A Bone Broth Recipe Worth Making (And the Glycine Reason Why)

Bone broth is one of those foods that sits at the intersection of the very old and the very new. Cultures around the world have been simmering bones for centuries, and for good reason. What food science has done recently is give us the mechanism: a slow, low simmer does something that no supplement entirely replicates. It releases glycine, proline, and hydroxyproline in a food matrix that your gut recognises and absorbs efficiently. The question of whether bone broth glycine genuinely supports gut health, sleep quality, and cellular repair in humans is a reasonable one, and there is now enough evidence to answer it honestly.

Glycine is the most abundant amino acid in collagen, and collagen is the structural protein that holds your gut lining, skin, tendons, and cartilage together. In a single cup of well-made bone broth, you are likely consuming two to four grams of glycine, depending on the bones and the length of the simmer. That matters because glycine is not just a building block. It is a neurotransmitter, a methyl donor precursor in the one-carbon cycle, and a direct regulator of core body temperature at the onset of sleep.

This post is both a recipe and an explanation. The recipe works on its own. The explanation tells you why it is worth the time.

What glycine actually does in your body

Glycine is classified as a non-essential amino acid, which means your body can synthesise it. The important caveat, which the literature has been quietly raising for the last decade, is that synthesis rates are often insufficient to meet demand, particularly as we age. A 2018 paper in Nutrients by Razak and colleagues estimated that the typical adult is short by around ten grams of glycine per day relative to what the body would ideally use. In your 40s and 50s, when collagen turnover slows and the demands on the gut lining increase alongside perimenopausal hormonal change, that shortfall becomes more relevant.

Glycine works on gut health through a specific pathway. The intestinal epithelial layer, the single-cell-thick barrier that separates your bloodstream from your gut contents, depends heavily on tight junction proteins. Collagen and its constituent amino acids, particularly glycine and proline, support the scaffolding that holds those tight junctions together. A 2025 review published in Digestive Diseases and Sciences by Matar, Abdelnaem, and Camilleri at the Mayo Clinic looked specifically at bone broth’s nutritional components and their effects on intestinal barrier integrity. The authors identified glycine, glutamine, and proline as the key actors, noting their roles in maintaining tight junction function and reducing intestinal permeability (Matar A et al., Dig Dis Sci, 2025. doi:10.1007/s10620-025-08997-x). This is a narrative review, not a clinical trial, but it draws on a solid body of mechanistic and clinical data.

For context on the gut lining’s relevance to perimenopause: oestrogen has a protective effect on intestinal barrier integrity. As levels fall during perimenopause, some women experience increased intestinal permeability, which may contribute to low-grade inflammation and the immune dysregulation that underlies symptoms ranging from joint aches to worsened food sensitivities. Bone broth is not a treatment for any of this. But as a food that regularly provides glycine and proline in a bioavailable form, it supports one of the structural systems under pressure. You will find more on this connection in my post on why fermented foods work differently in your 40s, which covers the broader microbiome-methylation picture.

Glycine and sleep: the mechanism behind the mug before bed

The sleep connection is where glycine becomes genuinely interesting, and the evidence here is more direct. A 2012 paper by Bannai and Kawai in Journal of Pharmacological Sciences reviewed the mechanisms by which oral glycine ingestion improves subjective sleep quality (Bannai M, Kawai N. J Pharmacol Sci. 2012;118(2):145-8. doi:10.1254/jphs.11r04fm). The key finding was this: glycine ingestion before bed significantly reduced core body temperature by increasing peripheral blood flow, particularly to the extremities. The onset of sleep is closely tied to a drop in core temperature, and glycine appears to accelerate that process via glycine receptors in the hypothalamic suprachiasmatic nucleus, the brain’s primary circadian clock.

The same group found improvements in polysomnographic sleep measures including reduced sleep latency (time to fall asleep) and reduced daytime fatigue the following morning. This is human data from controlled studies, not animal models. The doses used were three grams of isolated glycine, which is roughly the amount in a generous mug of well-made bone broth. It is worth being precise here: these studies used purified glycine supplements rather than broth, so extrapolating directly to broth requires a caveat. The amino acid content of broth varies considerably depending on the bones, the simmer time, and the water ratio. But the mechanism is sound, and using broth as a way to take in regular dietary glycine, particularly in the evening, is biologically coherent.

