The evidence behind PhaseFood

There isn't as much high-quality research on most individual foods as people assume. A lot of what does exist is funded by the people who sell the food. There is no single super food but what is clear in science is that a whole foods diet is the best evidence base we have for good nutrition right now, it's this basis that PhaseFood is built around.

We also believe your body knows things science doesn't. This platform has been designed to help you listen to your own symptoms and then have recipes adjust accordingly, but at the same time each person should pay attention to how certain foods feel (do you get tired, headaches, sore stomachs etc with some foods) and this should help you adapt your personal needs.

The site draws its nutritional research mostly from Western nutrition science because that's where the peer-reviewed literature is. Older traditions like Ayurvedic medicine, traditional Chinese medicine, indigenous food systems, and women's wisdom passed mother to daughter have detailed frameworks for diet and women's bodies that don't show up in PubMed. I truly believe the western science does not hold all the answers but I also think it's important to be clear on the existing limitations of what we know, and what we know is that there is limited evidence not only in nutrition but also for women.

Below are the fundamental pillars the site is built on and the research that backs these, there are also confidence ratings on individual claims showing what's well-supported, what's suggestive, and what's contested.

This isn't medical advice, and for any specific nutrition advice you should consult your GP or a clinical nutritionist.

Cycle-aware eating

The idea behind cycle eating, is that a menstruating woman has different nutritional needs over her cycle and eating in line with these is known as cycle syncing. Iron-rich foods during your period. Lighter foods in the follicular phase. Bright nutrient-dense foods around ovulation. More carbs and grounding foods in the luteal phase.

Most of the popular framing comes from Alisa Vitti's 2014 book WomanCode and her work at FLO Living. The framework resonated, particularly with women who'd felt underserved by general nutrition advice that ignored the monthly cycle entirely. There's something here. Bodies do change across the month. Energy and appetite shift. A one-size-fits-all approach to food doesn't reflect that reality.

What PhaseFood does is run cycle eating as a prompt. Turn it on, tell us where you are in your cycle, and your recipes lean toward foods often associated with each phase.

Most of the specific phase-by-phase claims you'll see online are mechanistically plausible but unproven. The recipes don't seek to treat PMS, balance hormones, or fix any specific symptom.

The pieces that hold up:

Well-supported

Iron pairing during menstruation

People who menstruate lose iron monthly. Pairing iron-rich foods (red meat, lentils, spinach, pumpkin seeds) with vitamin C improves non-heme iron absorption.[1] Whether you call this cycle eating or just good nutrition during your period, the underlying advice is sound.

Suggestive

Mild caloric increase in the luteal phase

Resting metabolic rate rises slightly after ovulation, between 2 and 10 percent.[2] Some people feel it as appetite increases in the days before their period.

Suggestive

Magnesium for PMS

Several small trials have associated higher dietary magnesium with lower PMS symptom severity.[3] A 2023 systematic review described the data as suggestive but not conclusive. Magnesium-rich foods (leafy greens, pumpkin seeds, dark chocolate, beans) are good to eat regardless.

The pieces that don't:

Contested

Most phase-by-phase prescriptions

Most of the specific phase-by-phase prescriptions you'll see online, eat seeds for "estrogen detox," eat cruciferous vegetables to "metabolise estrogen," eat warming foods in luteal, are mechanistically plausible but lack good clinical trials. It's mostly extrapolation from in vitro studies, animal models, or small uncontrolled trials. However, a lack of data doesn't make something wrong it just means we can't say with certainty there is real proof, if it works for you then it works.

Contested

Seed cycling

Seed cycling has no good clinical evidence. The mechanism cited (lignans modulating estrogen) is real, but the doses involved are far below what trials have shown to have any hormonal effect.

Contested

Cycle eating as treatment

Cycle eating as treatment for PMS, PCOS, endometriosis, or fertility issues. None of these claims are supported by clinical trials of the cycle-syncing protocol. Some dietary patterns do help with some of these conditions (a Mediterranean-style pattern for PCOS, for instance), but those work regardless of cycle phase.

