Energy vs. essential fatty acids: what do scallop larvae (Argopecten purpuratus) need most?

Larvae of the Chilean-Peruvian scallop Argopecten purpuratus were fed a Dunaliella tertiolecta diet (Dun-diet) supplemented with lipid emulsions, rich in 20:5n-3 (EmEPA), 22:6n-3 (EmDHA) or in saturated fatty acids (EmCOCO). A mixed algal diet of Isochrysis galbana (T-iso) and Chaetoceros neogracile served as a positive control (St-diet). Lipid supplementation to the Dun-diet improved the larval growth and increased the percentage of eyed larvae significantly, compared to the non-supplemented Dun-diet because of the extra energy supplied and not because of its fatty acid composition. No significant differences were observed between supplementation with EmEPA, EmDHA or EmCOCO. A mixture of 20% EmEPA+20% EmDHA (40% EmHUFA) was more efficient in raising the total lipid content in larvae than 40% EmCOCO. Both emulsions increased the triacylglycerol content in larvae compared to the non-supplemented Dun-diet. The best result, however, was obtained with the St-diet, probably because of a more suitable 18:2n-6/18:3n-3 ratio and a higher level of arachidonic acid. A positive relationship between the 18:2n-6/18:3n-3 ratio and the larval performance was found. No significant difference was observed in post-settlement larval size or percentage of metamorphosed larvae between the St-diet and the St-diet supplemented with 20% EmHUFA or 20% EmCOCO. The metamorphosed larvae had a constant DHA/EPA ratio of 3.7, independent from the diet, which suggested a metabolic control of the two fatty acids and a species-dependency of the ratio.

Individual fatty acids influence cultured human liver cells differently when compared to plant oils

Most work to date using fatty acids and cultured cells has concentrated on single fatty acids, yet cells in vivo are exposed to fatty acid combinations in the form of triacylglycerols and phosphoglycerides. We have quantitated the influence of the individual fatty acids that make up three plant oils, as well as the plant oils themselves, on the growth of normal and transformed human liver cell lines. The effects of the individual fatty acids were then combined in proportion to their concentration in each plant oil and compared to the effects of the intact oils. The oils initially induced synergistic effects with low concentrations, but with high concentrations competitive effects were shown, when compared to the combined effects of the individual fatty acids.

Botanicals and dietary supplements in diabetic peripheral neuropathy

BACKGROUND

Many persons use botanicals and dietary supplements for chronic conditions that do not respond to traditional Western medications. Tricyclic antidepressants, a common treatment option for diabetic neuropathy, can have many side effects and are a poor choice in certain populations (eg, the elderly). As such, patients might turn to botanicals and dietary supplements, not realizing that these products are not well regulated.

METHODS

This article reviews botanicals and dietary supplements that have been involved in randomized controlled trials (RCTs) for diabetic neuropathy. We searched MEDLINE for English-language literature dating from 1966 to April 2001 using the following subject headings: (1) diabetes and botanical, herb, and supplement, (2) neuropathy and botanical, herb, and supplement, and (3) diabetic neuropathy and botanical, herb, and supplement.

RESULTS

Our search found agents that might improve symptoms of neuropathy (eg, evening primrose oil, alpha-lipoic acid, capsaicin) without affecting glucose control. Botanicals and dietary supplements involved in only one RCT or associated with little clinical benefit were reviewed in brief.

CONCLUSIONS

Evening primrose oil, alpha-lipoic acid, and capsaicin have received the greatest attention for their use in diabetic neuropathy, but further studies are needed to confirm their efficacy. Patients using these products need to be informed of potential drug interactions and side effects.

