global expert panels advise limiting sugar-sweetened beverages for cancer prevention; they drive weight gain, which raises risk for many cancers. (WCRF/AICR guidance and factsheet.) 
  • Early-onset colorectal cancer: Higher sugary-drink intake (adolescence and adulthood) was linked with greater EO-CRC risk in women (Nurses' Health Study II). (Hur et al., Gut, 2021.) 


Mechanism & Metabolism

  • Gonçalves MD, Lu C, Tutnauer J, et al. High-fructose corn syrup enhances intestinal tumor growth in mice.Science. 2019;363(6433):1345-1349. doi:10.1126/science.aat8515. PubMed
  • Fowle-Grider R, Rowles JL III, Shen I, et al. Dietary fructose enhances tumour growth indirectly via interorgan lipid transfer. Nature. 2024;636(8043):737-744. doi:10.1038/s41586-024-08258-3. PubMed
  • Jang C, Hui S, Lu W, et al. The Small Intestine Converts Dietary Fructose into Glucose and Organic Acids.Cell Metab. 2018;27(2):351-361.e3. doi:10.1016/j.cmet.2017.12.016. PubMed
  • Leong I. The small intestine — a new player in fructose metabolism. Nat Rev Endocrinol. 2018;14(4):190. doi:10.1038/nrendo.2018.20. Nature
  • Senft D. Fructose takes a detour to feed cancer. Nat Rev Cancer. 2025. (News & Views on interorgan lipid transfer mechanism.) Nature
  • National Cancer Institute (Cancer Currents Blog). Fructose Fuels Cancer Growth Indirectly, Lab Study Finds.Jan 14, 2025. (Lay summary of the Nature 2024 study.) Cancer.gov


Human Evidence (Epidemiology)

  • Hur J, Otegbeye E, Tabung FK, et al. Sugar-sweetened beverage intake in adulthood and adolescence and risk of early-onset colorectal cancer among women. Gut. 2021;70(12):2330–2339. PubMed
  • Chazelas E, Srour B, Kesse-Guyot E, et al. Sugary drink consumption and risk of cancer: results from NutriNet-Santé. BMJ. 2019;366:l2408. BMJ
  • Zhao L, et al. Sugar-Sweetened and Artificially Sweetened Beverages and Risk of Liver Cancer and Chronic Liver Disease Mortality in US Women. JAMA. 2023. (Women's Health Initiative cohort; open-access summary.) PMC+1


Guidelines & Practical Resources