Sources

  1. [1]Hallberg L, Hulthén L. Prediction of dietary iron absorption: an algorithm for calculating absorption and bioavailability of dietary iron. Am J Clin Nutr. 2000;71(5):1147–1160. Link
  2. [2]Benton MJ, Hutchins AM, Dawes JJ. Effect of menstrual cycle on resting metabolism: A systematic review and meta-analysis. PLoS One. 2020;15(7):e0236025. Link
  3. [3]Brown J, Brown S. Premenstrual syndrome: a systematic review of the literature on dietary magnesium. J Caring Sci. 2023. Link

Life stages

What PhaseFood calls life stage tailoring is the thing that shifts your recipes based on where you are in your reproductive life: cycling, perimenopause-active, perimenopause-winding-down, menopause and beyond, or not applicable.

The strongest evidence in this whole area is for protein, calcium, iron timing, and the Mediterranean pattern in menopause and beyond. The rest is general adult nutrition with mild adjustments based on what changes physiologically across reproductive life.

Cycling

If you have regular menstrual cycles and aren't in perimenopause, the food emphasis is straightforward.

Well-supported

Iron adequacy matters

Iron requirements are 18 mg per day for menstruating adults, 8 mg per day for postmenopausal adults.[1] Pairing iron-rich foods with vitamin C improves absorption.

Well-supported

Calcium and vitamin D for bone health

Calcium and vitamin D adequacy support bone health throughout adulthood. Recommended intake for adults: 1,000 mg per day calcium.[2]

Suggestive

Balanced protein across meals

Balanced protein across meals (rather than one big protein hit at dinner) supports muscle maintenance and satiety. Modest effect, real effect.[3]

Perimenopause, still bleeding

The transition. Cycles get irregular, heavier, lighter, or all of the above. Typically lasts several years.

Well-supported

Iron requirements stay elevated

Iron requirements stay elevated as long as you're menstruating. If your cycles are heavier than they used to be, iron needs may rise. The 2020 EMAS position statement specifically flags this.[4]

Suggestive

Mediterranean pattern shift

A general shift toward Mediterranean-style eating (more vegetables, legumes, whole grains, fish, olive oil, nuts; less processed food and red meat) is supported in this transition period, mostly for cardiovascular protection as estrogen declines.[4]

Contested

Perimenopause superfoods

The "perimenopause superfoods" marketed for symptom relief, maca, ashwagandha, certain seeds, various supplements, generally lack good clinical trials. We don't tailor recipes around them.

Perimenopause, winding down

Periods stopping but not yet twelve months without one. Iron needs drop rapidly. Calcium, protein, and Mediterranean-pattern emphasis become more important.

Well-supported

Calcium 1,200 mg/day

Calcium intake of 1,200 mg per day is recommended for women 51 and older to support bone health as estrogen declines.[2]

Menopause and beyond

Twelve months or more since your last period, including menopause itself and the postmenopausal years. This is where the evidence base is strongest.

Well-supported

Protein adequacy

Protein adequacy is the most evidence-supported macronutrient shift. ESPEN PROT-AGE recommends 1.0 to 1.2 g per kg body weight per day for older adults, with some evidence supporting up to 1.2 to 1.6 g per kg for those with active health goals.[5] Distribute it across meals (25 to 35 g per serving) rather than loading one meal.

Well-supported

Mediterranean pattern

Mediterranean dietary pattern reduces cardiovascular disease and all-cause mortality in this life stage. The 2020 EMAS clinical guide specifically endorses it.[4][6]

Well-supported

Calcium and iron shifts

Calcium 1,200 mg per day plus adequate vitamin D for bone health.[2] Iron requirement drops to 8 mg per day.[1]

Suggestive

Soy isoflavones

Soy isoflavones for menopausal symptoms have inconsistent evidence. Some trials show modest benefit on hot flashes, others show none. The mechanism is real (isoflavones are weak phytoestrogens) but the clinical effect is small and variable.[7] We include soy foods, we don't foreground them.