Maternal and umbilical fatty acid status in relation to maternal diet

The aim of this study was to describe the dietary fat intake during pregnancy and to study the relationship between the intake of polyunsaturated fatty acids (PUFAs) and the fatty acid composition of maternal and umbilical plasma phospholipids (PLs) and cholesterol esters (CEs) at delivery. In addition, the contribution of food groups to the intake of total fat and fatty acids in the diet was quantified.Maternal and umbilical blood samples were collected at delivery from 30 healthy pregnant women. The women completed a food frequency questionnaire during the first and third trimesters. The total fat intake during pregnancy is 85 (SD 24) g/day. The mean intake of saturated fatty acids (SFAs) is 33.4 g/day, of monounsaturated fatty acids (MUFAs) 28.6 g/day and of PUFA 15.2 g/day. Major sources of fat, MUFA and PUFA are fats, oils and sauces. Major sources of SFA are meat and poultry followed by cheese and eggs. Meat and poultry contribute the most to the intake of 20:4n-6 whereas fish is the major source of 20:5n-3 (EPA) and 22:6n-3 (docosahexaenoic acid (DHA)) in the diet. Linoleic acid, EPA and DHA (w%) in PL of maternal plasma are positively related to the intake of these fatty acids during pregnancy. No association is found between the maternal intake of the two parent essential fatty acids (18:2n-6 and 18:3n-3) and their fraction in umbilical PL or CE. EPA and the sum of n-6 fatty acids (w%) in umbilical plasma PL are positively correlated with the dietary intake of these fatty acids.

Constituents in evening primrose oil with radical scavenging, cyclooxygenase, and neutrophil elastase inhibitory activities

Cold-pressed, non-raffinated evening primrose oil was found to contain lipophilic radical scavengers. A highly enriched fraction of these compounds could be obtained from the oil by extraction with aqueous ethanol and subsequent liquid-liquid partitioning with petroleum. LC-DAD-MS analysis revealed that the fraction contained three aromatic compounds with identical UV and ESI-MS spectra. The compounds were isolated by RP-HPLC and their structures established by chemical and spectroscopic means as 3-O-trans-caffeoyl derivatives of betulinic, morolic, and oleanolic acid. The morolic acid derivative was a new compound. The three esters exhibited pronounced radical scavenging activity against the stable 2,2-diphenyl-1-picrylhydrazyl radical and were potent inhibitors of neutrophil elastase and cyclooxygenase-1 and -2 in vitro. Commercial samples of evening primrose oils contained only traces of these lipophilic antioxidants.

The effect of gamma-linolenic acid on plasma and membrane lipids and renal prostaglandin synthesis in older subjects

Senescence is associated with a decreased activity of enzyme delta-6 desaturase, which converts linoleic acid to gamma-linolenic acid. This enzymatic defect may alter the composition of plasma and membrane lipids, and influences the biosynthesis of renal prostaglandins. Exogenous supplementation of GLA during 3 months increases the plasma level of dihomo-gamma-linolenic acid (p < 0.002), and to a smaller degree, the level in erythrocyte membrane lipids. This treatment was associated with a beneficial reduction of cardiovascular risk factors (arterial hypertension, total cholesterol, apolipoprotein B, HDL-cholesterol, apolipoprotein A-I) and the renal function has become stable reached. Epogam treatment also increased the biosynthesis of renal prostaglandins, especially that of prostaglandin E2, which has a vasodilatory effect on vessel walls and reduces the elevated blood pressure.

CONCLUSION

Dietary supplementation of essential fatty acids such as gamma-linolenic acid to old subjects has beneficial effect on their health condition. (Tab. 6, Fig. 5, Ref. 37.)

Effects of diabetes and evening primrose oil treatment on responses of aorta, corpus cavernosum and mesenteric vasculature in rats