If sleep quality is something you are working on, particularly the 3 a.m. waking pattern that many perimenopausal women describe, a small cup of warm broth about an hour before bed is one of the lower-effort things you can try. It is not a replacement for addressing cortisol patterns, blood sugar stability through the night, or the other factors I cover in the chrononutrition post. But it stacks well alongside those changes.

Glycine as a methyl donor: the one-carbon connection

The third reason glycine matters for biological age is its role in the one-carbon cycle. This is the metabolic pathway that drives DNA methylation, and it is central to what The Cellular Reset is built around. Glycine is not a direct methyl donor in the way that folate and B12 are, but it participates in a closely related pathway via serine and the enzyme serine hydroxymethyltransferase (SHMT). Glycine can be converted to serine, which then enters the folate cycle as a source of methyl groups for the synthesis of SAM (S-adenosylmethionine), the body’s universal methyl donor. It is a supporting role rather than a starring one, but in a system where the whole pathway needs to run smoothly, glycine availability matters.

This is why bone broth fits neatly alongside the leafy greens, legumes, eggs, and liver that characterise a methylation-supportive diet. It is not doing the heavy lifting that folate and B12 do, but it contributes to the broader amino acid pool that the one-carbon cycle draws from. If you are eating for epigenetic age, bone broth earns its place at the table.

A bone broth recipe worth making

The recipe below is what I make regularly. I use a mix of grass-fed beef marrow bones and a chicken carcass left over from a roast, though any combination works. The apple cider vinegar is not a wellness cliche: it lowers the pH of the water slightly, which helps draw minerals including calcium, magnesium, and phosphorus out of the bone matrix and into the broth. Eight hours is a minimum for a meaningful yield of glycine; twelve to twenty-four hours produces a noticeably richer result.

Ingredients

• 1 kg mixed bones (beef marrow, chicken carcass, or a mix)
• 2 tablespoons apple cider vinegar
• 1 onion, halved and charred in a dry pan
• 2 carrots, roughly chopped
• 2 celery sticks, roughly chopped
• 1 whole bulb of garlic, halved across the equator
• A small bunch of fresh thyme and rosemary
• 2 bay leaves
• 1 teaspoon black peppercorns
• Cold water to cover (approximately 2.5 litres)
• Sea salt, added only at the end

Method

Roast the bones in a hot oven (200C) for 30 minutes if using raw beef bones. This step is optional for chicken carcasses but adds depth of flavour. Place everything in a large heavy-based pot or slow cooker, cover with cold water, and add the apple cider vinegar. Bring just to a boil, skim off any grey foam from the surface, then reduce to a very gentle simmer. The broth should barely move. Simmer for a minimum of eight hours, ideally twelve. Add more water if the level drops significantly. Strain through a fine sieve, season lightly with sea salt, and cool. The broth will gel when cold if it has extracted sufficient collagen. That gel is a good sign. Store in the fridge for up to five days, or freeze in portions.

How to use it

Drink a small cup warmed gently in the evening, about an hour before bed. Use it as the base for soups, stews, and the cooking water for grains: a cup of broth-cooked quinoa or brown rice has a meaningfully different amino acid profile to one cooked in plain water. Add a ladle to the pan when you are wilting greens. It is a quiet addition that accumulates.

A note on stress, cortisol, and the sleep-gut connection

The reason bone broth tends to help most when people are also managing stress is straightforward: cortisol is catabolic. Sustained high cortisol breaks down collagen, increases intestinal permeability, and disrupts the same tight junction proteins that glycine helps to maintain. If you are in a period of high stress, the structural support from dietary glycine matters more, not less. I often recommend Ashwagandha KSM-66 alongside a broth-based approach for women managing both sleep disruption and elevated cortisol, given its clinical evidence for HPA axis modulation (Time Health Ashwagandha KSM-66 — affiliate link). But food comes first, and bone broth is the food-first version of the same logic.

The Cellular Reset programme works through this connection systematically, building the dietary and lifestyle framework that supports both the methylation cycle and the structural proteins that hold your gut, skin, and connective tissue together. If you would like to understand the full approach, you can find the programme here. If you would prefer to start with the science, the ebook is a good place to begin.

---

This post is for educational purposes only and does not constitute medical advice. If you have a diagnosed gut condition, are pregnant, or are under medical care, please discuss any dietary changes with your healthcare provider before making them.

---