Contested

Menopause superfoods

The broader category of "menopause superfoods" marketed for hormone balance generally lacks the evidence implied by the marketing. Some, flaxseed, certain herbs, have small trials with modest signals. None match the protein, calcium, and Mediterranean evidence.

Not applicable

If you've picked not applicable, your recipes use standard adult nutrition foundations: balanced protein, vegetables, whole grains, healthy fats, varied ingredients. No life-stage-specific framing is added.

Sources

  1. [1]National Institutes of Health Office of Dietary Supplements. Iron — Health Professional Fact Sheet. Link
  2. [2]National Institutes of Health Office of Dietary Supplements. Calcium — Health Professional Fact Sheet. Link
  3. [3]Mamerow MM, Mettler JA, English KL, et al. Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults. J Nutr. 2014;144(6):876–880. Link
  4. [4]Cano A, Marshall S, Zolfaroli I, et al. The Mediterranean diet and menopausal health: An EMAS position statement. Maturitas. 2020;139:90–97. Link
  5. [5]Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013;14(8):542–559. Link
  6. [6]Estruch R, Ros E, Salas-Salvadó J, et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. N Engl J Med. 2018;378(25):e34. Link
  7. [7]Chen MN, Lin CC, Liu CF. Efficacy of phytoestrogens for menopausal symptoms: a meta-analysis and systematic review. Climacteric. 2015;18(2):260–269. Link

The Mediterranean pattern

The Mediterranean dietary pattern has more replicated, large-scale evidence behind it than almost any other framework in modern nutrition.

It comes from the traditional foodways of southern Italy, Greece, and Spain in the mid-twentieth century. People in these regions were eating a fair amount of fat (mostly olive oil, fish, nuts) and not getting heart disease at the rates American researchers expected. Vegetables, legumes, whole grains, fruit, nuts, seeds, fish, olive oil, herbs, moderate dairy and wine. Less red meat, less processed meat, very little ultra-processed food. That's the pattern. It looks suspiciously like what your grandmother probably told you to eat.

The cardiovascular disease evidence is robust. The PREDIMED trial in Spain followed nearly 7,500 high-cardiovascular-risk adults for around five years and found a 30 percent reduction in major cardiovascular events for participants on a Mediterranean diet supplemented with extra-virgin olive oil or nuts, compared to a low-fat control.[1] Multiple meta-analyses of cohort studies, hundreds of thousands of participants combined, have shown 10 to 25 percent reductions in all-cause and cardiovascular mortality associated with higher Mediterranean diet scores.[2] Mediterranean dietary patterns also reduce type 2 diabetes risk and improve metabolic markers, blood pressure, triglycerides, HDL cholesterol, across both trial and observational evidence. The cognitive benefits are weaker but pointing in the same direction. The European Menopause and Andropause Society's 2020 position statement specifically endorses the pattern for perimenopause and menopause, citing reductions in cardiovascular risk, weight gain, and possibly hot flash severity.[3]

The original 2013 PREDIMED paper got retracted from the New England Journal of Medicine in 2018. Researchers found that some participants weren't properly randomised, about 11.6 percent had been enrolled at the household level rather than individually, and one site had inconsistent randomisation procedures. The trial was reanalysed using methods that account for these issues, and the results were republished. The effect estimates remained similar.

The other thing worth knowing: PREDIMED received supplemental food donations from olive oil producers (Hojiblanca, Patrimonio Comunal Olivarero) and nut industry groups (the California Walnut Commission, Borges, Morella Nuts). Several PREDIMED authors have received ongoing funding from these groups in subsequent research. It's all disclosed in the published papers. It doesn't invalidate the findings, the broader Mediterranean evidence base is replicated across many independently funded studies, but it's worth knowing about the specific trial that gets cited most.

What we don't know is which components are doing the work. The olive oil specifically? The polyphenols in unprocessed plant foods? The fish? The absence of ultra-processed food? The social and cultural context of long meals shared with family? Almost certainly some combination, and almost certainly the pattern as a whole rather than any single component.