Diabetes causes endothelial dysfunction, with deleterious effects on nitric oxide (NO) mediated vasodilatation. However, in many vessels other local vasodilators such as endothelium-derived hyperpolarizing factor (EDHF), prostacyclin, epoxides or endocannabinoids are also important. Several of these factors may be derived from omega-6 essential fatty acids via arachidonate metabolism. Diabetes inhibits this pathway, a defect that may be bypassed by diets enriched with omega-6 gamma-linolenic acid-containing oils such as evening primrose oil (EPO). The aim was to examine the effects of preventive EPO treatment on endothelium-dependent and neurally mediated vasorelaxation. Diabetes was induced by streptozotocin in rats; duration was 8 weeks. Vascular responses were examined in vitro on thoracic aorta, corpus cavernosum and perfused mesenteric bed preparations. Diabetes caused 25% and 35% deficits, respectively, in aorta and corpus cavernosum NO-mediated endothelium-dependent relaxation to acetylcholine that were largely unaffected by EPO treatment. Moreover, a 44% reduction in maximum corpus cavernosum vasorelaxation to nitrergic nerve stimulation was not prevented by EPO. However, for the mesenteric vascular bed, a 29% diminution of responses to acetylcholine, mediated by both NO and EDHF, was 84% attenuated by EPO treatment. When the EDHF component was isolated during NO synthase inhibition, a 76% diabetic deficit was noted. This was completely prevented by EPO treatment, which also caused supernormal EDHF responses in nondiabetic rats. EPO treatment prevented the development of deficits in endothelium-dependent relaxation in diabetic rats. Effects were particularly marked on the resistance vessel EDHF system, which may have potential therapeutic relevance for diabetic microvascular complications.

Maternal dietary intake of essential fatty acids affects adipose tissue growth and leptin mRNA expression in suckling rat pups

We have previously shown that maternal intake of essential fatty acids during late gestation and lactation affects the level of serum leptin in pups. The aim of the present study was to investigate the effect of dietary essential fatty acids on leptin content in the milk of rat dams and leptin expression in white adipose tissue of pups during the suckling period. During late gestation and throughout lactation, rats were fed a control or an essential fatty acid-deficient (EFAD) diet. Milk of the EFAD dams contained more saturated and less polyunsaturated fatty acids compared with the control dams. Milk leptin levels were higher in the EFAD dams than in the control dams at 3 wk of lactation. The weight of inguinal white adipose tissue depots and the serum leptin levels of the EFAD pups were significantly lower than in the control pups during the whole suckling period. In addition, semiquantitative reverse transcriptase-PCR analysis of leptin mRNA levels in inguinal white adipose tissue showed a reduction in the EFAD pups compared with the control pups at 3 wk of age. We conclude that maternal dietary essential fatty acid intake affects serum leptin levels in pups by regulating both the amount of adipose tissue and the leptin mRNA expression.

A double-blind, randomized, placebo-controlled trial of essential fatty acid supplementation in the maintenance of remission of ulcerative colitis

BACKGROUND

Essential fatty acid supplementation has been found to ameliorate certain chronic inflammatory diseases. This effect is thought to be mediated through the modulation of eicosanoid synthesis. Pro-inflammatory eicosanoids have been implicated in ulcerative colitis.

AIM

To investigate the possible therapeutic benefit of essential fatty acids in quiescent ulcerative colitis to reduce the frequency of disease relapse.

METHODS

A randomized, double-blind, placebo-controlled study was performed with a treatment duration of 12 months. Patients with quiescent disease received either trial medication (gamma-linolenic acid, 1.6 g, eicosapentaenoic acid, 270 mg, and docosahexaenoic acid, 45 mg, per day) or placebo (sunflower oil, 500 mg/day). The primary end-point was disease activity, assessed by a previously validated clinical index, sigmoidoscopic appearance and histology.

RESULTS

Sixty-three patients were randomized, 31 to receive essential fatty acid treatment and 32 to receive placebo. Disease relapse rates were similar at 12 months (placebo, 38%; essential fatty acids, 55%), as were changes in sigmoidoscopic grade from baseline.

CONCLUSIONS

The supplementation of the diet with this combination of essential fatty acids does not prolong the period of disease remission of ulcerative colitis.

