Lipids & Fats
Fats and lipids are often written about as if they are one and the same substance. This is not so although they are closely related. A little more digging reveals the reality. Lipids are a wide-ranging class of large biological molecules with no affinity to water which means that they do not mix with water at all and form separate layers in a settled solution. Fats are just one of many substances that belong to this class of molecules.
The chemistry of fats and lipids is so complex that I’m not even going to try to unravel it. We shall keep things simple. Fats, fat soluble vitamins (A, D, K & E), waxes, oils, phospholipids, steroids, and some pigments are all members of the lipid group. Fats often receive bad press in human health because they are related to cardiovascular disease but they are really important as fuel storage depots to provide energy when the body needs it most. The main role of fat then is energy storage, but in larger animals, fat also cushions vital organs like kidneys.
Nutritional Needs
Regarding honey bee nutrition, the most important lipids are fats, phospholipids and steroids. Insects cannot store fat to any great extent and so honey bees need to get it from a continuous supply of pollen. Nurse bees need protein and lipids for hypopharyngeal gland development. Brood food is manufactured in these glands and the pollen comes from stored and fermented supplies known commonly as bee bread. Older bees need a diet that supplies energy which comes mostly from carbohydrates in nectar and honey. However, they do also need proteins and lipids for body maintenance but they find them in fresh rather than stored pollen.
Phospholipids are very important in cell biology and structure and they form a protective barrier between the outer cell wall and its immediate environment. Steroids are a key group of lipids which include cholesterol and hormones that are essential for regulating body function. Cholesterol forms part of the cell membrane and is the steroid from which other important steroids are made and is therefore is essential in animal bodies.
Crude Protein
Many people are familiar with the pioneering work done in Australia by Dr. Doug Somerville1 on crude protein levels for different honey bee forage plants. We learned a lot about how many forage plants don’t provide enough crude protein to maintain good honey bee health. Protein in the pollen from sunflower crops, for example, falls short of requirements, and bee growth is reduced when pollen intake is limited. See an example here of plants and their protein contents: https://www.beelistener.co.uk/bee-health/plants-pollen-and-bees-the-early-days/
We learned a lot more about honey bee diets from Somerville’s important work and many people made changes where they could to honey bee forage. Beekeepers and landowners gave a lot more thought and attention to planting for bees to provide more valuable pollen sources. Many beekeepers began regularly supplying pollen supplements and bee feed manufacturers have incorporated pollen into some bee fondants over the last ten years.
Supplements
But over very recent years, honey bee overwintering losses have been very high in many countries across the world. In the U.S., winter losses 2024-2025 reached as high as c. 60% for some commercial beekeepers. While viruses, varroa, and other diseases have been implicated, it is reasonable to assume that nutrition probably plays a key role in contributing to these devastating losses.
All beekeepers want to do their best for their bees so most commercial beekeepers and many hobbyists continue to supply pollen patties. But now the question arises, are these pollen patties meeting the needs of the honey bee at all stages of development and life?
Scientists like Juliana Rangel have been studying honey bee nutrition for a number of years. She acknowledges that we know what constitutes the basics of good nutrition, but that poor nutrition remains poorly defined and a lot more work needs to be done to find out what a bad diet really looks like. She notes that honey bee nutritional needs vary as the bee ages and goes through all the stages of work inside the hive (age polyethism). The changes in dietary requirements are subtle and nutrition is a highly complex topic. But the good news is that Lau et al. (2025)2 have made an interesting discovery through experimental feeding of bees using the Nutritional Geometry Framework and food containing different ratios of proteins to lipids. During the experiment, the nurse bees (involved with feeding brood) that ate the most food out of any of the feeding groups were the ones that had been presented with a 30% protein to 20% lipid ratio (1.5 : 1). This group also had the largest hypopharyngeal glands. This appears to be the optimum protein/lipid ratio and bees stop feeding as soon as either the protein or lipid has been reached.
Rangel says that if she were to design a pollen substitute, she would ensure that it had enough omega-3 fatty acids because low levels impair a honey bee’s ability to learn and she would want to support its mental health too. There would be some, but not too many, omega-6 fatty acids and a wide variety of sterols. She would also ensure that the protein to lipid ratio was what bees prefer.
Even better news for us today, a Belgian company called APIX Sciences has designed pollen substitutes which will be on the shelves soon https://focusonbelgium.be/en/business/flemish-agrotech-company-offers-hope-honeybees-difficult-times . This is the first nutritionally complete diet on which colonies have thrived for months without access to fresh pollen (McAfee3)
References:
1 Somerville, D. (2005) Fat Bees Skinny Bees— a manual on honey bee nutrition for beekeepers, Rural Industries Research and Development Corporation.
You can download a copy here: https://agrifutures.com.au/product/fat-bees-skinny-bees-a-manual-on-honey-bee-nutrition-for-beekeepers/
2 Lau, P., et al. (2025) Do not compromise: nurse honeybees practice strict protein-lipid regulation, iScience.28 (7): 112895.
3 McAfee, A., (2026) Your Bees Are on a Diet, American Bee Journal, January 2026, p79.
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This article has given a rich seam of interest for research, so thanks again Ann .
Ive just dived down a rabbit hole (again) into nutrition and the difference between Spring and Autumn supplemental feeding. Interestingly, the difference between the two types, feeding Spring bees as opposed to developing Diutinus bees is quite marked, and, as a result I will modifying my feeding regime to take account of this. I never really considred before the issue if a dearth of pollen for the bees raising the Diutinus cohort.
I’m in Bromley, Kent and (especially last year) there was nothing for the bees after July, as it was so dry.
Traditionally we’ve never fed our bees pollen substitute, but (though I feel its not a particularly sustainable practice) I feel climate change related environmental stressors may make me rethink my tactics…
Best regards ,
Frazer
Hello, Frazer. Thank you for reading the post and commenting. I never routinely feed bees either, pollen or sugar. I’m always prepared to feed sugar syrup in an emergency though. One thing to caution is feeding pollen at the end of summer since discovering that dwindling pollen stimulates winter bee production, Mattila, H.R., Otis, G.W., 2007. Dwindling Pollen Resources Trigger the Transition to Broodless Populations of Long-lived Honey Bees Each Autumn. Ecological Entomology 32:496-505.
Best wishes, Ann.
Ann, what a great article. I really liked the reference to the paper by Lau, which gives a deep dive into the cutting edge of bee nutrition today. Some really exciting advances in pollen substitutes on the way, which should be beneficial in many situations where nutrition is poor for various reasons.
In that paper they used the “choice”, type of experiment, offering the nurse bees a choice of different ratios of protein to lipids. I find this problematic for a couple of reasons. First, if given a choice of diet, choosing one over the other does not necessarily mean it is the best nutritionally, for the bee’s requirements. There could be attractants that make the bees favor one over another diet. The second is these nurse bees were offered the choices without any brood present and I wonder if brood would factor into the nurse bees choices? Having said that, the work is fascinating and I believe these researchers know what they are doing with these types of experiments.
I enjoy reading your articles on the weekend, they provide some great stimulating thoughts whilst still in the depths of a cold Canadian winter, brrr.
Hello, Kevin. Thank you for reading the blog post and commenting. I see what you mean about lab studies compared with field studies. Maybe someone will compare this in the field with some of the new supplements v the old ones lacking proteins and lipids in ‘correct’ proportions. Good advances in nutrition though which probably would have taken longer if there hadn’t been such massive colony losses. I hope your winter is over soon. Best wishes, Ann.