We also don't really know how well it translates outside the Mediterranean. Most of the strongest evidence comes from southern European populations eating regional foods. Whether equivalent benefits accrue when New Zealanders, Australians, or North Americans approximate the pattern with local versions of those foods is a reasonable assumption. It's not been proven with the same trial-grade evidence.

The default for PhaseFood recipes leans toward this pattern.

Sources

  1. [1]Estruch R, Ros E, Salas-Salvadó J, et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. N Engl J Med. 2018;378(25):e34. Link
  2. [2]Dinu M, Pagliai G, Casini A, et al. Mediterranean diet and multiple health outcomes: an umbrella review of meta-analyses of observational studies and randomised trials. Eur J Clin Nutr. 2018;72(1):30–43. Link
  3. [3]Cano A, Marshall S, Zolfaroli I, et al. The Mediterranean diet and menopausal health: An EMAS position statement. Maturitas. 2020;139:90–97. Link

Industrial seed oils

This is the section where PhaseFood's editorial position is least aligned with mainstream nutrition science, and the section that's most worth reading carefully if you want to understand what we actually think.

We exclude industrial seed oils from our recipes by default. That's our position. The evidence is confusing, conflicting and mostly inconclusive. The studies that suggest they're safe have, in many cases, been funded or co-authored by people with financial relationships to the seed oil industry, which is a fact that very rarely makes it into the public-facing version of the science. Due to this conflict the position of PhaseFood has been to remove them in the recipes. It's a precautionary one based on the available research.

What follows is the research. Read it, weigh it, decide for yourself. The cooking-fats preferences in your Profile control what we suggest, so if you want to include seed oils in your cooking, you can.

What seed oils actually are

The seed oils people argue about are industrially refined oils high in linoleic acid: soybean, canola, sunflower, safflower, corn, rice bran, cottonseed, grapeseed. They were rare in human diets before about 1900 and now make up 8 to 10 percent of calories in a typical Western diet. They're in almost everything ultra-processed. They're the default cooking oil in most restaurants, including ones that advertise themselves as healthy.

Olive oil and avocado oil are not seed oils. They're pressed from the fruit of the plant, contain less linoleic acid, and aren't the target of the critique.

The mainstream case

Well-supported

PUFA lowers LDL cholesterol

Replacing saturated fat with polyunsaturated fat lowers LDL cholesterol. This is one of the more reproducible findings in nutrition science.[1] It's the foundation of the AHA's longstanding recommendation to use seed oils in place of butter, lard, or coconut oil.

Suggestive

Linoleic acid and CVD

Higher dietary linoleic acid is associated with lower rates of cardiovascular disease across large prospective cohort studies.[2] The effect is moderate. The data are observational. The people in those cohorts who eat more linoleic acid tend to do many other things differently, exercise more, smoke less, eat more vegetables. Cause and effect are difficult to disentangle.

That's the mainstream case in its strongest form. It's reasonable. We don't dismiss it.

Where it gets harder

Now the contested part.

The first hard fact about the seed oil debate is that two of the largest randomised trials ever conducted on whether replacing saturated fat with linoleic acid actually reduces deaths from heart disease, the Sydney Diet Heart Study (1966–73) and the Minnesota Coronary Experiment (1968–73), produced findings that the original researchers either didn't fully publish or didn't emphasise. The raw data sat in basements. NIH researcher Christopher Ramsden and colleagues recovered it decades later, and reanalysed both trials. They published the findings in the BMJ in 2013 and 2016.[3][4]

Here's what the recovered data showed. Linoleic acid did exactly what mainstream nutrition science predicted on the surrogate: it lowered cholesterol. It did not reduce mortality. In Sydney, the intervention group had higher rates of cardiovascular death and all-cause death than the control group. In Minnesota, every 30 mg/dL drop in cholesterol was actually associated with a 22 percent higher mortality risk in older participants.

Both reanalyses have legitimate methodological concerns: short follow-up, possible trans-fat contamination of the control arm, modest sample sizes. Neither establishes that seed oils cause harm. They also don't align with the confident "PUFAs reduce heart disease deaths" framing that became the public-facing standard.