Essential fatty acids given from conception prevent topographies of motor deficit in a transgenic model of Huntington's disease

Transgenic R6/1 mice incorporate a human genomic fragment containing promoter elements exon 1 and a portion of intron 2 of the Huntingtin gene responsible for Huntington's disease. They develop late-onset neurological deficits in a manner similar to the motor abnormalities of the disorder. As essential fatty acids are phospholipid components of cell membranes which may influence cell death and movement disorder phenotype, R6/1 and normal mice were randomised to receive a mixture of essential fatty acids or placebo on alternate days throughout life. Over mid-adulthood, topographical assessment of behaviour revealed R6/1 transgenics to evidence progressive shortening of stride length, with progressive reductions in locomotion, elements of rearing, sniffing, sifting and chewing, and an increase in grooming. These deficits were either not evident or materially diminished in R6/1 transgenics receiving essential fatty acids. R6/1 transgenics also showed reductions in body weight and in brain dopamine D(1)-like and D(2)-like quantitative receptor autoradiography which were unaltered by essential fatty acids.These findings indicate that early and sustained treatment with essential fatty acids are able to protect against motor deficits in R6/1 transgenic mice expressing exon 1 and a portion of intron 2 of the Huntingtin gene, and suggest that essential fatty acids may have therapeutic potential in Huntington's disease.

Dietary essential fatty acids and brain function: a developmental perspective on mechanisms

Brain development is a complex interactive process in which early disruptive events can have long-lasting effects on later functional adaptation. It is a process that is dependent on the timely orchestration of external and internal inputs through sophisticated intra- and intercellular signalling pathways. Long-chain polyunsaturated fatty acids (LCPUFA), specifically arachidonic acid and docosahexaenoic acid (DHA), accrue rapidly in the grey matter of the brain during development, and brain fatty acid (FA) composition reflects dietary availability. Membrane lipid components can influence signal transduction cascades in various ways, which in the case of LCPUFA include the important regulatory functions mediated by the eicosanoids, and extend to long-term regulation through effects on gene transcription. Our work indicates that FA imbalance as well as specific FA deficiencies can affect development adversely, including the ability to respond to environmental stimulation. For example, although the impaired water-maze performance of mice fed a saturated-fat diet improved in response to early environmental enrichment, the brains of these animals showed less complex patterns of dendritic branching. Dietary n-3 FA deficiency influences specific neurotransmitter systems, particularly the dopamine systems of the frontal cortex. We showed that dietary deficiency of n-3 FA impaired the performance of rats on delayed matching-to-place in the water maze, a task of the type associated with prefrontal dopamine function. We did not, however, find an association over a wider range of brain DHA levels and performance on this task. Some, but not all, studies of human infants suggest that dietary DHA may play a role in cognitive development as well as in some neurodevelopmental disorders; this possibility has important implications for population health.

Nitric oxide as the mediator of the antiosteoporotic actions of estrogen, statins, and essential fatty acids

Estrogen, statins, and essential fatty acids and their metabolites can prevent osteoporosis. However, it is not certain how these three structurally different agents can have the same beneficial action. It is suggested that all three, in addition to their other modes of action in the prevention of osteoporosis, have the ability to augment constitutional (or endothelial) nitric oxide generation, which is known to be beneficial in osteoporosis. If so, it will be interesting to study whether nitric oxide donors and/or nitric oxide precursors can be given together with estrogen, statins, or essential fatty acids to potentiate their benefit in osteoporosis.

Nutritional factors in the pathobiology of human essential hypertension

Endothelial cells produce vasodilator and vasoconstrictor substances. Dietary factors such as sodium, potassium, calcium, magnesium, zinc, selenium, vitamins A, C, and E, and essential fatty acids and their products such as eicosanoids can influence blood pressure, cardio- and cerebrovascular diseases, and concentrations of blood lipids and atherosclerosis. There might be a close interaction between these dietary factors, sympathetic and parasympathetic nervous systems, the metabolism of essential fatty acids, nitric oxide, prostacyclin, and endothelium in human essential hypertension. A deficiency in any one factor, dietary or endogenous, or alterations in their interactions with each other, can lead to endothelial dysfunction and development of hypertension. Therefore, alterations in the metabolism of essential fatty acids might be a predisposing factor to the development of essential hypertension and insulin resistance.