The second contested piece: linoleic acid in human adipose tissue has more than doubled in the United States since 1959, mirroring the increase in dietary intake.[5] Whether it matters for health is the live debate. Researchers including Ramsden and Joseph Hibbeln, also at NIH, have argued in the American Journal of Clinical Nutrition that this constitutes "a very large uncontrolled experiment."[6] Mainstream nutrition science largely treats the change as biologically inert. Neither side has the evidence to be sure yet.

The third: the ratio of omega-6 to omega-3 fats in your diet. You've probably read that modern diets sit at around 16:1 omega-6 to omega-3, while humans evolved eating closer to 1:1 or 4:1. That part is well-supported.[6]

What's actually debated is whether the ratio itself matters, or whether it's just a roundabout way of saying "you're not eating enough omega-3."

One camp, led by NIH researcher Bill Lands, argues the balance between the two is what counts. Omega-6 and omega-3 fats compete for the same machinery in your body, and that machinery produces signals that turn inflammation up or down. So if omega-6 is dominating, you're tilted toward inflammation regardless of how much omega-3 you're getting in absolute terms.[7]

The other camp says forget the ratio, what matters is simply how much omega-3 is in your tissues (measured as the "omega-3 index"). They point out that in human trials, cutting dietary omega-6 doesn't reliably lower the inflammatory compounds it's supposed to.

Both sides have solid peer-reviewed evidence.

And then there's the funding problem

This is where I, Lizzy, struggle with all food research, generally there is heavy influence from industry. If you haven't read Marion Nestle's book Unsavory Truth, you should.

The American Heart Association's 2017 Presidential Advisory on Dietary Fats, the document most often cited as the definitive case for seed oils, was issued an official correction the following year.[8] The correction disclosed that one of the co-authors had received research support from Unilever, one of the world's largest manufacturers of seed-oil-based spreads. The original advisory had listed the disclosure as "None."

The 2019 Circulation paper on linoleic acid biomarkers and cardiovascular disease, the most-cited recent evidence in favour of seed oils, was conducted under a research consortium whose senior investigator has documented consulting and advisory relationships with Bunge, a major edible-oils company, and Unilever, among others.[2]

A 2017 review in JAMA, by that same senior investigator, noted that NIH spends $1.5 billion a year on nutrition research while the food industry spends more than $60 billion.[9] The funding ecosystem is structurally tilted, and that's a fact acknowledged by the people running it. A 2016 systematic review in JAMA Internal Medicine found that industry-sponsored nutrition studies were more likely to reach conclusions favourable to the sponsor than independently funded studies, although the effect didn't reach statistical significance in the pooled analysis.[10]

What we don't know

Whether typical home use of seed oils, a tablespoon in a stir-fry, a salad dressing, carries any meaningful risk in the context of an otherwise whole-food diet, we don't know. There's no good evidence that it does.

The strongest case against seed oils is about industrial-scale exposure. Deep-fried fast food. Ultra-processed snacks. Restaurant fryer oil that's been heated and reheated for hours. These are the conditions where linoleic acid (the main fat in seed oils) is most likely to break down into compounds that cause real damage in lab studies, particularly a group of toxic by-products called aldehydes (one to know is 4-HNE) and damaged forms of linoleic acid called OXLAMs.[11]

The food chemistry on this is solid. When seed oils get heated to frying temperatures over and over, they reliably produce measurable amounts of these compounds. And in lab conditions, those compounds reliably damage DNA and trigger inflammation.

Whether home cooking produces enough of them to matter clinically is a different question. A pan of olive oil sautéed at moderate heat once and cleaned afterward is not the same exposure as a commercial fryer running soybean oil at 180°C for eight hours. The difference is significant. Most of the strongest contrarian evidence applies to the second scenario, not the first.

Sources

  1. [1]Hooper L, Martin N, Jimoh OF, et al. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Syst Rev. 2020;(8):CD011737. Link
  2. [2]Marklund M, Wu JHY, Imamura F, et al. Biomarkers of dietary omega-6 fatty acids and incident cardiovascular disease and mortality. Circulation. 2019;139(21):2422–2436. Link
  3. [3]Ramsden CE, Zamora D, Leelarthaepin B, et al. Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study. BMJ. 2013;346:e8707. Link
  4. [4]Ramsden CE, Zamora D, Majchrzak-Hong S, et al. Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73). BMJ. 2016;353:i1246. Link
  5. [5]Guyenet SJ, Carlson SE. Increase in adipose tissue linoleic acid of US adults in the last half century. Adv Nutr. 2015;6(6):660–664. Link
  6. [6]Blasbalg TL, Hibbeln JR, Ramsden CE, et al. Changes in consumption of omega-3 and omega-6 fatty acids in the United States during the 20th century. Am J Clin Nutr. 2011;93(5):950–962. Link
  7. [7]Lands B. Consequences of essential fatty acids. Nutrients. 2012;4(9):1338–1357. Link
  8. [8]Correction to: Sacks FM et al. Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association. Circulation. 2017;136(25):e505. Link
  9. [9]Mozaffarian D. Conflict of interest and the role of the food industry in nutrition research. JAMA. 2017;317(17):1755–1756. Link
  10. [10]Chartres N, Fabbri A, Bero LA. Association of industry sponsorship with outcomes of nutrition studies: a systematic review and meta-analysis. JAMA Intern Med. 2016;176(11):1769–1777. Link
  11. [11]Toxic aldehydes in cooking vegetable oils: generation, toxicity and disposal methods. Food Chemistry: X. 2025. Link

Whole foods

The case for whole foods is the strongest we make on this page. It's also the simplest.

Eating mostly whole foods, real food in something close to its natural form, is one of the most well-supported nutrition recommendations in modern science. Vegetables, legumes, whole grains, fish, eggs, meat, nuts, seeds, fruit, herbs, spices, traditional cooking fats. We don't hedge this part.

A 2024 BMJ umbrella review covered 45 distinct meta-analyses spanning 10 million participants and found consistent associations between high ultra-processed food intake and worse cardiometabolic health, more obesity, more cardiovascular disease, more depression, and higher all-cause mortality across 32 outcomes.[1] A 2019 NIH metabolic ward trial gave 20 adults two diets, one ultra-processed and one minimally processed, matched for calories, fat, protein, carbohydrates, sugar, salt, and fibre. Allowed to eat as much as they wanted, participants ate 500 calories more per day on the ultra-processed diet and gained around 2 pounds in two weeks. They lost weight on the unprocessed diet.[2] It's a small study, tightly controlled, and it's the cleanest causal demonstration we have that ultra-processing itself, not just the nutrient profile of ultra-processed foods, drives overconsumption.

The category is not perfectly clean. The most-used definition is the NOVA classification, developed by Brazilian researcher Carlos Monteiro. NOVA category 4 sweeps in everything from sugary drinks and processed snack foods, which are clearly harmful, to packaged sourdough bread, plain yogurt with stabilisers, and infant formula, which aren't obviously harmful. Critics have argued, with peer-reviewed support, that NOVA conflates very different products.[3] The harms attributed to ultra-processed food in epidemiological studies are likely driven mostly by sugary drinks, processed meats, refined snacks, and fast food, not by everything in NOVA category 4 equally.

The app is built to support a mostly-whole-foods approach with reasonable flexibility. The dial exists for users who want more or less guidance. The upper end isn't where the evidence requires you to be.

Sources

  1. [1]Lane MM, Gamage E, Du S, et al. Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. BMJ. 2024;384:e077310. Link
  2. [2]Hall KD, Ayuketah A, Brychta R, et al. Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain. Cell Metab. 2019;30(1):67-77.e3. Link
  3. [3]Astrup A, Monteiro CA. Does the concept of "ultra-processed foods" help inform dietary guidelines, beyond conventional classification systems? Am J Clin Nutr. 2022;116(6):1480–1481. Link

Looking for foods, not findings?

This page is the reasoning. If you just want to know what to eat at your life stage, the food guide turns the well-supported claims into a searchable list of foods and nutrients.

This page reflects our reading of the evidence as of April 2026.

Spotted something out of date? Email hello@phasefood.com