Essential fatty acids in visual and brain development

Essential fatty acids are structural components of all tissues and are indispensable for cell membrane synthesis; the brain, retina and other neural tissues are particularly rich in long-chain polyunsaturated fatty acids (LC-PUFA). These fatty acids serve as specific precursors for eicosanoids, which regulate numerous cell and organ functions. Recent human studies support the essential nature of n-3 fatty acids in addition to the well-established role of n-6 essential fatty acids in humans, particularly in early life. The main findings are that light sensitivity of retinal rod photoreceptors is significantly reduced in newborns with n-3 fatty acid deficiency, and that docosahexaenoic acid (DHA) significantly enhances visual acuity maturation and cognitive functions. DHA is a conditionally essential nutrient for adequate neurodevelopment in humans. Comprehensive clinical studies have shown that dietary supplementation with marine oil or single-cell oil sources of LC-PUFA results in increased blood levels of DHA and arachidonic acid, as well as an associated improvement in visual function in formula-fed infants matching that of human breast-fed infants. The effect is mediated not only by the known effects on membrane biophysical properties, neurotransmitter content, and the corresponding electrophysiological correlates but also by a modulating gene expression of the developing retina and brain. Intracellular fatty acids or their metabolites regulate transcriptional activation of gene expression during adipocyte differentiation and retinal and nervous system development. Regulation of gene expression by LC-PUFA occurs at the transcriptional level and may be mediated by nuclear transcription factors activated by fatty acids. These nuclear receptors are part of the family of steroid hormone receptors. DHA also has significant effects on photoreceptor membranes and neurotransmitters involved in the signal transduction process; rhodopsin activation, rod and cone development, neuronal dendritic connectivity, and functional maturation of the central nervous system.

The effects of treatment with alpha-lipoic acid or evening primrose oil on vascular hemostatic and lipid risk factors, blood flow, and peripheral nerve conduction in the streptozotocin-diabetic rat

Oxidative stress and defective fatty acid metabolism in diabetes may lead to impaired nerve perfusion and contribute to the development of peripheral neuropathy. We studied the effects of 2-week treatments with evening primrose oil (EPO; n = 16) or the antioxidant alpha-lipoic acid (ALA; n = 16) on endoneurial blood flow, nerve conduction parameters, lipids, coagulation, and endothelial factors, in rats with streptozotocin-induced diabetes. Compared with their nondiabetic littermates, untreated diabetic rats had impaired sciatic motor and saphenous sensory nerve-conduction velocity (NCV; P <.001), reduced endoneurial blood flow (P <.001), and increased serum triglycerides (P <.01), cholesterol (P < 0.01), plasma factor VII (P <.0001), and von Willebrand factor (vWF; P <.0001). Plasma fibrinogen and serum high-density lipoprotein concentrations were not significantly different. Treatment with either ALA or EPO effectively corrected the deficits in NCV and endoneurial blood flow. ALA was associated with marked and statistically significant decreases in fibrinogen, factor VII, vWF, and triglycerides (P <.01, paired t tests before v after treatment). In contrast, EPO was associated with significant (P <.05) increases in fibrinogen, factor VII, vWF, triglycerides, and cholesterol and a significant decrease in high-density lipoprotein. Changes in levels of coagulation factors and lipids, qualitatively similar to those found with EPO, were obtained with a diet containing sunflower oil (to control for calorific and lipid content) or with a normal diet alone. Blood glucose and hematocrit levels were not significantly altered by treatments. These data suggest that although both ALA and EPO improve blood flow and nerve function, their actions on vascular factors differ. The marked effects of ALA in lowering lipid and hemostatic risk factors for cardiovascular disease indicate potential antithrombotic and antiatherosclerotic actions that could be of benefit in human diabetes and merit further study.

Dietary gamma-linolenic acid suppresses aortic smooth muscle cell proliferation and modifies atherosclerotic lesions in apolipoprotein E knockout mice

The present study was conducted to evaluate the antiatherogenic effects of dietary gamma-linolenic acid (GLA) (primrose oil) in apolipoprotein E (apoE) genetic knockout mice. Five-wk-old male mice were fed cholesterol-free diets containing 10 g/100 g lipid as corn oil (CO) [control diet, 0 mol/100 mol GLA and (n-3) polyunsaturated fatty acids (PUFA)], primrose oil (PO, 10 mol/100 mol GLA), fish oil-CO mix [FC; 9:1 wt/wt, 0 mol/100 mol GLA and 17 mol/100 mol (n-3) PUFA] or fish oil-PO mix [FP, 1:3 wt/wt, 8 mol/100 mol GLA and 5 mol/100 mol (n-3) PUFA] for 15 wk. Subsequently, diets were supplemented with cholesterol (1.25 g/100 g) and sodium cholate (0.5 g/100 g) and fed for an additional 10 and 16 wk. Plasma cholesterol and triglyceride levels generally did not differ among groups at 20, 30 and 36 wk of age. Mice fed GLA-containing diets (PO and FP) had significantly (P < 0.05) higher liver phospholipid levels of dihomo-gamma-linolenic acid, the elongated product of GLA, relative to CO and FC groups. Consumption of GLA (PO and FP diets) significantly reduced (P < 0.05) aortic vessel wall medial layer thickness at 20 and 30 wk. A parallel GLA-dependent suppression in the number of proliferating (proliferating cell nuclear antigen positive) aortic smooth muscle cells was also observed. Diets containing either GLA or (n-3) PUFA reduced (P < 0.05) atherosclerotic lesion size in 30-wk-old mice. These results indicate that dietary GLA can suppress smooth muscle cell proliferation in vivo and retard the development of diet-induced atherosclerosis in apoE knockout mice.

Fatty acid regulates gene expression and growth of human prostate cancer PC-3 cells

It has been proposed that the omega-6 fatty acids increase the rate of tumor growth. Here we test that hypothesis in the PC-3 human prostate tumor. We found that the essential fatty acids, linoleic acid (LA) and arachidonic acid (AA), and the AA metabolite PGE(2) stimulate tumor growth while oleic acid (OA) and the omega-3 fatty acid, eicosapentaenoic acid (EPA) inhibited growth. In examining the role of AA in growth response, we extended our studies to analyze changes in early gene expression induced by AA. We demonstrate that c-fos expression is increased within minutes of addition in a dose-dependent manner. Moreover, the immediate early gene cox-2 is also increased in the presence of AA in a dose-dependent manner, while the constitutive cox-1 message was not increased. Three hours after exposure to AA, the synthesis of PGE(2) via COX-2 was also increased. Previous studies have demonstrated that AA was primarily delivered by low density lipoprotein (LDL) via its receptor (LDLr). Since it is known that hepatomas, acute myelogenous leukemia and colorectal tumors lack normal cholesterol feedback, we examined the role of the LDLr in growth regulation of the PC-3 prostate cancer cells. Analysis of ldlr mRNA expression and LDLr function demonstrated that human PC-3 prostate cancer cells lack normal feedback regulation. While exogenous LDL caused a significant stimulation of cell growth and PGE(2) synthesis, no change was seen in regulation of the LDLr by LDL. Taken together, these data show that normal cholesterol feedback of ldlr message and protein is lost in prostate cancer. These data suggest that unregulated over-expression of LDLr in tumor cells would permit increased availability of AA, which induces immediate early genes c-fos and cox-2 within minutes of uptake.

Dietary trans fatty acids combined with a marginal essential fatty acid status during the pre- and postnatal periods do not affect growth or brain fatty acids but may alter behavioral development in B6D2F(2) mice

The objective of this study was to investigate whether dietary trans fatty acids (TFA) during the pre- and postnatal periods would exacerbate the effects of marginal essential fatty acid (EFA) status on growth, brain long-chain polyunsaturated fatty acids (LC-PUFA) and behavioral development in B6D2F(2) mice. Pregnant B6D2F(1) females were randomly assigned to one of the following three diets: marginal EFA plus 22% trans 18:1 (mEFA + TFA); marginal EFA (mEFA); and control (CON). The total 18:1 content in all diets was similar. The offspring were weaned and maintained on the same diets. Both the mEFA and mEFA + TFA groups had reduced growth and brain weight compared with CON, but did not differ from one another. As expected, the mEFA and mEFA + TFA groups had reduced docosahexaenoic acid [DHA; 22:6(n-3)]) and increased 22:5(n-6) concentrations in brain phosphatidylcholine (PC) and phosphatidylethanolamine (PE) compared with the CON group, but again did not differ from one another. Reversal learning in the T-water maze was significantly slower in the mEFA + TFA groups compared with the mEFA group and both were slower than the CON group. These findings illustrate that TFA combined with a marginal EFA status do not exacerbate the effects of marginal EFA status on growth or brain LC-PUFA. However, long-term effects of dietary TFA during the pre- and postnatal period on behavioral development and neural function should be investigated in future studies.

Modulation of intestinal vitamin D receptor availability and calcium ATPase activity by essential fatty acids

The physiological mechanisms by which essential fatty acids (EFAs) affect calcium (Ca(2+)) retention is not clear, but suggestions have included changes in membrane fluidity, receptor modulation and induction of second messengers. The vitamin D receptor (VDR) is essential for the functioning of 1,25(OH)(2)D(3)which increases Ca(2+)absorption. Activity of the intestinal basolateral membrane (BLM) Ca(2+)ATPase correlates with the degree of Ca(2+)absorption. Therefore, changes in ATPase activity and VDR availability due to EFAs may influence calcium retention. We have investigated the effect of long-term dietary supplementation with EFAs on Ca(2+)ATPase activity (measured colourimetrically) and VDR availability (measured with the ELISA technique) after the loss of oestrogen induced by ovariectomy (OVX) in female Sprague Dawley rats. Control animals underwent anaesthesia and a surgical procedure but the ovaries were left intact (sham). Ca(2+)ATPase activity was significantly lower in OVX animals than in the intact animals (P<0.05) and following supplementation with EFAs, was significantly higher than in sham controls (P<0.05). A higher number of VDR was measured after OVX and declined due to EFA supplementation; these differences in activity of the ATPase and number of receptors could be ascribed to membrane changes due to EFA supplementation, feedback control by serum calcium or the direct influence of the EFAs.

Can manipulation of the ratios of essential fatty acids slow the rapid rate of postmenopausal bone loss?

The rapid rate of postmenopausal bone loss is mediated by the inflammatory cytokines interleukin-1, interleukin-6, and tumor necrosis factor alpha. Dietary supplementation with fish oil, flaxseeds, and flaxseed oil in animals and healthy humans significantly reduces cytokine production while concomitantly increasing calcium absorption, bone calcium, and bone density. Possibilities may exist for the therapeutic use of the omega-3 fatty acids, as supplements or in the diet, to blunt the increase of the inflammatory bone resorbing cytokines produced in the early postmenopausal years, in order to slow the rapid rate of postmenopausal bone loss. Evidence also points to the possible benefit of gamma-linolenic acid in preserving bone density.

Lack of effect of supplementation with essential fatty acids on bone mineral density in healthy pre- and postmenopausal women: two randomized controlled trials of Efacal v. calcium alone

Randomized controlled trials of the effects of the dietary supplement Efacal (Scotia Pharmaceuticals Plc, Guildford, Surrey, UK) v. Ca only on total body bone mineral density (BMD) and markers of bone turnover were conducted in healthy pre- and postmenopausal women separately. Total daily dose for 12 months for the Efacal groups was: Ca 1.0 g, evening primrose oil 4.0 g and marine fish oil 440 mg; and for the control groups was: Ca 1.0 g. Reported compliance was better than 90% in both age groups. For the forty-three premenopausal women (age range 25-40 years), initial mean total body BMD values were similar for Efacal and control groups and both groups showed highly significant mean increases of about 1%; however, there were no significant between-group differences for the changes in BMD or markers of bone turnover. For the forty-two postmenopausal women (age range 50-65 years), initial mean total body BMD values were again well-matched across treatment groups. Both Efacal and control groups showed highly significant decreases in total body BMD of about 1%, but again there were no significant between-group differences in total body BMD or markers of bone turnover. Possible confounding variables such as initial total body BMD were explored but had no effect on the outcome in either age group. Nail quality improved in both age groups and in both Efacal and control groups. Again, there was no significant difference between treatment groups. No evidence was found to support a beneficial effect of Efacal on BMD in these women.